GALK1 and classic galactosemia: Galactosemia is caused by any defect in the Leloir pathway of galactose metabolism, which is comprised of galactokinase (GALK1), galactose‐1‐phosphate uridylyltransferase (GALT), UDP‐galactose 4′‐epimerase (GALE) enzymatic components, as well as the new type IV galactosemia due to galactose mutarotase (GALM).1