CHSY1 and temtamy preaxial brachydactyly syndrome: Loss-of-function mutations in CHSY1 encoding chondroitin synthase 1 cause Temtamy preaxial brachydactyly syndrome, which is characterized by delayed motor and mental development as well as bilateral, symmetric preaxial brachydactyly and hyperphalangism of digits, facial dysmorphism, and dental anomalies (Li et al., 2010).