Niemann-Pick Type C disease is an autosomal recessive disorder affecting lipid metabolism (the breakdown and use of fats and cholesterol in the body), in a way which causes harmful amounts of lipids to accumulate in the spleen, liver, lungs, bone marrow, and brain.

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene must be altered for a person to be affected by the disorder. Most often, the parents of a child with an autosomal recessive disorder are not affected but are carriers of one copy of the altered gene.

Type C is characterized by onset in childhood, although infant and adult onsets are possible. Other signs include severe liver disease, breathing difficulties, developmental delay, seizures, neuro-degeneration, increased muscle tone (dystonia), lack of coordination, problems with feeding, and an inability to move the eyes vertically. People with this disorder can survive into adulthood. There are currently only about 500 known cases worldwide.