CAPN3 and autosomal recessive limb-girdle muscular dystrophy type 2A: Limb-girdle muscular dystrophy recessive 1 (LGMDR1), previously known as LGMD2A (calpainopathy), is the most common LGMD subtype worldwide and is caused by mutations in the CAPN3 gene, which encodes a skeletal muscle-specific, Ca2+-activated, nonlysosomal cysteine protease, calpain 3 (CAPN3).1