COL6A3 and Congenital muscular dystrophy, Ullrich type: In humans, mutations in any of the three genes coding for collagen VI (COL6A1, COL6A2, COL6A3) result in defective ECM composition and cause a wide clinical spectrum of collagen VI myopathies including Ullrich congenital muscular dystrophy (UCMD), Bethlem myopathy (BM) [8]–[11] and myosclerosis myopathy [12].