Hemochromatosis is a disease characterized by excess absorption and storage of iron in the body’s tissues. Eventually, a build-up of iron impairs liver, heart and pancreatic function and leads to the development of arthritis, diabetes, cirrhosis and heart failure. These abnormalities are accompanied by a bronzed pigmentation of the skin. Hemochromatosis can be inherited (primary hematochrosis or PH) or secondary (caused by other diseases or blood transfusions). Around 10% of the population carries a copy of the defective gene (C282Y mutation), which is transmissible from one generation to the next. The disease occurs when the person has two copies of the same defective gene (they are then said to be “homozygous” for that gene). Between 80% and 90% of PH cases are in people with two copies of the gene carrying the C282Y mutation, and around 5% in “compound heterozygo” individuals, i.e. people who have two copies of the gene carrying a different mutation, (mutations C282Y, H63D or S65, the most common mutations of the gene). About 10% of individuals with PH do not have any of these three mutations.
Genotyping results indicate either the absence of the three mutations screened for, or the status of a variant heterozygote for the C282Y mutation (healthy carriers). Homozygous individuals for the C282Y mutation, especially men, will generally show signs of clinical hemochromatosis, as will compound heterozygous individuals.