An inherited condition in which the body absorbs more iron from food than it needs. Over decades the surplus iron can build up in the liver, heart, pancreas and joints and cause damage.
Hereditary hemochromatosis is a condition in which the body takes in more iron from food than it actually needs. Iron is essential — it carries oxygen in your blood — but the body has no efficient way to get rid of a surplus. When absorption stays switched on year after year, the extra iron is parked in organs that were never designed to store it, and over decades it can damage them.
The form described on this page is type 1, or HFE-related hemochromatosis. It is by far the most common type and is caused by changes in a gene called HFE. Three other, much rarer types are caused by different genes.
The frustrating thing about hemochromatosis is that the early signs are vague and easy to blame on something else. People often report:
If iron keeps accumulating without treatment, the possible consequences are more serious: scarring of the liver (cirrhosis) and an increased risk of liver cancer, diabetes, an enlarged or poorly functioning heart, irregular heart rhythms, and reduced output from the hormone glands.
Symptoms rarely appear early in life. Iron accumulates slowly, so problems typically surface between roughly ages 40 and 60 in men. Women who menstruate lose iron every month, which partly offsets the extra absorption, so women who do develop symptoms usually do so after menopause. This is one reason the condition is diagnosed far more often in men.
Genetic changes in HFE are unusually common in people with Northern and Western European ancestry, and the condition is less common in other ancestry groups.
The HFE gene helps the body sense how much iron it already has. It does this by influencing a hormone called hepcidin, which acts like a valve on iron entering the bloodstream from the gut. When HFE does not work properly, hepcidin levels stay too low, the valve stays open, and iron keeps flowing in regardless of how much is already in storage.
Two HFE changes account for nearly all cases. The one usually called C282Y is the important one: having two copies of it is the classic cause of the condition. A second change, H63D, is even more common in the population but has a much weaker effect. On its own, two copies of H63D rarely lead to meaningful iron overload, and a single copy of either change is generally not expected to cause problems.
Carrying the high-risk genotype is not the same as having the disease. Many people with two copies of C282Y never develop iron overload at all, and only a minority ever go on to organ damage. Genetics sets the possibility; sex, age, alcohol intake, other liver conditions and blood loss all influence whether it is realized. This is why a genetic result is a reason to check iron levels with a blood test, not a diagnosis by itself.
Hemochromatosis is often picked up incidentally, when routine blood work shows unexpectedly high iron markers, or during evaluation of unexplained fatigue, joint pain or abnormal liver tests. Doctors look at two blood measurements in particular: transferrin saturation, which reflects how much iron is circulating, and ferritin, which reflects how much is stored. Genetic testing of HFE then confirms the cause. In selected cases, MRI or a liver biopsy is used to measure how much iron the liver actually holds.
The condition is also notable for having a simple, long-established treatment: removing blood on a schedule, much like donating it, which draws down the body's iron stores. Detected before cirrhosis or diabetes develop, life expectancy is typically normal — which is precisely why early detection matters. Any treatment decision belongs with a doctor who can see your full picture.
Gene and variants. HFE (OMIM 613609) encodes an MHC class I-like protein. The two common alleles are c.845G>A (p.Cys282Tyr; rs1800562), historically C282Y, and c.187C>G (p.His63Asp; rs1799945), historically H63D. Reference transcript NM_000410.4.
Mechanism. HFE forms a heterodimer with beta-2-microglobulin at the hepatocyte surface and participates in an iron-sensing complex involving transferrin receptor 2, hemojuvelin and BMP receptor signaling. The p.Cys282Tyr substitution abolishes a disulfide bond in the alpha-3 domain, altering conformation and disrupting association with beta-2-microglobulin and these partners. The downstream consequence is failure to upregulate hepcidin appropriately for the body's iron burden. With hepcidin inappropriately low, ferroportin on enterocytes and reticuloendothelial macrophages is not degraded, duodenal iron absorption and macrophage iron release continue unchecked, and non-transferrin-bound iron accumulates parenchymally — hepatocytes first, then pancreas, myocardium, synovium and pituitary.
Genotype distribution among affected individuals of European ancestry. Approximately 60%–90% of those with HFE hemochromatosis are p.Cys282Tyr homozygotes; roughly 3%–8% are p.Cys282Tyr/p.His63Asp compound heterozygotes, and about 1% are p.His63Asp homozygotes. Penetrance of the compound heterozygous and H63D homozygous genotypes is markedly lower than that of C282Y homozygosity; where such individuals do develop significant iron overload, a cofactor (another hemochromatosis-related pathogenic allele, alcohol use, metabolic dysfunction-associated steatotic liver disease, or another cause) should be sought.
Penetrance. Longitudinal population-based cohorts indicate that approximately 38%–50% of p.Cys282Tyr homozygotes develop an elevated serum ferritin, while only about 10%–33% ever develop clinically overt disease. Penetrance is strongly sex-dependent — GeneReviews cites clinical HFE hemochromatosis in roughly 28% of male versus 1% of female homozygotes — attributed largely to menstrual and pregnancy-related iron losses. Earlier menopause is associated with higher hepatic iron concentration.
Biochemical evaluation. Fasting transferrin saturation is the more sensitive early marker; thresholds prompting further evaluation are approximately ≥60% in males and ≥50% in females. Serum ferritin is usually normal below 300 µg/L in males and 200 µg/L in females, but it is an acute-phase reactant and rises with inflammation, alcohol use, hepatocellular injury and metabolic syndrome — so an isolated hyperferritinemia is not evidence of iron overload. Hepatic iron concentration by MRI (R2/R2*) has largely replaced biopsy for quantification; biopsy retains a role in fibrosis staging, most often considered when ferritin is markedly elevated or transaminases are abnormal.
Differential considerations. Secondary iron overload from transfusion dependence or ineffective erythropoiesis; dysmetabolic hyperferritinemia; alcohol-related liver disease; non-HFE hemochromatosis (HJV, HAMP, TFR2, SLC40A1) — the juvenile forms present before age 30 with cardiomyopathy and hypogonadism, and SLC40A1-related disease is autosomal dominant with a distinct ferroportin-disease phenotype.
Management principle. Therapeutic phlebotomy is the mainstay for iron-loaded individuals, with induction typically to a ferritin around 100 µg/L followed by maintenance; each unit removes roughly 160–200 mg of iron. Management decisions, including whether to treat a biochemically normal homozygote, belong to the treating clinician.
Inheritance and counseling. Autosomal recessive with low and variable clinical penetrance. Sibling risk of the same genotype is 25%; because of the high allele frequency, sibling testing is generally considered more informative than offspring testing, and biochemical screening is often used alongside genotype.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about Hereditary Hemochromatosis (HFE) comes down to these specific, well-studied positions — not a diagnosis.
No. Population studies suggest roughly 38-50% of C282Y homozygotes develop a raised ferritin level, and only about 10-33% ever develop clinical disease. Men are affected far more often than women. A genotype result is a reason to have your iron blood tests checked, not a diagnosis.
Much less than C282Y. H63D is common in the general population and has a weak effect on iron handling. Two copies of H63D, or one H63D together with one C282Y, carry substantially lower risk than two copies of C282Y, and most such people never develop iron overload. Where they do, doctors usually look for an additional contributing cause.
Two are used together: transferrin saturation, which reflects iron circulating in the blood and tends to rise first, and ferritin, which reflects stored iron. Ferritin also rises with inflammation, alcohol use and liver problems, so a single high ferritin is not proof of iron overload on its own.
Carrying a single copy of C282Y or H63D is generally not expected to cause iron overload. Carriers may show mildly higher iron markers on average, but this is not the same as having the condition. Carrier status is relevant mainly for family planning and for relatives.
Menstruation and pregnancy remove iron from the body regularly, which offsets the extra absorption for much of a woman’s life. That is why symptoms in women, when they occur, generally appear after menopause, while men more often present between roughly 40 and 60.
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