Galactokinase belongs to the GHMP kinase family and GalK subfamily. Galactokinase is more important to the galactose metabolism pathway. It modifies galactose to create a similar molecule called Galactose-1-Phosphate.Thus, a series of additional steps converts Galactose-1-Phosphate to another simple sugar Glucose, which is the main energy source for most cells. Galactokinase deficiency results in Galactosemia II, an autosomal recessive deficiency characterized by congenital cataracts during infancy and presenile cataracts in the adult population. The cataracts are secondary to accumulation of Galactitol in the lenses.