RESUMO
Background: Muscular dystrophies are a heterogeneous group of inherited disorders that cannot be diagnosed clinically due to overlapping clinical phenotypes. Whole-exome sequencing is considered as the diagnostic strategy of choice in these cases. In this study we aimed to determine the mutational spectrum of multiplex ligation-dependent probe amplification (MLPA)-negative muscular dystrophy patients in Pakistan using whole-exome sequencing. Subsequently the mutations identified via WES were used to screen additional dystrophinopathy patients by Sanger sequencing. Materials and Methods: DNA extracted from the peripheral blood of three MLPA-negative muscular dystrophy patients was sent for whole-exome sequencing. The identified variants in these 3 patients were then checked in 18 dystrophinopathy patients using Sanger sequencing. Results: Four missense variants and one nonsense variant in the Duchenne muscular dystrophy (DMD) gene were detected. WES diagnosed a DMD patient carrying a nonsense variant c.4375C>T (rs398123953) who can benefit from Ataluren therapy. The other two patients carried missense variant (c.572G>T) in the YARS2 gene (rs11539445) labeling them as patients of MLASA (myopathy, lactic acidosis, and sideroblastic anemia). The identified missense and nonsense variants in the DMD gene were detected in 18 clinically diagnosed dystrophinopathy patients using Sanger sequencing. Three missense variants were detected in our cohort of 18 dystrophinopathy patients. One missense variant c.3406A>T (rs3827462) and a nonsense variant c.4375C>T (rs398123953) were not detected in our cohort of 18 dystrophinopathy patients. Conclusions: Whole-exome sequencing identified a nonsense variant in Pakistani muscular dystrophy patients, which is amenable to treatment by Ataluren and a missense variant in YARS2 gene responsible for causing MLASA.
Assuntos
Distrofina/genética , Distrofias Musculares/genética , Adolescente , Alelos , Criança , Códon sem Sentido/genética , Éxons/genética , Feminino , Frequência do Gene/genética , Testes Genéticos/métodos , Genótipo , Humanos , Masculino , Reação em Cadeia da Polimerase Multiplex/métodos , Distrofias Musculares/metabolismo , Distrofia Muscular de Duchenne/genética , Mutação/genética , Mutação de Sentido Incorreto/genética , Paquistão/epidemiologia , Sequenciamento do Exoma/métodosRESUMO
OBJECTIVE: To derive Duchenne muscular dystrophy patient specific induced pluripotent stem cells (iPSCs) from CD3+T cells of DMD patients using episomal reprogramming and characterization of these DMD-iPSCs using immunofluorescence to confirm their pluripotent state. METHODS: DMD patients were selected based upon their clinical history and examination. Peripheral blood mononuclear cells were isolated from peripheral blood of DMD patients (n=3) by density gradient centrifugation and were used to generate DMD patient specific T cells (DMD-T cells) using rhIL-2, plate bound anti CD3 antibody and T cell specific media along with specific culture conditions that promote T cell expansion. CD3+ T cells were characterized by flow cytometry and reprogrammed using episomal plasmid to generate DMD-iPSCs. These DMD-iPSCs were characterized using immunofluorescence. The study was carried out at Dow Research Institute of Biotechnology and Biomedical Sciences during August 2017- July 2018 for a period of approximately 12 months. RESULTS: The peripheral blood mononuclear cells (PBMNC) derived T cells appeared as suspended cell clumps morphologically were positive for the expression of CD3 and negative for CD31. The DMD patient specific iPSCs appeared as round, compact and flat colonies with well-defined edges morphologically and were positive for the expression of pluripotency markers OCT4, SSEA-4 and TRA-1-81 on immunofluorescence. CONCLUSION: CD3+ T cell derived DMD-iPSCs were obtained under feeder free and xeno-free culture conditions using episomal reprogramming.
