Galactokinase is an essential enzyme for the metabolism of galactose and its deficiency causes congenital cataracts during infancy and presenile cataracts in the adult population.
Patients with reduced activity of galactokinase or galactose-1-phosphate uridyl transferase (presumed heterozygotes) compose about 1% of the general population, appear to be more susceptible to idiopathic presenile cataract formation, and may be more prone to secondary cataract formation after a variety of lenticular insults.
Even when Black subjects were excluded from analysis because of their high incidence of polymorphism for galactokinase, these findings are significantly different from those expected from population surveys and suggest that many patients with presenile cataracts have a biochemical abnormality which can be detected by examination of red blood-cells and which may be corrected by dietary restrictions or supplements.