Type C, D & E

Niemann-Pick Type C occurs when the body can not properly break down cholesterol and other lipids (fats). This leads to too much cholesterol in the liver and spleen and excessive amounts of other lipids in the brain. There may be reduced ASM activity in some cells. Type C Niemann-Pick disease has been reported in all ethnic groups but it is most common among Puerto Ricans of Spanish descent.

Type D Niemann-Pick involves a defect that interferes with the movement of cholesterol between brain cells. It is now thought to be a variant of type C. This type of Niemann-Pick disease has only been found in the French Canadian population of Yarmouth County, Nova Scotia.

An adult-onset form of Niemann-Pick disease has been suggested. It is sometimes referred to as Type E disease.