Screening test is done primarily to detect clinically devastating classic galactosemia (CG, OMIM #230400) due to defective function of galactose-1-phosphate-uridyl transferase (GALT) and generalized forms of epimerase deficiency galactosemia (GALE deficiency galactosemia, OMIM #230350), due to defective function of UDP-galactose-4-epimerase (GALE) [39–41]. The gene discussed is GALT; the disease is galactose epimerase deficiency.