Spectrum of mutations in sarcoglycan genes in the Mumbai region of western India: High prevalence of 525del T

Background : While the clinical and immunocytochemical features of sarcoglycanopathies have been reported from India, genetic aspects have not been studied. There is large variation in the sarcoglycan mutations among the studied populations.
Aim : To study the spectrum of mutations in sarcoglycan genes (SG).
Materials and Methods : Patients fulfilling Bushby′s criteria for limb girdle muscular dystrophy were prospectively analyzed. Patients gave their medical history and underwent a clinical examination, serum creatine kinase estimation, electrophysiology, muscle biopsy with immunostaining for alpha, beta, gamma, and delta subunits and mutational analysis using denaturing high pressure liquid chromatography and direct sequencing.
Results : Mutations in SG accounted for 26.4% of the cohort of limb girdle muscular dystrophy. The mean age of these 18 patients was 22.5 years. Generally, proximal weakness affected the flexor and adductor compartments of the lower and upper limbs. The clinical profile of various mutations was indistinguishable from each other. Gamma SG mutations were most common, seen in 8 patients, followed by delta SG mutation in 5 patients and alpha mutation in 4 patients, while only 1 patient had mutation in the beta sarcoglycan gene. The most prevalent mutation in the gamma SG gene was 525del T. This is of interest as the mutation has been known to exist only in specific populations.
Conclusion : This study, the first mutational analysis of Indian patients with sarcoglycanopathies suggests gamma SG mutations were the most common and the most prevalent mutation in the gamma SG gene was 525del T.