ABSTRACT

Niemann Pick disease type C ( NPC ) is an autosomal recessive neurometabolic disorder characterized biochemically by a disturbed intracelluler processing of exogenous cholesterol with lysosomal accumulation of unesterified cholesterol in certain tissues. Genetic heterogeneity has recently been established and the mapping of the major gene has been assigned to 18q 11-12. The classic NPC patient present in early childhood with ataxia and progressive dementia. The neurologic features of this disease are vertical supranuclear ophtalmoplegia, ataxia, dysartria, mental-motor retardation and seizures. Hepatosplenomegaly is usually detected during early childhood. We report a rare case of NPC in a13 year-old boy who is presented with splenomegaly, mentalmotor retardation, ataxia and seizures. Diagnosis was guided by the morphological finding in bone marrow smears of foamy and sea-blue histiocytes and confirmed by the measurement of lysosomal sphingomyelinase activity below normal values