Loss-of-function mutations in CHST3 are causative of spondyloepiphyseal dysplasia (SED) Omani type (OMIM 143095) (Thiele et al., 2004), in which a missense mutation in CHST3 leads to a generalized defect in the chain sulfation of chondroitin sulfate resulting in severe chondrodysplasia. Here, CHST3 is linked to chondrodysplasia.