COL2A1 and spondyloepiphyseal dysplasia congenita: Mutations in the gene encoding the type II collagen gene (COL2A1) cause a series of type II collagenopathies that manifest as inheritable skeletal disorders, including achondrogenesis type 2 (ACG2; Langer-Saldino type), hypochondrogenesis, platyspondylic (Torrance type), congenital spondyloepiphyseal (SEDC), spondyloepimetaphyseal (SEMD) and Kniest dysplasia, Stickler syndrome type 1 and Stickler-like syndrome.