Miyoshi myopathy associated with spine rigidity and multiple contractures: a case report.

BACKGROUND: Dysferlinopathy is a phenotypically heterogeneous group of hereditary diseases caused by mutations in the DYSF gene. Early contractures are considered rare, and rigid spine syndrome in dysferlinopathy has been previously reported only once. CASE PRESENTATION: We describe a 23-year-old patient with Miyoshi myopathy with a rigid spine and multiple contractures, a rare phenotypic variant. The disease first manifested when the patient was 13 years old, with fatigue of the gastrocnemius muscles and the development of pronounced contractures of the Achilles tendons, flexors of the fingers, and extensors of the toes, followed by the involvement of large joints and the spine. Magnetic resonance imaging revealed signs of connective tissue and fatty replacement of the posterior muscles of the thighs and lower legs. Edema was noted in the anterior and medial muscle groups of the thighs, lower legs, and the multifidus muscle of the back. Whole genome sequencing revealed previously described mutations in the DYSF gene in exon 39 (c.4282 C > T) and intron 51 (c.5785-824 C > T). An immunohistochemical analysis and Western blot showed the complete absence of dysferlin protein expression in the muscle fibers. CONCLUSIONS: This case expands the range of clinical and phenotypic correlations of dysferlinopathy and complements the diagnostic search for spine rigidity.

Genetic screening of an endemic mutation in the DYSF gene in an isolated, mountainous population in the Republic of Dagestan.

BACKGROUND: Dysferlinopathy has a high prevalence in relatively isolated ethnic groups where consanguineous marriages are characteristic and/or the founder effect exists. However, the frequency of endemic mutations in most isolates has not been investigated. METHODS: The prevalence of the pathological DYSF gene variant (NM_003494.4); c.200_201delinsAT, p. Val67Asp (rs121908957) was investigated in an isolated Avar population in the Republic of Dagestan. Genetic screenings were conducted in a remote mountainous region characterized by a high level of consanguinity among its inhabitants. In total, 746 individuals were included in the screenings. RESULTS: This pathological DYSF gene variant causes two primary phenotypes of dysferlinopathy: limb-girdle muscular dystrophy (LGMD) type R2 and Miyoshi muscular dystrophy type 1. Results indicated a high prevalence of the allele at 14% (95% confidence interval [CI]: 12-17; 138 out of 1518 alleles), while the allele in the homozygous state was detected in 29 cases-3.8% (CI: 2.6-5.4). The population load for dysferlinopathy was 832.3 ± 153.9 per 100,000 with an average prevalence of limb-girdle muscular dystrophies ranging from 0.38 ± 0.38 to 5.93 ± 1.44 per 100,000. CONCLUSION: A significant burden of the allele was due to inbreeding, as evidenced by a deficiency of heterozygotes and the Wright fixation index equal to 0.14 (CI 0.06-0.23).