Abstract 48

Aim: Prospective evaluation of scanning the entire coding region of the galactose-1-P uridyltransferase (GALT) gene for sequence changes as a confirmatory test in newborn screening for classical galactosemia. Probands: 110 newborns with initial positive total galactose test including one patient with classical galactosemia among 43.688 consecutively screened newborns. Methods: Denaturing gradient gel electrophoresis of exons 2-11 and Cleavase digestion of exon 1 of the GALT gene using a single 3mm punch of the initial dried blood spot. Results: In all 110 probands the 11 exons of the GALT gene could be analysed. The patient with classical galactosemia was identified correctly and was homozygous for a rare mutation on exon 5. A second proband carrying two sequence changes had a normal galactose follow up test. 21 probands carried one suspected galactosemia allele. 87 of the 110 probands would not have required a recall (20 carrying Duarte alleles only, 67 without sequence changes). Conclusion: Scanning the entire GALT gene for sequence changes could reduce the recall rate by about five fold. A confirmatory test for the common galactosemia alleles Q188R and K285N only would havemisclassified the patient with classical galactosemia caused by a rare mutation.