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HEMOCHROMATOSIS GENOTYPING ASSAY

Test Code: HCHGA
Description: Hereditary hemochromatosis is an autosomal recessive disorder in which biallelic inactivation of the HFE gene leads to increased intestinal iron uptake and subsequent iron deposition throughout the body, including in the liver, heart, pancreas, and CNS.  The majority of hereditary hemochromatosis cases in the Caucasian population of the United States and Western Europe are caused by homozygosity for the p.Cys282Tyr (C282Y, c.845G>A) mutation, where the minor allele frequency approaches 10%. The remaining cases are primarily due to the involvement of the p.His63Asp (c.187C>G) with a much smaller proportion demonstrating p.Ser65Cys (c.193A>T) mutations.

The presence of two mutations is compatible with a diagnosis of hereditary hemochromatosis only in the proper clinical context. The large majority of patients with biallelic HFE mutations will be entirely free from clinical disease (72%-99%, depending on the definition of “clinical disease”); as such, HFE genotyping is only indicated in the context of clinical suspicion for hereditary hemochromatosis (e.g. abnormal iron studies/end-organ damage), NOT as a first-line screen.

This assay amplifies the genomic DNA region surrounding the c.845 and c.187/c.193 positions and uses melting curve analysis of allele-specific probe hybridization to assess for the presence of any non-reference variants within the small (25-30bp) region containing these specific loci. The presence of the common c.845G>A, c.187C>G, and c.193A>T mutations will result in distinct and reproducible changes in the melting curve measured by this method.


 
 


 
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