Galactosemia: screening and diagnosis.

Galactose is normally metabolized to glucose through the coordinated activities of three enzymes: galactokinase, galactose-1-phosphate uridyl transferase (GALT), and uridine diphospho-glucose 4-epimerase (epimerase). High concentrations of galactose and their metabolites are toxic to mammals. Hereditary deficiencies of galactokinase and of GALT and perhaps rarely of epimerase cause clinical disorders that can be prevented by early recognition and institution of a galactose-free diet. The genetics of disorders of galactose metabolisms and the methods used currently for their detection are reviewed. Future prospects in the diagnosis of these disorders are discussed.