COL6A3 and Congenital muscular dystrophy, Ullrich type: Mutations in COL6A1, COL6A2, and COL6A3 genes cause a group of myopathies (COL6-related myopathies, or COL6-RMs) [4], which comprise two major clinical forms, Bethlem myopathy (BM, MIM #158810) and Ullrich congenital muscular dystrophy (UCMD, MIM #254090) [5], and a phenotype in between UCMD and BM, referred to as intermediate COL6-RM, or the myosclerosis myopathy variants (MM, MIM #255600) [6].