Niemann-Pick Type C (NPC) is very different than Type A or B (ASMD). NPC Patients are not able to metabolize cholesterol and other lipids properly within the cell. Consequently, excessive amounts of cholesterol accumulate within the liver and spleen and excessive amounts of other lipids accumulate in the brain. NPC causes a secondary reduction of ASM activity, which led all three types to be considered forms of the same disease.