GALT and classic galactosemia: Classic galactosemia (type I galactosemia, OMIM #230400) is caused by deficient activity of galactose-1-phosphate uridylyltransferase (GALT, EC 2.7.7.12), the second enzyme of the main pathway of galactose metabolism, the Leloir pathway, and its prevalence is 1:16,000-60,000 live-births (Ashino et al. 1995; Coss et al. 2013; Fridovich-Keil and Walter 2008).