Improved Molecular Diagnosis of Hereditary Hemochromatosis Using a DNA Enzyme Immunoassay

Abstract

Hereditary hemochromatosis (HH) is an autosomal recessive disorder of iron metabolism characterized by excessive absorption of dietary iron from the small intestine, leading to gradual accumulation in several organ systems (1). In the Caucasian population, HH affects ∼3–8 in 1000 individuals, with an estimated prevalence of heterozygous carriers of 1 in 10 (2). The molecular basis for HH was completely unknown until the identification by Feder et al. (3) in 1996 of a gene on chromosome 6p, designated HLA-A . The gene, subsequently renamed HFE by the Nomenclature Committee of the Genome Database, is a MHC class Ib gene. A single missense mutation, a G-to-A transition at nucleotide 845 that produces a cysteine-to-tyrosine substitution at position 282 (C282Y) in the HFE protein, has been observed in the majority of HH patients, with frequencies ranging from 64% to 100% in different geographic areas. The role of a second mutation, which produces a histidine-to-aspartic acid substitution at position 63 (H63D), remains controversial, although it is clearly associated with HH. The strategies developed to screen HH chromosomes for the C282Y (845A) mutation include allele-specific oligonucleotide hybridization (4), restriction enzyme analysis (5), and oligonucleotide ligation assays (3). However, the use of all of these techniques is still confined to research laboratories because they are relatively expensive, time-consuming, and complicated for routine screening. In this report, we describe a PCR-based method that uses a DNA enzyme immunoassay (DEIA) for the specific detection of C282Y mutations. After receiving informed consent, we analyzed 75 subjects. Of these, 46 were unrelated cases with a suspicion of hemochromatosis, whereas the remaining 29 subjects were members …