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| DiseaseID |
HGD21 |
| Genetic
Disorder |
Hemochromatosis
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| Gene
Name |
HFE gene |
| Description |
Hemochromatosis is an inherited disease in which too much iron builds up in your body. It is one of the most common genetic diseases in the United States.
Iron is a mineral found in many foods. Your body normally absorbs about 10 percent of the iron in the food you eat. If you have hemochromatosis, you absorb more iron than you need. Your body has no natural way to get rid of the extra iron. It stores it in body tissues, especially the liver, heart and pancreas. The extra iron can damage your organs. Without treatment, it can cause your organs to fail.
The most common treatment is to remove some blood, just like when you donate blood. This is called therapeutic phlebotomy. Medicines may also help remove the extra iron. Your doctor might suggest some changes in your diet.
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| Symptoms |
Although the genetic defect that causes hemochromatosis is present at birth, most people don't experience signs and symptoms until later in life — usually between the ages of 30 and 50 in men and after age 50 in women. Women are more likely to have symptoms after menopause, when they no longer lose iron with menstruation and pregnancy.
Some people with hemochromatosis never have symptoms. Others experience a wide range of problems. These can vary considerably from person to person and may be different for men and women. In addition, early signs and symptoms of hemochromatosis mimic those of many other common conditions, making hemochromatosis difficult to diagnose. Signs and symptoms include:
? Arthritis, especially in your hands
? Chronic fatigue
? Loss of sex drive (libido) or impotence
? Lack of normal menstruation (amenorrhea)
? Abdominal pain
? High blood sugar levels
? Low thyroid function (hypothyroidism)
? Abnormal liver function tests, even if no other symptoms are present
In advanced stages of the disease, you may develop serious conditions such as:
? Cirrhosis — a condition marked by irreversible scarring of the liver
? Liver failure
? Liver cancer
? Diabetes
? Congestive heart failure
? Cardiac arrhythmia
Some people with advanced hemochromatosis develop a bronze color to their skin when iron deposits in the skin cells produce excess melanin — the pigment that gives skin its normal color. Visible iron deposits can also make skin appear gray.
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| Causes |
Iron plays an essential role in the formation of hemoglobin — a protein in red blood cells that transports oxygen from your lungs to all the tissues of your body — and of myoglobin, a form of hemoglobin in your muscles. Iron is also necessary for energy production and a strong immune system and is a component of many important enzymes.
You normally consume about 10 milligrams (mg) of iron every day in the food you eat. Of that, your body absorbs about 1 mg, or 10 percent of the iron you ingest. Most of this is stored in the hemoglobin, but a small amount is stored in your bone marrow, spleen and liver. When these stores are adequate, your body reduces the amount of iron absorbed by your intestine so that you don't accumulate excess amounts.
But if you have hemochromatosis, you may absorb as much as 20 percent of the iron you ingest. Because your body can't use or eliminate this extra iron, it's stored in the tissues of major organs, especially your liver. Eventually you may accumulate five to 20 times as much iron as normal. Over a period of years, the stored iron can severely damage many organs, leading to organ failure and chronic diseases such as cirrhosis and diabetes.
Although excess iron (iron overload) is a common problem, it's not always the result of hemochromatosis. Several factors, including frequent blood transfusions, high amounts of dietary iron and certain types of anemia, can cause excess iron in your body. People with chronic liver disease may also have increased iron levels. But in the United States, hemochromatosis is the most frequent cause of high blood iron levels.
The genetics of hemochromatosis
You have approximately 30,000 genes — information centers in your cells that control your body's growth, development and function. A mutation in just one gene can drastically alter the way your body works.
The gene that controls the amount of iron you absorb from food is called HFE. The HFE gene has two common mutations, C282Y and H63D. In the United States, most people with hemochromatosis have inherited two copies of C282Y — one from each parent.
Inheriting just one gene with the C282Y mutation means you're a carrier. You aren't likely to develop the disease yourself, although you may absorb more iron than normal. About one in every 10 Caucasians carries one gene for hemochromatosis. If both your parents are carriers, you have a 25 percent chance of inheriting two mutated genes.
A few people inherit one copy of C282Y and one of H63D. Of these, a small percentage develop symptoms of hemochromatosis. An even smaller number of people inherit two copies of H63D. Whether they're at risk of hemochromatosis is a matter of debate.
Complicating matters further, not everyone with two C282Y gene mutations develops problems with iron overload. Experts aren't sure of the exact number of people who do, and it's not possible to determine who will experience symptoms and who won't.
In addition, researchers continue to discover new proteins and genes that are responsible for rare cases of iron overload and that may lead to symptoms in people with HFE-related disease |
| Diagnosis |
Hemochromatosis can be difficult to diagnose. Early symptoms such as stiff joints and fatigue can result from a number of conditions that are more common than hemochromatosis. And in the latter stages of the disease, your doctor may focus on treating serious problems such as cirrhosis and heart disease rather than on checking for iron overload. But at any stage — even before symptoms appear — doctors can detect iron overload with two blood tests:
? Serum transferrin saturation. This test measures the amount of iron bound to a protein (transferrin) that carries iron in your blood. Transferrin saturation values greater than 45 percent are considered too high.
? Serum ferritin. This test measures the amount of iron stored in your body. If the results of your serum transferrin saturation test are higher than normal, your doctor will check your serum ferritin. Because a number of infectious and inflammatory conditions other than hemochromatosis can cause elevated ferritin, both tests are needed to diagnose the disorder. You may need the tests repeated for the most accurate results.
Serum transferrin saturation and serum ferritin tests aren't a part of routine medical testing. Public health officials recommend that you be tested for hemochromatosis if you have a parent, child or sibling with the disease, or if you have any of the following signs and symptoms:
? Joint disease
? Severe fatigue
? Heart disease
? Elevated liver enzymes
? Impotence
? Diabetes
If you receive a diagnosis of hemochromatosis, your doctor may refer you to a specialist for one of the following:
? Liver biopsy. Until recently, this test was the only way to confirm a diagnosis of hemochromatosis. During the procedure, your doctor removes a sample of tissue from your liver, using a thin needle. The sample is sent to a laboratory where it's checked for the presence of iron as well as for evidence of liver damage, especially scarring or cirrhosis. Risks of biopsy include bruising, bleeding and infection.
? Genetic testing. The discovery of the HFE gene made genetic testing for hemochromatosis possible. Some researchers advocate universal screening for HFE gene mutations. They point out that hemochromatosis is a common condition that can cause serious complications when it's not treated and that a simple, inexpensive and effective treatment exists.
Other doctors, as well as the Centers for Disease Control and Prevention and the U.S. Human Genome Research Project, recommend this type of testing only for adult family members of someone with hemochromatosis. If you're considering genetic testing for hemochromatosis, discuss the pros and cons carefully with your doctor or a genetic counselor.
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| Treatment |
Doctors can treat hemochromatosis safely and effectively by removing blood from your body (phlebotomy) on a regular basis, just as if you were donating blood. But in this case, the goal is to reduce your iron levels to normal. The amount of blood drawn depends on your age, your overall health and the severity of iron overload. Some people need many phlebotomies to achieve normal iron levels.
Initially, you may have a pint of blood taken once or twice a week — usually in a hospital or your doctor's office. This process shouldn't be uncomfortable. While you recline in a chair, a needle is inserted into a vein in your arm. The blood flows from the needle into a tube that's attached to a blood bag. Depending on your veins and the consistency of your blood, the time needed to remove a pint of blood can range from 10 to 30 minutes. Once your iron levels have returned to normal, you may only need to have blood drawn four times a year.
Donating your blood
Until recently, blood drawn from people with hemochromatosis was discarded. But in 1999, the Food and Drug Administration (FDA) ruled that hemochromatosis blood could be donated to blood banks that applied to the FDA for a variance. You can contact a blood bank in your area to see whether it participates in this program. Or check the American Hemochromatosis Society Web site for more information.
What you can expect from treatment
Treating hemochromatosis before damage to your organs has occurred prevents serious complications such as liver disease, heart disease and diabetes. If you already have one of these conditions, phlebotomy may slow the progression of the disease, and in some cases even reverse it. People with cirrhosis are often monitored for liver cancer with an abdominal ultrasound and an alpha-fetoprotein blood test every six months. |
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