Objectives

The HEIRS Study evaluated the prevalence and genetic and environmental determinants and potential clinical, personal, and societal impact of iron overload and hereditary hemochromatosis in a multi-center, multiethnic, primary care-based sample of adults.

Background

Hereditary iron overload, or hemochromatosis, is a common inherited disorder resulting from overabsorption of dietary iron. Excess iron is deposited in body tissues, and can accumulate to toxic levels over time causing damage in multiple organ systems. If untreated, these conditions may lead to death. Evidence suggests that early diagnosis and treatment can prevent disease manifestations and enable normal life expectancy. Thus, hemochromatosis may be suitable for detection and intervention through primary care screening strategies; however, much remains to be learned about the penetrance and expression of the known gene variants, HFE C282Y and H63D, associated with hemochromatosis. Iron overload and hereditary hemochromatosis have not been as extensively studied in racial/ethnic groups other than Caucasians.

Participants

The initial screen phase included 102,000 adults recruited over a 2-year period from 5 North American Field Centers (approx. 51% white, 24% African American, 11% Asian, 11% Hispanic, and 3% unidentified race; 63% are female and 37% are male).

Design

During the initial screen phase in 2001-2002, participants were recruited from primary care practices and blood-drawing laboratories. Blood specimens were tested for transferrin saturation (TS), serum ferritin (SF), and HFE C282Y and H63D genetic variants. Before genetic screening, participants were asked whether they had a history of medical conditions related to iron overload. Those participants with elevated iron levels and/or C282Y homozygosity, their family members, and frequency-matched control participants completed an examination that obtained data on personal and family medical history, lifestyle characteristics, genetic counseling and assessment of ethical, legal and social implications of screening, as well as clinical and biochemical measures. A separate randomized study examined the acceptability of genotypic or phenotypic (biochemical) screening for hemochromatosis.

The majority of HEIRS participants have a consent limited to research on iron related disorders; however, specimens and data from ~6770 participants are available for broader research use.

Conclusions

Findings include: 1) transferrin saturation (TS) and serum ferritin (SF) mean levels differ across race/ethnic groups; 2) HFE C282Y variant does not account for these levels in non-Caucasians (Adams et al, NEJM 352:1769-78, 2005); and 3) there is similar participant acceptance for genotypic as for phenotypic testing (Anderson et al, Genet Med. 7:557-63, 2005).

Additional Details

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