Defective ST3GAL3 causes MCT12 and EIEE15

CMP-N-acetylneuraminate-beta-1,4-galactoside alpha-2,3-sialyltransferase (ST3GAL3) mediates the transfer of sialic acid from CMP-sialic acid to galactose-containing glycoproteins and forms the sialyl Lewis a epitope on proteins which are required for attaining and/or maintaining higher cognitive functions. Some defects in ST3GAL3 result in mental retardation, autosomal recessive 12 (MRT12; MIM:611090), a disorder characterised by below average general intellectual function and impaired adaptive behaviour. Another defect of ST3GAL3 can cause early infantile epileptic encephalopathy-15 (EIEE15: MIM:615006), resulting in severe mental retardation.

Summary from Reactome (R-HSA-3656243), read 2026-09-23.