Niemann disease

Niemann-Pick disease a lysosomal storage disease due to a deficiency of sphingomyelin phosphodiesterase with sphingomyelin accumulation in the reticuloendothelial system. There are five types distinguished by age of onset and by the amount of CNS involvement and of sphingomyelin phosphodiesterase activity. Type A (acute neuronopathic) is the classic type, accounting for 85 per cent of patients; onset is in early infancy, CNS damage is severe, and death occurs by 4 years. Type B (chronic nonneuronopathic) has onset in early infancy but does not affect the CNS or intelligence, and a normal lifespan is possible. Type C (chronic neuronopathic) has variable ages of onset (at 2 years or older) and of death (from age 5 to adulthood) and variable CNS involvement. Type D (the Nova Scotia variant) resembles type C; type E (the adult, nonneuronopathic form) may be a late-onset variant of type C. Called also sphingomyelin lipidosis and sphingomyelinase deficiency.