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, COL6A1 is linked to Ullrich congenital muscular dystrophy.