Detection of the C282Y and H63D Polymorphisms Associated With Hereditary Hemochromatosis Using the ABI 7500 FAST Real Time PCR Platform

Abstract

Classic hereditary hemochromatosis is an autosomal recessive disorder characterized by iron overload and sequence variants in the HFE gene. The HFE gene is located at 6p21.3 and contains 2 common single nucleotide polymorphisms (SNPs) C282Y and H63D, which are routinely tested for in the molecular diagnostics laboratory. In this study, we used DNA samples from 59 patients in which clinicians wanted to confirm or rule-out hereditary hemochromatosis that had been previously tested for the HFE SNPs using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay and the ABI 7700 real time PCR assay with a MGB Eclipse ASR Probe system. The new assay used TAQman SNP Genotyping Assays, which were performed on the ABI 7500 FAST real time PCR platform. Allelic discrimination was determined during a postamplification plate read. Of the 59 samples genotyped, 7 were homozygous for C282Y, 6 were heterozygous for C282Y, 9 were homozygous for H63D, 10 were heterozygous for H63D, 6 were compound heterozygotes, and 20 were wild type. With the exception of one sample that was indeterminate by the TAQman SNP Genotyping Assay, all others showed 100% concordance between the 3 assays. The one indeterminate sample was heterozygous for C282Y by the PCR-RFLP and ABI 7700 real time PCR assays, but there was an insufficient quantity of DNA to perform the TAQman SNP Genotyping Assay. Our study suggests that the ABI 7500 FAST TAQman SNP Genotyping Assay is comparable with the PCR-RFLP and ABI 7700 real time PCR methods in detecting and characterizing these 2 HFE SNPs. Improved software and thermocycling capabilities have resulted in a very robust TAQman assay with the advantage of a much improved turn-around-time and throughput.