For example, among the 26 newborns referred to the clinical center for increased DBS total galactose considerable overlaps in DBS galactose-1-P-uridyltransferase (GALT) activities did not allow to discriminate between newborns with variable combinations of compound heterozygosity for classic galactosemia due to pathogenic GALT gene mutations and Duarte alleles. The gene discussed is GALT; the disease is classic galactosemia.