These genes are orthologs of those causing four different skeletal diseases in group 13 (ddrgk1 for SEMD Shohat type, extl3 for SEMD with immune deficiency EXTL3 type, nans for SEMD with intellectual disability NANS type, and tonsl for SPONASTRIME Dysplasia; Supplementary Table 1). Here, EXTL3 is linked to spondyloepimetaphyseal dysplasia.