The utility of whole-exome sequencing in accurate diagnosis of neuromuscular disorders in consanguineous families in Jordan.

BACKGROUND: Neuromuscular disorders (NMDs) encompass a large group of genetic and acquired diseases affecting muscles, leading to progressive muscular weakness. These disorders are frequently inherited in an autosomal-recessive (AR) pattern with extreme heterogeneity and various clinical presentations. Consanguinity increases the likelihood of AR disorders, with high rates of cousin inbreeding in Jordan and other Arab countries. In Jordan, the implementation of genetic diagnosis is limited, with delayed or misdiagnosis of genetic disorders. Thus, the lack of genetic counselling and specialized treatment options is frequently encountered in the country. METHODS: Whole-exome sequencing (WES) was conducted for eleven probands from ten Jordanian families who have been formerly diagnosed with limb-girdle dystrophy (LGMD) and Charcot-Marie-Tooth disease (CMT). The previous diagnoses were established principally on clinical examination in the absence of genetic testing. Additionally, Sanger sequencing and segregation analysis were used to validate the resulted pathogenic variants. RESULTS: Multiple variants were identified using WES: For DYSF gene, a missense variant (c. 4076 T > C, p.Leu1359Pro) in exon 38; a nonsense variant (c. 4321C > T, p.Gln1441Ter) in exon 39; a single-nucleotide deletion (c. 5711delG, p.Gly1904AlafsTer101) in exon 51. Other variants included a missense variant (c. 122G > A, p.Arg41Gln) in exon 3 of MPV17 gene, a single-nucleotide deletion (c. 859 delC, p.Lue287Ser fs14*) in exon 6 of SGCB gene, a missense variant (c. 311G > A, p.Gly104Asp) in exon 2 of SLC25A46 gene, a nonsense variant (c. 496C > T, p.Arg166Ter) in exon 5 of SGCG gene, and a nonsense variant (c.3202C > T, p.Gln1068Ter) in exon 13 of SH3TC2 gene. CONCLUSION: Utilization of WES is helpful to facilitate rapid and accurate NMDs diagnosis, complementing a thorough clinical evaluation. This approach can be invaluable to aid in the identification of genetic risks among consanguineous couples. Subsequently, well-informed genetic counselling and potential individualized treatment can be provided.

Generation of an induced pluripotent stem cell (iPSC) line (JUCTCi017-A) from a patient with limb-girdle muscular dystrophy (LGMD) due to a homozygous p.Lue287Ser fs14* mutation in the SGCB gene.

Limb-girdle muscular dystrophies (LGMDs) are a large group of heterogenous genetic diseases characterized by muscle weakness. In this study, an induced pluripotent stem cell (iPSC) line was generated from LGMD patient's skin dermal fibroblasts, carrying a homozygous mutation in the Sarcoglycan Beta (SGCB) gene; chr4:52890221, c. 859 delC, p.Lue 287Ser fs14*. The reprogramming process was carried out using Sendai viruses encoding for Yamanaka factors. The resulting iPSCs showed normal morphology and karyotype, expressed pluripotency markers, demonstrated the potential to differentiate in vitro into three germ layers and retained the disease-causing SGCB mutation. This iPSC line represents an ideal source of cells for the investigation of LGMD disease mechanisms.