Niemann-Pick disease type C (NPC) is an inherited disorder where the body cannot break down lipids (fats) and cholesterol properly within their cells. As a result, cholesterol builds up in their spleen and liver and extra lipids are found in the brain. This build-up reduces spleen and liver function and can cause them to be abnormally large, sometimes leading to severe liver disease. Additional symptoms of NPC include breathing difficulties, developmental delay, seizures, lack of muscle tone, lack of coordination, and the inability of the individual with NPC to move their eyes up and down. Typically these symptoms appear between 4 and 10 years of age, but can appear in infancy or later on in adulthood. Currently there is no cure for NPC, although medical surveillance and care may help to improve some symptoms and overall condition of life. The majority of patients will pass away before they are 20 years old. One of the causes of NPC is pathogenic variants in the NPC1 gene.