GALK1 and classic galactosemia: In the first report, eight patients with unexplained congenital galactosemia detected in newborn screening (NBS) without pathogenic variants in GALT, GALE, or GALK1 or other explanation for increased galactose, were found to have pathogenic biallelic variants in GALM in combination with decreased GALM enzyme activity (measured in two patients) and decreased GALM protein expression (measured in three patients) [7].