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.
Certain groups have higher riskNiemann-Pick disease affects all groups of people and both males and females. However, certain populations have a higher incidence of the disease:
- 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
- Caused by deficiency of the enzyme acid sphingomyelinase (ASM) which is needed to break down a type of fat called sphingomyelin
- Usually less than 1% of the normal level of the enzyme present in the body
- This leads to accumulation of a fat (sphingomyelin) which damages cells
- Causes severe nervous system disease
- Usually leads to death usually by 18 months to 2 years of age
- Most cases (85%) of Neimann-Pick are Type A
Niemann-Pick Type B
- Like Type A is caused by deficiency of acid sphingomyelinase (ASM), but less servere
- In Type B, there is usually about 10% of the normal level is present in the body
- Leads to accumulation of sphingomyelin which damages cells
- Little or no neurological problems
- Longer life expectancy than the other types--into adulthood
Neimann-Pick Types C and D
- Caused by inability to break down or transport cholesterol
- Leads to accumulation of cholesterol and other fats in the liver, spleen, and brain
- Nervous system disease develops
- Leads to death usually by age 20
- Most rare type of Niemann-Pick (possibly 500 cases worldwide)
SymptomsOne 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
DiagnosisTypes A and B can be diagnosed by measuring the ASM activity in white blood cells. Low levels would point to Niemann-Pick disease. Type C can be diagnosed by examining a skin sample (biopsy) for cholesterol storage.
TreatmentAs yet, there are no specific treatments for any of the types of Niemann-Pick disease. Bone marrow transplant has been attempted in several individuals with Type B. People with Types C and D are often placed on a low-cholesterol diet. Supportive care through nutrition, medication, physical therapy, and being followed by specialists can help with quality of life.
"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.