GTR Home > Conditions/Phenotypes > Niemann-Pick disease, type A


Excerpted from the GeneReview: Acid Sphingomyelinase Deficiency
Acid sphingomyelinase (ASM) deficiency has been categorized in the past as either neuronopathic (Niemann-Pick disease type A [NPD-A]), with death in early childhood, or non-neuronopathic (Niemann-Pick disease type B [NPD-B]). While forms intermediate to these two extremes occur, all ASM deficiency that is not NPD-A is designated in this review as NPD-B, despite its wide range of manifestations and severity. The first symptom in NPD-A is hepatosplenomegaly, usually noted by age three months; over time the liver and spleen become massive. Psychomotor development progresses no further than the 12-month level, after which neurologic deterioration is relentless. A classic cherry-red spot of the macula of the retina, which may not be present in the first few months, is eventually present in all affected children. Interstitial lung disease caused by storage of sphingomyelin in pulmonary macrophages results in frequent respiratory infections and often respiratory failure. Most children succumb before the third year. NPD type B, later in onset and milder in manifestations than NPD type A, is characterized by hepatosplenomegaly with progressive hypersplenism and stable liver dysfunction, gradual deterioration in pulmonary function, osteopenia, and atherogenic lipid profile. Progressive and/or clinically significant neurologic manifestations occur infrequently. Survival to adulthood can occur.

Genes See tests for all associated and related genes

  • Also known as: ASM, ASMASE, NPD, SMPD1
    Summary: sphingomyelin phosphodiesterase 1

Clinical features


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Practice guidelines

  • ACOG, 2009
    ACOG Committee Opinion No. 442: Preconception and prenatal carrier screening for genetic diseases in individuals of Eastern European Jewish descent.
  • ACMG, 2008
    Carrier screening in individuals of Ashkenazi Jewish descent.

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