Molecular analysis of gene in Argentinian population: Correlation with enzyme activity and characterization of a novel Duarte-like allele.

BACKGROUND

Classical galactosemia is an autosomal recessive inherited metabolic disorder caused by mutations in the galactose-1-phosphate uridyltransferase () gene. GALT enzyme deficiency leads to the accumulation of galactose-1-phosphate in various organs, causing hepatic, renal and cerebral impairment. Over 300 mutations have been reported in the gene. The aim of this study was to describe molecular characterization of gene in Argentinian patients with decreased GALT activity, and to correlate molecular results with enzyme activity.

METHODS

37 patients with enzyme activity below 6.3 μmol/h/g Hb (35% of normal value) were included. GALT activity was measured on red blood cells. DNA was extracted from peripheral blood. p.Gln188Arg mutation was studied by PCR-RFLP and, on samples negative or heterozygous, gene was sequenced. splicing analysis of the gene was performed on RNA extracted from leukocytes of one patient.

RESULTS

14 different sequence variations were identified among 72 unrelated alleles. The two most common disease-causing mutations were p.Gln188Arg (24/72) and p.Lys285Asn (9/72). Three novel mutations were detected. One of them, c.688G>A, caused partial skipping of exon 9 of the gene. Enzyme activity correlated with genotype in 36 of the 37 patients.

CONCLUSION

This is the first report of sequence variations in the gene in the Argentinian population. This study highlights the contribution of the molecular analysis to the diagnosis of Galactosemia and reveals c.688G>A as a novel Duarte-like variant, with a high prevalence in our population.