Ganglioside GM3 synthase (also called lactosylceramide alpha-2,3-sialyltransferase) deficiency (OMIM 609056) is caused by a mutation in the ST3GAL5 gene and is a rare metabolic disorder inherited as an autosomal recessive trait. Here, ST3GAL5 is linked to hyperinsulinemic hypoglycemia, familial, 4.