GALE (UDP-galactose-4-epimerase) catalyzes the reversible epimerization of UDP-glucose to UDP-galactose and UDP-N-acetylglucosamine to UDP-N-acetylgalactosamine, playing a critical role in the Leloir pathway of galactose catabolism. This enzyme enables conversion of dietary galactose to glucose-6-phosphate and supports endogenous biosynthesis of UDP-galactose and UDP-N-acetylgalactosamine when exogenous sources are limited. GALE functions as a cytosolic protein homodimer essential for glycoprotein and glycolipid synthesis. At the molecular level, GALE regulates nucleotide sugar (NS) levels and pathway flux 1. CRISPR-mediated GALE deletion in human cells causes major imbalances in nucleotide sugars and dramatic reductions in sialic acid, galactose, and GalNAc levels in glycans, affecting cell-surface glycoproteins including integrins and death receptors 1. These changes directly impact cell signaling, with GALE-deficient cells showing altered apoptotic responses 1. Mutations in GALE cause Galactosemia 3 and Thrombocytopenia 13 (syndromic), linking NS imbalances to pathological outcomes. GALE dysfunction may contribute to metabolic disorders characterized by NS imbalances, including galactosemia and metabolic syndrome 1. The enzyme's role in regulating glycan structure is fundamental to normal cell physiology and immune function.