Hemochromatosis is an autosomal recessive inherited disease characterized by an increase in the absorption of iron by the gastrointestinal mucosa, which can cause excessive iron accumulation in various organs of the body.In its initial phases, it can cause joint and abdominal pain, weakness, lack of energy and weight loss; in addition, it can cause liver scarring, darkening of the skin, diabetes, infertility, heart failure, irregular heartbeat (arrhythmia) and arthritis. However, many people have no symptoms in the early stages. This is why it is usually detected between the ages of 40 and 60.
There are four types of hereditary hemochromatosis, depending on the altered gene:
- Type 1: variants of the HFE gene.
- Type 2 (juvenile hemochromatosis): variants of the HJV and HAMP genes.
- Type 3: variants of the TFR2 gene.
- Type 4 (ferroportin disease): variants of the SLC40A1 gene.
Type 1 is classical hereditary hemochromatosis, also called HFE-related hemochromatosis. Between 60 to 90% of individuals diagnosed with hereditary hemochromatosis are homozygous for the C282Y variant, while only 3 to 8% of those affected are double heterozygous for the C282Y/H63D variants. Finally, homozygotes for the H63D variant have an even lower penetrance than in the case of double heterozygotes, and represent only 1% of cases.
In this type of hemochromatosis, liver disease is the most common complication, and can progress to cirrhosis (20 to 30% of patients with cirrhosis have hepatocellular carcinoma). Cardiomyopathy with heart failure is the second most fatal complication in order of frequency.