NIEMANN-PICK DISEASE (NPD) - Type A

Acute Neuronopathic form-type A-classic infantile form; Niemann Disease; Sphingomyelin Lipidosis; Sphingomyelinase Deficiency

Niemann-Pick Disease (NPD) 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. NPD Type A, neurodegenerative form, occurs in infants. It is characterized by jaundice, an enlarged liver; and profound brain damage. In NPD Type A, insufficient activity of an enzyme called sphingomyelinase causes the build up of toxic amounts of sphingomyelin, a fatty substance present in every cell of the body.

Diagnostic testing: NPD Type A is diagnosed by measuring the amount of acid sphingomyelinase (ASM) in white blood cells. The test can be done using a blood or bone marrow sample. Sphingomyelinase assays (analysis) can also be used. DNA tests can be done to diagnose carriers. Prenatal testing is available when a mutation is known to exist in the family.

Physical findings: Symptoms may include:

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  Lack of muscle coordination;

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  Brain degeneration;

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  Learning problems;

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  Loss of muscle tone;

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  Increased sensitivity to touch;

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  Spasticity;

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  Feeding and swallowing difficulties;

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  Slurred speech; and

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  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.

ICD-9: 272.7, 330.2

ICD-10: E75.240

There is currently no effective treatment for persons with NPD Type A. Medicines are available to control or relieve many symptoms, such as cataplexy and seizures.

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  ASM activity level in blood or bone marrow white blood cells;

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  Physical findings of hepatosplenomegaly (enlarged liver and spleen); and

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  Evidence of neurodevelopmental regression and progressive delay.