Dysferlin Gene Mutation Spectrum in a Large Cohort of Chinese Patients with Dysferlinopathy

Abstract

Background:Dysferlinopathy is caused by mutations in the dysferlin (DYSF) gene. Here, we described the genetic features of a large cohort of Chinese patients with this disease.Methods:Eighty-nine index patients were included in the study. DYSF gene analysis was performed by Sanger sequencing in 41 patients and targeted next generation sequencing (NGS) in 48 patients. Multiplex ligation-dependent probe amplification (MLPA) was performed to detect exon duplication/deletion in patients with only one pathogenic mutation.Results:Among the 89 index patients, 79 patients were demonstrated to carry two disease-causing (73 cases) or possibly disease-causing mutations (6 cases), including 26 patients with homozygous mutations. We identified 105 different mutations, including 59 novel ones. Notably, in 13 patients in whom only one pathogenic mutation was initially found by Sanger sequencing or NGS, 3 were further identified to carry exon deletions by MLPA. The mutations identified in this study appeared to cluster in the N-terminal region. Mutation types included missense mutations (30.06%), nonsense mutations (17.18%), frameshift mutations (30.67%), in-frame deletions (2.45%), intronic mutations (17.79%), and exonic rearrangement (1.84%). No genotype-phenotype correlation was identified.Conclusions:DYSF mutations in Chinese patients clustered in the N-terminal region of the gene. Exonic rearrangements were found in 23% of patients with only one pathogenic mutation identified by Sanger sequencing or NGS. The novel mutations found in this study greatly expanded the mutational spectrum of dysferlinopathy.

The genetic profile of dysferlinopathy in a cohort of 209 cases: Genotype–phenotype relationship and a hotspot on the inner DysF domain

“…Korea (Shin et al, 2015), China (Jin et al, 2016;Xi et al, 2014), Iran (Fatehi et al, 2015), France (Krahn et al, 2009), as well as from an international multicenter study (Harris et al, 2016), demonstrating the genetic character in each population including the existence of have been reported to be located deep in intronic regions (Dominov et al, 2019). Hence, RNA analysis combined with genomic DNA will be needed to characterize undiagnosed cases.…”

The clinical spectrum and genetic variability of limb-girdle muscular dystrophy in a cohort of Chinese patients

“…Eighteen of these variants were shown to be novel: c.714G > T (p.K238 N), c.5909C > T (p.P1970L), c.5357G > A (p.W1786*), and c.3550C > T (p.Q1184*) in DYSF ; c.468C > A (p.I156=), c.382G > T (p.D128Y), and c.753delC (p.I251Ifs*2) in CAPN3 ; c.702 + 1G > A, c.756G > A (p.W252*), and c.477delG (p.V160Lfs*8) in SGCG ; c.892delC (p.L298Cfs*23) and c.262delT (p.F88Sfs*123) in SGCA ; c.1336G > T (p.D446Y) and c.431A > C (p.K144 T) in LMNA ; c.503-2A > G and c.414delA (p.K138Nfs*4) in SGCD ; and c.25006 T > C (p.C8336R) and c.33938dupC (p.E11314Rfs*24) in TTN , while other identified variants have been reported earlier (Table 2 ) [ 31 – 43 ]. In family 6, in addition to two pathogenic variants, c.565C > G (p.L189 V) and c.4742G > A (p.R1581H) in DYSF were found to be single nucleotide polymorphisms (SNPs).…”

“…Patient 5 was found to carry two pathogenic variants in one chromosome (c.680 T > C; c.714G > T) and one pathogenic variant in this gene in another chromosome (c.799_800del). Furthermore, c.680 T > C was identified in a patient with dysferlinopathy [ 31 ], and both c.680 T > C and c.714G > T can be classified as pathogenic according to the ACMG guidelines [ 20 ]. Although it is unclear whether one of these variants is more pathogenic or not, it is not a crucial issue that will affect reproductive counselling, because, owing to their very small genetic distance, they are tightly linked [ 61 ].…”

A novel mutation in the DYSF gene in a patient with a presumed inflammatory myopathy

“…Other atypical clinical characteristics of dysferlinopathy include scapuloperoneal syndrome, elevated serum creatinine kinase (CK) concentration, and congenital muscular dystrophy. 6 Sanger sequencing, considered a time-consuming, labor-intensive method for DYSF genetic testing, has been gradually replaced by next generation sequencing (NGS). However, altered immunolocalization of dysferlin is observed not only in primary dysferlinopathy, but also in other myopathies with normal protein content, including calpainopathy, sarcoglycanopathy and dystrophinopathy.…”

“…Furthermore, sequencing identified one pathogenic mutation in these patients. 6 Sanger sequencing, considered a time-consuming, labor-intensive method for DYSF genetic testing, has been gradually replaced by next generation sequencing (NGS). 7 In this study, we applied NGS for a precise diagnosis in a patient with muscular dystrophy who was misdiagnosed This study was approved by the ethics committee of the Second Hospital of Hebei Medicine University and informed consent was obtained from the patient involved in the study.…”