In another study, a severe chondrodysplasia characterized by the substantial upregulation of TGF-β signalling was revealed in a gene trap mutation in the chondroitin-4-sulfotransferase 1 (C4st1) gene, which causes downregulation of 4-O-sulfated chondroitin production [108]. The gene discussed is CHST11; the disease is chondrodysplasia.