What you carry at this position in your DNA and what research says about it.
Iron Overload Risk: 10/10 evidence, 50 publications.
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Sample genotype (not yours): C/C
Typical Iron Overload Risk
You do not carry the H63D variant associated with hereditary hemochromatosis. Your body's iron regulation and blood pressure levels are expected to be typical.
What this genotype means: Typical iron absorption; Typical blood pressure levels.
Sample genotype (not yours): C/G
Carrier of Mild Iron Overload Variant
You carry one copy of the H63D variant. While you are highly unlikely to develop iron overload from this alone, you can pass it to your children.
What this genotype means: Carrier status for hemochromatosis; Slightly higher blood pressure baseline.
Sample genotype (not yours): G/G
Mildly Elevated Iron Overload Risk
You carry two copies of the H63D variant. This can lead to slightly higher iron levels and a mild risk of iron accumulation, though clinical symptoms are rare.
What this genotype means: Mildly increased iron absorption; Slightly higher blood pressure baseline.
Gene function and biological role
Gene Function: HFE encodes the homeostatic iron regulator protein, which plays a crucial role in maintaining iron balance in the body [1]. It interacts with transferrin receptors on cell surfaces to detect circulating iron levels [1]. Based on these signals, HFE regulates the production of hepcidin, a hormone that controls how much iron is absorbed from food [1]. When HFE is mutated, this signaling pathway is disrupted, leading to low hepcidin levels and excessive iron absorption [1]. Over time, this excess iron can accumulate in organs like the liver, heart, and joints [1].
Variant Impact: The rs1799945 variant, commonly known as H63D, is a missense mutation in the HFE gene [2]. This genetic change replaces the amino acid histidine with aspartate at position 63 of the HFE protein [2]. This alteration mildly impairs the protein's ability to regulate iron absorption, leading to slightly increased iron levels in the blood [2]. While much milder than the classic C282Y mutation, it is highly prevalent in populations of European descent [2]. Having two copies of this variant can lead to mild iron accumulation, especially when other genetic or lifestyle factors are present [2].
Key Insight: While the H63D variant is linked to iron absorption, having two copies rarely causes severe hemochromatosis on its own without other genetic factors. Interestingly, this variant is also associated with a slight increase in blood pressure and a lower risk of heart damage from certain chemotherapy drugs.
Location: HFE. Chromosome 6 · 6p22.2 · 26.1 Mb
Estimated prevalence by population
Global 81.1%; European 72.2%; African 94.2%; East Asian 94.7%; South Asian 85.1%; Americas 79.2%; Ashkenazi 77.3%; Finnish 81.7%; Middle Eastern 80.0%; Amish 86.0%.
Estimated CC genotype frequency.
Global 17.6%; European 25.5%; African 5.7%; East Asian 5.2%; South Asian 14.3%; Americas 19.6%; Ashkenazi 21.2%; Finnish 17.3%; Middle Eastern 18.9%; Amish 13.4%.
Estimated CG genotype frequency.
Global 1.3%; European 2.3%; African 0.1%; East Asian 0.1%; South Asian 0.6%; Americas 1.2%; Ashkenazi 1.5%; Finnish 0.9%; Middle Eastern 1.1%; Amish 0.5%.
Estimated GG genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Blood Cell & Iron Traits
Iron Overload. Evidence: 3/10. Source: PMID 8696333. Typical Risk.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 27863252. Typical.
Hypertension
Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Typical.
Pharmacogenomics
Chemotherapy Response
Chemotherapy Safety. Evidence: 5/10. Source: PMID 40741000. Typical Risk.
Showing effects for C/G genotype
Iron Overload. Evidence: 3/10. Source: PMID 8696333. Slightly Elevated.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 27863252. Slightly Higher.
Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Slightly Higher.
Chemotherapy Safety. Evidence: 5/10. Source: PMID 40741000. Lower Risk of Damage.
Showing effects for G/G genotype
Iron Overload. Evidence: 3/10. Source: PMID 8696333. Elevated Risk.
Hemoglobin Levels. Evidence: 10/10. Source: PMID 27863252. Higher.
Blood Pressure. Evidence: 10/10. Source: PMID 38689001. Higher.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Inheriting two copies of the normal C allele means the H63D mutation is absent from the HFE gene [1]. Your HFE protein functions normally, allowing your body to regulate iron absorption from food effectively [1]. Consequently, you have a typical risk of developing iron overload or hereditary hemochromatosis [1]. Your blood pressure and hemoglobin levels are also expected to be within the typical range for your demographic [2]. While you do not carry this specific risk factor, maintaining a balanced diet and regular health checkups remains important for overall cardiovascular and metabolic health.
Typical iron absorption; Typical blood pressure levels.
Sample genotype: CG (Heterozygous)
Presence of one copy of the G allele makes a person a carrier of the H63D mutation [1]. On its own, carrying a single copy of this variant rarely leads to clinical iron overload or symptoms of hemochromatosis [1]. However, if you also carry the more severe C282Y mutation, you may have a slightly elevated risk of mild iron accumulation [1]. This genotype is also associated with a very small increase in blood pressure [2]. Most carriers lead completely healthy lives without requiring any special medical interventions or dietary restrictions.
Carrier status for hemochromatosis; Slightly higher blood pressure baseline.
Sample genotype: GG (Homozygous)
Possessing two copies of the G allele means a person is homozygous for the H63D mutation [1]. This genotype can lead to slightly lower levels of hepcidin, resulting in increased dietary iron absorption [1]. While some individuals with this genotype show mildly elevated blood iron markers, very few develop clinical symptoms of hemochromatosis without other contributing factors [1]. You may also have a slightly higher baseline for blood pressure and hemoglobin concentration [2].
Mildly increased iron absorption; Slightly higher blood pressure baseline.
Variants with shared genetic architecture
rs1800562 · HFE Gene · Chr 6 · Iron Overload Risk
rs79220007 · HFE Gene · Chr 6 · Iron Overload Risk
rs1800730 · HFE Gene · Chr 6 · Iron Overload Risk
A novel MHC class I-like gene is mutated in patients with hereditary haemochromatosis.
Content updated August 2026.
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