Hereditary Hemochromatosis (HH) is an adult-onset genetic condition characterized by too much iron circulating in the body. This is often referred to as iron overload. Typical symptoms include joint pain, weakness, and fatigue. There are several types of HH. Type 1 Hemochromatosis is one of the most common genetic conditions in the United States.
Type I HH is caused by a change in the HFE gene, which controls the amount of iron absorbed from food. Not all individuals who carry a change in the HFE gene associated with Type I HH experience signs or symptoms of this condition. In fact, studies indicate that as few as 2% of individuals who are genetically affected with this condition actually experience clinical symptoms (1). This means that genetically speaking, Type I HH is characterized by reduced penetrance, probably due to a combination of genetic, environmental, and lifestyle factors. However, in certain cases of HH, the excess iron absorbed from food becomes stored in vital organs such as the liver and heart and can lead to diabetes, heart failure and liver disease.
Type I HH is inherited in an autosomal recessive manner. This means that for an individual to be affected with this condition, s/he must inherit two copies of the genetic change, one from each parent. These individuals may be at risk to develop symptoms and complications of this condition if they exhibit significantly higher iron levels. Individuals who have only one copy of the genetic change, called carriers, are not affected but can also have higher than normal iron levels.
Many of us are carriers for Type I HH. Indeed, approximately 1 in 9 individuals of European descent is a carrier for this condition. Some theories suggests that being a carrier for Type I HH may actually be beneficial. Because carriers of Type I HH often have somewhat higher iron levels, they are less likely to have iron-deficient anemia. As premenopausal women are especially likely to be anemic, carrying Type I HH can protect from iron-deficient anemia. In the past, women who were Type I HH carriers may thereby have been healthier and able to bear more children. Another theory suggests that individuals affected with Type I HH may be somewhat resistant to some infections because certain bacteria, such as those that cause tuberculosis and typhoid fever, do not thrive in iron-high environments (2).
Screening for clinical signs and symptoms of Hemochromatosis involves monitoring iron levels via a blood test. As with many other disorders, an early diagnosis can help those affected by HH live longer, healthy lives. Hemochromatosis is managed with routine phlebotomy treatments, or blood draws, to reduce iron levels. For more information, please visit CooperGenomics.com/diseases and Hemochromatosis.org.
1. Beutler E, Felitti VJ, Koziol JA, Ho NJ, Gelbart T. Penetrance of 845G> A (C282Y) HFE hereditary haemochromatosis mutation in the USA. Lancet. 2002;359:211–8. PubMed ID: 11812557
2. Perspect Biol Med. 2008 Winter;51(1):98102. doi: 10.1353/pbm.2008.0001. PubMed ID: 18192769