Contributor: Gordon K. Klintworth
Niemann-Pick disease type IA is an acute variant of Niemann-Pick disease type I and it accounts for ~75% of reported cases of Niemann-Pick disease.  It is characterized by an onset from early infancy and a marked visceromegaly with nervous system involvement. Neurological deterioration is rapid and death occurs < 5 years of age. Sphingomyelinase activity is < 5% of normal and persons with this lysosomal storage disease develop cherry-red spots at the macula, opacification of the cornea and a brown discolored anterior lens capsule. Lamellar inclusions are present in some cells (fibrocytes, epithelium and capillaries (pericytes and vascular endothelium). The Schwann cells contain especially myelin-like whorls. 

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