COL6A3 and Ullrich congenital muscular dystrophy: Mutations in the genes encoding COLVI (COL6A1, COL6A2, and COL6A3) cause the COLVI-related myopathies, which comprise two major clinical forms, Bethlem myopathy (BM [MIM 158810]) and Ullrich congenital muscular dystrophy (UCMD [MIM 254090]), and the limb girdle and the Myosclerosis myopathy (MM) variants.