Heterozygous mutations in the COL2A1 gene cause a spectrum of type II collagenopathies, including those that are lethal in neonates, such as achondrogenesis type II/hypochondrogenesis [MIM:200610], and nonlethal conditions, such as spondyloepiphyseal dysplasia congenital [MIM:183900]; spondyloperipheral dysplasia [MIM:271700]; spondyloepimetaphyseal dysplasia, Strudwick type [MIM:184250]; Kniest dysplasia [MIM:156550]; and Stickler syndrome. The gene discussed is COL2A1; the disease is spondyloperipheral dysplasia.