[Muscular dystrophy due to a deficit of gamma-sarcoglycan. A report of three patients with the Delta-521t mutation].

Introduction. γ-sarcoglicanopathies, also classified as limb girdle muscular dystrophy type 2C (LGMD2C) are a group of autosomal recessive muscular dystrophies due to mutations in 13q12 and subsequent γ-sarcoglican deficiency. The protein is one of the components of the dystrophin-associated gycoprotein complex and is thought to impart structural integrity to the myofibre. The clinical course ofthe disease may be heterogeneous, ranging from severe forms whith onset in the first decade and rapid progression resembling Progressive Duchenne muscular dystrophy (DMD) to milder forms with later onset and slower course. Cases hitherto reported in Sapin corresponds to gypsie patients, homozygous for C283Y missense mutation. Casereports. Here, we report three newgalician (Northwest Spain) patients (one male and one female sibling cases) with a severe DMD-like muscular dystrophy homozygous for Δ-521T. In the first male familial case, initial diagnosis of DMD was made. On reevaluation fourteen years later, inmunohistochemical and molecular studies allowed for a definitive γ-sarcoglicanopathy diagnosis. Conclusions. Patients with a primary sarcoglycanopathy may be clynically indistinguishable from those with the primary dystrophinopathies. Probably, the diagnosis of LGMD are underestimated and a number of male patients diagnosed as DMD really corresponds to a recessive form o muscular dystrophy. Consequently, a definitive diagnosis rests on appropriate inmunohistochemical and molecular analysis, specially in those patients showing a normal pattern ofdystrophin and/or suggestive for an autosomal recessive mode of inheritance.