Hemochromatosis type 2

Other Names: Juvenile hemochromatosis; Hemochromatosis juvenile; Iron overload disease juvenile; Juvenile hereditary hemochromatosis

Hemochromatosis type 2 is a disease in which too much iron builds up in the body. This is also called iron overload. Accumulation of iron in the organs is toxic and can cause organ damage. While many organs can be affected, iron overload is especially likely to affect the liver, heart, and pancreas.

Cause

Hemochromatosis type 2 is caused by genetic changes (mutations or pathogenic variants) in the HFE2 (also known as HJV) or HAMP genes. The HAMP gene provides instructions to the body to make a protein called hepcidin. Hepcidin controls iron absorption in the small intestine. Pathogenic variants in the HAMP gene cause hepcidin to not be able to limit iron absorption when there is already too much iron in the body.The HFE2 (HJV) gene is thought to provide instructions to the body to help regulate hepcidin. Pathogenic variants in the HFE2 (HJV) gene, cause this protein to not be able to regulate hepcidin. Therefore, pathogenic variants in either of these genes cause iron to accumulate in tissues and organs, which can result in organ damage.

Inheritance

Autosomal recessive inheritance, a 25% chance

Hemochromatosis type 2 is inherited in an autosomal recessive manner.This means that people with hemochromatosis type 2 have a genetic change (mutation or pathogenic variant) in both copies of the HFE2 (HJV) or HAMP genes in each cell of the body. We inherit one copy of every gene from our mother and the other from our father. The parents of a person with hemochromatosis type 2 are expected to each have one changed copy of a gene causing hemochromatosis type 2. People with one changed copy of a gene are known as carriers. Carriers typically do not have signs or symptoms of hemochromatosis type 2.

When two carriers of hemochromatosis type 2 have children, each child has a: 25% chance to have hemochromatosis type 2 50% chance to be a carrier like each parent 25% chance to have two working copies of the HFE2 (HJV) and HAMP genes, meaning the child is unaffected and is not a carrier of hemochromatosis type 2.

Symptoms

Symptoms of hemochromatosis type 2 typically begin during childhood. Early symptoms of hemochromatosis type 2 typically include liver disease, heart disease, and low levels of sex hormones.Having low levels of sex hormones can cause women to stop having their monthly periods and men to have delayed puberty. People with hemochromatosis type 2 may have heart disease by age 30. Other symptoms may include abdominal pain, diabetes, and skin discoloration. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Congenital hepatic fibrosis(Excessive buildup of connective tissue and scarring of liver at birth)
• Elevated transferrin saturation
• Increased serum ferritin
• High ferritin level

30%-79% of people have these symptoms

• Arthropathy(Disease of the joints)
• Diabetes mellitus
• Dilated cardiomyopathy(Stretched and thinned heart muscle)
• Elevated hepatic transaminase(High liver enzymes)
• Generalized hyperpigmentation
• Hypogonadism(Decreased activity of gonads)
• Impotence(Difficulty getting a full erection)
• Lethargy
• Muscle weakness(Muscular weakness)

5%-29% of people have these symptoms

• Abnormality of endocrine pancreas physiology
• Osteoporosis

1%-4% of people have these symptoms

• Cardiomyopathy(Disease of the heart muscle)
• Cirrhosis(Scar tissue replaces healthy tissue in the liver)
• Hepatomegaly(Enlarged liver)
• Hypogonadotropic hypogonadism
• Increased serum iron

Diagnosis

A diagnosis of hemochromatosis type 2 is suspected when a doctor observes signs and symptoms of the disease. A doctor may decide to order laboratory tests including a liver biopsy, MRI, or blood test. The diagnosis can be confirmed with genetic testing.

Treatment

Treatment for hemochromatosis type 2 may include reducing iron levels by removing blood (phlebotomy), iron chelation therapy, dietary changes, and treatment for complications of the disease. The goal of treatment is to reduce the amount of iron in the body to normal levels, prevent or delay organ damage from excess iron, and maintain normal amounts of iron throughout the lifetime.

Phlebotomy helps to remove excess iron from the body. Most people begin treatment with weekly therapeutic phlebotomy, although sometimes treatment is initially twice a week if iron levels are very elevated. Maintenance phlebotomy usually involves treatment every 2-4 months.Iron chelation therapy may be recommended for some people with hemochromatosis type 2 if they have other health issues. This involves removing excess iron using medications. The use of these therapies to treat hemochromatosis type 2 can greatly reduce the risk of organ damage.

Dietary recommendations for people with hemochromatosis may include avoiding alcohol and red meat. People with hemochromatosis are not recommended to take iron or vitamin C supplements. Hormone replacement therapy may be used to replace low sex hormones.

NIH genetic and rare disease info

• NIH info on Hemochromatosis type 2

Hemochromatosis type 2 is a rare disease.

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