SLC30A2 and Zinc deficiency: Since the two missense mutations of the SLC30A2/ZnT2 gene causing W152R and S296L substitutions were found on different alleles, we conclude that the compound heterozygous mutations in SLC30A2/ZnT2 are responsible for the low zinc levels in the breast milk of the Japanese mother in our study, which caused severe zinc deficiency in her infant.