Sphingomyelinase deficiency Niemann-Pick type A & B disease and intracellular lipid transport defect Niemann-Pick type C disease are to be considered as two genetically and molecularly distinct entities. This book is devoted to these two disorders and comprehensively presents the diagnostic options, including how to distinguish between Niemann-Pick type A & B and type C, as well as current therapeutic approaches. It also considers molecular biology, the latest findings in the field of basic science, and the current understanding of clinical features. A separate chapter on diagnosis can be used as a quick reference work from clinical symptoms to a suspected diagnosis and the confirmation of diagnosis in the laboratory.