SULF1 and achondrogenesis type IB: Mutations in other genes of the sulfation cascade, such as chondroitin-4-sulfotransferase 1 (Chst11) [45], diastropic dysplasia transporter (Dtdst or Slc26a2) [46,47] and extracellular heparan endosulfatases (Sulf-1 and Sulf-2) [48], have also been shown to result in various types of chondrodysplasias, some of which are lethal (mutations in Dtdst: achondrogenesis type IB [OMIM:600972]; atelosteogenesis type 2 [OMIM:256050]).