In our laboratory, limb-girdle muscular dystrophy (LGMD) accounted for 20% of all patients with muscular dystrophy. To determine the incidence of various forms of LGMD phenotypes, we looked for mutations in the calpain 3 gene and, for deficiencies in dysferlin and sarcoglycan by immunohistochemical studies with specific antibodies on muscle biopsies from patients with probable autosomal recessive inheritance (LGMD2), which were mostly sporadic cases of LGMD. Fourteen of 276 (5%) patients examined had sarcoglycan complex deficiency (sarcoglycanopathy) and 21 of 80 (26%) had mutations in the calpain 3 gene. Although we have not performed gene analysis in all patients, 10 of 64 (15%) patients examined had no apparent immunoreactivity against the dysferlin antibody. Thus, approximately 46% of LGMD2 patients had the above 3 distinct disorders, but in 54% the causative defects remain unknown.