Defective CHSY1 causes TPBS

Chondroitin sulfate synthases (CHSY) are involved in the synthesis of chondroitin sulfate, adding alternatingly glucuronate (GlcA) and N-acetylgalactosamine (GalNAc) to the growing chondroitin polymer. Defects in CHSY1 cause temtamy preaxial brachydactyly syndrome (TPBS; MIM:605282), a syndrome characterized by multiple congenital anomalies, mental retardation, sensorineural deafness, growth retardation and bilateral symmetric digital anomalies mainly in the form of preaxial brachydactyly (literally, shortness of fingers and toes) and hyperphalangism.

Summary from Reactome (R-HSA-3595177), read 2026-09-23.