Niemann-Pick

Definition:

An inherited disease characterized by abnormal storage of cholesterol and sphingomyelin in various body tissues and progressive neurological damage.

Causes, incidence, and risk factors:

Niemann-Pick disease (Type A) is inherited as an autosomal recessive disorder and is found more frequently among Ashkenazi Jews than among other ethnic groups. The disease results from the absence of an enzyme, sphingomyelinase, which results in the storage of abnormal amounts of sphingomyelin and cholesterol in the brain, bone marrow, liver, and spleen. Damage to the brain accounts for the neurological symptoms.

Symptoms may begin in the first few months of life with feeding problems and delayed motor development. Although some motor skills may be acquired, they soon begin to regress as the child looses muscle strength and tone. Other neurological damage includes progressive visual loss and hearing loss. The disease is rapidly progressive and death occurs in the first few years of life.

Like many storage diseases, Niemann-Pick disease has a late onset form. These children have movement disorders and seizures in addition to the other neurological symptoms.

Three other types of Niemann-Pick disease exist -- Types B, C and D. Type B is similar to Type A but there is little or no neurological damage and the condition is compatible with a normal lifespan. Types C and D are also milder forms of the disease.