Mutations in the human aggrecan gene (ACAN or AGC1) lead to a broad range of non-lethal skeletal dysplasia including spondyloepimetaphyseal dysplasia (SEMD) [10], osteochondritis dissecans with early onset of OA [11], and various short stature syndromes with accelerated bone maturation [12]. Here, ACAN is linked to spondyloepimetaphyseal dysplasia.