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Hussein D, Altın B, Bajin MD. Audiological findings of a patient with H syndrome: case report. THE EGYPTIAN JOURNAL OF OTOLARYNGOLOGY 2021. [PMCID: PMC8642771 DOI: 10.1186/s43163-021-00185-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Background H syndrome is an autosomal recessive disorder caused by mutations in SLC29A3. Hyperpigmentation, hypertrichosis, hyperglycemia, and hearing loss are some characteristics of this disorder, and it has a prevalence of < 1/1000. The aim of this report is to spread awareness among otologists, audiologists, and pediatricians about this syndrome and its audiological features. Case presentation An 8-year-old male with a diagnosed H syndrome registered to our clinic with a complaint of hearing loss. The patient was diagnosed with hearing loss in a different clinic using only the air-conducted click auditory brainstem response test which showed wave V at 60 dB nHL for the right ear and at 80 dB nHL for the left ear. The initially performed pure tone audiometry (PTA) test in our clinic revealed a bilateral asymmetric hearing loss with a moderate sensorineural hearing loss in the right ear and a profound mixed hearing loss in the left ear. The performed air conducted click auditory brainstem response (ABR) result showed wave V at 55 dB nHL for the right ear and at 70 dB nHL for the left ear. Then, the repeated PTA test revealed a mild-severe sensorineural sloping hearing loss in the right ear and a severe sensorineural hearing loss in the left ear. Conclusion Although hearing thresholds in H syndrome could be within normal limits in some patients, sensorineural hearing loss is an important characteristic feature for this syndrome. Sensorineural hearing loss could be progressive or of sudden onset and ranges from mild to profound. Thus, it must be taken into consideration to apply the audiological follow-up regularly and paying attention to the patient’s complaints; also, a regular follow-up for language development of children with H syndrome and for the hearing aids is advised.
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Phenotypic intrafamilial variability including H syndrome and Rosai-Dorfman disease associated with the same c.1088G > A mutation in the SLC29A3 gene. Hum Genomics 2021; 15:63. [PMID: 34657628 PMCID: PMC8522101 DOI: 10.1186/s40246-021-00362-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 10/05/2021] [Indexed: 02/03/2023] Open
Abstract
Background Mutations in the SLC29A3 gene, which encodes the nucleoside transporter hENT3, have been implicated in syndromic forms of histiocytosis including H syndrome, pigmented hypertrichosis with insulin-dependent diabetes, Faisalabad histiocytosis and Familial Rosai–Dorfman disease (RDD). Herein, we report five new patients from a single family who present with phenotypes that associate features of H syndrome and Familial Rosai–Dorfman disease. Methods We investigated the clinical, biochemical, histopathological and molecular findings in five Tunisian family members' diagnosed with Familial RDD and/or H syndrome. The solute carrier family 29 (nucleoside transporters), member 3 (SLC29A3) gene was screened for molecular diagnosis using direct Sanger sequencing. Results Genetic analysis of all affected individuals revealed a previously reported missense mutation c.1088 G > A [p.Arg363Gln] in exon 6 of the SLC29A3 gene. Four affected members presented with clinical features consistent with the classical H syndrome phenotype. While their cousin’s features were in keeping with Familial Rosai–Dorfman disease diagnosis with a previously undescribed cutaneous RDD presenting as erythematous nodular plaques on the face. This report underlines the clinical variability of SLC29A3 disorders even with an identical mutation in the same family. Conclusion We report a rare event of 5 Tunisian family members' found to be homozygous for SLC29A3 gene mutations but showing a different phenotype severity. Our study reveals that despite a single mutation, the clinical expression of the SLC29A3 disorders may be significantly heterogeneous suggesting a poor genotype–phenotype correlation for the disease.
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Lee TL, Lin PH, Chen PL, Hong JB, Wu CC. Hereditary Hearing Impairment with Cutaneous Abnormalities. Genes (Basel) 2020; 12:43. [PMID: 33396879 PMCID: PMC7823799 DOI: 10.3390/genes12010043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 12/25/2020] [Accepted: 12/26/2020] [Indexed: 12/15/2022] Open
Abstract
Syndromic hereditary hearing impairment (HHI) is a clinically and etiologically diverse condition that has a profound influence on affected individuals and their families. As cutaneous findings are more apparent than hearing-related symptoms to clinicians and, more importantly, to caregivers of affected infants and young individuals, establishing a correlation map of skin manifestations and their underlying genetic causes is key to early identification and diagnosis of syndromic HHI. In this article, we performed a comprehensive PubMed database search on syndromic HHI with cutaneous abnormalities, and reviewed a total of 260 relevant publications. Our in-depth analyses revealed that the cutaneous manifestations associated with HHI could be classified into three categories: pigment, hyperkeratosis/nail, and connective tissue disorders, with each category involving distinct molecular pathogenesis mechanisms. This outline could help clinicians and researchers build a clear atlas regarding the phenotypic features and pathogenetic mechanisms of syndromic HHI with cutaneous abnormalities, and facilitate clinical and molecular diagnoses of these conditions.
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Affiliation(s)
- Tung-Lin Lee
- Department of Medical Education, National Taiwan University Hospital, Taipei City 100, Taiwan;
| | - Pei-Hsuan Lin
- Department of Otolaryngology, National Taiwan University Hospital, Taipei 11556, Taiwan;
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
| | - Pei-Lung Chen
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei City 100, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 10041, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei 10041, Taiwan
| | - Jin-Bon Hong
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei City 100, Taiwan
- Department of Dermatology, National Taiwan University Hospital, Taipei City 100, Taiwan
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei 11556, Taiwan;
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 10041, Taiwan
- Department of Medical Research, National Taiwan University Biomedical Park Hospital, Hsinchu City 300, Taiwan
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Noavar S, Behroozi S, Tatarcheh T, Parvini F, Foroutan M, Fahimi H. A novel homozygous frame-shift mutation in the SLC29A3 gene: a new case report and review of literature. BMC MEDICAL GENETICS 2019; 20:147. [PMID: 31464584 PMCID: PMC6716938 DOI: 10.1186/s12881-019-0879-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 08/22/2019] [Indexed: 02/06/2023]
Abstract
Background The SLC29A3 gene, encoding a nucleoside transporter protein, is found in intracellular membranes. Based on the literatures, mutations in this gene cause a wide range of clinical manifestations including H syndrome, pigmented hypertrichosis with insulin dependent diabetes, Faisalabad histiocytosis, and dysosteosclerosis. However, all these disorders with their different names and terminologies are actually the same entity termed H syndrome. Case presentation We report four GJB2 and GJB6 negative deaf patients from two Iranian related families who present the associated symptoms of SLC29A3-disorder. Whole Exome Sequencing (WES) using Next Generation Illumina Sequencing was used to enrich all exons of protein-coding genes as well as some other important genomic regions in one of studied patients. A novel homozygous frame-shift mutation c.307-308delTT (p.Phe103fs) in exon 3 of SLC29A3 gene was identified in a 35 years old man with profound hearing loss, camptodactyly, rheumatoid arthritis and delayed puberty without any skin changes, short stature and insulin dependent diabetes mellitus. The mutation found was also confirmed by Sanger sequencing in other studied patients and their healthy parents. In compared to proband, however the clinical manifestations of these patients were different, indicating variable expressivity of mutant SLC29A3 gene as well as possible involvement of other modifier genes. Conclusion The present study uncovered a rare novel homozygous frame-shift mutation c.307-308delTT in SLC29A3 gene of four related patients with various manifestation of SLC29A3-disorder. Such studies can help to conduct genetic counseling and subsequently, prenatal diagnosis more accurately for individuals at the high risk of these types of genetic disorders.
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Affiliation(s)
- Sadaf Noavar
- Pharmaceutical Sciences Research Center, Tehran medical Sciences, Islamic Azad University, Tehran, Iran
| | - Samira Behroozi
- Pharmaceutical Sciences Research Center, Tehran medical Sciences, Islamic Azad University, Tehran, Iran
| | - Taraneh Tatarcheh
- Pharmaceutical Sciences Research Center, Tehran medical Sciences, Islamic Azad University, Tehran, Iran
| | - Farshid Parvini
- Department of Biology, Faculty of Basic Sciences, Semnan University, Semnan, 35131-19111, Iran.
| | - Majid Foroutan
- Department of Internal Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Hossein Fahimi
- Department of Genetics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, 1916893813, Iran.
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Jaouadi H, Zaouak A, Sellami K, Messaoud O, Chargui M, Hammami H, Jones M, Jouini R, Chadli Debbiche A, Chraiet K, Fenniche S, Mrad R, Mokni M, Turki H, Benkhalifa R, Abdelhak S. H syndrome: Clinical, histological and genetic investigation in Tunisian patients. J Dermatol 2018; 45:978-985. [PMID: 29808591 DOI: 10.1111/1346-8138.14359] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022]
Abstract
H syndrome is a rare autosomal recessive disorder with characteristic dermatological findings consisting of hyperpigmentation and hypertrichosis patches mainly located on the inner thighs and multisystemic involvement including hepatosplenomegaly, hearing loss, heart abnormalities and hypogonadism. The aim of this study was to conduct a clinical and genetic investigation in five unrelated Tunisian patients with suspected H syndrome. Hence, genetic analysis of the SLC29A3 gene was performed for four patients with a clinical diagnosis of H syndrome. We identified a novel frame-shift mutation in the SLC29A3 gene in a female patient with a severe clinical presentation. Furthermore, we report two mutations previously described, the p.R363Q mutation in a male patient and the p.P324L mutation in two patients of different age and sex. This paper extends the mutation spectrum of H syndrome by reporting a novel frame-shift mutation, the p.S15Pfs*86 in exon 2 of SLC29A3 gene and emphasizes the relevance of genetic testing for its considerable implications in early diagnosis and clinical management.
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Affiliation(s)
- Hager Jaouadi
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia
| | - Anissa Zaouak
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia.,Department of Dermatology, Habib Thameur Hospital, Tunis, Tunisia
| | - Khadija Sellami
- Department of Dermatology, Hedi Chaker Hospital, Sfax, Tunisia
| | - Olfa Messaoud
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia
| | - Mariem Chargui
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia
| | - Houda Hammami
- Department of Dermatology, Habib Thameur Hospital, Tunis, Tunisia
| | - Meriem Jones
- Department of Dermatology, Charles Nicolle Hospital, Tunis, Tunisia
| | - Raja Jouini
- Department of Pathology, Habib Thameur Hospital, Tunis, Tunisia
| | | | - Karima Chraiet
- Department of Pediatrics, Mohamed Tahar Maamouri Hospital, Nabeul, Tunisia
| | - Sami Fenniche
- Department of Dermatology, Habib Thameur Hospital, Tunis, Tunisia
| | - Ridha Mrad
- Department of Congenital and Hereditary Diseases, Charles Nicolle Hospital, Tunis, Tunisia
| | - Mourad Mokni
- Department of Dermatology, La Rabta Hospital, Tunis, Tunisia
| | - Hamida Turki
- Department of Dermatology, Hedi Chaker Hospital, Sfax, Tunisia
| | - Rym Benkhalifa
- Venoms and Therapeutic Biomolecules Laboratory LR16IPT08, Pasteur Institute of Tunis, Tunis, Tunisia
| | - Sonia Abdelhak
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia
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Abarca Barriga HH, Trubnykova M, Polar Córdoba V, Ramos Diaz KJ, Aviles Alfaro N. [H syndrome: First reported paediatric case in Latin America]. ACTA ACUST UNITED AC 2016; 87:494-499. [PMID: 27143505 DOI: 10.1016/j.rchipe.2016.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 03/14/2016] [Accepted: 03/20/2016] [Indexed: 02/06/2023]
Abstract
INTRODUCTION H Syndrome is an extremely rare genetic disease, with a multisystemic character and which can be identified in early childhood, offering the opportunity of specific treatment and genetic counselling. OBJECTIVE To present a clinical case with "typical" characteristics of H Syndrome. CLINICAL CASE The case is presented of an 8-year-old male patient who presented with testicular tumours and skin lesions characterised by hyperpigmentation with hypertrichosis, language delay, short stature, and joint deformities. He also presented with bilateral sensorineural hearing loss, anaemia, hypergammaglobulinaemia, and bone disorders. Histopathology studies of the skin and testicular masses reported lymphoplasmacytic infiltration. Sequencing analysis of gene SLC29A3 showed the homozygote mutation c.1087 C>T (p.Arg363Trp; rs387907067). CONCLUSIONS These findings are consistent with H syndrome, and this is the first reported case in Latin America. The key to the diagnosis is the finding of hyperpigmentation with hypertrichosis.
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Affiliation(s)
- Hugo Hernán Abarca Barriga
- Servicio de Genética y Errores Innatos del Metabolismo, Instituto Nacional de Salud del Niño, Lima, Perú.
| | - Milana Trubnykova
- Servicio de Genética y Errores Innatos del Metabolismo, Instituto Nacional de Salud del Niño, Lima, Perú
| | - Victoria Polar Córdoba
- Departamento de Endocrinología Pediátrica, Hospital Nacional Cayetano Heredia, Lima, Perú
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Liu JW, Si N, Wang LQ, Shen T, Zeng XJ, Zhang X, Ma DL. Identification of a novel mutation in solute carrier family 29, member 3 in a Chinese patient with H syndrome. Chin Med J (Engl) 2016; 128:1336-9. [PMID: 25963354 PMCID: PMC4830313 DOI: 10.4103/0366-6999.156778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Background: H syndrome (OMIM 612391) is a recently described autosomal recessive genodermatosis characterized by indurated hyperpigmented and hypertrichotic skin, as well as other systemic manifestations. Most of the cases occurred in the Middle East areas or nearby countries such as Spain or India. The syndrome is caused by mutations in solute carrier family 29, member 3 (SLC29A3), the gene encoding equilibrative nucleoside transporter 3. The aim of this study was to identify pathogenic SLC29A3 mutations in a Chinese patient clinically diagnosed with H syndrome. Methods: Peripheral blood samples were collected from the patient and his parents. Genomic DNA was isolated by the standard method. All six SLC29A3 exons and their flanking intronic sequences were polymerase chain reaction (PCR)-amplified and the PCR products were subjected to direct sequencing. Results: The patient, an 18-year-old man born to a nonconsanguineous Chinese couple, had more extensive cutaneous lesions, involving both buttocks and knee. In his genomic DNA, we identified a novel homozygous insertion-deletion, c. 1269_1270delinsA, in SLC29A3. Both of his parents were carriers of the mutation. Conclusions: We have identified a pathogenic mutation in a Chinese patient with H syndrome.
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Affiliation(s)
| | | | | | | | | | | | - Dong-Lai Ma
- Department of Dermatology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
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H syndrome: The first 79 patients. J Am Acad Dermatol 2014; 70:80-8. [DOI: 10.1016/j.jaad.2013.09.019] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 09/05/2013] [Accepted: 09/09/2013] [Indexed: 11/19/2022]
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de Jesus J, Imane Z, Senée V, Romero S, Guillausseau PJ, Balafrej A, Julier C. SLC29A3 mutation in a patient with syndromic diabetes with features of pigmented hypertrichotic dermatosis with insulin-dependent diabetes, H syndrome and Faisalabad histiocytosis. DIABETES & METABOLISM 2013; 39:281-5. [PMID: 23623699 DOI: 10.1016/j.diabet.2013.03.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 03/12/2013] [Accepted: 03/15/2013] [Indexed: 11/27/2022]
Abstract
AIMS Atypical forms of diabetes may be caused by monogenic mutations in key genes controlling beta-cell development, survival and function. This report describes an insulin-dependent diabetes patient with a syndromic presentation in whom a homozygous SLC29A3 mutation was identified. METHODS SLC29A3 was selected as the candidate gene based on the patient's clinical manifestations, and all exons and flanking regions in the patient's genomic DNA were sequenced. RESULTS A homozygous splice mutation (c.300+1G>C) resulting in a frameshift and truncated protein (p.N101LfsX34) was identified. The patient had insulin-dependent diabetes, congenital deafness, short stature, hyperpigmented patches on the skin, dysmorphic features, cardiomegaly, arthrogryposis, hepatosplenomegaly, anaemia with erythroblastopenia, and an inflammatory syndrome with fever and arthritis; she also presented with a fibrotic mediastinal mass. These clinical features overlapped with pigmented hypertrichosis with insulin-dependent diabetes (PHID), H syndrome, Faisalabad histiocytosis and sinus histiocytosis with massive lymphadenopathy (SHML), all of which are also caused by SLC29A3 mutations. CONCLUSION This is the most severe case reported of SLC29A3 mutations with cumulative features of all these syndromes. This extreme severity coincides with the most N-terminal location of the truncation mutation, thereby affecting all alternative transcripts of the gene. This case report extends the clinical variability of homozygous SLC29A3 mutations that result in a spectrum of multisystemic manifestations.
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Affiliation(s)
- J de Jesus
- Inserm UMR-S958, Medical Faculty Paris 7, site Villemin, Paris, France
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Melki I, Lambot K, Jonard L, Couloigner V, Quartier P, Neven B, Bader-Meunier B. Mutation in the SLC29A3 gene: a new cause of a monogenic, autoinflammatory condition. Pediatrics 2013; 131:e1308-13. [PMID: 23530176 DOI: 10.1542/peds.2012-2255] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Germline mutations in the SLC29A3 gene result in a range of recessive, clinically related syndromes: H syndrome, pigmented hypertrichosis with insulin-dependent diabetes mellitus syndrome, Faisalabad histiocytosis, and sinus histiocytosis with massive lymphadenopathy. The main symptoms of these diseases are hyperpigmentation with hypertrichosis, sensorineural deafness, diabetes, short stature, uveitis, and Rosai-Dorfman like histiocytosis. Here, we report the case of an 11-month-old boy with early-onset, recurrent episodes of unprovoked fever lasting 7 to 10 days and associated with pericardial effusion, abdominal pain, diarrhea, and inflammation. Physical examination revealed hyperpigmentation with hypertrichosis, dysmorphic features, and spleen and liver enlargement. Failure to thrive, sensorineural deafness, retarded psychomotor development, and a Rosai-Dorfman like cheek lesion developed subsequently. The febrile episodes did not respond to tumor necrosis factor α antagonists and interleukin-1. Sequencing of the SLC29A3 gene revealed a homozygous missense mutation c.1088G>A (p.Arg363Gln). These observations suggest that a newly identified mutation in the SLC29A3 gene may be associated with an autoinflammatory disorder. Genetic defects in SLC29A3 should be considered in patients with autoinflammatory manifestations, recurrent febrile attacks, and 1 or more of the symptoms found in the broad spectrum of SLC29A3-related disorders (especially hyperpigmentation with hypertrichosis).
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Affiliation(s)
- Isabelle Melki
- Department of Pediatric Immunology and Rheumatology (UIH), Hôpital Necker-Enfants Malades, 149 rue de Sèvres, F-75743 Paris, France.
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Campeau PM, Lu JT, Sule G, Jiang MM, Bae Y, Madan S, Högler W, Shaw NJ, Mumm S, Gibbs RA, Whyte MP, Lee BH. Whole-exome sequencing identifies mutations in the nucleoside transporter gene SLC29A3 in dysosteosclerosis, a form of osteopetrosis. Hum Mol Genet 2012; 21:4904-9. [PMID: 22875837 DOI: 10.1093/hmg/dds326] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dysosteosclerosis (DSS) is the form of osteopetrosis distinguished by the presence of skin findings such as red-violet macular atrophy, platyspondyly and metaphyseal osteosclerosis with relative radiolucency of widened diaphyses. At the histopathological level, there is a paucity of osteoclasts when the disease presents. In two patients with DSS, we identified homozygous or compound heterozygous missense mutations in SLC29A3 by whole-exome sequencing. This gene encodes a nucleoside transporter, mutations in which cause histiocytosis-lymphadenopathy plus syndrome, a group of conditions with little or no skeletal involvement. This transporter is essential for lysosomal function in mice. We demonstrate the expression of Slc29a3 in mouse osteoclasts in vivo. In monocytes from patients with DSS, we observed reduced osteoclast differentiation and function (demineralization of calcium surface). Our report highlights the pleomorphic consequences of dysfunction of this nucleoside transporter, and importantly suggests a new mechanism for the control of osteoclast differentiation and function.
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Affiliation(s)
- Philippe M Campeau
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Bolze A, Abhyankar A, Grant AV, Patel B, Yadav R, Byun M, Caillez D, Emile JF, Pastor-Anglada M, Abel L, Puel A, Govindarajan R, de Pontual L, Casanova JL. A mild form of SLC29A3 disorder: a frameshift deletion leads to the paradoxical translation of an otherwise noncoding mRNA splice variant. PLoS One 2012; 7:e29708. [PMID: 22238637 PMCID: PMC3251605 DOI: 10.1371/journal.pone.0029708] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 12/01/2011] [Indexed: 02/06/2023] Open
Abstract
We investigated two siblings with granulomatous histiocytosis prominent in the nasal area, mimicking rhinoscleroma and Rosai-Dorfman syndrome. Genome-wide linkage analysis and whole-exome sequencing identified a homozygous frameshift deletion in SLC29A3, which encodes human equilibrative nucleoside transporter-3 (hENT3). Germline mutations in SLC29A3 have been reported in rare patients with a wide range of overlapping clinical features and inherited disorders including H syndrome, pigmented hypertrichosis with insulin-dependent diabetes, and Faisalabad histiocytosis. With the exception of insulin-dependent diabetes and mild finger and toe contractures in one sibling, the two patients with nasal granulomatous histiocytosis studied here displayed none of the many SLC29A3-associated phenotypes. This mild clinical phenotype probably results from a remarkable genetic mechanism. The SLC29A3 frameshift deletion prevents the expression of the normally coding transcripts. It instead leads to the translation, expression, and function of an otherwise noncoding, out-of-frame mRNA splice variant lacking exon 3 that is eliminated by nonsense-mediated mRNA decay (NMD) in healthy individuals. The mutated isoform differs from the wild-type hENT3 by the modification of 20 residues in exon 2 and the removal of another 28 amino acids in exon 3, which include the second transmembrane domain. As a result, this new isoform displays some functional activity. This mechanism probably accounts for the narrow and mild clinical phenotype of the patients. This study highlights the 'rescue' role played by a normally noncoding mRNA splice variant of SLC29A3, uncovering a new mechanism by which frameshift mutations can be hypomorphic.
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Affiliation(s)
- Alexandre Bolze
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, New York, United States of America.
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