Iron Overload (cont.)
Dennis Lee, MD
Dennis Lee, MD
Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.
In this Article
How is hereditary hemachromatosis inherited?
Hereditary hemochromatosis is an autosomal recessive disorder, which means an individual has the possibility of developing iron overload only when a pair of abnormal genes are inherited from both parents. (An autosomal recessive disorder is different from autosomal dominant disorder in which individuals can develop disease by inheriting a single abnormal gene from only one parent.)
The human body is composed of trillions of cells. Inside the inner core (nucleus) of each cell are chromosomes. Every human cell has two sets of 23 chromosomes (total of 46 chromosomes). Each set is inherited from one parent. Chromosomes contain DNA that carries genes that govern all bodily functions including cell metabolism, appearance, height, intelligence, hair and eye color, and other physical traits. Defects in DNA (also called mutations) are passed from one generation to the next, and sometimes can cause diseases.
There are primarily two mutations associated with hereditary hemochromatosis; C282Y and H63D. The numbers 282 and 63 designate the location of the defects on the HFE gene located on chromosome number 6. An individual who inherits two C282Y mutations (one from each parent) is called a C282Y homozygote, and has a significant chance of developing hemochromatosis. In fact, C282Y homozygotes account for the majority of cases of hereditary hemochromatosis. Patients who inherit one C282Y mutation from one parent and another H63D mutation from another parent are called compound heterozygotes, accounting for a small number of the cases of hereditary hemochromatosis.
What are the symptoms and signs of hemochromatosis?
Patients with early hemochromatosis have no symptoms and are unaware of their condition. The disease may then be discovered when elevated iron blood levels are noted by routine blood testing. In men, symptoms may not appear until 40-50 years of age. Iron deposits in the skin cause darkening of the skin. Since females lose iron through menstrual blood loss, nonmenstruating women develop symptoms 15 to 20 years later.
Iron deposits in the pituitary gland and testicles cause shrinkage of the testicles and impotence. Iron deposits in the pancreas cause a decrease in insulin production resulting in diabetes mellitus (please read the Diabetes Mellitus article). Iron deposits in the heart muscle can cause heart failure as well as abnormal heart rhythms. Iron accumulation in the liver causes scarring of the liver (cirrhosis) and an increased risk of developing liver cancer. For further information on the consequences of cirrhosis, please read the Cirrhosis article.
Medically Reviewed by a Doctor on 1/7/2014