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Lyahyai J, Bencheikh BOA, Elalaoui SC, Mansouri M, Boualla L, DIonne-Laporte A, Spiegelman D, Dion PA, Cossette P, Rouleau GA, Sefiani A. Correction to: Exome sequencing reveals a novel PLP1 mutation in a Moroccan family with connatal Pelizaeus-Merzbacher disease: a case report. BMC Pediatr 2018; 18:138. [PMID: 29665810 PMCID: PMC5905117 DOI: 10.1186/s12887-018-1114-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Lyahyai J, Ouled Amar Bencheikh B, Elalaoui SC, Mansouri M, Boualla L, DIonne-Laporte A, Spiegelman D, Dion PA, Cossette P, Rouleau GA, Sefiani A. Exome sequencing reveals a novel PLP1 mutation in a Moroccan family with connatal Pelizaeus-Merzbacher disease: a case report. BMC Pediatr 2018; 18:90. [PMID: 29486744 PMCID: PMC5830319 DOI: 10.1186/s12887-018-1063-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 02/15/2018] [Indexed: 11/20/2022] Open
Abstract
Background Epilepsy regroups a common and diverse set of chronic neurological disorders that are characterized by spontaneous, unprovoked, and recurrent epileptic seizures. Epilepsies have a highly heterogeneous background with a strong genetic contribution and various mode of inheritance. X-linked epilepsy usually manifests as part of a syndrome or epileptic encephalopathy. The variability of clinical manifestations of X-linked epilepsy may be attributed to several factors including the causal genetic mutation, making diagnosis, genetic counseling and treatment decisions difficult. We report the description of a Moroccan family referred to our genetic department with X-linked epileptic seizures as the only initial diagnosis. Case presentation Knowing the new contribution of Next-Generation Sequencing (NGS) for clinical investigation, and given the heterogeneity of this group of disorders we performed a Whole-Exome Sequencing (WES) analysis and co-segregation study in several members of this large family. We detected a novel pathogenic PLP1 missense mutation c.251C > A (p.Ala84Asp) allowing us to make a diagnosis of Pelizaeus-Merzbacher Disease for this family. Conclusion This report extends the spectrum of PLP1 mutations and highlights the diagnostic utility of NGS to investigate this group of heterogeneous disorders.
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Debiec H, Dossier C, Letouzé E, Gillies CE, Vivarelli M, Putler RK, Ars E, Jacqz-Aigrain E, Elie V, Colucci M, Debette S, Amouyel P, Elalaoui SC, Sefiani A, Dubois V, Simon T, Kretzler M, Ballarin J, Emma F, Sampson MG, Deschênes G, Ronco P. Transethnic, Genome-Wide Analysis Reveals Immune-Related Risk Alleles and Phenotypic Correlates in Pediatric Steroid-Sensitive Nephrotic Syndrome. J Am Soc Nephrol 2018; 29:2000-2013. [PMID: 29903748 PMCID: PMC6050942 DOI: 10.1681/asn.2017111185] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 04/09/2018] [Indexed: 12/20/2022] Open
Abstract
Background Steroid-sensitive nephrotic syndrome (SSNS) is a childhood disease with unclear pathophysiology and genetic architecture. We investigated the genomic basis of SSNS in children recruited in Europe and the biopsy-based North American NEPTUNE cohort.Methods We performed three ancestry-matched, genome-wide association studies (GWAS) in 273 children with NS (Children Cohort Nephrosis and Virus [NEPHROVIR] cohort: 132 European, 56 African, and 85 Maghrebian) followed by independent replication in 112 European children, transethnic meta-analysis, and conditional analysis. GWAS alleles were used to perform glomerular cis-expression quantitative trait loci studies in 39 children in the NEPTUNE cohort and epidemiologic studies in GWAS and NEPTUNE (97 children) cohorts.Results Transethnic meta-analysis identified one SSNS-associated single-nucleotide polymorphism (SNP) rs1063348 in the 3' untranslated region of HLA-DQB1 (P=9.3×10-23). Conditional analysis identified two additional independent risk alleles upstream of HLA-DRB1 (rs28366266, P=3.7×10-11) and in the 3' untranslated region of BTNL2 (rs9348883, P=9.4×10-7) within introns of HCG23 and LOC101929163 These three risk alleles were independent of the risk haplotype DRB1*07:01-DQA1*02:01-DQB1*02:02 identified in European patients. Increased burden of risk alleles across independent loci was associated with higher odds of SSNS. Increased burden of risk alleles across independent loci was associated with higher odds of SSNS, with younger age of onset across all cohorts, and with increased odds of complete remission across histologies in NEPTUNE children. rs1063348 associated with decreased glomerular expression of HLA-DRB1, HLA-DRB5, and HLA-DQB1.Conclusions Transethnic GWAS empowered discovery of three independent risk SNPs for pediatric SSNS. Characterization of these SNPs provide an entry for understanding immune dysregulation in NS and introducing a genomically defined classification.
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Affiliation(s)
- Hanna Debiec
- Sorbonne Université, UPMC Paris 06, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche S 1155, Paris, France
| | | | - Eric Letouzé
- Pediatric Pharmacology and Pharmacogenetics, CIC1426, Hôpital Robert Debré, Paris, France
- Université Paris Diderot, Institut Universitaire d'Hématologie, Paris, France
| | - Christopher E Gillies
- Pediatric Nephrology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Marina Vivarelli
- Nephrology and Dialysis Department, Istituto di Ricovero e Cura a Carattere Scientifico Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - Rosemary K Putler
- Pediatric Nephrology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Elisabet Ars
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Evelyne Jacqz-Aigrain
- Pediatric Pharmacology and Pharmacogenetics, CIC1426, Hôpital Robert Debré, Paris, France
| | - Valery Elie
- Pediatric Pharmacology and Pharmacogenetics, CIC1426, Hôpital Robert Debré, Paris, France
| | - Manuela Colucci
- Nephrology and Dialysis Department, Istituto di Ricovero e Cura a Carattere Scientifico Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - Stéphanie Debette
- University of Bordeaux, Institut National de la Santé et de la Recherche Médicale, Bordeaux Population Health Research Center, Unité Mixte de Recherche 1219, CHU Bordeaux, Bordeaux, France
| | - Philippe Amouyel
- University of Lille, Institut National de la Santé et de la Recherche Médicale, CHU Lille, Institut Pasteur de Lille, U1167 RID-AGE, Lille, France
| | - Siham C Elalaoui
- Department of Medical Genetics, Institut National d'Hygiène, Rabat, Morocco
| | - Abdelaziz Sefiani
- Human Genomic Center, Faculté de Médecine et de Pharmacie Rabat, Université Mohamed V. Rabat, Rabat, Morocco
| | - Valérie Dubois
- Etablissement Français du Sang Rhone-Alpes, Lyon, Rhone-Alpes, France
| | - Tabassome Simon
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint Antoine, Department of Clinical Pharmacology, Unité de Recherche Clinique, Paris, France
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche S1148, Paris, France
| | - Matthias Kretzler
- Department of Internal Medicine and Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan;
| | - Jose Ballarin
- Department of Nephrology, Fundación Puigvert, Barcelona, Spain
| | - Francesco Emma
- Pediatric Nephrology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Matthew G Sampson
- Pediatric Nephrology, University of Michigan School of Medicine, Ann Arbor, Michigan;
| | - Georges Deschênes
- Department of Paediatric Nephrology and
- Institut National de la Santé et de la Recherche Médicale U1149, Unité de Formation et de Recherche de Médecine Xavier Bichat, Université Sorbonne Paris Cité, Paris, France; and
| | - Pierre Ronco
- Sorbonne Université, UPMC Paris 06, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche S 1155, Paris, France;
- Assistance Publique-Hôpitaux de Paris, Nephrology and Dialysis Department, Tenon Hospital, Paris, France
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Twigg SRF, Ousager LB, Miller KA, Zhou Y, Elalaoui SC, Sefiani A, Bak GS, Hove H, Hansen LK, Fagerberg CR, Tajir M, Wilkie AOM. Acromelic frontonasal dysostosis and ZSWIM6 mutation: phenotypic spectrum and mosaicism. Clin Genet 2016; 90:270-5. [PMID: 26706854 PMCID: PMC5025718 DOI: 10.1111/cge.12721] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 12/22/2015] [Accepted: 12/22/2015] [Indexed: 11/24/2022]
Abstract
Acromelic frontonasal dysostosis (AFND) is a distinctive and rare frontonasal malformation that presents in combination with brain and limb abnormalities. A single recurrent heterozygous missense substitution in ZSWIM6, encoding a protein of unknown function, was previously shown to underlie this disorder in four unrelated cases. Here we describe four additional individuals from three families, comprising two sporadic subjects (one of whom had no limb malformation) and a mildly affected female with a severely affected son. In the latter family we demonstrate parental mosaicism through deep sequencing of DNA isolated from a variety of tissues, which each contain different levels of mutation. This has important implications for genetic counselling.
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Affiliation(s)
- S R F Twigg
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - L B Ousager
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
| | - K A Miller
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Y Zhou
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - S C Elalaoui
- Human Genomics Center, Faculty of Medicine and Pharmacy of Rabat, Rabat, Morocco.,Department of Medical Genetics, National Institute of Health, Rabat, Morocco
| | - A Sefiani
- Human Genomics Center, Faculty of Medicine and Pharmacy of Rabat, Rabat, Morocco.,Department of Medical Genetics, National Institute of Health, Rabat, Morocco
| | - G S Bak
- Department of Obstetrics and Gynecology, Odense University Hospital, Odense, Denmark
| | - H Hove
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - L K Hansen
- Department of Paediatrics, Hans Christian Andersen Children's Hospital, Odense University Hospital, Odense, Denmark
| | - C R Fagerberg
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
| | - M Tajir
- Human Genomics Center, Faculty of Medicine and Pharmacy of Rabat, Rabat, Morocco.,Department of Medical Genetics, National Institute of Health, Rabat, Morocco
| | - A O M Wilkie
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
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Doubaj Y, Pingault V, Elalaoui SC, Ratbi I, Azouz M, Zerhouni H, Ettayebi F, Sefiani A. A novel mutation in the endothelin B receptor gene in a moroccan family with shah-waardenburg syndrome. Mol Syndromol 2015; 6:44-9. [PMID: 25852447 DOI: 10.1159/000371590] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2014] [Indexed: 11/19/2022] Open
Abstract
Waardenburg syndrome (WS) is a neurocristopathy disorder combining sensorineural deafness and pigmentary abnormalities. The presence of additional signs defines the 4 subtypes. WS type IV, also called Shah-Waardenburg syndrome (SWS), is characterized by the association with congenital aganglionic megacolon (Hirschsprung disease). To date, 3 causative genes have been related to this congenital disorder. Mutations in the EDNRB and EDN3 genes are responsible for the autosomal recessive form of SWS, whereas SOX10 mutations are inherited in an autosomal dominant manner. We report here the case of a 3-month-old Morrocan girl with WS type IV, born to consanguineous parents. The patient had 3 cousins who died in infancy with the same symptoms. Molecular analysis by Sanger sequencing revealed the presence of a novel homozygous missense mutation c.1133A>G (p.Asn378Ser) in the EDNRB gene. The proband's parents as well as the parents of the deceased cousins are heterozygous carriers of this likely pathogenic mutation. This molecular diagnosis allows us to provide genetic counseling to the family and eventually propose prenatal diagnosis to prevent recurrence of the disease in subsequent pregnancies.
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Affiliation(s)
- Yassamine Doubaj
- Département de Génétique Médicale, Institut National d'Hygiène, France ; Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, France
| | | | - Siham C Elalaoui
- Département de Génétique Médicale, Institut National d'Hygiène, France ; Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, France
| | - Ilham Ratbi
- Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, France
| | - Mohamed Azouz
- Service des Urgences Chirurgicales Pédiatriques, Hôpital d'Enfants, Rabat, Morocco, France
| | - Hicham Zerhouni
- Service des Urgences Chirurgicales Pédiatriques, Hôpital d'Enfants, Rabat, Morocco, France
| | - Fouad Ettayebi
- Service des Urgences Chirurgicales Pédiatriques, Hôpital d'Enfants, Rabat, Morocco, France
| | - Abdelaziz Sefiani
- Département de Génétique Médicale, Institut National d'Hygiène, France ; Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, France
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Makrythanasis P, Nelis M, Santoni FA, Guipponi M, Vannier A, Béna F, Gimelli S, Stathaki E, Temtamy S, Mégarbané A, Masri A, Aglan MS, Zaki MS, Bottani A, Fokstuen S, Gwanmesia L, Aliferis K, Bustamante Eduardo M, Stamoulis G, Psoni S, Kitsiou-Tzeli S, Fryssira H, Kanavakis E, Al-Allawi N, Sefiani A, Al Hait S, Elalaoui SC, Jalkh N, Al-Gazali L, Al-Jasmi F, Bouhamed HC, Abdalla E, Cooper DN, Hamamy H, Antonarakis SE. Diagnostic exome sequencing to elucidate the genetic basis of likely recessive disorders in consanguineous families. Hum Mutat 2014; 35:1203-10. [PMID: 25044680 DOI: 10.1002/humu.22617] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 06/30/2014] [Indexed: 01/19/2023]
Abstract
Rare, atypical, and undiagnosed autosomal-recessive disorders frequently occur in the offspring of consanguineous couples. Current routine diagnostic genetic tests fail to establish a diagnosis in many cases. We employed exome sequencing to identify the underlying molecular defects in patients with unresolved but putatively autosomal-recessive disorders in consanguineous families and postulated that the pathogenic variants would reside within homozygous regions. Fifty consanguineous families participated in the study, with a wide spectrum of clinical phenotypes suggestive of autosomal-recessive inheritance, but with no definitive molecular diagnosis. DNA samples from the patient(s), unaffected sibling(s), and the parents were genotyped with a 720K SNP array. Exome sequencing and array CGH (comparative genomic hybridization) were then performed on one affected individual per family. High-confidence pathogenic variants were found in homozygosity in known disease-causing genes in 18 families (36%) (one by array CGH and 17 by exome sequencing), accounting for the clinical phenotype in whole or in part. In the remainder of the families, no causative variant in a known pathogenic gene was identified. Our study shows that exome sequencing, in addition to being a powerful diagnostic tool, promises to rapidly expand our knowledge of rare genetic Mendelian disorders and can be used to establish more detailed causative links between mutant genotypes and clinical phenotypes.
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Affiliation(s)
- Periklis Makrythanasis
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland; Service of Genetic Medicine, University Hospitals of Geneva, Geneva, Switzerland
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Piard J, Aral B, Vabres P, Holder-Espinasse M, Mégarbané A, Gauthier S, Capra V, Pierquin G, Callier P, Baumann C, Pasquier L, Baujat G, Martorell L, Rodriguez A, Brady AF, Boralevi F, González-Enseñat MA, Rio M, Bodemer C, Philip N, Cordier MP, Goldenberg A, Demeer B, Wright M, Blair E, Puzenat E, Parent P, Sznajer Y, Francannet C, DiDonato N, Boute O, Barlogis V, Moldovan O, Bessis D, Coubes C, Tardieu M, Cormier-Daire V, Sousa AB, Franques J, Toutain A, Tajir M, Elalaoui SC, Geneviève D, Thevenon J, Courcet JB, Rivière JB, Collet C, Gigot N, Faivre L, Thauvin-Robinet C. Search for ReCQL4 mutations in 39 patients genotyped for suspected Rothmund-Thomson/Baller-Gerold syndromes. Clin Genet 2014; 87:244-51. [PMID: 24635570 DOI: 10.1111/cge.12361] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 02/12/2014] [Accepted: 02/12/2014] [Indexed: 11/28/2022]
Abstract
Three overlapping conditions, namely Rothmund-Thomson (RTS), Baller-Gerold (BGS) and RAPADILINO syndromes, have been attributed to RECQL4 mutations. Differential diagnoses depend on the clinical presentation, but the numbers of known genes remain low, leading to the widespread prescription of RECQL4 sequencing. The aim of our study was therefore to determine the best clinical indicators for the presence of RECQL4 mutations in a series of 39 patients referred for RECQL4 molecular analysis and belonging to the RTS (27 cases) and BGS (12 cases) spectrum. One or two deleterious RECQL4 mutations were found in 10/27 patients referred for RTS diagnosis. Clinical and molecular reevaluation led to a different diagnosis in 7/17 negative cases, including Clericuzio-type poikiloderma with neutropenia, hereditary sclerosing poikiloderma, and craniosynostosis/anal anomalies/porokeratosis. No RECQL4 mutations were found in the BGS group without poikiloderma, confirming that RECQL4 sequencing was not indicated in this phenotype. One chromosomal abnormality and one TWIST mutation was found in this cohort. This study highlights the search for differential diagnoses before the prescription of RECQL4 sequencing in this clinically heterogeneous group. The combination of clinically defined subgroups and next-generation sequencing will hopefully bring to light new molecular bases of syndromes with poikiloderma, as well as BGS without poikiloderma.
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Affiliation(s)
- J Piard
- EA 4271 GAD "Génétique des Anomalies du Développement", IFR Santé STIC, Université de Bourgogne, Dijon, France; Centre de Génétique Humaine, CHU Besançon, Besançon, France
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Elalaoui SC, Garin I, Sefiani A, Perez de Nanclares G. Maternal Hypomethylation of KvDMR in a Monozygotic Male Twin Pair Discordant for Beckwith-Wiedemann Syndrome. Mol Syndromol 2013; 5:41-6. [PMID: 24550765 DOI: 10.1159/000356689] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2013] [Indexed: 12/12/2022] Open
Abstract
Beckwith-Wiedemann syndrome (BWS; OMIM 130650) is a heterogeneous overgrowth syndrome characterized by visceromegaly, macroglossia, tumor predisposition, and other congenital abnormalities. BWS is usually associated with abnormalities of chromosome 11p15, including (epi)genetic changes, paternal disomy and point mutations. A number of identical twin pairs, mostly female, have been reported to be clinically discordant for BWS. Studies of monozygotic twins discordant for BWS provide more information about failure in the DNA methylation maintenance machinery during very early embryonic development. Here, we report a case of monozygotic male twins discordant for BWS phenotype. Methylation analysis of the 2 imprinted domains at 11p15.5 (H19DMR and KvDMR) was performed by methylation-specific MLPA and pyrosequencing of DNA extracted from peripheral blood and buccal swabs of both twins. Hypomethylation at KvDMR was identified in both cell types of the affected twin, whereas his healthy brother presented hypomethylation only in blood cells and a normal methylation profile in buccal swab. For diagnostic purposes, it is important to remember that twins can share fetal circulation and possibly share hematopoietic stem cells early in development; therefore, the affected and unaffected twins can share an epigenotype that will resemble partial hypomethylation. If a patient is a twin, it is valuable to obtain a sample from a tissue other than blood.
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Affiliation(s)
- S C Elalaoui
- Département de Génétique Médicale, Institut National d'Hygiène, Rabat, Morocco ; Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, Rabat, Morocco
| | - I Garin
- Molecular (Epi)Genetics Laboratory, Hospital Universitario-Araba-Txagorritxu, Vitoria-Gazteiz, Spain
| | - A Sefiani
- Département de Génétique Médicale, Institut National d'Hygiène, Rabat, Morocco ; Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, Rabat, Morocco
| | - G Perez de Nanclares
- Molecular (Epi)Genetics Laboratory, Hospital Universitario-Araba-Txagorritxu, Vitoria-Gazteiz, Spain
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Canals I, Elalaoui SC, Pineda M, Delgadillo V, Szlago M, Jaouad IC, Sefiani A, Chabás A, Coll MJ, Grinberg D, Vilageliu L. Molecular analysis of Sanfilippo syndrome type C in Spain: seven novel HGSNAT mutations and characterization of the mutant alleles. Clin Genet 2010; 80:367-74. [PMID: 20825431 DOI: 10.1111/j.1399-0004.2010.01525.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Sanfilippo syndrome type C [mucopolysaccharidosis IIIC (MPS IIIC)] is caused by mutations in the HGSNAT gene, encoding an enzyme involved in heparan sulphate degradation. We report the first molecular study on several Spanish Sanfilippo syndrome type C patients. Seven Spanish patients, one Argentinean and three Moroccan patients were analysed. All mutant alleles were identified and comprised nine distinct mutant alleles, seven of which were novel, including four missense mutations (p.A54V, p.L113P, p.G424V and p.L445P) and three splicing mutations due to two point mutations (c.633+1G>A and c.1378-1G>A) and an intronic deletion (c.821-31_821-13del). Furthermore, we found a new single nucleotide polymorphism (SNP) (c.564-98T>C). The two most frequent changes were the previously described c.372-2A>G and c.234+1G>A mutations. All five splicing mutations were experimentally confirmed by studies at the RNA level, and a minigene experiment was carried out in one case for which no fibroblasts were available. Expression assays allowed us to show the pathogenic effect of the four novel missense mutations and to confirm that the already known c.710C>A (p.P237Q) is a non-pathogenic SNP. Haplotype analyses suggested that the two mutations (c.234+1G>A and c.372-2A>G) that were present in more than one patient have a common origin, including one (c.234+1G>A) that was found in Spanish and Moroccan patients.
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Affiliation(s)
- I Canals
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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