GALT and classic galactosemia: In type I, classic galactosemia (OMIM 230400), the conversion of α-d-galactose-1-phosphate (Gal-1-P) to α-d-glucose-1-phosphate (Glc-1-P) and uridine diphosphate-galactose (UDP-Gal) is hampered by the severe GALT deficiency.