GALK1 and classic galactosemia: Galactosemia is a family of rare autosomal recessive hereditary liver disorders resulting from impairment of one of the four galactose metabolizing enzymes, i.e., galactokinase (GALK), galactose-1-phosphate uridylyltransferase (GALT), UDP-galactose 4-epimerase (GALE), and galactose mutarotase (GALM), that are involved in the Leloir pathway of galactose metabolism.