Both sexes are equally affected. This acute form has an onset at one to two months and involves learning difficulties and failure to thrive. Life expectancy does not usually exceed 3 years. Niemann-Pick Type B Onset of the condition manifests itself later. Enlargement of the spleen is usually a first sign of the condition with enlargement of the liver taking place later.
Respiratory infections are common.
Usually there is normal development until the age of two, occasionally much later. Enlargement of the spleen is accompanied by progressive loss of speech, ataxia and grand mal seizures may occur. Learning difficulties are progressive with a very varied life expectancy of between five and forty years. Inheritance patterns Autosomal recessive. The Group also covers Neville's Disease, Sphingomyelin Lipidosis, DAF Syndrome and Juvenile Dystonic Lipidosis.