Mutations in COL6A1, COL6A2, and COL6A3 lead to a spectrum of collagen VI-related muscular dystrophies, ranging from the severe Ullrich congenital muscular dystrophy (UCMD) via intermediate phenotypes to the milder Bethlem muscular dystrophy (BM). Here, COL6A3 is linked to Congenital muscular dystrophy, Ullrich type.