COL6A2 and deafness: Genetic mutations in collagen α chain may result in spondyloepiphyseal dysplasia, spondyloepimetaphyseal dysplasia, achondrogenesis, hypochondrogenesis, kniest dysplasia, stickler syndrome (COL2A1) [33]; bethlem myopathy (COL6A1) and ullrich congenital muscular dystrophy (COL6A2) [34]; stickler syndrome, Marshall syndrome, otospondylomegaepiphyseal dysplasia and deafness (COL11A1) [35].