GALK1 and hyperinsulinemic hypoglycemia, familial, 4: Apart from GALT deficiency galactosemia, there are also other rare types of galactose metabolism diseases, Type II Galactosemia (OMIM 230200), caused by deficiency of the enzyme Galactokinase (GALK, EC 2.7.1.6), characterized by early onset bilateral cataract and some neurological manifestations [26], and type III Galactosemia (OMIM #230350) caused by mutations in GALE gene (EC 5.1.3.2) leading to UDP-galactose 4-epimerase deficiency [27].