Ullrich congenital muscular dystrophy (UCMD), Bethlem myopathy (BM), and myosclerosis myopathy (MM) are diseases caused by mutations in each of the three genes (COL6A1, COL6A2, and COL6A3) encoding the extracellular matrix protein collagen VI. The gene discussed is COL6A3; the disease is Congenital muscular dystrophy, Ullrich type.