Niemann-Pick Disease

An Incurable Hereditary Disease

Niemann pick cell in spleen
W.CC/Wikimedia Commons/Creative Commons

Niemann-Pick disease refers to a group of inherited disorders known as leukodystrophies, or lipid storage disorders, in which certain fats accumulate in the tissues like the brain and liver and cause damage. In Niemann-Pick disease, the body is unable to break down fats completely so they accumulate in the tissues and cause damage.

Who Is at Risk?

The four types of Niemann-Pick disease are commonly called Type A, Type B, Type C and Type D.

The disease can occur in anyone, regardless of gender. However, because it is an inherited disease, certain populations have a higher incidence. These include:

  • Ashkenazi Jewish population (Types A and B)
  • French Canadian population of Nova Scotia (Type D)
  • Maghreb region (Tunisia, Morocco, Algeria) of North Africa (Type B)
  • Spanish-American population of southern New Mexico and Colorado (Type C)

Niemann-Pick Type A

Niemann-Pick Type A is the most common type of the disease, with 85 percent of people with Niemann-Pick having Type A. It is caused by deficiency of the enzyme acid sphingomyelinase (ASM), which is needed to break down a type of fat called sphingomyelin. People with this type of the disease usually have less than 1 percent of the normal level of the enzyme present in their body, which leads to accumulation of fat that damages cells. Type A can cause severe nervous system disease, and usually leads to death by 18 months to 2 years of age.

Niemann-Pick Type B

Like Type A, Niemann-Pick Type B is caused by deficiency of the enzyme ASM, but less so than in Type A. People with Type B usually have about 10 percent of the normal level of the enzyme present in their body, which leads to accumulation of sphingomyelin that damages cells. This type usually causes little or no neurological problems, and people with the disease usually live into adulthood.

Niemann-Pick Types C and D

Niemann-Pick Types C and D are the most rare type of the disease, with only about 500 known cases worldwide. It is caused by an inability to break down or transport cholesterol, which leads to an accumulation of cholesterol and other fats in the liver, spleen and brain. Sufferers usually die by age 20 due to the development of nervous system disease.

Symptoms of Niemann-Pick Disease

One of the difficulties in correctly diagnosing Niemann-Pick disease is that its symptoms can be different in each person affected. Types A and C may have symptoms such as:

  • Enlarged liver
  • Brain damage
  • Difficulty walking and swallowing
  • Increased sensitivity to touch
  • Difficulty speaking
  • Loss of muscle tone (hypotonia)
  • Learning difficulties

Type B does not have the nervous system symptoms, but people with this type usually have repeated respiratory infections and an enlarged liver and spleen.

Diagnosis

Niemann-Pick types A and B can be diagnosed by measuring the ASM activity in white blood cells.

Low levels would point to disease. Type C can be diagnosed by a doctor through a skin biopsy to test for cholesterol storage.

Treatment

There is currently no cure for Niemann-Pick disease. Treatments focus on offering relief. Supportive care through nutrition, medication, physical therapy, and being followed by specialists can help with quality of life.

Sources:

"NINDS Niemann-Pick Disease Information Page." Disorders A - Z. 18 June 2007. National Institute of Neurological Disorders and Stroke. 20 Feb 2009.

"Disease Overview." Niemann-Pick Disease. National Niemann-Pick Disease Foundation. 20 Feb 2009.

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