ACAN and X-linked spondyloepimetaphyseal dysplasia: The mutations in the ACAN gene can be classified into four categories: spondyloepiphyseal dysplasia, Kimberley type (SEDK, OMIM#608361); spondylo-epi-metaphyseal dysplasia, aggrecan type (SEMD, OMIM#612813); osteochondritis dissecans (OCD, OMIM#165800); and short stature and advanced bone age.