Meta-Biol

• Pathways

Cytosolic galactokinase (GALK1) catalyses the first step in the Leloir pathway of galactose metabolism. GALK1 catalyses the phosphorylation of D-galactose (Gal) to form D-galactose 1-phosphate (Gal1P). Defects in GALK1 can cause Galactosemia II (GALCT2; MIM:230200), an autosomal recessive deficiency characterised by congenital cataracts during infancy and presenile cataracts in the adult population. Galactitol accumulation in the lens is the cause of these cataracts. Mutations causing GALCT2 include V32M, E80*, P28T, Q382* and R256W (Stambolian et al. 1995, Kalaydjieva et al. 1999, Kolosha et al 2000, Bayarchimeg et al. 2012). There is a wide spectrum of severity and age of onset. However, beyond cataract formation, no long-term complications have been documented (Bosch et al. 2002, Timson & Reece 2003).