Carrier Frequency of the c.525delT Mutation in theSGCGGene and Estimated Prevalence of Limb Girdle Muscular Dystrophy Type 2C Among the Moroccan Population

Abstract

Autosomal recessive limb-girdle muscular dystrophies (AR-LGMDs) are characterized by clinical and genetic heterogeneity. LGMD type 2C, or γ-sarcoglycanopathy, is the most frequent in North African populations as a result of the founder c.525delT mutation in the SGCG gene. Its epidemiology is poorly known in Morocco, and its prevalence among the Moroccan population has never been evaluated. This study screened 26 patients with a LGMD2C and 45 patients with an AR-LGMD phenotype for the c.525delT mutation. DNA extracted from umbilical cord blood samples of 250 newborns was tested for the same mutation. Molecular epidemiologic methods were used to calculate the frequency of heterozygotes for this mutation in Moroccan newborns and to estimate the prevalence of LGMD2C in the Moroccan population. The carrier frequency was estimated to be 1/250, which would imply that the prevalence of LGMD2C would be approximately 1/20,492 considering the effect of consanguinity. The homozygous c.525delT mutation was found in 65% of all patients with AR-LGMDs. These findings suggest that AR-LGMDs are prevalent in the Moroccan population and LGMD2C is one of the most common forms. This information might be useful for the development of diagnostic strategies on a large scale for better management of patients with AR-LGMD and genetic counseling of families.