Genetic Disorders

What is Niemann-Pick (NP) disease?

A Answers (3)

  • Niemann-Pick (NP) disease refers to a group of inherited metabolic disorders known as the leukodystrophies or lipid storage diseases in which harmful quantities of a fatty substance (lipids) accumulate in the spleen, liver, lungs, bone marrow, and the brain. The symptoms of NP may include lack of muscle coordination, brain degeneration, learning problems, loss of muscle tone, increased sensitivity to touch, spasticity, feeding and swallowing difficulties, slurred speech, and an enlarged liver and spleen. There may be clouding of the cornea and a characteristic cherry-red halo develops around the center of the retina. The disease has 4 related types: Type A, Type B, Type C, and Type D. Type A, the most common type, occurs in infants. It is characterized by jaundice, an enlarged liver, and profound brain damage. Children with this type rarely live beyond 18 months. Type B involves an enlarged liver and spleen, which usually occurs in the preteen years. The brain is not affected. In types A and B, insufficient activity of an enzyme called sphingomyelinase causes the buildup of toxic amounts of sphingomyelin, a fatty substance present in every cell of the body. Types C and D may appear early in life or develop in the teen or adult years. Affected individuals have only moderate enlargement of the spleen and the liver, but brain damage may be extensive and cause an inability to look up and down, difficulty in walking and swallowing, and progressive loss of vision and hearing. Types C and D are characterized by a defect that disrupts the transport of cholesterol between brain cells. Type D usually occurs in people with an ancestral background in Nova Scotia.

    This Answer is based on source information from  the National Institute of Neurological Disorders and Stroke .

  • Niemann-Pick disease (NPD) interferes with the breakdown of lipids (fats) and cholesterol in the body in a way that causes harmful amounts of lipids to build up in the spleen, liver, lungs, bone marrow, and brain.

    NPD belongs to a group of inherited disorders known as leukodystrophies, or lipid storage disorders.

    NPD is a relatively rare disease: the incidence of NPD type A and B is 1 in 250,000, and NPD type C affects one out of every 150,000 live births. However, certain populations may be affected more frequently by NPD.

    There are five identified types of NPD: type A, type B, type C, type D, and type E.

    NPD types A and B, also called type I NPD, are caused by low levels of an enzyme called acid sphingomyelinase, which is required to break down a lipid called sphingomyelin. Sphingomyelin is found in all cells in the body. When sphingomyelin is not metabolized properly, it builds up in cells, resulting in organ failure.

    NPD type A occurs in infants and primarily affects the brain and liver. People with NPD type A rarely survive beyond 18 months of age.

    Symptoms of NPD type B usually develop in the preteen years and affect the liver, lung, and spleen. Lung infections are common, and overall growth is impaired. Unlike NPD type A, the brain is not affected in NPD type B.

    NPD types C and D, also called type II NPD, are characterized by a defect that disrupts the movement of cholesterol between brain cells.

    NPD types C and D may appear anytime between infancy and adulthood. People with NPD types C or D have only moderate enlargement of the spleen and liver, but brain damage may be extensive.

    NPD type D has only been identified in the French-Canadian population of Nova Scotia and is believed to be a form of NPD type C.

    NPD type E occurs in adults and is extremely rare. Symptoms include swelling of the spleen and neurological problems.

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    • AHealthwise answered

      Niemann-Pick disease is a rare inherited degenerative nerve disease caused by the deficiency of the enzyme called sphingomyelinase, which leads to the buildup of a fatty substance (sphingomyelin) in cells in the liver, spleen, lymph nodes and bone marrow. Niemann-Pick disease is most commonly seen in families of Eastern European (Ashkenazi) Jewish heritage. At least five types of Niemann-Pick disease have been identified. The most common are type A and type B.

      • Type A usually causes symptoms by 6 months of age. Symptoms may include feeding difficulty, vomiting and abdominal distention from an enlarged spleen and liver. Some babies have a cherry-red spot in the membrane that lines the back of the eye (retina). Infections such as pneumonia are common. Death usually occurs by the age of 4.
      • Type B disease is a milder form that does not affect the brain. Children are usually diagnosed during early childhood because of enlargement of the liver or spleen. Teenagers with type B disease may have frequent lung infections. Most people with type B Niemann-Pick disease live into their 30s or 40s.
      • Type C usually shows up during childhood. It can cause breathing problems, liver disease, developmental delays, seizures, low muscle tone and feeding problems. It is the rarest type of Niemann-Pick disease. Most people with type C die by the age of 20. The kind of genetic change (mutation) determines whether a person has type C1 or C2.

      There is no treatment for Niemann-Pick disease. Support groups and counseling can be helpful for people with Niemann-Pick disease and for their families. Genetic testing is recommended to identify carriers of the disease and help guide decisions about having children.

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