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Wu H, Ying H, Zhao W, Sun Y, Wang Y, Chen X, Li G, Yao Y, Xu S, Li T, Fang L, Sun X, Wang N, Xu J, Guan Q, Xia W, Wang L, Gao L, Zhao J, Xu C. Characterization of Novel PHEX Variants in X-linked Hypophosphatemic Rickets and Genotype-PHEX Activity Correlation. J Clin Endocrinol Metab 2024; 109:2242-2255. [PMID: 38442738 PMCID: PMC11318995 DOI: 10.1210/clinem/dgae120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/12/2023] [Accepted: 03/05/2024] [Indexed: 03/07/2024]
Abstract
BACKGROUND X-linked hypophosphatemia (XLHR) is the most common genetic form of hypophosphatemic rickets (HR), which is caused by phosphate regulating endopeptidase homolog X-linked (PHEX) gene mutation. At present, the genotype-phenotype relationship of XLHR and the pathogenic role of PHEX are not fully understood. METHODS In this study, we summarized clinical features in a new cohort of 49 HR patients and detected 16 novel PHEX and 5 novel non-PHEX variants. Subsequently, we studied the pathogenesis of new variants by protein expression, glycosylation analysis, subcellular localization, and endopeptidase activity. RESULTS The results showed that missense variants (Q189H and X750R) slightly reduced protein expression without obviously altering protein length and localization, whereas truncating variants significantly impaired the synthesis of PHEX and produced a shorter immature protein in cells. Interestingly, no evident correlation was observed between mutation types and clinical phenotypes. However, when we analyzed the relationship between PHEX activity and serum phosphorus level, we found that patients with low PHEX activity tended to have severe hypophosphatemia and high rickets severity score. Following this observation, we established 2 new knock-in XLHR mouse models with 2 novel Phex variants (c.T1349C and c.C426G, respectively) using CRISPR/Cas9 technology. Both mouse models demonstrated clinical manifestations of XLHR seen in patients, and PhexC426G mice showed more severe phenotype than PhexT1349C mice, which further confirmed the rationality of genotype-PHEX enzymatic activity correlation analysis. CONCLUSION Therefore, our findings demonstrated that novel PHEX variants could disrupt protein function via affecting protein synthesis, post-translational modification, cellular trafficking, and catalytic activity. Our study facilitates a better understanding of XLHR pathogenic mechanism and PHEX activity-phenotype correlation, which is of crucial importance for future diagnosis and treatment of XLHR.
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Affiliation(s)
- Huixiao Wu
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Hui Ying
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Wanyi Zhao
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Yan Sun
- Department of Pediatric, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
| | - Yanzhou Wang
- Department of Pediatric Orthopedics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
| | - Xinyu Chen
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Guimei Li
- Department of Pediatric, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
| | - Yangyang Yao
- Department of Pediatric Orthopedics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
| | - Shuo Xu
- Department of Medical Imaging, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
| | - Tianyou Li
- Department of Pediatric Orthopedics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
| | - Li Fang
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Xiaoqing Sun
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Ning Wang
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Jin Xu
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Qingbo Guan
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Weibo Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
| | - Li Wang
- Independent Researcher, Tucson, AZ 85705, USA
| | - Ling Gao
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Jiajun Zhao
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
| | - Chao Xu
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, Shandong, China
- Department of Endocrinology and Metabolism, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong, China
- Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, Shandong, China
- Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan 250021, Shandong, China
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Pan F, Zhang R, Liu X, Shi X, Xin Q, Qiao D, Li C, Zhang Y, Chen M, Guo W, Luan S, Shao L. Three exonic variants in the PHEX gene cause aberrant splicing in a minigene assay. Front Genet 2024; 15:1353674. [PMID: 38841723 PMCID: PMC11150636 DOI: 10.3389/fgene.2024.1353674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 04/24/2024] [Indexed: 06/07/2024] Open
Abstract
Background: X-linked hypophosphatemia (XLH, OMIM 307800) is a rare phosphorus metabolism disorder caused by PHEX gene variants. Many variants simply classified as missense or nonsense variants were only analyzed at the DNA level. However, growing evidence indicates that some of these variants may alter pre-mRNA splicing, causing diseases. Therefore, this study aimed to use bioinformatics tools and a minigene assay to ascertain the effects of PHEX variations on pre-mRNA splicing. Methods: We analyzed 174 variants in the PHEX gene described as missense or nonsense variants. Finally, we selected eight candidate variants using bioinformatics tools to evaluate their effects on pre-mRNA splicing using a minigene assay system. The complementary DNA (cDNA) sequence for the PHEX gene (RefSeq NM_000444.6) serves as the basis for DNA variant numbering. Results: Of the eight candidate variants, three were found to cause abnormal splicing. Variants c.617T>G p.(Leu206Trp) and c.621T>A p.(Tyr207*) in exon 5 altered the splicing of pre-mRNA, owing to the activation of a cryptic splice site in exon 5, which produced an aberrant transcript lacking a part of exon 5, whereas variant c.1700G>C p.(Arg567Pro) in exon 16 led to the activation of a cryptic splice site in intron 16, resulting in a partial inclusion of intron 16. Conclusion: Our study employed a minigene system, which has a great degree of flexibility to assess abnormal splicing patterns under the circumstances of patient mRNA samples that are not available, to explore the impact of the exonic variants on pre-mRNA splicing. Based on the aforementioned experimental findings, we demonstrated the importance of analyzing exonic variants at the mRNA level.
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Affiliation(s)
- Fengjiao Pan
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Ruixiao Zhang
- Department of Emergency, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Xuyan Liu
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Xiaomeng Shi
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Qing Xin
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Chongqing Clinical Research Center of Kidney and Urology Diseases, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Dan Qiao
- Department of Nephrology, Dalian Medical University, Dalian, China
| | - Changying Li
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Yan Zhang
- Department of Nephrology, Weifang Medical University, Weifang, China
| | - Mengke Chen
- Department of Nephrology, Liaocheng Third People’s Hospital, Liaocheng, China
| | - Wencong Guo
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, China
| | - Shufang Luan
- Department of Medical Insurance Administration, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Leping Shao
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
- Department of Nephrology, The First Affiliated Hospital of Xiamen University, Xiamen, China
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3
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Jacob P, Bhavani GS, Udupa P, Wang Z, Hariharan SV, Delampady K, Dalal A, Kamath N, Ikegawa S, Shenoy RD, Handattu K, Shah H, Girisha KM. Exome Sequencing in Monogenic Forms of Rickets. Indian J Pediatr 2023; 90:1182-1190. [PMID: 36692815 PMCID: PMC10627992 DOI: 10.1007/s12098-022-04393-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 09/27/2022] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To understand the phenotypic and genotypic spectrum of genetic forms of rickets in 10 families. METHODS Detailed clinical, radiographic, and biochemical evaluation of 10 families with phenotypes suggestive of a genetic cause of rickets was performed. Molecular testing using exome sequencing aided in the diagnosis of six different forms of known genetic causes. RESULTS Eleven disease-causing variants including five previously reported variants (CYP27B1:c.1319_1325dup, p.(Phe443Profs*24), VDR:c.1171C>T, p.(Arg391Cys), PHEX: c.1586_1586+1del, PHEX: c.1482+5G>C, PHEX: c.58C>T, p.(Arg20*)) and six novel variants (CYP27B1:c.974C>T, p.(Thr325Met), CYP27B1: c.1376G>A, p.(Arg459His), CYP2R1: c.595C>T, p.(Arg199*), CYP2R1:c.1330G>C, p.(Gly444Arg),SLC34A3:c.1336-11_1336-1del, SLC2A2: c.589G>C, p.(Val197Leu)) in the genes known to cause monogenic rickets were identified. CONCLUSION The authors hereby report a case series of individuals from India with a molecular diagnosis of rickets and provide the literature review which would help in enhancing the clinical and molecular profile for rapid and differential diagnosis of rickets.
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Affiliation(s)
- Prince Jacob
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Gandham SriLakshmi Bhavani
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Prajna Udupa
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Zheng Wang
- Laboratory for Bone and Joint Diseases, RIKEN Center for Integrative Medical Sciences, Tokyo, Japan
| | - Sankar V Hariharan
- Department of Pediatrics, Genetics Clinic, SAT Hospital, Government Medical College, Thiruvananthapuram, Kerala, India
| | - Kishan Delampady
- Department of Endocrinology, AJ Hospital & Research Center, Mangalore, Karnataka, India
| | - Ashwin Dalal
- Diagnostics Division, Center for DNA Fingerprinting & Diagnostics, Hyderabad, Telangana, India
| | - Nutan Kamath
- Department of Pediatrics, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Shiro Ikegawa
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
- Laboratory for Bone and Joint Diseases, RIKEN Center for Integrative Medical Sciences, Tokyo, Japan
| | - Rathika D Shenoy
- Department of Pediatrics, K S Hegde Medical Academy, Nitte University, Mangalore, Karnataka, India
| | - Koushik Handattu
- Department of Pediatrics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Hitesh Shah
- Department of Pediatric Orthopedics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India.
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Boros E, Ertl DA, Berkenou J, Audrain C, Lecoq AL, Kamenicky P, Briot K, Amouroux C, Zhukouskaya V, Gueorguieva I, Mignot B, Girerd B, Porquet Bordes V, Salles JP, Edouard T, Coutant R, Bacchetta J, Linglart A, Rothenbuhler A. Adult height improved over decades in patients with X-linked hypophosphatemia: a cohort study. Eur J Endocrinol 2023; 189:469-475. [PMID: 37831782 DOI: 10.1093/ejendo/lvad144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/28/2023] [Accepted: 09/07/2023] [Indexed: 10/15/2023]
Abstract
OBJECTIVES The aim of this study is to analyze height after cessation of growth (final height [FH]) and its evolution over the last decades in X-linked hypophosphatemia (XLH) patients in France, as the data on natural history of FH in XLH are lacking. DESIGN We performed a retrospective observational study in a large cohort of French XLH patients with available data on FH measurements. MATERIALS AND METHODS We divided patients into 3 groups according to their birth year: group 1 born between 1950 and 1974, group 2 born between 1975 and 2000, and group 3 born between 2001 and 2006, respectively, and compared their FHs. RESULTS A total of 398 patients were included. Mean FHs were the following: for group 1, -2.31 ± 1.11 standard deviation score (SDS) (n = 127), 156.3 ± 9.7 cm in men and 148.6 ± 6.5 cm in women; for group 2, -1.63 ± 1.13 SDS (n = 193), 161.6 ± 8.5 cm in men and 153.1 ± 7.2 cm in women; and for group 3, -1.34 ± 0.87 SDS (n = 78), 165.1 ± 5.5 cm in men and 154.7 ± 6 cm in women. We report a significant increase in mean FH SDS over 3 generations of patients, for both men and women (P < .001). Final height SDS in male (-2.08 ± 1.18) was lower than in female (-1.70 ± 1.12) (P = .002). CONCLUSION The FH of XLH patients in France increased significantly over the last decades. Even though men's FHs improved more than women's, men with XLH remain shorter reflecting a more severe disease phenotype. While the results are promising, most patients with XLH remain short leaving room for improvement.
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Affiliation(s)
- Emese Boros
- Pediatric Endocrinology Unit, Hôpital Universitaire de Bruxelles (HUB), Hôpital Universitaire des Enfants Reine Fabiola (HUDERF), Université Libre de Bruxelles, Brussels 1020, Belgium
| | - Diana-Alexandra Ertl
- AP-HP, Department of Endocrinology and Diabetes for Children, Department of Adolescent Medicine, Bicetre Paris-Saclay University Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
- AP-HP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filiere OSCAR and Platform of Expertise for Rare Diseases Paris-Saclay, Bicetre Paris-Saclay Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
| | - Jugurtha Berkenou
- AP-HP, Department of Endocrinology and Diabetes for Children, Department of Adolescent Medicine, Bicetre Paris-Saclay University Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
- AP-HP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filiere OSCAR and Platform of Expertise for Rare Diseases Paris-Saclay, Bicetre Paris-Saclay Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
| | - Christelle Audrain
- AP-HP, Department of Endocrinology and Diabetes for Children, Department of Adolescent Medicine, Bicetre Paris-Saclay University Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
- AP-HP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filiere OSCAR and Platform of Expertise for Rare Diseases Paris-Saclay, Bicetre Paris-Saclay Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
| | - Anne Lise Lecoq
- AP-HP, Centre de Recherche Clinique Paris Saclay, Hôpital Bicêtre, Le Kremlin-Bicêtre 94270, France
- Assistance Publique-Hôpitaux de Paris (AP-HP), Hôpital de Bicêtre, Service d'Endocrinologie et des Maladies de la Reproduction, Centre de Référence des Maladies Rares du Métabolisme du Calcium et du Phosphate, Filière OSCAR, 78 rue du Général Leclerc, Le Kremlin-Bicêtre 94270, France
| | - Peter Kamenicky
- Assistance Publique-Hôpitaux de Paris (AP-HP), Hôpital de Bicêtre, Service d'Endocrinologie et des Maladies de la Reproduction, Centre de Référence des Maladies Rares du Métabolisme du Calcium et du Phosphate, Filière OSCAR, 78 rue du Général Leclerc, Le Kremlin-Bicêtre 94270, France
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, Le Kremlin-Bicêtre 94276, France
| | - Karine Briot
- Rheumatology Department, Université Paris-Cité, Cochin Hospital, Paris 75014, France
| | - Cyril Amouroux
- Service de Néphrologie et Endocrinologie Pédiatriques, CHU de Montpellier, Montpellier 34090, France
- Faculté de Médecine, Université de Montpellier, Montpellier 34090, France
- Centres Maladies Rares Métabolisme du Calcium et du Phosphore et Maladies Osseuses Constitutionnelles, Filière de Santé Maladies Rares OSCAR, 34090 Montpellier, France
| | - Volha Zhukouskaya
- AP-HP, Department of Endocrinology, Hôpital Cochin, Paris 75014, France
- Institut des Maladies Musculo-squelettiques, Laboratory Orofacial Pathologies, Imaging and Biotherapies URP2496 and FHU-DDS-Net, Dental School, and Plateforme d'Imagerie du Vivant (PIV), Université Paris Cité, Montrouge 92129, France
- Centre de Référence des Maladies Rares du Métabolisme du Calcium et du Phosphate, Plateforme d'Expertise Maladies Rares Paris Saclay, Filière OSCAR, EndoRare and BOND ERN, Hôpital de Bicêtre, Le Kremlin-Bicêtre 94270, France
| | - Iva Gueorguieva
- Pediatric Endocrine Unit, CHU Lille, Université Lille, Lille 59800, France
| | - Brigitte Mignot
- Service de Médecine Pédiatrique, CHRU J Minjoz, 3 Boulevard Fleming, Besançon 25030, France
| | - Barbara Girerd
- AP-HP, Department of Endocrinology and Diabetes for Children, Department of Adolescent Medicine, Bicetre Paris-Saclay University Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
- AP-HP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filiere OSCAR and Platform of Expertise for Rare Diseases Paris-Saclay, Bicetre Paris-Saclay Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
| | - Valerie Porquet Bordes
- Endocrine, Bone Diseases and Genetics Unit, Reference Centre for Rare Diseases of Calcium and Phosphate Metabolism, Competence Centre for Bone Diseases, ERN BOND, OSCAR Network, Children's Hospital, Toulouse University Hospital, Toulouse 31059, France
| | - Jean Pierre Salles
- Unité d'Endocrinologie, Maladies Osseuses, Hôpital des Enfants, Centre de Référence des Maladies Rares du Calcium et du Phosphate, ENR BOND, Hôpital des Enfants, CHU de Toulouse, TSA 70034, Toulouse 31059, France
- INFINITY CENTER, INSERM CNRS UMR 1291, Université de Toulouse, Paul Sabatier Toulouse III, Hôpital Purpan, Toulouse 31024, France
| | - Thomas Edouard
- Endocrine, Bone Diseases and Genetics Unit, Toulouse University Hospital, Toulouse 31059, France
| | - Régis Coutant
- Unité d' Endocrinologie Diabetologie Pédiatrique and Centre des Maladies Rares de la Réceptivité Hormonale, CHU-Angers, Angers 49055, France
| | - Justine Bacchetta
- Centre de Référence des Maladies Rénales Rares, Centre de Référence des Maladies Rares du Calcium et du Phosphore, Filières Santé Maladies Rares OSCAR et ORKID, Filières Santé ERKNet et BOND, INSERM1033, Université de Lyon, Lyon 69372, France
| | - Agnès Linglart
- AP-HP, Department of Endocrinology and Diabetes for Children, Department of Adolescent Medicine, Bicetre Paris-Saclay University Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
- AP-HP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filiere OSCAR and Platform of Expertise for Rare Diseases Paris-Saclay, Bicetre Paris-Saclay Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, Le Kremlin-Bicêtre 94276, France
| | - Anya Rothenbuhler
- AP-HP, Department of Endocrinology and Diabetes for Children, Department of Adolescent Medicine, Bicetre Paris-Saclay University Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
- AP-HP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filiere OSCAR and Platform of Expertise for Rare Diseases Paris-Saclay, Bicetre Paris-Saclay Hospital, 78 Rue du General Leclerc, Le Kremlin-Bicêtre 94270, France
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5
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Borghi M, da Silva LM, Bispo L, Longui CA. A genetic study of a Brazilian cohort of patients with X-linked hypophosphatemia reveals no correlation between genotype and phenotype. Front Pediatr 2023; 11:1215952. [PMID: 37794959 PMCID: PMC10546205 DOI: 10.3389/fped.2023.1215952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 09/04/2023] [Indexed: 10/06/2023] Open
Abstract
Aim X-linked hypophosphatemia (XLH) is the most common inherited form of rickets, and it is caused by pathogenic inactivating variants of the phosphate-regulating endopeptidase homolog X-linked (PHEX) gene. The main purpose of this study is to identify the presence of a genotype-phenotype correlation in a cohort of XLH patients. Methods This is a retrospective study including patients diagnosed with hypophosphatemic rickets, confirmed by clinical, radiological, and laboratory findings. Medical records were reviewed for phenotypic analyses. Genomic DNA was extracted from the peripheral blood lymphocytes, and PHEX sequencing was performed by exomic NGS sequencing. The Wilcoxon rank-sum test and the two-tailed Fisher's exact test were employed for the statistical analyses of this study. Results A total of 41 patients were included in this study, and 63.41% (26/41) of the patients were female. The mutation analyses identified 29.27% missense variants and 29.72% nonsense variants, most of them were considered deleterious (66.41%). Six novel deleterious variants in the PHEX gene were detected in seven patients. The median concentrations of pretreatment serum calcium, phosphorus, and parathyroid hormone (PTH) were not significantly different among patients with different genotypes. An orthopedic surgery due to bone deformity was required in 57.69%. Conclusions Our analysis did not identify any specific genotype as a predictor. No significant genotype-phenotype correlation was found, suggesting that the recognition of subjacent pathogenic mutation in the PHEX gene may have limited prognostic value. Despite this finding, genetic testing may be useful for identifying affected individuals early and providing appropriate treatment.
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Affiliation(s)
- Mauro Borghi
- School of Medical Sciences Santa Casa SP and Pediatric Endocrinology Unit, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil
- Hospital São Luiz—Rede D´Or—CMA, Departament of Anesthesiology, São Paulo, Brazil
| | | | - Luciana Bispo
- Laboratório Mendelics, Department of Genetic, São Paulo, Brazil
| | - Carlos A. Longui
- School of Medical Sciences Santa Casa SP and Pediatric Endocrinology Unit, Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil
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6
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Nabeshima Y, Sato T, Zukeran H, Komatsu R, Nakano S, Ichihashi Y, Tominaga T, Miwa M, Amano N, Ishii T, Hasegawa T. Fibroblast growth factor 23 levels in cord and peripheral blood during early neonatal period as possible predictors of affected offspring of X-linked hypophosphatemic rickets: report of three female cases from two pedigrees. J Pediatr Endocrinol Metab 2023; 36:786-790. [PMID: 37342899 DOI: 10.1515/jpem-2023-0120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 05/29/2023] [Indexed: 06/23/2023]
Abstract
OBJECTIVES The role of serum fibroblast growth factor 23 (FGF23) level in early neonatal period on the diagnosis of X-linked hypophosphatemic rickets (XLH) remains unclear. CASE PRESENTATION Two female patients from the first pedigree had an affected mother, and the other female from the second pedigree had an affected father. In all three cases, FGF23 levels were high in cord blood and peripheral blood at day 4-5. Additionally, the FGF23 levels considerably increased from birth to day 4-5. We identified a PHEX pathogenic variant and initiated treatment during infancy in each case. CONCLUSIONS In neonates with a parent diagnosed as PHEX-associated XLH, FGF23 in cord blood and peripheral blood at day 4-5 may be useful markers for predicting the presence of XLH.
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Affiliation(s)
- Yukiyo Nabeshima
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
- Department of Pediatrics, Tokyo Metropolitan Hospital Otsuka, Tokyo, Japan
| | - Takeshi Sato
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Hiroaki Zukeran
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Rieko Komatsu
- Department of Pediatrics, Saitama City Hospital, Saitama, Japan
| | - Satsuki Nakano
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Yosuke Ichihashi
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | | | - Masayuki Miwa
- Department of Pediatrics, Saitama City Hospital, Saitama, Japan
| | - Naoko Amano
- Department of Pediatrics, Saitama City Hospital, Saitama, Japan
| | - Tomohiro Ishii
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Tomonobu Hasegawa
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
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Terracciano A, De Bernardi ML, Novizio R, De Brasi D, Iolascon A, Della Monica M, Scavuzzo F, Serino D, Novelli A, Piscopo C. A New de novo Mosaic Mutation of PHEX Gene: A Case Report of a Boy with Hypophosphatemic Rickets. Endocr Metab Immune Disord Drug Targets 2023; 23:1235-1239. [PMID: 36847234 PMCID: PMC10518859 DOI: 10.2174/1871530323666230227142202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 12/28/2022] [Accepted: 01/03/2023] [Indexed: 03/01/2023]
Abstract
BACKGROUND X-linked hypophosphatemia is the most prevalent form of heritable rickets, characterized by an X-linked dominant inheritance pattern. The genetic basis of X-linked hypophosphatemia is a loss-of-function mutation in the PHEX gene (Phosphate regulating gene with Homology to Endopeptidases on the X chromosome), which leads to an enhanced production of phosphaturic hormone FGF23. X-linked hypophosphatemia causes rickets in children and osteomalacia in adults. Clinical manifestations are numerous and variable, including slowdown in growth, swing-through gait and progressive tibial bowing, related to skeletal and extraskeletal actions of FGF23. PHEX gene spans over 220 kb and consists of 22 exons. To date, hereditary and sporadic mutations are known (missense, nonsense, deletions and splice site mutations). CASE PRESENTATION Herein, we describe a male patient carrying a novel de novo mosaic nonsense mutation c.2176G>T (p.Glu726Ter) located in exon 22 of PHEX gene. CONCLUSION We highlight this new mutation among possible causative of X-linked hypophosphatemia and suggest that mosaicism of PHEX mutations is not so uncommon and should be excluded in diagnostic workflow of heritable rickets both in male and female patients.
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Affiliation(s)
- Alessandra Terracciano
- Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | | | | | | | - Achille Iolascon
- Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy
| | | | | | | | - Antonio Novelli
- Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Carmelo Piscopo
- Medical and Laboratory Genetic Unit, Cardarelli Hospital, Naples, Italy
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8
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Tavana N, Ting TH, Lai K, Kennerson ML, Thilakavathy K. Whole exome sequencing identifies two novel variants in PHEX and DMP1 in Malaysian children with hypophosphatemic rickets. Ital J Pediatr 2022; 48:193. [PMID: 36482408 PMCID: PMC9730657 DOI: 10.1186/s13052-022-01385-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 11/15/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Hypophosphatemic rickets (HR) is a genetic disease of phosphate wasting that is characterized by defective bone mineralization. The most common cause of the disease is mutations in the phosphate regulating gene with homologies to endopeptidases on the X chromosome (PHEX) gene. The aims of this study were to identify the gene variants responsible for HR in three cases of Malaysian origin from three independent families and to describe their clinical, biochemical, and radiological features. METHODS Whole exome sequencing (WES) was performed on all patients and their parents, followed by Sanger sequencing validation. Bioinformatics tools were used to provide supporting evidence for pathogenicity of variants. To confirm that a mutation is de novo, paternity test was carried out. High resolution melting curve analysis was performed to assess the allele frequency in normal controls for mutations that were found in the patients. RESULTS The patients showed typical characteristics of HR including lower limb deformity, hypophosphatemia, and elevated alkaline phosphatase. WES revealed two variants in the PHEX gene and one variant in the dentin matrix protein 1 (DMP1) gene. Two of the three variants were novel, including c.1946_1954del (p.Gly649_Arg651del) in PHEX and c.54 + 1G > A in DMP1. Our data suggests that the novel p.Gly649_Arg651del variant is likely pathogenic for HR disease. CONCLUSIONS This study extends the variant spectrum of the PHEX and DMP1 genes. Our findings indicate that WES is an advantageous approach for diagnosis of genetic diseases which are heterogeneous.
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Affiliation(s)
- Nahid Tavana
- grid.11142.370000 0001 2231 800XDepartment of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor Malaysia
| | - Tzer Hwu Ting
- grid.11142.370000 0001 2231 800XDepartment of Paediatrics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor Malaysia
| | - Kaitao Lai
- grid.1013.30000 0004 1936 834XNorthcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW Australia ,grid.1013.30000 0004 1936 834XSydney Medical School, University of Sydney, Sydney, NSW Australia
| | - Marina L. Kennerson
- grid.1013.30000 0004 1936 834XNorthcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW Australia ,grid.414685.a0000 0004 0392 3935Molecular Medicine Laboratory, Concord Hospital, Concord, NSW Australia
| | - Karuppiah Thilakavathy
- grid.11142.370000 0001 2231 800XDepartment of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor Malaysia ,grid.11142.370000 0001 2231 800XGenetics and Regenerative Medicine Research Group, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor Malaysia
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9
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Ma X, Pang Q, Zhang Q, Jiang Y, Wang O, Li M, Xing X, Xia W. A Novel Synonymous Variant of PHEX in a Patient with X-Linked Hypophosphatemia. Calcif Tissue Int 2022; 111:634-640. [PMID: 35831717 DOI: 10.1007/s00223-022-01003-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 06/23/2022] [Indexed: 11/29/2022]
Abstract
X-linked dominant hypophosphatemia (XLH), the most common form of hereditary hypophosphatemic rickets/osteomalacia, is caused by loss-of-function phosphate-regulating endopeptidase homolog X-linked gene (PHEX) variants. However, synonymous PHEX variants are rare in XLH. We report a 7-year-old boy with hypophosphatemia, short stature, and lower limb deformity. Whole-exome sequencing, reverse transcription-polymerase chain reaction, and Sanger sequencing were performed to identify the pathogenicity of the variant. A novel synonymous PHEX variant (NM_000444.4:c.1530 C>T, p.Arg510Arg) was detected in the proband. Further analysis revealed a 58-bp deletion at the 5' site of exon 14 during splicing. This study extends the genetic spectrum of XLH and confirms the rarity and significance of synonymous PHEX variants.
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Affiliation(s)
- Xiaosen Ma
- Department of Endocrinology, Key Laboratory of Endocrinology, National Commission of Health, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, People's Republic of China
| | - Qianqian Pang
- Department of Endocrinology, Key Laboratory of Endocrinology, National Commission of Health, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, People's Republic of China
| | - Qi Zhang
- Laboratory Department, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Yan Jiang
- Department of Endocrinology, Key Laboratory of Endocrinology, National Commission of Health, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, People's Republic of China
| | - Ou Wang
- Department of Endocrinology, Key Laboratory of Endocrinology, National Commission of Health, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, People's Republic of China
| | - Mei Li
- Department of Endocrinology, Key Laboratory of Endocrinology, National Commission of Health, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, People's Republic of China
| | - Xiaoping Xing
- Department of Endocrinology, Key Laboratory of Endocrinology, National Commission of Health, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, People's Republic of China
| | - Weibo Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, National Commission of Health, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, People's Republic of China.
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10
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Nielsen SR, Hansen SG, Bistrup C, Brusgaard K, Frederiksen AL. Bone Deformities and Kidney Failure: Coincidence of PHEX-Related Hypophosphatemic Rickets and m.3243A>G Mitochondrial Disease. Calcif Tissue Int 2022; 111:641-645. [PMID: 35916905 DOI: 10.1007/s00223-022-01010-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/08/2022] [Indexed: 12/01/2022]
Abstract
X-linked hypophosphatemic rickets (XLH) and m.3243A>G mitochondrial disease share several clinical findings, including short stature, hearing impairment (HI), nephropathy, and hypertension. Here, we report on a case with the rare coincidence of these two genetic conditions. In early childhood, the patient presented with hypophosphatemia and bone deformities and was clinically diagnosed with XLH. This was genetically verified in adulthood with the identification of a de novo pathogenic deletion in phosphate-regulating endopeptidase homolog X-linked (PHEX). In addition, the patient developed HI and hypertension and when his mother was diagnosed with m.3243A>G, subsequent genetic testing confirmed the patient to carry the same variant. Over the next two decades, the patient developed progressive renal impairment however without nephrocalcinosis known to associate with XLH which could indicate an m.3243A>G-related kidney disease. Parallel with the progression of renal impairment, the patient developed hyperphosphatemia and secondary hyperparathyroidism. In conclusion, this case represents a complex clinical phenotype with the reversal of hypo- to hyperphosphatemia in XLH potentially mediated by the development of an m.3243A>G-associated nephropathy.
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Affiliation(s)
- Simone Rask Nielsen
- Department of Clinical Genetics, Aalborg University Hospital, Ladegaardsgade 5, 5. Floor, 9000, Aalborg, Denmark.
- Department of Clinical Research, Aalborg University, Aalborg, Denmark.
| | | | - Claus Bistrup
- Department of Nephrology, Odense University Hospital, Odense, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Klaus Brusgaard
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Anja Lisbeth Frederiksen
- Department of Clinical Genetics, Aalborg University Hospital, Ladegaardsgade 5, 5. Floor, 9000, Aalborg, Denmark
- Department of Clinical Research, Aalborg University, Aalborg, Denmark
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11
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Alhamoudi KM, Alghamdi B, Alswailem M, Nasir A, Aljomaiah A, Al-Hindi H, Alzahrani AS. A Unique Mechanism of a Novel Synonymous PHEX Variant Causing X-Linked Hypophosphatemia. J Clin Endocrinol Metab 2022; 107:2883-2891. [PMID: 35896147 DOI: 10.1210/clinem/dgac435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Indexed: 11/19/2022]
Abstract
CONTEXT Synonymous mutations are usually nonpathogenic. OBJECTIVE We report here a family with X-linked hypophosphatemia (XLH) due to a novel synonymous PHEX variant with a unique mechanism. METHODS We studied a 4-member family (a mother, a son, and 2 daughters), all affected with XLH. Genomic DNA was extracted from peripheral leucocytes. Whole exome sequencing (WES) was used to identify the underlying genetic variant in the proband (the son). Sanger sequencing was used to confirm this variant in the proband and his family members. RT-PCR and sequencing of the cDNA revealed the effect of this variant on the PHEX structure and function. RESULTS A synonymous variant in the PHEX gene (c.1701A>C) was identified in all affected members. This variant changes the first nucleotide of exon 17 from adenine to cytosine. Using RT-PCR, this variant was shown to interfere with splicing of exons 16 with 17 resulting in a single shorter PHEX transcript in the proband compared to normal control. Sanger sequencing of the cDNA revealed a complete skipping of exon 17 and direct splicing of exons 16 and 18. This led to a frameshift and an introduction of a new stop codon in the next codon (codon 568), which ultimately led to truncation and loss of the final 183 amino acids of PHEX. CONCLUSION This novel variant shows how a synonymous exonic mutation may induce a complex series of changes in the transcription and translation of the gene and causes a disease, a mechanism that is not commonly recognized.
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Affiliation(s)
- Kheloud M Alhamoudi
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, MBC#03, PO BOX 3354, Riyadh, 11211, Saudi Arabia
| | - Balgees Alghamdi
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, MBC#03, PO BOX 3354, Riyadh, 11211, Saudi Arabia
| | - Meshael Alswailem
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, MBC#03, PO BOX 3354, Riyadh, 11211, Saudi Arabia
| | - Abdul Nasir
- Department of Molecular science and Technology, Ajou University, Suwon, 443-749, South Korea
| | - Abeer Aljomaiah
- Department of Medicine, King Faisal Specialist Hospital & Research Centre, P.O Box 3354, Riyadh 11211, Saudi Arabia
| | - Hindi Al-Hindi
- Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital & Research Centre, P.O Box 3354, Riyadh 11211, Saudi Arabia
| | - Ali S Alzahrani
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, MBC#03, PO BOX 3354, Riyadh, 11211, Saudi Arabia
- Department of Medicine, King Faisal Specialist Hospital & Research Centre, P.O Box 3354, Riyadh 11211, Saudi Arabia
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12
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Pathogenic Variants of the PHEX Gene. ENDOCRINES 2022. [DOI: 10.3390/endocrines3030040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Twenty-five years ago, a pathogenic variant of the phosphate-regulating endopeptidase homolog X-linked (PHEX) gene was identified as the cause of X-linked hypophosphatemic rickets (XLH). Subsequently, the overproduction of fibroblast growth factor 23 (FGF23) due to PHEX defects has been found to be associated with XLH pathophysiology. However, the mechanism by which PHEX deficiency contributes to the upregulation of FGF23 and the function of PHEX itself remain unclear. To date, over 700 pathogenic variants have been identified in patients with XLH, and functional assays and genotype–phenotype correlation analyses based on pathogenic variant data derived from XLH patients have been reported. Genetic testing for XLH is useful for the diagnosis. Not only have single-nucleotide variants causing missense, nonsense, and splicing variants and small deletion/insertion variants causing frameshift/non-frameshift alterations been observed, but also gross deletion/duplication variants causing copy number variants have been reported as pathogenic variants in PHEX. With the development of new technologies including next generation sequencing, it is expected that an increasing number of pathogenic variants will be identified. This chapter aimed to summarize the genotype of PHEX and related analyses and discusses the pathophysiology of PHEX defects to seek clues on unsolved questions.
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13
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PHEXL222P Mutation Increases Phex Expression in a New ENU Mouse Model for XLH Disease. Genes (Basel) 2022; 13:genes13081356. [PMID: 36011266 PMCID: PMC9407253 DOI: 10.3390/genes13081356] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 07/26/2022] [Accepted: 07/26/2022] [Indexed: 02/02/2023] Open
Abstract
PhexL222P mouse is a new ENU mouse model for XLH disease due to Leu to Pro amino acid modification at position 222. PhexL222P mouse is characterized by growth retardation, hypophosphatemia, hypocalcemia, reduced body bone length, and increased epiphyseal growth plate thickness and femur diameter despite the increase in PHEXL222P expression. Actually, PhexL222P mice show an increase in Fgf23, Dmp1, and Mepe and Slc34a1 (Na-Pi IIa cotransporter) mRNA expression similar to those observed in Hyp mice. Femoral osteocalcin and sclerostin and Slc34a1 do not show any significant variation in PhexL222P mice. Molecular dynamics simulations support the experimental data. P222 might locally break the E217-Q224 β-sheet, which in turn might disrupt inter-β-sheet interactions. We can thus expect local protein misfolding, which might be responsible for the experimentally observed PHEXL222P loss of function. This model could be a valuable addition to the existing XLH model for further comprehension of the disease occurrence and testing of new therapies.
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Lin X, Li S, Zhang Z, Yue H. Clinical and Genetic Characteristics of 153 Chinese Patients With X-Linked Hypophosphatemia. Front Cell Dev Biol 2021; 9:617738. [PMID: 34141703 PMCID: PMC8204109 DOI: 10.3389/fcell.2021.617738] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/16/2021] [Indexed: 11/27/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is caused by inactivating mutations in the phosphate-regulating endopeptidase homolog, X-linked (PHEX) gene, resulting in an excess of circulating intact fibroblast growth factor-23 (iFGF-23) and a waste of renal phosphate. In the present study, we retrospectively reviewed the clinical and molecular features of 153 Chinese patients, representing 87 familial and 66 sporadic cases with XLH. A total of 153 patients with XLH presented with signs or symptoms at a median age of 18.0 months (range, 9.0 months–26.0 years). Lower-limb deformity was the most frequent clinical manifestation, accounting for 79.1% (121/153). Biochemical screening showed increased serum levels of iFGF23 in patients with XLH, with a wide variation ranging from 14.39 to 730.70 pg/ml. Median values of serum iFGF23 in pediatric and adult patients were 94.87 pg/ml (interquartile range: 74.27–151.86 pg/ml) and 72.82 pg/ml (interquartile range: 39.42–136.00 pg/ml), respectively. Although no difference in circulating iFGF23 levels between these two groups was observed (P = 0.062), the proportion of patients with high levels of circulating iFGF23 (>42.2 pg/ml) was greater in the pediatric group than in the adult group (P = 0.026). Eighty-eight different mutations in 153 patients were identified, with 27 (30.7%) being novel. iFGF23 levels and severity of the disease did not correlate significantly with truncating and non-truncating mutations or N-terminal and C-terminal PHEX mutations. This study provides a comprehensive description of the clinical profiles, circulating levels of iFGF23 and gene mutation features of patients with XLH, further enriching the genotypic spectrum of the diseases. The findings show no evident correlation of circulating iFGF23 levels with the age or disease severity in patients with XLH.
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Affiliation(s)
- Xiaoyun Lin
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
| | - Shanshan Li
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
| | - Zhenlin Zhang
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
| | - Hua Yue
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
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Turan I, Erdem S, Kotan LD, Ozdemir Dilek S, Tastan M, Gurbuz F, Bişgin A, Karabay Bayazıt A, Topaloglu AK, Yuksel B. Experience with the targeted next-generation sequencing in the diagnosis of hereditary hypophosphatemic rickets. J Pediatr Endocrinol Metab 2021; 34:639-648. [PMID: 33852231 DOI: 10.1515/jpem-2020-0624] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 02/02/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Hereditary Hypophosphatemic Rickets (HHR) is a heterogeneous group of disorders characterized by hypophosphatemia. Although the X-linked dominant HHR is the most common form, the genetic etiology of HHR is variable. Recently, developed next-generation sequencing techniques may provide opportunities for making HHR diagnosis in a timely and efficient way. METHODS We investigated clinical and genetic features for 18 consecutive probands and their 17 affected family members with HHR. All patient's clinical and biochemical data were collected. We first analyzed a single gene with Next-generation sequencing if the patients have a strong clue for an individual gene. For the remaining cases, a Hypophosphatemic Rickets gene panel, including all known HHR genes by Next-generation sequencing, was employed. RESULTS We were able to diagnosis all of the consecutive 35 patients in our tertiary care center. We detected nine novel and 10 previously described variants in PHEX (9; 50%), SLC34A3 (3; 17%), ENPP1 (3; 17%), SLC34A1 (1; 5%), CLCN5 (1; 5%), and DMP1 (1; 5%). CONCLUSIONS To delineate the etiology of HHR cases in a cost and time-efficient manner, we propose single gene analysis by next-generation sequencing if findings of patients indicate a strong clue for an individual gene. If that analysis is negative or for all other cases, a Next-generation Sequence gene panel, which includes all known HHR genes, should be employed.
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Affiliation(s)
- Ihsan Turan
- Department of Pediatrics, Division of Pediatric Endocrinology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Sevcan Erdem
- Department of Pediatrics, Division of Pediatric Cardiology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Leman Damla Kotan
- Department of Pediatrics, Division of Pediatric Endocrinology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Semine Ozdemir Dilek
- Department of Pediatrics, Division of Pediatric Endocrinology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Mehmet Tastan
- Department of Pediatrics, Division of Pediatric Endocrinology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Fatih Gurbuz
- Department of Pediatrics, Division of Pediatric Endocrinology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Atıl Bişgin
- AGENTEM (Adana Genetic Diseases Diagnosis and Treatment Center), Cukurova University, Adana, Turkey.,and Department of Medical Genetics, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Aysun Karabay Bayazıt
- Department of Pediatrics, Division of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Ali Kemal Topaloglu
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Mississippi Medical Center, Jackson, MS, USA
| | - Bilgin Yuksel
- Department of Pediatrics, Division of Pediatric Endocrinology, Cukurova University Faculty of Medicine, Adana, Turkey
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16
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Lin Y, Xu J, Li X, Sheng H, Su L, Wu M, Cheng J, Huang Y, Mao X, Zhou Z, Zhang W, Li C, Cai Y, Wu D, Lu Z, Yin X, Zeng C, Liu L. Novel variants and uncommon cases among southern Chinese children with X-linked hypophosphatemia. J Endocrinol Invest 2020; 43:1577-1590. [PMID: 32253725 DOI: 10.1007/s40618-020-01240-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/24/2020] [Indexed: 12/17/2022]
Abstract
PURPOSE X-linked hypophosphatemia (XLH) is the most common inherited renal phosphate wasting disorder and is often misdiagnosed as vitamin D deficiency. This study aims to provide clinical and mutational characteristics of 65 XLH pediatric patients in southern China. METHODS In this work, a combination of DNA sequencing and qPCR analysis was used to study the PHEX gene in 80 pediatric patients diagnosed with hypophosphatemia. The clinical and laboratory data of confirmed 65 XLH patients were assessed and analyzed retrospectively. RESULTS In 65 XLH patients from 61 families, 51 different variants in the PHEX gene were identified, including 23 previously reported variants and 28 novel variants. In this cohort of XLH patients, the c.1601C>T(p.Pro534Leu) variant appears more frequently. Fourteen uncommon XLH cases were described, including four boys with de novo mosaic variants, eight patients with large deletions and a pair of monozygotic twins. The clinical manifestations in this cohort are very similar to those previously reported. CONCLUSION This study extends the mutational spectrum of the PHEX gene, which will contribute to accurate diagnosis. This study also suggests a supplementary qPCR or MLPA assay may be performed along with classical sequencing to confirm the gross insertion/deletion.
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Affiliation(s)
- Y Lin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - J Xu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - X Li
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - H Sheng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - L Su
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - M Wu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - J Cheng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Y Huang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - X Mao
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Z Zhou
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - W Zhang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - C Li
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Y Cai
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - D Wu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Z Lu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - X Yin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - C Zeng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China.
| | - L Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China.
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17
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Vesela B, Kratochvilova A, Svandova E, Benes P, Rihova K, Poliard A, Matalova E. Caspase-12 Is Present During Craniofacial Development and Participates in Regulation of Osteogenic Markers. Front Cell Dev Biol 2020; 8:589136. [PMID: 33178702 PMCID: PMC7593616 DOI: 10.3389/fcell.2020.589136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/17/2020] [Indexed: 11/13/2022] Open
Abstract
Caspases are evolutionary conserved proteases traditionally known as participating in apoptosis and inflammation but recently discovered also in association with other processes such as proliferation or differentiation. This investigation focuses on caspase-12, ranked among inflammatory caspases but displaying other, not yet defined functions. A screening analysis pointed to statistically significant (P < 0.001) increase in expression of caspase-12 in a decisive period of mandibular bone formation when the original mesenchymal condensation turns into vascularized bone tissue. Immunofluorescence analysis confirmed the presence of caspase-12 protein in osteoblasts. Therefore, the osteoblastic cell line MC3T3-E1 was challenged to investigate any impact of caspase-12 on the osteogenic pathways. Pharmacological inhibition of caspase-12 in MC3T3-E1 cells caused a statistically significant decrease in expression of some major osteogenic genes, including those for alkaline phosphatase, osteocalcin and Phex. This downregulation was further confirmed by an alkaline phosphatase activity assay and by a siRNA inhibition approach. Altogether, this study demonstrates caspase-12 expression and points to its unknown physiological engagement in bone cells during the course of craniofacial development.
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Affiliation(s)
- Barbora Vesela
- Laboratory of Odontogenesis and Osteogenesis, Institute of Animal Physiology and Genetics, Academy of Sciences, Brno, Czechia
| | - Adela Kratochvilova
- Laboratory of Odontogenesis and Osteogenesis, Institute of Animal Physiology and Genetics, Academy of Sciences, Brno, Czechia
| | - Eva Svandova
- Laboratory of Odontogenesis and Osteogenesis, Institute of Animal Physiology and Genetics, Academy of Sciences, Brno, Czechia
| | - Petr Benes
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Kamila Rihova
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Anne Poliard
- Laboratory of Orofacial Pathologies, Imaging and Biotherapies, UFR Odontology Montrouge, Paris University, Paris, France
| | - Eva Matalova
- Laboratory of Odontogenesis and Osteogenesis, Institute of Animal Physiology and Genetics, Academy of Sciences, Brno, Czechia.,Department of Physiology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czechia
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18
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Maio P, Mano L, Rocha S, Baptista RB, Francisco T, Sousa H, Freixo JP, Abranches M. X-linked hypophosphatemic rickets: a new mutation. J Bras Nefrol 2020; 43:279-282. [PMID: 32897287 PMCID: PMC8257286 DOI: 10.1590/2175-8239-jbn-2020-0027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 06/10/2020] [Indexed: 11/22/2022] Open
Abstract
Phosphopenic rickets may be caused by mutations in the PHEX gene
(phosphate regulating endopeptidase homolog X-linked). Presently, more than 500
mutations in the PHEX gene have been found to cause
hypophosphatemic rickets. The authors report a clinical case of a 4-year-old
girl with unremarkable family history, who presented with failure to thrive and
bowing of the legs. Laboratory tests showed hypophosphatemia, elevated alkaline
phosphatase, normal calcium, mildly elevated PTH and normal levels of 25(OH)D
and 1.25(OH)D. The radiological study showed bone deformities of the radius and
femur. Clinical diagnosis of phosphopenic rickets was made and the genetic study
detected a heterozygous likely pathogenic variant of the PHEX
gene: c.767_768del (p.Thr256Serfs*7). This variant was not previously described
in the literature or databases. Knowledge about new mutations can improve
patient’s outcome. Genetic analysis can help to establish a genotype-phenotype
correlation.
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Affiliation(s)
- Patrícia Maio
- Hospital do Espírito Santo de Évora, Évora, Portugal
| | - Lia Mano
- Centro Hospitalar e Universitário de Lisboa Central, Hospital Dona Estefânia, Lisboa, Portugal
| | - Sara Rocha
- Hospital de Santarém, Santarém, Portugal
| | - Rute Baeta Baptista
- Centro Hospitalar e Universitário de Lisboa Central, Hospital Dona Estefânia, Unidade de Nefrologia Pediátrica, Lisboa, Portugal
| | - Telma Francisco
- Centro Hospitalar e Universitário de Lisboa Central, Hospital Dona Estefânia, Unidade de Nefrologia Pediátrica, Lisboa, Portugal
| | - Helena Sousa
- Hospital de Vila Franca de Xira, Vila Franca de Xira, Lisboa, Portugal
| | - João Parente Freixo
- Centro Hospitalar e Universitário de Lisboa Central, Hospital Dona Estefânia, Departamento de Genética Médica, Lisboa, Portugal
| | - Margarida Abranches
- Centro Hospitalar e Universitário de Lisboa Central, Hospital Dona Estefânia, Unidade de Nefrologia Pediátrica, Lisboa, Portugal
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19
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Hughes M, Macica C, Meriano C, Doyle M. Giving Credence to the Experience of X-Linked Hypophosphatemia in Adulthood: An Interprofessional Mixed-Methods Study. J Patient Cent Res Rev 2020; 7:176-188. [PMID: 32377551 DOI: 10.17294/2330-0698.1727] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Purpose X-linked hypophosphatemia (XLH) is a rare X-linked dominant metabolic bone disease, often diagnosed in childhood but causing increasing physical debilitation and pain in adulthood. Physical comorbidities of XLH in adulthood include pervasive and early-onset degenerative arthritis, mineralizing enthesophytes and osteophytes, osteomalacia and pseudofracture, dental abscesses, and hearing loss. Methods This mixed-methods analysis included physical findings, diagnostic imaging, occupational and physical therapy assessments, and semi-structured interviews by social work to understand the functional outcomes and lived experience of XLH in adulthood, through connections between qualitative data obtained by social work and occupational therapy with the quantitative findings from other disciplines. Results Three primary themes of chronic pain, fear of falling, and lack of credence given by health care providers emerged from qualitative data and could be correlated with physical findings from functional outcome assessments These concerns contrasted with resilience, adaption, and compensation demonstrated by participants. Conclusions While new treatments may ease the burden of disease for adults with XLH, further research, increased provider awareness and education, and further development of standards of care are needed to promote accurate and adequate assessment and intervention for adults with XLH.
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Affiliation(s)
- Melissa Hughes
- Frank H. Netter MD School of Medicine, Quinnipiac University, North Haven, CT
| | - Carolyn Macica
- Frank H. Netter MD School of Medicine, Quinnipiac University, North Haven, CT
| | - Catherine Meriano
- Occupational Therapy, School of Health Sciences, Quinnipiac University, North Haven, CT
| | - Maya Doyle
- Social Work, School of Health Sciences, Quinnipiac University, North Haven, CT
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20
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Steele A, Gonzalez R, Garbalosa JC, Steigbigel K, Grgurich T, Parisi EJ, Feinn RS, Tommasini SM, Macica CM. Osteoarthritis, Osteophytes, and Enthesophytes Affect Biomechanical Function in Adults With X-linked Hypophosphatemia. J Clin Endocrinol Metab 2020; 105:5734494. [PMID: 32047911 PMCID: PMC8416779 DOI: 10.1210/clinem/dgaa064] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 02/06/2020] [Indexed: 12/17/2022]
Abstract
CONTEXT X-Linked hypophosphatemia (XLH) is a lifelong metabolic disease with musculoskeletal comorbidities that dominate the adult clinical presentation. OBJECTIVE The adult XLH disorder has yet to be quantified on the basis of the physical and functional limitations that can affect activities of daily living. Our goal was to report the impact of the musculoskeletal manifestations on physical function. DESIGN AND SETTING Musculoskeletal function was evaluated by validated questionnaires and in an interdisciplinary clinical space where participants underwent full-body radiologic imaging, goniometric range of motion (ROM) measurements, general performance tests, and kinematic gait analysis. PATIENTS Nine adults younger than 60 years with a diagnosis of XLH and self-reported musculoskeletal disability, but able to independently ambulate, were selected to participate. Passive ROM and gait analysis were also performed on age-approximated controls to account for differences between individual laboratory instrumentation. RESULTS Enthesophytes, degenerative arthritis, and osteophytes were found to be consistently bilateral and diffusely present at the spine and synovial joints across participants, with predominance at weight-bearing joints. Passive ROM in adults with XLH was decreased at the cervical spine, hip, knee, and ankle compared to controls. Gait analysis relative to controls revealed increased step width, markedly increased lateral trunk sway, and physical restriction at the hip, knees, and ankle joints that translated into limitations through the gait cycle. CONCLUSIONS The functional impact of XLH musculoskeletal comorbidities supports the necessity for creating an interprofessional health-care team with the goal of establishing a longitudinal plan of care that considers the manifestations of XLH across the lifespan.
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Affiliation(s)
- Amy Steele
- Department of Medical Sciences, Frank H. Netter MD School of Medicine at Quinnipiac University, North Haven, Connecticut
| | - Ramon Gonzalez
- Department of Diagnostic Imaging, School of Health Sciences at Quinnipiac University, North Haven, Connecticut
| | - Juan C Garbalosa
- Department of Physical Therapy, School of Health Sciences at Quinnipiac University, North Haven, Connecticut
| | - Keith Steigbigel
- Department of Physical Therapy, School of Health Sciences at Quinnipiac University, North Haven, Connecticut
| | - Tania Grgurich
- Department of Diagnostic Imaging, School of Health Sciences at Quinnipiac University, North Haven, Connecticut
| | - Erika J Parisi
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Richard S Feinn
- Department of Medical Sciences, Frank H. Netter MD School of Medicine at Quinnipiac University, North Haven, Connecticut
| | - Steven M Tommasini
- Department of Orthopaedics, Yale University School of Medicine at Quinnipiac University, New Haven, Connecticut
| | - Carolyn M Macica
- Department of Medical Sciences, Frank H. Netter MD School of Medicine at Quinnipiac University, North Haven, Connecticut
- Correspondence and Reprint Requests: Carolyn M. Macica, PhD, Department of Medical Sciences, Frank H. Netter MD School of Medicine, Quinnipiac University, NH-MED, 275 Mt Carmel Avenue, Hamden, CT 06518. E-mail:
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21
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Forero-Delgadillo JM, Cleves D, Ochoa V, Londoño-Correa H, Restrepo JM, Nastasi-Catanese JA, Pachajoa H. PHEX Gene Mutation in a Patient with X-Linked Hypophosphatemic Rickets in a Developing Country. Appl Clin Genet 2020; 13:57-62. [PMID: 32104046 PMCID: PMC7025672 DOI: 10.2147/tacg.s232448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/23/2019] [Indexed: 12/03/2022] Open
Abstract
Introduction X-linked hypophosphatemic rickets is part of a larger group of hereditary diseases characterized by renal phosphate loss, which causes growth disorders, rickets, and osteomalacia. These conditions are characterized by disorders in phosphate equilibrium, which is essential for bone formation. Case Report A female patient presented with bone deformities of the inferior extremities, prominent joints, and loss of teeth. She received initial management with oral calcium and orthotics in inferior extremities, with poor clinical outcome. PHEX gene sequencing revealed a pathogenic variant c.1601C>T (p.Pro534Leu). Discussion XLHR is caused by mutations in the PHEX gene; to date, more than 460 mutations have been associated with the disease. Clinically, it is characterized by bowing of the lower extremities, decreased growth, musculoskeletal complaints, dental abscesses, and other clinical signs and symptoms of rickets.
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Affiliation(s)
- Jessica María Forero-Delgadillo
- Pediatric Nephrology Fellow, Universidad Icesi-Fundación Valle de Lili, Cali, Colombia.,Facultad de Ciencias de la Salud, Universidad Icesi, Cali, Colombia
| | - Daniela Cleves
- Facultad de Ciencias de la Salud, Universidad Icesi, Cali, Colombia.,Pediatrics Resident, Universidad Icesi-Fundación Valle de Lili, Cali, Colombia
| | - Vanessa Ochoa
- Pediatric Nephrology Fellow, Universidad Icesi-Fundación Valle de Lili, Cali, Colombia.,Facultad de Ciencias de la Salud, Universidad Icesi, Cali, Colombia
| | | | | | - José Antonio Nastasi-Catanese
- Pediatric Nephrology Department, Fundación Valle del Lili, Cali, Colombia.,Clinical Genetics Department, Fundación Valle del Lili, Cali, Colombia
| | - Harry Pachajoa
- Facultad de Ciencias de la Salud, Universidad Icesi, Cali, Colombia.,Clinical Genetics Department, Fundación Valle del Lili, Cali, Colombia
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22
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Zhao Y, Yang F, Wang L, Che H. Familial hypophosphatemic rickets caused by a PHEX gene mutation accompanied by a NPR2 missense mutation. J Pediatr Endocrinol Metab 2020; 33:305-311. [PMID: 31927522 DOI: 10.1515/jpem-2019-0380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 11/29/2019] [Indexed: 01/10/2023]
Abstract
Background Familial hypophosphatemic rickets, which is usually acknowledged as X-linked hypophosphatemic rickets (XLH), is a rare hereditary disease. XLH caused by mutations in the PHEX gene often manifests as growth retardation, skeletal deformities, osteodynia and dental dysplasia. NPR2 mutations are reported to cause disproportionate short stature. Our study was designed to identify the gene mutations of three patients in one family. Case description A 40-year-old Chinese male visited the hospital for continuous osteodynia and presented with bilateral leg bowing, absent teeth and a progressive limp. The age of onset was approximately 2 years old. His 63-year-old mother and 42-year-old brother both shared identical symptoms with him. The laboratory tests were consistent with XLH, which showed decreased levels of blood phosphorus and 1,25-dihydroxyvitamin D3 as well as increased urinary phosphorus excretion. Mutation analysis revealed that the proband as well as his mother and his brother all had a PHEX mutation in exon 14 (c.1543C > T), and the proband also had a NPR2 mutation in exon 21 (c.3058C > T). Conclusions We report the familial hypophosphatemic rickets of three patients in a Chinese family caused by a PHEX gene mutation in exon 14 (c.1543C > T), which had never been reported in Chinese patients. We first report an XLH case together with a NPR2 mutation that had never been reported before.
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Affiliation(s)
- Yongting Zhao
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, P.R. China
| | - Fan Yang
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, China
| | - Lihong Wang
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, P.R. China.,Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Hui Che
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
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23
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BinEssa HA, Zou M, Al-Enezi AF, Alomrani B, Al-Faham MSA, Al-Rijjal RA, Meyer BF, Shi Y. Functional analysis of 22 splice-site mutations in the PHEX, the causative gene in X-linked dominant hypophosphatemic rickets. Bone 2019; 125:186-193. [PMID: 31102713 DOI: 10.1016/j.bone.2019.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/24/2019] [Accepted: 05/13/2019] [Indexed: 12/19/2022]
Abstract
CONTEXT X-linked hypophosphatemic rickets (XLH) is caused by inactivating mutations in the PHEX gene and is the most common form of hereditary rickets. The splice-site mutations account for 17% of all reported PHEX mutations. The functional consequence of these splice-site mutations has not been systemically investigated. OBJECTIVE The current study was undertaken to functionally annotate previously reported 22 splice-site mutations in the PHEX gene. METHODS PHEX mini-genes with different splice-site mutations were created by site-directed mutagenesis and expressed in HEK293 cells. The mRNA transcripts were analyzed by RT-PCR, cloning, and sequencing. RESULTS These splicing mutations led to a variety of consequences, including exon skipping, intron retention, and activation of cryptic splice sites. Among 22 splice-site mutations, exon skipping was the most common event accounting for 73% (16/22). Non-canonical splice-site mutations could result in splicing errors to the same extent as canonical splice-site mutations such as c.436+3G>C, c.436+4A>C, c.436+6T>C, c.437-3C>G, c.850-3C>G, c.1080-3C>A, c.1482+5G>C, c.1586+6T>C, c.1645+5G>A, c.1645+6T>C, c.1701-16T>A, c.1768+5G>A, and c.1899+5G>A. Interestingly, non-canonical (c.436+6T>C and c.1586+6T>C) and canonical splice-site mutations (c.1769-1G>C) could generate partial splicing errors (both wild-type and mutant transcripts were detected), resulting in incomplete inactivation of PHEX gene, which may explain the mild disease phenotype reported previously, providing evidence of genotype-phenotype correlation. c.1645C>T (p.R549*) had no impact on pre-mRNA splicing although it is located next to canonical splice donor site GT. CONCLUSIONS Exon skipping is the most common outcome due to splice-site mutations. Both canonical and non-canonical splice-site mutations can result in either severe or mild RNA splicing defects, contributing to phenotype heterogeneity. Non-canonical splice-site mutations should not be overlooked in genetic screening especially those located within 50 bp from canonical splice site.
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Affiliation(s)
- Huda A BinEssa
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Minjing Zou
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Anwar F Al-Enezi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Basma Alomrani
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Manar S A Al-Faham
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Roua A Al-Rijjal
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Brian F Meyer
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Yufei Shi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.
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24
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Zhang C, Zhao Z, Sun Y, Xu L, JiaJue R, Cui L, Pang Q, Jiang Y, Li M, Wang O, He X, He S, Nie M, Xing X, Meng X, Zhou X, Yan L, Kaplan JM, Insogna KL, Xia W. Clinical and genetic analysis in a large Chinese cohort of patients with X-linked hypophosphatemia. Bone 2019; 121:212-220. [PMID: 30682568 DOI: 10.1016/j.bone.2019.01.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/11/2019] [Accepted: 01/20/2019] [Indexed: 01/09/2023]
Abstract
X-linked Hypophosphatemia (XLH) is caused by loss of function mutations in the PHEX gene. Given the recent availability of a new therapy for XLH, a retrospective analysis of the most recent 261 Chinese patients with XLH evaluated at Peking Union Medical College Hospital was conducted. Clinical, biochemical, radiographic studies, as well as genetic analyses, including Sanger sequencing for point mutations and Multiplex Ligation-dependent Probe Amplification (MLPA) to detect large deletions/duplications were employed. Based on the structure of Neprilysin (NEP), a member of M13 family that includes PHEX, a three-dimensional (3D) model of PHEX was constructed, missense and nonsense mutations were positioned on the predicted structure to visualize relative positions of these two types of variants. Sex differences and genotype-phenotype correlations were also undertaken. Genetic analyses identified 166 PHEX mutations in 261 XLH patients. One hundred and eleven of the 166 mutations were unreported. Four mutational 'hot-spots' were identified in this cohort (P534L, G579R, R747X, c.1645+1 G>A). Missense mutations, but not nonsense mutations, clustered in the two putative lobes of the PHEX protein, suggesting these are functionally important regions of the molecule. Circulating levels of intact FGF23 were significantly elevated (median level 101.9 pg/mL; reference range 16.1-42.2 pg/mL). No significant sex differences, as well as no phenotypic differences were identified between patients with putative truncating and non-truncating PHEX mutations. However, patients with N-terminal PHEX mutations had an earlier age of onset of disease (P = 0.015) and higher iFGF23 levels (P = 0.045) as compared to those with C-terminal mutations. These data provide a comprehensive characterization of the largest cohort of patients with XLH reported to date from China, which will help in evaluating the applicability of emerging therapies for this disease in this ethnic group.
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Affiliation(s)
- Cong Zhang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Zhen Zhao
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China; Department of Geriatrics, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing 100050, China
| | - Yue Sun
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Lijun Xu
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Ruizhi JiaJue
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Lijia Cui
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Qianqian Pang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Yan Jiang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Mei Li
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Ou Wang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Xiaodong He
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China; Department of Endocrinology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, China
| | - Shuli He
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Min Nie
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Xiaoping Xing
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Xunwu Meng
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Xueying Zhou
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Lina Yan
- Department of Endocrinology, Baogang Hospital, Baotou, Inner Mongolia 014000, China
| | - Jared M Kaplan
- Department of Medicine, Section of Endocrinology, Yale School of Medicine, New Haven, CT, USA
| | - Karl L Insogna
- Department of Medicine, Section of Endocrinology, Yale School of Medicine, New Haven, CT, USA
| | - Weibo Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China.
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Yang M, Kim J, Yang A, Jang J, Jeon TY, Cho SY, Jin DK. A novel de novo mosaic mutation in PHEX in a Korean patient with hypophosphatemic rickets. Ann Pediatr Endocrinol Metab 2018; 23:229-234. [PMID: 30599486 PMCID: PMC6312911 DOI: 10.6065/apem.2018.23.4.229] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/17/2018] [Accepted: 06/17/2018] [Indexed: 11/24/2022] Open
Abstract
X-linked hypophosphatemic rickets is caused by loss-of-function mutations in PHEX, which encodes a phosphate-regulating endopeptidase homolog. We report a 26-year-old man with X-linked hypophosphatemic rickets who showed decreased serum phosphate accompanied by bilateral genu valgum and short stature. He had received medical treatment with vitamin D (alfacalcidol) and phosphate from the age of 3 to 20 years. He underwent surgery due to valgus deformity at the age of 14 and 15. Targeted gene panel sequencing for Mendelian genes identified a nonsense mutation in PHEX (c.589C>T; p.Gln197Ter) and a mosaic pattern where only 38% of sequence reads showed the variant allele. This mutation was not found in his mother, who had a normal phenotype. This is a case of a sporadic nonsense mutation in PHEX and up to date, this is the first case of a mosaic mutation in PHEX in Korea.
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Affiliation(s)
- Misun Yang
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jinsup Kim
- Department of Pediatrics, Hanyang University Guri Hopistal, Hanyang University College of Medicine, Guri, Korea
| | - Aram Yang
- Department of Pediatrics, Inha University School of Medicine, Incheon, Korea
| | | | - Tae Yeon Jeon
- Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sung Yoon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Dong-Kyu Jin
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Coyac BR, Falgayrac G, Penel G, Schmitt A, Schinke T, Linglart A, McKee MD, Chaussain C, Bardet C. Impaired mineral quality in dentin in X-linked hypophosphatemia. Connect Tissue Res 2018; 59:91-96. [PMID: 29745817 DOI: 10.1080/03008207.2017.1417989] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
X-linked hypophosphatemia (XLH) is a skeletal disorder arising from mutations in the PHEX gene, transmitted in most cases as an X-linked dominant trait. PHEX deficiency leads to renal phosphate wasting and hypophosphatemia, as well as impaired mineralization of bone and dentin, resulting in severe skeletal and dental complications. Dentin mineralization defects appear as characteristic, large interglobular spaces resulting from the lack of fusion of calculospherites in the circumpulpal region during the mineralization process. Here, we examined changes in the composition and structure of dentin using Raman spectroscopy on XLH human teeth, and using transmission electron microscopy on the dentin of Hyp mice (the murine model of XLH). The dentin of patients with XLH showed changes in the quality of the apatitic mineral, with greater carbonate substitution and lower crystallinity compared to the dentin of age-matched control teeth. In addition, ultrastructural analysis by transmission electron microscopy revealed a major disorganization of the peri- and intertubular structure of the dentin, with odontoblast processes residing within an unmineralized matrix sheath in the Hyp mouse. Taken together, these results indicate that like for bone and tooth cementum, there are impaired mineral quality and matrix changes in XLH dentin reflecting high sensitivity to systemic serum phosphate levels and possibly other local changes in the dentin matrix.
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Affiliation(s)
- Benjamin R Coyac
- a Orofacial Pathologies, Imaging and Biotherapies Laboratory EA2496, Dental School , Paris Descartes University , Paris , France.,b Department of Periodontology, U.F.R. of Odontology , Rothschild Hospital, AP-HP, Paris Diderot University , Paris , France
| | - Guillaume Falgayrac
- c EA 4490-PMOI-Physiopathologie des Maladies Osseuses Inflammatoires , Univ. Lille, Univ. Littoral Côte d'Opale , Lille , France
| | - Guillaume Penel
- c EA 4490-PMOI-Physiopathologie des Maladies Osseuses Inflammatoires , Univ. Lille, Univ. Littoral Côte d'Opale , Lille , France
| | - Alain Schmitt
- d Cochin Institute, Transmission Electron Microscopy Platform, INSERM U1016, CNRS UMR8104 , Paris Descartes University Sorbonne Paris Cité , Paris , France
| | - Thorsten Schinke
- e Department of Osteology and Biomechanics , University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Agnès Linglart
- f APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism , Plateforme d'Expertise Paris Sud Maladies Rares and Filière OSCAR , Le Kremlin Bicêtre , France.,g INSERM U1169 , University Paris Sud Paris-Saclay , Le Kremelin Bicêtre, France
| | - Marc D McKee
- h Faculties of Dentistry and Medicine, Department of Anatomy and Cell Biology , McGill University , Montreal , Canada
| | - Catherine Chaussain
- a Orofacial Pathologies, Imaging and Biotherapies Laboratory EA2496, Dental School , Paris Descartes University , Paris , France.,i Department of Odontology , Bretonneau Hospital PNVS, AP-HP , Paris , France
| | - Claire Bardet
- a Orofacial Pathologies, Imaging and Biotherapies Laboratory EA2496, Dental School , Paris Descartes University , Paris , France
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Lin X, Zhu Y, Luo J, Huang J. Genetic analysis of three families with X-linked dominant hypophosphatemic rickets. J Pediatr Endocrinol Metab 2018; 31:789-797. [PMID: 29858904 DOI: 10.1515/jpem-2017-0451] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 04/23/2018] [Indexed: 01/25/2023]
Abstract
Background Hypophosphatemic rickets, including familial hypophosphatemic vitamin D-resistant rickets, which commonly manifests in childhood, is generally hereditary. X-linked dominant hypophosphatemic rickets (XLH, MIM307800), caused by inactivating mutations in the PHEX gene, is the most common form. This study aimed to identify the gene mutations responsible for three cases of XLH and its clinical phenotype. Methods We conducted a genetic diagnosis and clinical phenotypic linkage analysis of three pedigrees with XLH. Three probands finally diagnosed as XLH were analyzed by next-generation sequencing (NGS). Sanger sequencing was used for mutation scanning in other family members. Results For the three patients with XLH, the age of onset ranged from 1.5 to 2 years and their heights were less than three standard deviations (SDs) below the median. The patients exhibited curved deformities in both lower limbs, hypophosphatemia, elevated serum FGF23 levels and elevated levels of blood alkaline phosphatase, with normal levels of blood parathyroid hormone (PTH) and calcium. X-ray analysis of the limbs and chest revealed characteristic rickets signs. Three candidate pathogenic mutations were identified in PHEX (NM_000444.5): c.433G>T (p.Glu145*, p.E145*) in exon 4, c.1735G>A (p.Gly579Arg, p.G579R) (rs875989883) in exon 17 and c.2245T>C (p.Trp749Arg, p.W749R) in exon 22. The nonsense mutation (p.E145*) in PHEX is novel and is predicted to cause a truncation of the encoded protein, resulting in loss of function. Conclusions The novel nonsense mutation (p.E145*) in PHEX is possibly involved in inherited XLH.
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Affiliation(s)
- Xinfu Lin
- Provincial Clinical Medical College, Fujian Medical University, Fuzhou, P.R. China.,Department of Paediatrics, Fujian Provincial Hospital, Fuzhou, P.R. China
| | - Yaobin Zhu
- Department of Traditional Chinese Medicine, The First Affiliated Hospital, Fujian Medical University, Fuzhou, P.R. China
| | - Jiewei Luo
- Provincial Clinical Medical College, Fujian Medical University, Fuzhou, P.R. China.,Department of Traditional Chinese Medicine, Fujian Provincial Hospital, Fuzhou, P.R. China
| | - Jianbin Huang
- Provincial Clinical Medical College, Fujian Medical University, Fuzhou, P.R. China.,Department of Traditional Chinese Medicine, Fujian Provincial Hospital, Fuzhou, P.R. China
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Kinoshita Y, Fukumoto S. X-Linked Hypophosphatemia and FGF23-Related Hypophosphatemic Diseases: Prospect for New Treatment. Endocr Rev 2018; 39:274-291. [PMID: 29381780 DOI: 10.1210/er.2017-00220] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 01/23/2018] [Indexed: 12/21/2022]
Abstract
Phosphate plays essential roles in many biological processes, and the serum phosphate level is tightly controlled. Chronic hypophosphatemia causes impaired mineralization of the bone matrix and results in rickets and osteomalacia. Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that regulates phosphate metabolism. FGF23 excess induces hypophosphatemia via impaired phosphate reabsorption in the renal proximal tubules and decreased phosphate absorption in the intestines. There are several types of genetic and acquired FGF23-related hypophosphatemic diseases. Among these diseases, X-linked hypophosphatemia (XLH), which is caused by inactivating mutations in the phosphate-regulating endopeptidase homolog, X-linked (PHEX) gene, is the most prevalent form of genetic FGF23-related hypophosphatemic rickets. Another clinically relevant form of FGF23-related hypophosphatemic disease is tumor-induced osteomalacia (TIO), a paraneoplastic syndrome associated with FGF23-producing tumors. A combination of active vitamin D and phosphate salts is the current medical therapy used to treat patients with XLH and inoperative TIO. However, this therapy has certain efficacy- and safety-associated limitations. Several measures to inhibit FGF23 activity have been considered as possible new treatments for FGF23-related hypophosphatemic diseases. In particular, a humanized monoclonal antibody for FGF23 (burosumab) is a promising treatment in patients with XLH and TIO. This review will focus on the phosphate metabolism and the pathogenesis and treatment of FGF23-related hypophosphatemic diseases.
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Affiliation(s)
- Yuka Kinoshita
- Division of Nephrology and Endocrinology, Department of Medicine, The University of Tokyo Hospital, Tokyo, Japan
| | - Seiji Fukumoto
- Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
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29
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Marik B, Bagga A, Sinha A, Hari P, Sharma A. Genetics of Refractory Rickets: Identification of Novel PHEX Mutations in Indian Patients and a Literature Update. J Pediatr Genet 2018; 7:47-59. [PMID: 29707405 PMCID: PMC5916800 DOI: 10.1055/s-0038-1624577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 12/25/2017] [Indexed: 10/18/2022]
Abstract
Refractory rickets is a genetic disorder that cannot be treated by vitamin D supplementation and adequate dietary calcium and phosphorus. Hereditary hypophosphatemic rickets is one of the major forms of refractory rickets in Indian children and caused due to mutations in the PHEX , FGF23 , DMP1 , ENPP1 , and SLC34A3 genes. This is the first study in India on a large number of patients reporting on mutational screening of the PHEX gene. Direct sequencing in 37 patients with refractory rickets revealed eight mutations in 13 patients of which 1 was nonsense, 2 were deletions, 1 was a deletion-insertion, and 4 were missense mutations. Of these mutations, four (c.566_567 delAG, c.651_654delACAT, c.1337delinsAATAA, and c.2048T > A) were novel mutations. This article discusses the mutations in Indian patients, collates information on the genetic causes of refractory rickets, and emphasizes the significance of genetic testing for precise diagnosis, timely treatment, and management of the condition, especially in developing countries.
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Affiliation(s)
- Binata Marik
- Division of Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Arvind Bagga
- Department of Paediatrics, All India Institute of Medical Sciences, New Delhi, India
| | - Aditi Sinha
- Department of Paediatrics, All India Institute of Medical Sciences, New Delhi, India
| | - Pankaj Hari
- Department of Paediatrics, All India Institute of Medical Sciences, New Delhi, India
| | - Arundhati Sharma
- Division of Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
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30
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Acar S, BinEssa HA, Demir K, Al-Rijjal RA, Zou M, Çatli G, Anık A, Al-Enezi AF, Özışık S, Al-Faham MSA, Abacı A, Dündar B, Kattan WE, Alsagob M, Kavukçu S, Tamimi HE, Meyer BF, Böber E, Shi Y. Clinical and genetic characteristics of 15 families with hereditary hypophosphatemia: Novel Mutations in PHEX and SLC34A3. PLoS One 2018; 13:e0193388. [PMID: 29505567 PMCID: PMC5837132 DOI: 10.1371/journal.pone.0193388] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 02/11/2018] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Hereditary hypophosphatemia is a group of rare renal phosphate wasting disorders. The diagnosis is based on clinical, radiological, and biochemical features, and may require genetic testing to be confirmed. METHODOLOGY Clinical features and mutation spectrum were investigated in patients with hereditary hypophosphatemia. Genomic DNA of 23 patients from 15 unrelated families were screened sequentially by PCR-sequencing analysis for mutations in the following genes: PHEX, FGF23, DMP1, ENPP1, CLCN5, SLC34A3 and SLC34A1. CytoScan HD Array was used to identify large deletions. RESULTS Genetic evaluation resulted in the identification of an additional asymptomatic but intermittent hypophosphatemic subject. Mutations were detected in 21 patients and an asymptomatic sibling from 13 families (86.6%, 13/15). PHEX mutations were identified in 20 patients from 12 families. Six of them were novel mutations present in 9 patients: c.983_987dupCTACC, c.1586+2T>G, c.1206delA, c.436+1G>T, c.1217G>T, and g.22,215,887-22,395,767del (179880 bp deletion including exon 16-22 and ZNF645). Six previously reported mutations were found in 11 patients. Among 12 different PHEX mutations, 6 were de novo mutations. Patients with de novo PHEX mutations often had delayed diagnosis and significantly shorter in height than those who had inherited PHEX mutations. Novel compound heterozygous mutations in SLC34A3 were found in one patient and his asymptomatic sister: c.1335+2T>A and c.1639_1652del14. No mutation was detected in two families. CONCLUSIONS This is the largest familial study on Turkish patients with hereditary hypophosphatemia. PHEX mutations, including various novel and de novo variants, are the most common genetic defect. More attention should be paid to hypophosphatemia by clinicians since some cases remain undiagnosed both during childhood and adulthood.
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Affiliation(s)
- Sezer Acar
- Division of Pediatric Endocrinology, Dokuz Eylul University School of Medicine, Izmir, Turkey
| | - Huda A. BinEssa
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Korcan Demir
- Division of Pediatric Endocrinology, Dokuz Eylul University School of Medicine, Izmir, Turkey
| | - Roua A. Al-Rijjal
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Minjing Zou
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Gönül Çatli
- Division of Pediatric Endocrinology, Katip Çelebi University School of Medicine, Izmir, Turkey
| | - Ahmet Anık
- Division of Pediatric Endocrinology, Adnan Menderes University School of Medicine, Izmir, Turkey
| | - Anwar F. Al-Enezi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Seçil Özışık
- Department of Endocrinology, Dokuz Eylul University School of Medicine, Izmir, Turkey
| | - Manar S. A. Al-Faham
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Ayhan Abacı
- Division of Pediatric Endocrinology, Dokuz Eylul University School of Medicine, Izmir, Turkey
| | - Bumin Dündar
- Division of Pediatric Endocrinology, Katip Çelebi University School of Medicine, Izmir, Turkey
| | - Walaa E. Kattan
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Maysoon Alsagob
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Salih Kavukçu
- Division of Pediatric Nephrology, Dokuz Eylul University School of Medicine, Izmir, Turkey
| | - Hamdi E. Tamimi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Brian F. Meyer
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Ece Böber
- Division of Pediatric Endocrinology, Dokuz Eylul University School of Medicine, Izmir, Turkey
| | - Yufei Shi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
- * E-mail:
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Coyac BR, Falgayrac G, Baroukh B, Slimani L, Sadoine J, Penel G, Biosse-Duplan M, Schinke T, Linglart A, McKee MD, Chaussain C, Bardet C. Tissue-specific mineralization defects in the periodontium of the Hyp mouse model of X-linked hypophosphatemia. Bone 2017; 103:334-346. [PMID: 28764922 DOI: 10.1016/j.bone.2017.07.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 07/22/2017] [Accepted: 07/27/2017] [Indexed: 01/28/2023]
Abstract
X-linked hypophosphatemia (XLH) is a dento-osseous disorder caused by inactivating mutations in the PHEX gene, leading to renal phosphate wasting and hypophosphatemia, and impaired mineralization of bones and teeth. In the oral cavity, recent reports suggest a higher susceptibility of XLH patients to periodontitis, where patients present with impaired tooth cementum - a bone-like tissue involved in tooth attachment to the jaw bones and post-eruption tooth positioning - and a higher frequency of intrabony defects. In the present study, the pathobiology of alveolar bone and tooth cementum was investigated in the Hyp mouse, the murine analog of XLH. PHEX deficiency in XLH/Hyp dramatically alters the periodontal phenotype, with hypoplasia of tooth root cementum associated with a lack of periodontal ligament attachment and the presence of an immature apatitic mineral phase of all periodontal mineralized tissues. Challenging the Hyp periodontium in two surgical experimental models - ligature-induced periodontal breakdown and repair, and a model of tooth movement adaptation inducing cementum formation - we show that bone and cementum formation, and their healing, are altered. Bone and cementum mineralization appear similarly disturbed, where hypomineralized pericellular matrix surrounds cells, and where the protein osteopontin (OPN, a mineralization inhibitor) accumulates in a tissue-specific manner, most notably in the perilacunar matrix surrounding osteocytes. Although the pathobiology is different between XLH/Hyp bone and cementum, our results show a major XLH phenotype in oral mineralized tissues consistent with variations in patient susceptibility to periodontal disorders.
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Affiliation(s)
- Benjamin R Coyac
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France; Department of Periodontology, U.F.R. of Odontology, Rothschild Hospital, AP-HP, Paris Diderot University, Paris, France
| | - Guillaume Falgayrac
- Univ. Lille, Univ. Littoral Côte d'Opale, EA 4490 - PMOI - Physiopathologie des Maladies Osseuses Inflammatoires, F-59000 Lille, France
| | - Brigitte Baroukh
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France
| | - Lotfi Slimani
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France
| | - Jérémy Sadoine
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France
| | - Guillaume Penel
- Univ. Lille, Univ. Littoral Côte d'Opale, EA 4490 - PMOI - Physiopathologie des Maladies Osseuses Inflammatoires, F-59000 Lille, France
| | - Martin Biosse-Duplan
- Department of Odontology, Bretonneau Hospital PNVS, AP-HP, Paris, France; APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Plateforme d'Expertise Maladies Rares Paris-Sud, Hôpital Bicêtre Paris Sud, Le Kremlin Bicêtre, France
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Agnès Linglart
- APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Plateforme d'Expertise Maladies Rares Paris-Sud, Hôpital Bicêtre Paris Sud, Le Kremlin Bicêtre, France; INSERM U1169, Hôpital Bicêtre, Le Kremlin Bicêtre, and Université Paris-Saclay, France
| | - Marc D McKee
- Faculties of Dentistry and Medicine, Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
| | - Catherine Chaussain
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France; Department of Odontology, Bretonneau Hospital PNVS, AP-HP, Paris, France; APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Plateforme d'Expertise Maladies Rares Paris-Sud, Hôpital Bicêtre Paris Sud, Le Kremlin Bicêtre, France
| | - Claire Bardet
- EA2496, Faculty of Dentistry, Paris Descartes University, Montrouge, France.
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Ran Q, Xiong F, Zhu M, Deng LL, Lei PY, Luo YH, Zeng Y, Zhu GH, Song C. [Novel PHEX gene mutations in patients with X-linked hypophosphatemic rickets: an analysis of 2 cases]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2017; 19:534-538. [PMID: 28506344 PMCID: PMC7389139 DOI: 10.7499/j.issn.1008-8830.2017.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/03/2017] [Indexed: 06/07/2023]
Abstract
OBJECTIVE To investigate PHEX gene mutations in 2 patients with X-linked hypophosphatemic rickets (XLH) and their families and to clarify the genetic etiology. METHODS A retrospective analysis was performed for the clinical data of two patients with XLH. High-throughput sequencing was used to detect the PHEX gene, a pathogenic gene of XLH. PCR-Sanger sequencing was used to verify the distribution of mutations in families. RESULTS Both patients had novel mutations in the PHEX gene; one patient had a frameshift mutation, c.931dupC, which caused early termination of translation and produced the truncated protein p.Gln311Profs*13; the other patient had a splice site mutation, IVS14+1G>A, which caused the skipping of exon 15 and produced an incomplete amino acid chain. Their parents had normal gene phenotypes. CONCLUSIONS c.931dupC and IVS14+1G>A are two novel mutations of the PHEX gene and might be the new pathogenic mutations of XLH.
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Affiliation(s)
- Qing Ran
- Department of Endocrinology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
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Ichikawa S, Gerard-O'Riley RL, Acton D, McQueen AK, Strobel IE, Witcher PC, Feng JQ, Econs MJ. A Mutation in the Dmp1 Gene Alters Phosphate Responsiveness in Mice. Endocrinology 2017; 158:470-476. [PMID: 28005411 PMCID: PMC5460778 DOI: 10.1210/en.2016-1642] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Accepted: 12/21/2016] [Indexed: 01/23/2023]
Abstract
Mutations in the dentin matrix protein 1 (DMP1) gene cause autosomal recessive hypophosphatemic rickets (ARHR). Hypophosphatemia in ARHR results from increased circulating levels of the phosphaturic hormone, fibroblast growth factor 23 (FGF23). Similarly, elevated FGF23, caused by mutations in the PHEX gene, is responsible for the hypophosphatemia in X-linked hypophosphatemic rickets (XLH). Previously, we demonstrated that a Phex mutation in mice creates a lower set point for extracellular phosphate, where an increment in phosphorus further stimulates Fgf23 production to maintain low serum phosphorus levels. To test the presence of the similar set point defect in ARHR, we generated 4- and 12-week-old Dmp1/Galnt3 double knockout mice and controls, including Dmp1 knockout mice (a murine model of ARHR), Galnt3 knockout mice (a murine model of familial tumoral calcinosis), and phenotypically normal double heterozygous mice. Galnt3 knockout mice had increased proteolytic cleavage of Fgf23, leading to low circulating intact Fgf23 levels with consequent hyperphosphatemia. In contrast, Dmp1 knockout mice had little Fgf23 cleavage and increased femoral Fgf23 expression, resulting in hypophosphatemia and low femoral bone mineral density (BMD). However, introduction of the Galnt3 null allele to Dmp1 knockout mice resulted in a significant increase in serum phosphorus and normalization of BMD. This increased serum phosphorus was accompanied by markedly elevated Fgf23 expression and circulating Fgf23 levels, an attempt to reduce serum phosphorus in the face of improving phosphorus levels. These data indicate that a Dmp1 mutation creates a lower set point for extracellular phosphate and maintains it through the regulation of Fgf23 cleavage and expression.
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Affiliation(s)
| | | | | | | | | | | | - Jian Q. Feng
- Department of Biomedical Sciences, Texas A&M College of Dentistry, Dallas, Texas 75246
| | - Michael J. Econs
- Departments of Medicine and
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202; and
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Boukpessi T, Hoac B, Coyac BR, Leger T, Garcia C, Wicart P, Whyte MP, Glorieux FH, Linglart A, Chaussain C, McKee MD. Osteopontin and the dento-osseous pathobiology of X-linked hypophosphatemia. Bone 2017; 95:151-161. [PMID: 27884786 DOI: 10.1016/j.bone.2016.11.019] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/11/2016] [Accepted: 11/19/2016] [Indexed: 01/13/2023]
Abstract
Seven young patients with X-linked hypophosphatemia (XLH, having inactivating PHEX mutations) were discovered to accumulate osteopontin (OPN) at the sites of defective bone mineralization near osteocytes - the so-called hallmark periosteocytic (lacunar) "halos" of XLH. OPN was also localized in the pericanalicular matrix extending beyond the osteocyte lacunae, as well as in the hypomineralized matrix of tooth dentin. OPN, a potent inhibitor of mineralization normally degraded by PHEX, is a member of a family of acidic, phosphorylated, calcium-binding, extracellular matrix proteins known to regulate dental, skeletal, and pathologic mineralization. Associated with the increased amount of OPN (along with inhibitory OPN peptide fragments) in XLH bone matrix, we found an enlarged, hypomineralized, lacuno-canalicular network - a defective pattern of skeletal mineralization that decreases stiffness locally at: i) the cell-matrix interface in the pericellular environment of the mechanosensing osteocyte, and ii) the osteocyte's dendritic network of cell processes extending throughout the bone. Our findings of an excess of inhibitory OPN near osteocytes and their cell processes, and in dentin, spatially correlates with the defective mineralization observed at these sites in the skeleton and teeth of XLH patients. These changes likely contribute to the dento-osseous pathobiology of XLH, and participate in the aberrant bone adaptation and remodeling seen in XLH.
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Affiliation(s)
- Tchilalo Boukpessi
- Faculty of Dentistry, McGill University, Montreal, QC, Canada; EA 2496, Laboratory of Orofacial Pathologies, Imaging and Biotherapies, School of Dentistry University Paris Descartes Sorbonne Paris Cité, Paris, France; AP-HP Department of Odontology, Charles Foix and Bretonneau Hospitals, Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France.
| | - Betty Hoac
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Benjamin R Coyac
- Faculty of Dentistry, McGill University, Montreal, QC, Canada; EA 2496, Laboratory of Orofacial Pathologies, Imaging and Biotherapies, School of Dentistry University Paris Descartes Sorbonne Paris Cité, Paris, France
| | - Thibaut Leger
- Jacques Monod Institute, Proteomic Facility, University Paris Diderot Sorbonne Paris Cité, Paris, France
| | - Camille Garcia
- Jacques Monod Institute, Proteomic Facility, University Paris Diderot Sorbonne Paris Cité, Paris, France
| | - Philippe Wicart
- AP-HP Department of Pediatric Orthopedics, Necker Hospital, School of Medicine University Paris Descartes Sorbonne Paris Cité, Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA
| | | | - Agnès Linglart
- AP-HP Department of Pediatric Endocrinology, Kremlin Bicêtre Hospital, School of Medicine University Paris Sud, Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France
| | - Catherine Chaussain
- EA 2496, Laboratory of Orofacial Pathologies, Imaging and Biotherapies, School of Dentistry University Paris Descartes Sorbonne Paris Cité, Paris, France; AP-HP Department of Odontology, Charles Foix and Bretonneau Hospitals, Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France
| | - Marc D McKee
- Faculty of Dentistry, McGill University, Montreal, QC, Canada; Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, QC, Canada.
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Li SS, Gu JM, Yu WJ, He JW, Fu WZ, Zhang ZL. Seven novel and six de novo PHEX gene mutations in patients with hypophosphatemic rickets. Int J Mol Med 2016; 38:1703-1714. [PMID: 27840894 PMCID: PMC5117772 DOI: 10.3892/ijmm.2016.2796] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 10/18/2016] [Indexed: 11/11/2022] Open
Abstract
Inactivating mutations in phosphate-regulating gene with homologies to endopeptidase on the X chromosome (PHEX) have been identified as a cause of X-linked hypophosphatemic rickets (XLH; OMIM 307800). In the present study, we enrolled 43 patients from 18 unrelated families clinically diagnosed with hypophosphatemic rickets and 250 healthy controls. For each available individual, all 22 exons with their exon-intron boundaries of the PHEX gene were directly sequenced. The levels of serum fibroblast growth factor 23 (FGF23) were measured as well. Sequencing analysis detected 17 different PHEX gene mutations, and 7 of these were identified as novel: 3 missense mutations, including c.304G>A (p.Gly102Arg) in exon 3, c.229T>C (p.Cys77Arg) in exon 3 and c.824T>C (p.Leu275Pro) in exon 7; 2 deletion mutations, including c.528delT (p.Glu177LysfsX44) in exon 5 and c.1234delA (p.Ser412ValfsX12) in exon 11; and 2 alternative splicing mutations, including c.436_436+1delAG in intron 4 at splicing donor sites and c.1483-1G>C in intron 13 at splicing acceptor sites. Moreover, 6 mutations were proven to be de novo in 6 sporadic cases and the probands were all females. No mutations were found in the 250 healthy controls. The serum levels of FGF23 varied widely among the patients with XLH, and no significant difference was found when compared with those of the healthy controls. On the whole, the findings of this study provide new insight into the spectrum of PHEX mutations and provide potential evidence of a critical domain in PHEX protein. In addition, the finding of an overlap of the serum FGF23 levels between the patients with XLH and the healthy controls indicates its limited diagnostic value in XLH.
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Affiliation(s)
- Shan-Shan Li
- Metabolic Bone Disease and Genetics Research Unit, Department of Osteoporosis and Bone Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, P.R. China
| | - Jie-Mei Gu
- Metabolic Bone Disease and Genetics Research Unit, Department of Osteoporosis and Bone Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, P.R. China
| | - Wei-Jia Yu
- Metabolic Bone Disease and Genetics Research Unit, Department of Osteoporosis and Bone Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, P.R. China
| | - Jin-Wei He
- Metabolic Bone Disease and Genetics Research Unit, Department of Osteoporosis and Bone Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, P.R. China
| | - Wen-Zhen Fu
- Metabolic Bone Disease and Genetics Research Unit, Department of Osteoporosis and Bone Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, P.R. China
| | - Zhen-Lin Zhang
- Metabolic Bone Disease and Genetics Research Unit, Department of Osteoporosis and Bone Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, P.R. China
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Capelli S, Donghi V, Maruca K, Vezzoli G, Corbetta S, Brandi ML, Mora S, Weber G. Clinical and molecular heterogeneity in a large series of patients with hypophosphatemic rickets. Bone 2015; 79:143-9. [PMID: 26051471 DOI: 10.1016/j.bone.2015.05.040] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 05/05/2015] [Accepted: 05/18/2015] [Indexed: 12/21/2022]
Abstract
CONTEXT Hypophosphatemic rickets (HR) is a rare disease that includes a group of hereditary and sporadic conditions characterized by renal phosphate loss associated with normal to low vitamin D serum concentration. The most common form is the X-linked hypophosphatemic rickets, with an incidence of 1:20,000. Several mutations have recently been identified in the PHEX, FGF23, DMP1 and ENPP1 genes in patients with HR. Moreover, in vitro and in vivo studies suggested an involvement of MEPE for defective mineralization in HR. OBJECTIVE The present case series describes the clinical features and the analysis of genes implicated in HR in a cohort of 26 Italian HR patients. SETTING AND DESIGN All patients were analyzed for the PHEX and FGF23 genes by direct sequencing. When no mutations were detected, Multiplex Ligation-dependent Probe Amplification (MLPA) analysis was performed. The negative patients were screened for the DMP1, MEPE and ENPP1 genes by direct sequencing. RESULTS Twenty-two patients (84%) harbored mutations in the PHEX gene. In particular, we detected 19 different mutations, 15 of which were novel. One patient presented a novel splice variation in the ENPP1 gene while no alterations were identified in the FGF23, DMP1 and MEPE genes. The genetic study of the families showed that 11 patients (55%) had de novo mutations. Clinical presentation and disease severity did not show an evident correlation between the mutation types. CONCLUSIONS This report represents the first large familial study performed on Italian patients. It confirms that mutations in PHEX are the most frequent cause of HR. Furthermore, the variety of clinical manifestations identified in our HR patients underlines the extreme clinical and genetic heterogeneity of this disease.
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Affiliation(s)
- Silvia Capelli
- Laboratory of Pediatric Endocrinology, Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
| | - Valentina Donghi
- Department of Pediatrics, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
| | - Katia Maruca
- Laboratory of Pediatric Endocrinology, Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
| | - Giuseppe Vezzoli
- Nephrology and Dialysis Unit, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
| | - Sabrina Corbetta
- Endocrinology and Diabetology Unit, Department of Biomedical Sciences for Health, University of Milan, IRCCS Policlinico S. Donato, Piazza E. Malan 1, 20097 San Donato Milanese, Italy
| | - Maria Luisa Brandi
- Department of Internal Medicine, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy
| | - Stefano Mora
- Laboratory of Pediatric Endocrinology, Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy.
| | - Giovanna Weber
- Department of Pediatrics, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy
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Razali NN, Hwu TT, Thilakavathy K. Phosphate homeostasis and genetic mutations of familial hypophosphatemic rickets. J Pediatr Endocrinol Metab 2015; 28:1009-17. [PMID: 25894638 DOI: 10.1515/jpem-2014-0366] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 02/26/2015] [Indexed: 01/17/2023]
Abstract
Hypophosphatemic rickets (HR) is a syndrome of hypophosphatemia and rickets that resembles vitamin D deficiency, which is caused by malfunction of renal tubules in phosphate reabsorption. Phosphate is an essential mineral, which is important for bone and tooth structure. It is regulated by parathyroid hormone, 1,25-dihydroxyvitamin D and fibroblast-growth-factor 23 (FGF23). X-linked hypophosphatemia (XLH), autosomal dominant HR (ADHR), and autosomal recessive HR (ARHR) are examples of hereditary forms of HR, which are mainly caused by mutations in the phosphate regulating endopeptidase homolog, X-linked (PHEX), FGF23, and, dentin matrix protein-1 (DMP1) and ecto-nucleotide pyro phosphatase/phosphodiesterase 1 (ENPP1) genes, respectively. Mutations in these genes are believed to cause elevation of circulating FGF23 protein. Increase in FGF23 disrupts phosphate homeostasis, leading to HR. This review aims to summarize phosphate homeostasis and focuses on the genes and mutations related to XLH, ADHR, and ARHR. A compilation of XLH mutation hotspots based on the PHEX gene database and mutations found in the FGF23, DMP1, and ENPP1 genes are also made available in this review.
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Poon KS, Sng AA, Ho CW, Koay ESC, Loke KY. Genetic Testing Confirmed the Early Diagnosis of X-Linked Hypophosphatemic Rickets in a 7-Month-Old Infant. J Investig Med High Impact Case Rep 2015; 3:2324709615598167. [PMID: 26904698 PMCID: PMC4748509 DOI: 10.1177/2324709615598167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Loss-of-function mutations in the phosphate regulating gene with homologies to endopeptidases on the X-chromosome (PHEX) have been causally associated with X-linked hypophosphatemic rickets (XLHR). The early diagnosis of XLHR in infants is challenging when it is based solely on clinical features and biochemical findings. We report a 7-month-old boy with a family history of hypophosphatemic rickets., who demonstrated early clinical evidence of rickets, although serial biochemical findings could not definitively confirm rickets. A sequencing assay targeting the PHEX gene was first performed on the mother’s DNA to screen for mutations in the 5′UTR, 22 coding exons, and the exon-intron junctions. Targeted mutation analysis and mRNA studies were subsequently performed on the boys’ DNA to investigate the pathogenicity of the identified mutation. Genetic screening of the PHEX gene revealed a novel mutation, c.1080-2A>C, at the splice acceptor site in intron 9. The detection of an aberrant mRNA transcript with skipped (loss of) exon 10 establishes its pathogenicity and confirms the diagnosis of XLHR in this infant. Genetic testing of the PHEX gene resulted in early diagnosis of XLHR, thus enabling initiation of therapy and prevention of progressive rachitic changes in the infant.
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Affiliation(s)
| | | | | | - Evelyn Siew-Chuan Koay
- National University Health System, Singapore; National University of Singapore, Singapore
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Novel de novo nonsense mutation of the PHEX gene (p.Lys50Ter) in a Chinese patient with hypophosphatemic rickets. Gene 2015; 565:150-4. [DOI: 10.1016/j.gene.2015.03.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 03/18/2015] [Accepted: 03/29/2015] [Indexed: 01/20/2023]
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Yuan L, Wu S, Xu H, Xiao J, Yang Z, Xia H, Liu A, Hu P, Lu A, Chen Y, Xu F, Deng H. Identification of a novel PHEX mutation in a Chinese family with X-linked hypophosphatemic rickets using exome sequencing. Biol Chem 2015; 396:27-33. [PMID: 25060345 DOI: 10.1515/hsz-2014-0187] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 07/20/2014] [Indexed: 01/23/2023]
Abstract
Abstract
Familial hypophosphatemic rickets (HR), the most common inherited form of rickets, is a group of inherited renal phosphate wasting disorders characterized by growth retardation, rickets with bone deformities, osteomalacia, poor dental development, and hypophosphatemia. The purpose of this study was to identify the genetic defect responsible for familial HR in a four-generation Chinese Han pedigree by exome sequencing and Sanger sequencing. Clinical features include skeletal deformities, teeth abnormalities, hearing impairments and variable serum phosphate level in patients of this family. A novel deletion mutation, c.1553delT (p.F518Sfs*4), was identified in the X-linked phosphate regulating endopeptidase homolog gene (PHEX). The mutation is predicted to result in prematurely truncated and loss-of-function PHEX protein. Our data suggest that exome sequencing is a powerful tool to discover mutation(s) in HR, a disorder with genetic and clinical heterogeneity. The findings may also provide new insights into the cause and diagnosis of HR, and have implications for genetic counseling and clinical management.
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Mumm S, Huskey M, Cajic A, Wollberg V, Zhang F, Madson KL, Wenkert D, McAlister WH, Gottesman GS, Whyte MP. PHEX 3'-UTR c.*231A>G near the polyadenylation signal is a relatively common, mild, American mutation that masquerades as sporadic or X-linked recessive hypophosphatemic rickets. J Bone Miner Res 2015; 30:137-43. [PMID: 25042154 DOI: 10.1002/jbmr.2307] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 06/11/2014] [Accepted: 07/01/2014] [Indexed: 01/11/2023]
Abstract
Heritable forms of hypophosphatemic rickets (HR) include X-linked dominant (XLH), autosomal recessive, and autosomal dominant HR (from deactivating mutations in PHEX, DMP1 or ENPP1, and activating mutations in FGF23, respectively). Over 30 years, we have cared for 284 children with HR. For those 72 deemed sporadic XLH, we preliminarily reported mutation analysis for 30 subjects. Eleven had PHEX mutations. However, the remaining 19 lacked readily identifiable defects in PHEX, DMP1, or FGF23. In 2008, a novel single-base change near the polyadenylation (pA) signal in the 3'-UTR of PHEX was identified in XLH by other investigators. This c.*231A > G mutation is 3-bp upstream of the putative pA signal (AATAAA) in PHEX. Accordingly, we investigated whether this 3'-UTR defect accounted for HR in any of these 19 sporadic XLH patients. PCR amplification and sequencing of their 3'-UTR region showed the c.*231A > G mutation in four unrelated boys. Then, among an additional 22 of our 72 "sporadic" XLH patients, one boy and one girl were found to have the 3'-UTR defect, totaling six patients. Among these 52 sporadic XLH patients with PHEX analysis, 36 were girls and 16 were boys; ie, a ∼2:1 gender ratio consistent with XLH. However, finding five boys and only one girl with this 3'-UTR mutation presented an unexplained gender bias (p = 0.02). Haplotyping for the five boys, all reportedly unrelated, showed a common core haplotype suggesting a founder. Five of their six mothers had been studied clinically and biochemically (three radiologically). Remarkably, the seemingly unaffected mothers of four of these boys carried the 3'-UTR mutation. These healthy women had normal height, straight limbs, lacked the radiographic presentation of XLH, and showed normal or slight decreases in fasting serum Pi levels and/or TmP/GFR. Hence, PHEX c.*231A > G can masquerade as sporadic or X-linked recessive HR.
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Affiliation(s)
- Steven Mumm
- Division of Bone and Mineral Diseases, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA; Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO, USA
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Zou M, Buluş D, Al-Rijjal RA, Andıran N, BinEssa H, Kattan WE, Meyer B, Shi Y. Hypophosphatemic rickets caused by a novel splice donor site mutation and activation of two cryptic splice donor sites in the PHEX gene. J Pediatr Endocrinol Metab 2015; 28:211-6. [PMID: 25153221 DOI: 10.1515/jpem-2014-0103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 06/19/2014] [Indexed: 11/15/2022]
Abstract
X-linked hypophosphatemic rickets (XLH) is the most common inherited form of rickets. XLH is caused by inactivating mutations in the PHEX gene and is transmitted as an X-linked dominant disorder. We investigated PHEX mutation in a sporadic Turkish girl with hypophosphatemic rickets. The patient was 2 years of age with a complaint of inability to walk. She had bowing of legs and growth retardation. Laboratory data showed normal calcium, low phosphate with markedly elevated ALP, and low phosphate renal tubular reabsorption. She was treated with Calcitriol 0.5 mg/kg/day and oral phosphate supplement with good response. The entire coding region of PHEX gene was sequenced from patient's peripheral leukocyte DNA and a novel 13 bp deletion at the donor splice site of exon5 was found (c.663+12del). Instead of using the donor splice site of intron 4 to splice out exon 5 and intron 5, the spliceosome utilized two nearby cryptic donor splice sites (5' splice site) to splice out intron 4, resulting in two smaller transcripts. Both of them could not translate into functional proteins due to frameshift. Her parents did not carry the mutation, indicating that this is a de novo PHEX mutation likely resulting from mutagenesis of X chromosome in paternal germ cells. We conclude that c.663+12del is a novel mutation that can activate nearby cryptic 5' splice sites. The selection of cryptic 5' splice sites adds the complexity of cell's splicing mechanisms. The current study extends the database of PHEX mutation and cryptic 5' splice sites.
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Yue H, Yu JB, He JW, Zhang Z, Fu WZ, Zhang H, Wang C, Hu WW, Gu JM, Hu YQ, Li M, Liu YJ, Zhang ZL. Identification of two novel mutations in the PHEX gene in Chinese patients with hypophosphatemic rickets/osteomalacia. PLoS One 2014; 9:e97830. [PMID: 24836714 PMCID: PMC4024000 DOI: 10.1371/journal.pone.0097830] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 04/25/2014] [Indexed: 11/25/2022] Open
Abstract
Objective X-linked dominant hypophosphatemia (XLH) is the most prevalent form of inherited rickets/osteomalacia in humans. The aim of this study was to identify PHEX gene mutations and describe the clinical features observed in 6 unrelated Chinese families and 3 sporadic patients with hypophosphatemic rickets/osteomalacia. Methods For this study, 45 individuals from 9 unrelated families of Chinese Han ethnicity (including 16 patients and 29 normal phenotype subjects), and 250 healthy donors were recruited. All 22 exons and exon-intron boundaries of the PHEX gene were amplified by polymerase chain reaction (PCR) and directly sequenced. Results The PHEX mutations were detected in 6 familial and 3 sporadic hypophosphatemic rickets/osteomalacia. Altogether, 2 novel mutations were detected: 1 missense mutation c.1183G>C in exon 11, resulting in p.Gly395Arg and 1 missense mutation c.1751A>C in exon 17, resulting in p.His584Pro. No mutations were found in the 250 healthy controls. Conclusions Our study increases knowledge of the PHEX gene mutation types and clinical phenotypes found in Chinese patients with XLH, which is important for understanding the genetic basis of XLH. The molecular diagnosis of a PHEX genetic mutation is of great importance for confirming the clinical diagnosis of XLH, conducting genetic counseling, and facilitating prenatal intervention, especially in the case of sporadic patients.
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Affiliation(s)
- Hua Yue
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Jin-bo Yu
- Department of pediatrics, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Jin-wei He
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Zeng Zhang
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P.R. China
| | - Wen-zhen Fu
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Hao Zhang
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Chun Wang
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Wei-wei Hu
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Jie-mei Gu
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Yun-qiu Hu
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Miao Li
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Yu-juan Liu
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
| | - Zhen-Lin Zhang
- Department of Osteoporosis, Metabolic Bone Disease and Genetic Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, P. R. China
- * E-mail:
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Cheon CK, Lee HS, Kim SY, Kwak MJ, Kim GH, Yoo HW. A novel de novo mutation within PHEX gene in a young girl with hypophosphatemic rickets and review of literature. Ann Pediatr Endocrinol Metab 2014; 19:36-41. [PMID: 24926462 PMCID: PMC4049552 DOI: 10.6065/apem.2014.19.1.36] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/23/2013] [Accepted: 10/26/2013] [Indexed: 01/30/2023] Open
Abstract
X-linked hypophosphatemia (XLH) is the most common form of familial hypophosphatemic rickets and it is caused by loss-of-function mutations in the PHEX gene. Recently, a wide variety of PHEX gene defects in XLH have been revealed; these include missense mutations, nonsense mutations, splice site mutations, insertions, and deletions. Recently, we encountered a 2-year-9-month-old female with sporadic hypophosphatemic rickets. She underwent osteotomy, dental abscess was evident, and there was severe bowing of the legs. A low serum phosphorus level in combination with elevated serum alkaline phosphatase activity and normal serum calcium is suggestive of hypophosphatemic rickets. PHEX gene analysis revealed a splice acceptor site mutation, c.934-1G>T (IVS8(-1)G>T), at the intron8 and exon9 junction. To the best of our knowledge, this mutation is novel and has not been reported. The results of this study expand and improve our understanding of the clinical and molecular characteristics and the global pool of patients with sporadic hypophosphatemic rickets.
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Affiliation(s)
- Chong Kun Cheon
- Department of Pediatrics, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Hoon Sang Lee
- Department of Pediatrics, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Su Yung Kim
- Department of Pediatrics, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Min Jung Kwak
- Department of Pediatrics, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea
| | - Gu-Hwan Kim
- Medical Genetics Clinic and Laboratory, Asan Medical Center Children's Hospital, Seoul, Korea
| | - Han-Wook Yoo
- Medical Genetics Clinic and Laboratory, Asan Medical Center Children's Hospital, Seoul, Korea
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Lim YH, Ovejero D, Sugarman JS, Deklotz CMC, Maruri A, Eichenfield LF, Kelley PK, Jüppner H, Gottschalk M, Tifft CJ, Gafni RI, Boyce AM, Cowen EW, Bhattacharyya N, Guthrie LC, Gahl WA, Golas G, Loring EC, Overton JD, Mane SM, Lifton RP, Levy ML, Collins MT, Choate KA. Multilineage somatic activating mutations in HRAS and NRAS cause mosaic cutaneous and skeletal lesions, elevated FGF23 and hypophosphatemia. Hum Mol Genet 2013; 23:397-407. [PMID: 24006476 DOI: 10.1093/hmg/ddt429] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Pathologically elevated serum levels of fibroblast growth factor-23 (FGF23), a bone-derived hormone that regulates phosphorus homeostasis, result in renal phosphate wasting and lead to rickets or osteomalacia. Rarely, elevated serum FGF23 levels are found in association with mosaic cutaneous disorders that affect large proportions of the skin and appear in patterns corresponding to the migration of ectodermal progenitors. The cause and source of elevated serum FGF23 is unknown. In those conditions, such as epidermal and large congenital melanocytic nevi, skin lesions are variably associated with other abnormalities in the eye, brain and vasculature. The wide distribution of involved tissues and the appearance of multiple segmental skin and bone lesions suggest that these conditions result from early embryonic somatic mutations. We report five such cases with elevated serum FGF23 and bone lesions, four with large epidermal nevi and one with a giant congenital melanocytic nevus. Exome sequencing of blood and affected skin tissue identified somatic activating mutations of HRAS or NRAS in each case without recurrent secondary mutation, and we further found that the same mutation is present in dysplastic bone. Our finding of somatic activating RAS mutation in bone, the endogenous source of FGF23, provides the first evidence that elevated serum FGF23 levels, hypophosphatemia and osteomalacia are associated with pathologic Ras activation and may provide insight in the heretofore limited understanding of the regulation of FGF23.
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Abstract
Over the last decade the discovery of fibroblast growth factor 23 (FGF23) and the progressive and ongoing clarification of its role in phosphate and mineral metabolism have led to expansion of the diagnostic spectrum of primary hypophosphatemic syndromes. This article focuses on the impairment of growth in these syndromes. Growth retardation is a common, but not constant, feature and it presents with large variability. As a result of the very low prevalence of other forms of primary hypophosphatemic syndromes, the description of longitudinal growth and the pathogenesis of its impairment have been mostly studied in X-linked hypophosphatemia (XLH) patients and in Hyp mice, the animal model of this disease. In general, children with XLH have short stature with greater shortness of lower limbs than trunk. Treatment with phosphate supplements and 1α vitamin D derivatives heals active lesions of rickets, but does not normalize growth of XLH patients. Patients might benefit from recombinant human growth hormone (rhGH) therapy, which may accelerate the growth rate without increasing body disproportion or correcting hypophosphatemia. These clinical data as well as research findings obtained in Hyp mice suggest that the pathogenesis of defective growth in XLH and other hypophosphatemic syndromes is not entirely dependent on the mineralization disorder and point to other effects of hypophosphatemia itself or FGF23 on the metabolism of bone and growth plate.
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Affiliation(s)
- Fernando Santos
- Hospital Universitario Central de Asturias & University of Oviedo, Oviedo, Asturias, Spain.
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Yang L, Yang J, Huang X. PHEX gene mutation in a Chinese family with six cases of X-linked hypophosphatemic rickets. J Pediatr Endocrinol Metab 2013; 26:1179-83. [PMID: 23813354 DOI: 10.1515/jpem-2013-0101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 06/03/2013] [Indexed: 12/15/2022]
Abstract
OBJECTIVE X-linked hypophosphatemic (XLH) rickets is caused by inactivating mutations in the PHEX gene, which encodes a metalloprotease that cleaves small peptide hormone. So far there are only a few reports on XLH patients from China. In the present study, we report on six XLH patients from one family. A PHEX missense mutation was found in exon 22, and a literature review on the mutations of Chinese patients was undertaken. CASE DESCRIPTION The family included six XLH patients with five females and one male (the proband). All the patients showed a low serum phosphorus, increased blood alkaline phosphatase and normal calcium levels. Mutation analysis revealed a PHEX mutation in exon 22 (c.2237G>A). In total, 15 PHEX mutations have been reported in Chinese populations at this time. CONCLUSION These data extend the spectrum of mutations in the PHEX gene in Chinese populations.
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Durmaz E, Zou M, Al-Rijjal RA, Baitei EY, Hammami S, Bircan I, Akçurin S, Meyer B, Shi Y. Novel and de novo PHEX mutations in patients with hypophosphatemic rickets. Bone 2013; 52:286-91. [PMID: 23079138 DOI: 10.1016/j.bone.2012.10.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 10/07/2012] [Accepted: 10/08/2012] [Indexed: 01/18/2023]
Abstract
X-linked hypophosphatemic rickets (XLH) is the most common inherited rickets. XLH is caused by inactivating mutations in the PHEX gene and is transmitted as an X-linked dominant disorder. We investigated PHEX mutation in 10 patients from 6 unrelated Turkish families by PCR-sequence analysis. Six different PHEX mutations were detected in the patients. Four of them were novel: c.1217G>A (p.C406Y) in exon 11, c.2078G>T (p.C693F) in exon 21, a splice donor site mutation in intron 13 (IVS13+1G>T), and a splice acceptor site mutation in intron 13 (IVS13-2A>G). De novo PHEX mutations were found exclusively in female patients from 4 families and inherited mutations were detected from remaining two families. The patients' phenotype was consistent with the loss of PHEX function. Literature review of 78 sporadic cases shows that de novo mutations are present in 83% female patients and female/male ratio is 5 to 1. One patient had biallilic PHEX mutations at c.1735G>A (p.G579R) whereas her mother and two siblings carried a monoallelic mutation. The clinical and laboratory findings of the patient with biallilic PHEX mutation were similar to those with monoallelic mutation. The study shows that PHEX mutation is a common cause of either familial or sporadic hypophosphatemic rickets in Turkish population. Gene dosage effect is not observed. The frequent de novo mutations found in the female patients are likely resulting from mutagenesis of X chromosome in paternal germ cells.
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Affiliation(s)
- Erdem Durmaz
- Department of Pediatric Endocrinology, Akdeniz University School of Medicine, Antalya, Turkey
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Karaplis AC, Bai X, Falet JP, Macica CM. Mineralizing enthesopathy is a common feature of renal phosphate-wasting disorders attributed to FGF23 and is exacerbated by standard therapy in hyp mice. Endocrinology 2012; 153:5906-17. [PMID: 23038738 PMCID: PMC3512070 DOI: 10.1210/en.2012-1551] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 09/07/2012] [Indexed: 11/19/2022]
Abstract
We have previously confirmed a paradoxical mineralizing enthesopathy as a hallmark of X-linked hypophosphatemia. X-linked hypophosphatemia is the most common of the phosphate-wasting disorders mediated by elevated fibroblast growth factor 23 (FGF23) and occurs as a consequence of inactivating mutations of the PHEX gene product. Despite childhood management of the disease, these complications of tendon and ligament insertion sites account for a great deal of the disease's morbidity into adulthood. It is unclear whether the enthesopathy occurs in other forms of renal phosphate-wasting disorders attributable to high FGF23 levels. Here we describe two patients with autosomal recessive hypophosphatemic rickets due to the Met1Val mutation in dentin matrix acidic phosphoprotein 1 (DMP1). In addition to the biochemical and skeletal features of long-standing rickets with elevated FGF23 levels, these individuals exhibited severe, debilitating, generalized mineralized enthesopathy. These data suggest that enthesophytes are a feature common to FGF23-mediated phosphate-wasting disorders. To address this possibility, we examined a murine model of FGF23 overexpression using a transgene encoding the secreted form of human FGF23 (R176Q) cDNA (FGF23-TG mice). We report that FGF23-TG mice display a similar mineralizing enthesopathy of the Achilles and plantar facial insertions. In addition, we examined the impact of standard therapy for phosphate-wasting disorders on enthesophyte progression. We report that fibrochondrocyte hyperplasia persisted in Hyp mice treated with oral phosphate and calcitriol. In addition, treatment had the untoward effect of further exacerbating the mineralization of fibrochondrocytes that define the bone spur of the Achilles insertion. These studies support the need for newer interventions targeted at limiting the actions of FGF23 and minimizing both the toxicities and potential morbidities associated with standard therapy.
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Owen C, Chen F, Flenniken AM, Osborne LR, Ichikawa S, Adamson SL, Rossant J, Aubin JE. A novel Phex mutation in a new mouse model of hypophosphatemic rickets. J Cell Biochem 2012; 113:2432-41. [PMID: 22573557 DOI: 10.1002/jcb.24115] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
X-linked hypophosphatemic rickets (XLH) is a dominantly inherited disease characterized by renal phosphate wasting, aberrant vitamin D metabolism, and defective bone mineralization. It is known that XLH in humans and in certain mouse models is caused by inactivating mutations in PHEX/Phex (phosphate-regulating gene with homologies to endopeptidases on the X chromosome). By a genome-wide N-ethyl-N-nitrosourea (ENU)-induced mutagenesis screen in mice, we identified a dominant mouse mutation that exhibits the classic clinical manifestations of XLH, including growth retardation, skeletal abnormalities (rickets/osteomalacia), hypophosphatemia, and increased serum alkaline phosphatase (ALP) levels. Mapping and sequencing revealed that these mice carry a point mutation in exon 14 of the Phex gene that introduces a stop codon at amino acid 496 of the coding sequence (Phex(Jrt) also published as Phex(K496X) [Ichikawa et al., 2012]). Fgf23 mRNA expression as well as that of osteocalcin, bone sialoprotein, and matrix extracellular phosphoglycoprotein was upregulated in male mutant long bone, but that of sclerostin was unaffected. Although Phex mRNA is expressed in bone from mutant hemizygous male mice (Phex(Jrt)/Y mice), no Phex protein was detected in immunoblots of femoral bone protein. Stromal cultures from mutant bone marrow were indistinguishable from those of wild-type mice with respect to differentiation and mineralization. The ability of Phex(Jrt)/Y osteoblasts to mineralize and the altered expression levels of matrix proteins compared with the well-studied Hyp mice makes it a unique model with which to further explore the clinical manifestations of XLH and its link to FGF23 as well as to evaluate potential new therapeutic strategies.
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Affiliation(s)
- Celeste Owen
- Centre For Modeling Human Disease, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
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