We describe 2 siblings who are homozygous for the G787A mutation in the γ-sarcoglycan gene (SGCG), who presented with a severe childhood onset limb-girdle muscular dystrophy, and share a similar clinical phenotype and disease course consistent with LGMD 2C. The siblings' mother is asymptomatic and is heterozygous for the same mutation. The father is estranged but presumably was also an asymptomatic heterozygous carrier as the father's sister (siblings' aunt) died of complications related to a muscular dystrophy at the age of 14. The paternal grandparents of these siblings were first cousins. All members of the family are of Puerto Rican ancestry supporting the theory that this is a founder mutation, as has been previously suggested by Duncan et al The clinical presentation, workup, and course of our patients are described in detail. These 2 cases effectively double the reported cases of this founder mutation.