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Cai M, Chen X, Li Y, Lin N, Huang H, Xu L. Genetic analysis, ultrasound phenotype, and pregnancy outcomes of fetuses with Xp22.33 or Yp11.32 microdeletions. J Perinat Med 2024; 52:96-101. [PMID: 37846158 DOI: 10.1515/jpm-2023-0190] [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: 05/05/2023] [Accepted: 08/27/2023] [Indexed: 10/18/2023]
Abstract
OBJECTIVES The phenotypes of Xp22.33 or Yp11.32 microdeletions comprising the short-stature homeobox (SHOX) gene have been extensively described in adults and children. Herein, the prenatal ultrasound phenotype and pregnancy outcomes of fetuses with Xp22.33/Yp11.32 microdeletions were analyzed to improve our understanding, diagnosis, and monitoring of this genetic condition in the fetal stage. METHODS A total of 9,100 pregnant women referred to tertiary units for prenatal diagnosis were evaluated by chromosomal microarray analysis(CMA). RESULTS Seven (0.08 %) fetuses had Xp22.33/Yp11.32 microdeletions, ranging from 243 kb to 1.1 Mb, that comprised SHOX. The ultrasonic phenotypes differed among these fetuses, with three fetuses presenting abnormal bone development, one had labial-palatal deformity and strawberry head, two had an abnormal ultrasonic soft marker, and one had no abnormalities. After genetic counseling, only one couple underwent pedigree assessment, which confirmed the paternal origin of the microdeletion. This infant presented delayed speech development, whereas other three infants showed a typical postnatal development. In three cases, the parents chose to terminate the pregnancy. CONCLUSIONS The ultrasonic phenotype of fetuses with Xp22.33/Yp11.32 microdeletions resulting in SHOX heterozygosity loss is variable. Prenatal CMA can quickly and effectively diagnose Xp22.33/Yp11.32 microdeletions and SHOX loss, which may help prenatal counseling.
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Affiliation(s)
- Meiying Cai
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fuzhou, P.R. China
| | - Xuemei Chen
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fuzhou, P.R. China
| | - Ying Li
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fuzhou, P.R. China
| | - Na Lin
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fuzhou, P.R. China
| | - Hailong Huang
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fuzhou, P.R. China
| | - Liangpu Xu
- Medical Genetic Diagnosis and Therapy Center, Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Key Laboratory for Prenatal Diagnosis and Birth Defect, Fuzhou, P.R. China
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2
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Liu L, Li J, Li J, Hu H, Liu J, Tang P. Novel heterozygous mutation in the SHOX gene leading to familial idiopathic short stature: A case report and literature review. Medicine (Baltimore) 2023; 102:e35471. [PMID: 37832088 PMCID: PMC10578768 DOI: 10.1097/md.0000000000035471] [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: 07/05/2023] [Accepted: 09/13/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND The pathogenic mutation of short stature homeobox (SHOX) gene is one of the main genetic causes of short stature in children, with an incidence rate of 1/1000~1/2000 and the main clinical manifestations are short stature and (or) limb skeletal abnormalities. SHOX gene mutations are mostly large deletions of regulatory sequence genes, while exon mutations are relatively rare. The pathogenic rate of mutations occurring in exon 5 is only 1/50 000~1/100 000. This study reviewed the clinical data of a child with SHOX gene mutation in exon 5, and analyzed the clinical phenotype, pathogenesis, diagnosis, treatment and prognosis of SHOX gene mutation in combination with relevant literature at home and abroad. CASE PRESENTATION The patient was an 8-year-old girl with a height of 105.2 cm (-4.31 standard deviations). Her sitting height/height ratio was 56.8% (>55.5%), and she exhibited high-arched palate, irregular dentition, micrognathia, short fingers, and a normal growth hormone stimulation test. Whole-exome sequencing was performed, and Sanger sequencing was used for site validation. The sequencing results revealed a heterozygous mutation of c.577G > A in exon 5 of the SHOX gene, inherited from the father. The clinical symptoms of the proband were consistent with the phenotype of short stature idiopathic familial associated with SHOX gene mutations. The father, grandfather, uncle, and sister of the proband all had the c.577G > A heterozygous mutation. Therefore, the clinical diagnosis was childhood short stature caused by SHOX gene defects. The SHOX: c.577G > A mutation is likely to be the genetic etiology of familial idiopathic short stature in this family, and this novel mutation enriches the mutation spectrum of the SHOX gene. CONCLUSION This is the first case report of familial idiopathic dwarfism caused by mutation at the c.577G > A locus of exon 5 of SHOX gene in the world. This novel mutation enriches the mutation spectrum of the SHOX gene. It is important to emphasize genetic testing, including the SHOX gene, in patients with familial idiopathic short stature and to provide timely growth hormone therapy to individuals with short stature caused by SHOX gene mutations in order to improve their adult height.
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Affiliation(s)
- Lifang Liu
- Lishui Maternal and Child Health Hospital, Lishui, Zhejiang, China
| | - Junsheng Li
- Lishui Maternal and Child Health Hospital, Lishui, Zhejiang, China
| | - Jiarui Li
- Department of Orthopaedic Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hui Hu
- Lishui Maternal and Child Health Hospital, Lishui, Zhejiang, China
| | - Jiao Liu
- Lishui Maternal and Child Health Hospital, Lishui, Zhejiang, China
| | - Ping Tang
- Jiaxing Maternity and Children Health Care Hospital/The Affiliated Women and Children’s Hospital of Jiaxing University, Jiaxing, Zhejiang, China
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Abstract
Growth hormone (GH) is an injectable medication originally used to replace the deficiency of the hormone, but has expanded to treating conditions that may reduce growth and adult height even when the body maintains endogenous GH production. In the United States, there are 8 Food and Drug Administration (FDA)-approved indications for pediatric GH therapy: GH deficiency, Prader-Willi Syndrome, small for gestational age (SGA) without catch-up growth, idiopathic short stature, Turner syndrome, SHOX gene haploinsufficiency, Noonan Syndrome, and chronic renal insufficiency. We characterize the growth patterns and effects of GH treatment in each of these indications. We also review patterns of growth that warrant referral to a pediatric endocrinologist, as well as safety updates. This review is intended to guide practitioners on the initial evaluation and management of patients with short stature, and the indications for GH therapy.
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Affiliation(s)
- Melinda Danowitz
- CHOP Division of Pediatric Endocrinology, Abramson Building, Office 804F, 3401 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Adda Grimberg
- Children's Hospital of Philadelphia, The Hub for Clinical Collaboration, Division of Endocrinology, 7th floor, 3500 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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4
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Giordano M, Stuppia L. Editorial: Novel Insights Into the Genetics of Growth Disorders. Front Genet 2022; 13:920469. [PMID: 35754806 PMCID: PMC9214029 DOI: 10.3389/fgene.2022.920469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 04/27/2022] [Indexed: 11/21/2022] Open
Affiliation(s)
- Mara Giordano
- Laboratory of Genetics, SCDU Clinical Biochemistry, University Hospital "Maggiore della Carità", Novara and Department of Health Sciences, University of Eastern Piedmont, Novara, Italy
| | - Liborio Stuppia
- Department of Psychological, Health and Territorial Sciences and Center for Advanced Sciences and Technology (CAST), G. d'Annunzio University, Chieti-Pescara, Italy
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Orso M, Polistena B, Granato S, Novelli G, Di Virgilio R, La Torre D, d’Angela D, Spandonaro F. Pediatric growth hormone treatment in Italy: A systematic review of epidemiology, quality of life, treatment adherence, and economic impact. PLoS One 2022; 17:e0264403. [PMID: 35213607 PMCID: PMC8880399 DOI: 10.1371/journal.pone.0264403] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 02/09/2022] [Indexed: 11/18/2022] Open
Abstract
Objectives This systematic review aims to describe 1) the epidemiology of the diseases indicated for treatment with growth hormone (GH) in Italy; 2) the adherence to the GH treatment in Italy and factors associated with non-adherence; 3) the economic impact of GH treatment in Italy; 4) the quality of life of patients treated with GH and their caregivers in Italy. Methods Systematic literature searches were performed in PubMed, Embase and Web of Science from January 2010 to March 2021. Literature selection process, data extraction and quality assessment were performed by two independent reviewers. Study protocol has been registered in PROSPERO (CRD42021240455). Results We included 25 studies in the qualitative synthesis. The estimated prevalence of growth hormone deficiency (GHD) was 1/4,000–10,000 in the general population of children; the prevalence of Short Stature HOmeoboX Containing gene deficiency (SHOX-D) was 1/1,000–2,000 in the general population of children; the birth prevalence of Turner syndrome was 1/2,500; the birth prevalence of Prader-Willi syndrome (PWS) was 1/15,000. Treatment adherence was suboptimal, with a range of non-adherent patients of 10–30%. The main reasons for suboptimal adherence were forgetfulness, being away from home, pain/discomfort caused by the injection. Economic studies reported a total cost for a complete multi-year course of GH treatment of almost 100,000 euros. A study showed that drug wastage can amount up to 15% of consumption, and that in some Italian regions there could be a considerable over- or under-prescribing. In general, patients and caregivers considered the GH treatment acceptable. There was a general satisfaction among patients with regard to social and school life and GH treatment outcomes, while there was a certain level of intolerance to GH treatment among adolescents. Studies on PWS patients and their caregivers showed a lower quality of life compared to the general population, and that social stigma persists. Conclusion Growth failure conditions with approved GH treatment in Italy constitute a significant burden of disease in clinical, social, and economic terms. GH treatment is generally considered acceptable by patients and caregivers. The total cost of the GH treatment is considerable; there are margins for improving efficiency, by increasing adherence, reducing drug wastage and promoting prescriptive appropriateness.
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Affiliation(s)
- Massimiliano Orso
- C.R.E.A. Sanità (Centre for Applied Economic Research in Healthcare), Rome, Italy
- * E-mail:
| | - Barbara Polistena
- C.R.E.A. Sanità (Centre for Applied Economic Research in Healthcare), Rome, Italy
- University of Rome Tor Vergata, Rome, Italy
| | | | - Giuseppe Novelli
- Health Economics & Outcomes Research, Pfizer Italia, Rome, Italy
| | | | - Daria La Torre
- Global Medical Affairs, Pfizer Rare Disease, Rome, Italy
| | - Daniela d’Angela
- C.R.E.A. Sanità (Centre for Applied Economic Research in Healthcare), Rome, Italy
- University of Rome Tor Vergata, Rome, Italy
| | - Federico Spandonaro
- C.R.E.A. Sanità (Centre for Applied Economic Research in Healthcare), Rome, Italy
- San Raffaele University, Rome, Italy
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Fanelli A, Vannelli S, Babu D, Mellone S, Cucci A, Monzani A, Al Essa W, Secco A, Follenzi A, Bellone S, Prodam F, Giordano M. Copy number variations residing outside the SHOX enhancer region are involved in Short Stature and Léri-Weill dyschondrosteosis. Mol Genet Genomic Med 2021; 10:e1793. [PMID: 34811950 PMCID: PMC8801136 DOI: 10.1002/mgg3.1793] [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: 11/16/2020] [Revised: 07/19/2021] [Accepted: 08/16/2021] [Indexed: 11/25/2022] Open
Abstract
Background SHOX enhancer CNVs, affecting one or more of the seven recognized evolutionary conserved non‐coding elements (CNEs) represent one of the most frequent cause of SHOX‐haploinsufficiency. During the diagnostic workflow deletions/duplications have been identified downstream SHOX not including any of the these CNEs. Methods Fine tiling aCGH and breakpoint PCR were used to characterize the critical interval and to search for novel alterations in a cohort of selected patients. Results Screening of 252 controls provided evidence that duplications in this area represent likely benign variants whereas none of the deletions were detected. These findings suggested that other alterations relevant for SHOX‐haploinsufficiency might be missed by the standard diagnostic methods. To identify such undisclosed elements, the aCGH was used to reanalyze 52 unresolved cases with clinical features strongly suggestive of SHOX‐haploinsufficiency. This analysis followed by the screening of 210 patients detected two partially overlapping small deletions of ~12 and ~8 kb in four unrelated individuals, approximately 15 kb downstream SHOX, that were absent in 720 normal stature individuals. Conclusion Our results strengthen the hypothesis that alterations of yet unidentified cis‐regulatory elements residing outside those investigated through conventional methods, might explain the phenotype in ISS/LWD patients thus enlarging the spectrum of variants contributing to SHOX‐haploinsufficiency.
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Affiliation(s)
- Antonella Fanelli
- Dipartimento di Scienze della Salute, Università del Piemonte Orientale, Novara, Italy
| | - Silvia Vannelli
- Endocrinologia Pediatrica, Dipartimento di Pediatria e Specialità Pediatriche, Ospedale Regina Margherita, Citta della Salute e della Scienza, Torino, Italy
| | - Deepak Babu
- Dipartimento di Scienze della Salute, Università del Piemonte Orientale, Novara, Italy
| | - Simona Mellone
- Laboratorio di Genetica, S.C.D.U Biochimica Clinica, Azienda Ospedaliera Universitaria "Maggiore della Carità", Novara, Italy
| | - Alessia Cucci
- Dipartimento di Scienze della Salute, Università del Piemonte Orientale, Novara, Italy
| | - Alice Monzani
- Divisione di Pediatria, AOU "Maggiore della Carità", Novara, Italy
| | - Wael Al Essa
- Dipartimento di Scienze della Salute, Università del Piemonte Orientale, Novara, Italy
| | - Andrea Secco
- SC Pediatria e DEA Pediatrico, Azienda Ospedaliera SS. Antonio e Biagio e Cesare Arrigo, Alessandria, Italy
| | - Antonia Follenzi
- Dipartimento di Scienze della Salute, Università del Piemonte Orientale, Novara, Italy
| | - Simonetta Bellone
- Dipartimento di Scienze della Salute, Università del Piemonte Orientale, Novara, Italy.,Divisione di Pediatria, AOU "Maggiore della Carità", Novara, Italy
| | - Flavia Prodam
- Dipartimento di Scienze della Salute, Università del Piemonte Orientale, Novara, Italy.,Divisione di Endocrinologia, AOU "Maggiore della Carità", Novara, Italy
| | - Mara Giordano
- Dipartimento di Scienze della Salute, Università del Piemonte Orientale, Novara, Italy.,Laboratorio di Genetica, S.C.D.U Biochimica Clinica, Azienda Ospedaliera Universitaria "Maggiore della Carità", Novara, Italy
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7
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Lee JS, Kim HY, Lee YA, Lee SY, Cho TJ, Ko JM. Clinical and Genetic Characteristics of 23 Korean Patients with Haploinsufficiency of the Short-stature Homeobox-containing Gene. Exp Clin Endocrinol Diabetes 2020; 129:611-620. [PMID: 32932528 DOI: 10.1055/a-1247-4863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
BACKGROUND The short-stature homeobox-containing gene (SHOX) is one of the major growth genes in humans. The clinical spectrum of SHOX haploinsufficiency ranges from Léri-Weill dyschondrosteosis to idiopathic short stature. Herein, we describe the clinical and genetic characteristics of 23 Korean patients with SHOX deficiency disorders. METHODS Medical records of 23 patients (19 females and 4 males) from 15 unrelated families who were genetically confirmed to have SHOX deficiency were retrospectively reviewed. SHOX gene deletions or mutations were determined by sequence analyses using multiplex ligation-dependent probe amplification, chromosomal microarray, and/or Sanger sequencing methods. RESULTS In the 15 families, 9 probands were de novo cases. All 23 patients showed mesomelia. Madelung deformity and tibia vara were observed in 13 (56.5%) and 3 (13.1%) patients, respectively. Genetically, 11 (73.3%) of the 15 families showed SHOX deletions of various sizes, and the other 4 families harboured SHOX sequence variants. Four patients had undergone orthopaedic surgeries (3 for tibia vara and 1 for Madelung deformity). Among 7 patients who had received growth hormone treatment for ≥1 year, 5 showed good responses, with a median first-year change-in-height standard deviation score of +0.6. There were no significant differences in the clinical characteristics of the deletion and point mutation groups. CONCLUSIONS A high index of suspicion and the genetic confirmation of SHOX deficiency are helpful for the timely management of the condition and are needed to provide genetic counselling to the family members of the patients.
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Affiliation(s)
- Jeong-Seon Lee
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul
| | - Hwa Young Kim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul
| | - Young-Ah Lee
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul
| | - Seong-Young Lee
- Department of Pediatrics, SMG-SNU Boramae Medical Center, Seoul
| | - Tae-Joon Cho
- Department of Orthopaedics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul
| | - Jung Min Ko
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul
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Joustra SD, Kamp GA, Stalman SE, Donze SH, Losekoot M, Kant SG, de Bruin C, Oostdijk W, Wit JM. Novel Clinical Criteria Allow Detection of Short Stature Homeobox-Containing Gene Haploinsufficiency Caused by Either Gene or Enhancer Region Defects. Horm Res Paediatr 2020; 92:372-381. [PMID: 32344414 DOI: 10.1159/000507215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 03/11/2020] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Short stature homeobox-containing gene (SHOX) haploinsufficiency is associated with short stature, Madelung deformity and mesomelia. Current clinical screening tools are based on patients with intragenic variants or deletions. However, recent discoveries showed that deletions of the enhancer elements are quite common. The majority of these patients show less body disproportion and respond better to recombinant human growth hormone treatment. We redefined clinical criteria for genetic analysis to facilitate detection of the full spectrum of SHOX haploinsufficiency. METHODS We analyzed 51 children with SHOX variants or deletions and 25 children with a deletion in its enhancer region. Data were compared to 277 children referred for suspicion of growth failure without endocrine or genetic pathology. RESULTS Only half of the patients with an enhancer region deletion fulfilled any of the current screening criteria. We propose new clinical criteria based on sitting height to height ratio >1 SDS or arm span ≥3 cm below height, with a sensitivity of 99%. When these criteria are combined with obligatory short stature, the sensitivity to detect SHOX haploinsufficiency is 68.1%, the specificity 80.6%, and the number needed to screen 21 patients. CONCLUSION Novel clinical criteria for screening for SHOX haploinsufficiency allow the detection of patients within the full genetic spectrum, that is, intragenic variants and enhancer region deletions.
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Affiliation(s)
- Sjoerd D Joustra
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands,
| | - Gerdine A Kamp
- Department of Pediatric Endocrinology, Tergooi Hospital, Blaricum, The Netherlands
| | - Susanne E Stalman
- Department of Pediatrics, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Stephany H Donze
- Department of Pediatrics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Dutch Growth Research Foundation, Rotterdam, The Netherlands
| | - Monique Losekoot
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Sarina G Kant
- Department of Clinical Genetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Christiaan de Bruin
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands
| | - Wilma Oostdijk
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands
| | - Jan M Wit
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands
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9
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Variants in the 5'UTR reduce SHOX expression and contribute to SHOX haploinsufficiency. Eur J Hum Genet 2020; 29:110-121. [PMID: 32647378 PMCID: PMC7852508 DOI: 10.1038/s41431-020-0676-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/08/2020] [Accepted: 06/23/2020] [Indexed: 11/08/2022] Open
Abstract
SHOX haploinsufficiency causes 70-90% of Léri-Weill dyschondrosteosis (LWD) and 2-10% of idiopathic short stature (ISS). Deletions removing the entire gene or enhancers and point mutations in the coding region represent a well-established cause of haploinsufficiency. During diagnostic genetic testing on ISS/LWD patients, in addition to classic SHOX defects, five 5'UTR variants (c.-58G > T, c.-55C > T, c.-51G > A, c.-19G > A, and c.-9del), were detected whose pathogenetic role was unclear and were thus classified as VUS (Variants of Uncertain Significance). The purpose of the present study was to investigate the role of these noncoding variations in SHOX haploinsufficiency. The variants were tested for their ability to interfere with correct gene expression of a regulated reporter gene (luciferase assay). The negative effect on the mRNA splicing predicted in silico for c.-19G > A was assayed in vitro through a minigene splicing assay. The luciferase assay showed that c.-51G > A, c.-19G > A, and c.-9del significantly reduce luciferase activity by 60, 35, and 40% at the homozygous state. Quantification of the luciferase mRNA showed that c.-51G > A and c.-9del might interfere with the correct SHOX expression mainly at the post-transcriptional level. The exon trapping assay demonstrated that c.-19G > A determines the creation of a new branch site causing an aberrant mRNA splicing. In conclusion, this study allowed us to reclassify two of the 5'UTR variants identified during SHOX diagnostic screening as likely pathogenic, one remains as a VUS, and two as likely benign variants. This analysis for the first time expands the spectrum of the genetic causes of SHOX haploinsufficiency to noncoding variations in the 5'UTR.
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Navarro-Cobos MJ, Balaton BP, Brown CJ. Genes that escape from X-chromosome inactivation: Potential contributors to Klinefelter syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:226-238. [PMID: 32441398 PMCID: PMC7384012 DOI: 10.1002/ajmg.c.31800] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/01/2020] [Accepted: 05/03/2020] [Indexed: 12/18/2022]
Abstract
One of the two X chromosomes in females is epigenetically inactivated, thereby compensating for the dosage difference in X-linked genes between XX females and XY males. Not all X-linked genes are completely inactivated, however, with 12% of genes escaping X chromosome inactivation and another 15% of genes varying in their X chromosome inactivation status across individuals, tissues or cells. Expression of these genes from the second and otherwise inactive X chromosome may underlie sex differences between males and females, and feature in many of the symptoms of XXY Klinefelter males, who have both an inactive X and a Y chromosome. We review the approaches used to identify genes that escape from X-chromosome inactivation and discuss the nature of their sex-biased expression. These genes are enriched on the short arm of the X chromosome, and, in addition to genes in the pseudoautosomal regions, include genes with and without Y-chromosomal counterparts. We highlight candidate escape genes for some of the features of Klinefelter syndrome and discuss our current understanding of the mechanisms underlying silencing and escape on the X chromosome as well as additional differences between the X in males and females that may contribute to Klinefelter syndrome.
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Affiliation(s)
- Maria Jose Navarro-Cobos
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
| | - Bradley P Balaton
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
| | - Carolyn J Brown
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
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