GALT and classic galactosemia: At the hub of the Leloirpathway is galactose-1-phosphate uridylyltransferase (GALT; EC 2.7.7.12),which converts galactose-1-phosphate (Gal-1-P) and UDP-glucose (UDP-Glc)into glucose-1-phosphate and UDP-galactose.2 Inherited mutations of the GALT gene lead to theautosomal recessive disorder classic galactosemia (OMIM 230400),3 affecting 1:16 000–60 000live births.