PURPOSE: We previously reported a deletion of the Galactose-1-Phosphate Uridyl Transferase (GALT) gene. This deletion can cause apparent homozygosity for variants located on the opposite allele, potentially resulting in a discrepancy between the biochemical phenotype and the apparent genotype in an individual. The purpose of this study was to determine the deletion breakpoints, allowing the development of a rapid and reliable molecular test for the mutation. METHODS: A Polymerase Chain Reaction walking strategy was used to map the 5′ and 3′ breakpoints. The junction fragment was amplified and sequenced to precisely characterize the deletion breakpoints. RESULTS: The deletion has a bipartite structure involving two large segments of the GALT gene, while retaining a short internal segment of the gene. Molecular characterization allowed the development of a deletion specific Polymerase Chain Reaction-based assay. In 25 individuals who had a biochemical carrier galactosemia phenotype, but tested negative for 8 common GALT gene variants, 3 carried this deletion. CONCLUSION: This deletion occurs at an appreciable frequency and should be considered when there is a discrepancy between the genotype and biochemical phenotype. Many of the individuals carrying the allele were of Ashkenazi Jewish ancestry suggesting that the deletion may be a common cause of galactosemia in that population. © 2006 The American College of Medical Genetics.
CITATION STYLE
Coffee, B., Hjelm, L. N., DeLorenzo, A., Courtney, E. M., Yu, C., & Muralidharan, K. (2006). Characterization of an unusual deletion of the galactose-1-phosphate uridyl transferase (GALT) gene. Genetics in Medicine, 8(10), 635–640. https://doi.org/10.1097/01.gim.0000237720.78475.fb
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