Defective GALE causes EDG

Cytosolic UDP-galactose 4'-epimerase (GALE) catalyses the reversible interconversion of UDP-D-galactose (UDP-Gal) and UDP-glucose (UDP-Glc), the third reacton in the Leloir pathway of galactose metabolism. GALE can also catalyse the epimerisation of UDP-N-acetylglucosamine to UDP-N-acetylgalactosamine. The active form of the enzyme is a homodimer with one molecule of bound NAD per monomer (GALE:NAD+ dimer). Defects in GALE can cause Epimerase-deficiency galactosemia (EDG; MIM:230350), or type III galactosemia (diseases of galactose metabolism) whose clinical features include early-onset cataracts, liver damage, deafness and mental retardation. Historically, it was considered that there were two forms of GALE deficidency; a benign ("peripheral") form where there is no GALE activity in red blood cells and characterised by mild symptoms and a rarer "generalised" form with no detectable GALE activity in all tissues resulting in more severe symptoms. The disease is now considered to be a continuum.

Summary from Reactome (R-HSA-5609977), read 2026-09-23.