TRPS type 2 or Langer-Giedion syndrome (OMIM #150230) involves TPRS1, RAD21 and EXT1, and the facial phenotype is mainly determined by loss of TRPS1, whereas the bony abnormalities arise from the loss of EXT1 (Maas et al. 2015). Here, EXT1 is linked to Langer-Giedion syndrome.