Niemann-Pick disease caused by acid sphingomyelinase deficiecncy is subdivided into two types. Type A, also called neuronopathic, is the more severe. These patients will usually present with hepatosplenomegaly within the first few months and will have progressive neurologic deterioration typically beginning by 12 months. A cherry-red spot on the retina will eventually be present in all affected children. Children with Niemann-Pick type A do not typically survive past 3 years.
Type B, or non-neuronopathic, is usually milder with a later onset. Progressive hepatosplenomegaly, gradual deterioration in pulmonary function, and an abnormal lipid profile are common manifestations for these patients. A small percentage of individuals with type B will have neurologic signs or a cherry-red spot.