<unk>  <unk>  is a group of autosomal recessive disorders that are classified into two broad types. Types A and B<unk>  are lysosomal storage<unk> s due to sphingomyelinase deficiency. Type C<unk>  results from defective intracellular trafficking of cholesterol. Both types are featured by deposition of lipids such as cholesterol, sphingomyelin, and bisphosphonate in various organs.
Types A and B are charachterized by an early age of onset and progressive CNS<unk>  in type A. Type A typically has onset in the first 6 months, with rapidly progressive CNS deterioration, spasticity, failure to thrive, and massive hepatosplenomegaly. In contrast, type B has a later, more variable onset and progression of hepatosplenomegaly, with eventual development of cirrhosis and hepatic replacement by foam cells. Affected patients develop progressive pulmonary<unk>  with dyspnea, hypoxemia, and a reticular infiltrative pattern on chest x-ray.
The diagnosis is established by markedly decreased (1–10% of normal) sphingomyelinase activity in nucleated cells. There is no specific treatment for<unk> . The efficacy of hepatic or bone marrow transplantation has not been proven yet.  Clinical trials using enzyme therapy are expected in the near future.
Niemann-Pick disease
Wilson-Mikity syndrome
Wilson's disease
Leigh's disease
Bannayan-Riley-Ruvalcaba syndrome
Glycogen storage disease type I CT
Gaucher's disease
Glycogen storage disease type III