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Summary
Niemann-Pick disease type C (NPC) is a rare progressive genetic disorder characterized by an inability of the body to transport cholesterol and other fatty substances (lipids) inside of cells. This leads to the abnormal accumulation of these substances within various tissues of the body, including brain tissue. The accumulation of these substances damages the affected areas. NPC is highly variable, and the age of onset and specific symptoms can vary from one person to another, sometimes even among members of the same family. NPC can range from a fatal disorder within the first few months after birth (neonatal period) to a late onset, chronic progressive disorder that remains undiagnosed well into adulthood. Most cases are detected during childhood and progress to cause life-threatening complications by the second or third decade of life.
NPC is caused by changes (variants) in the NPC1 gene (NPC type 1C) or the NPC2 gene (NPC type 2C) and is inherited in an autosomal recessive manner.
Recently, the U.S. Food and Drug Administration (FDA) approved arimoclomol (Miplyffa) in combination with the enzyme inhibitor miglustat to treat neurological symptoms associated with NPC in adults and children 2 years of age and older. Levacetylleucine (Aqneursa) has been FDA approved to treat the neurological symptoms caused by NPC in both adults and children.
Other treatments depend on the specific symptoms that the affected person has.
Introduction
NPC belongs to a larger group of more than 50 disorders known as lysosomal storage disorders. Lysosomes are membrane-bound compartments within cells. They contain enzymes that break down large molecules such as proteins, carbohydrates and fats into their building blocks. Abnormal functioning of a transport protein leads to the accumulation of cholesterol and other fatty substances in various tissues of the body, including brain tissue. NPC used to be grouped together with two other disorders, named Niemann-Pick disease type A and Niemann-Pick disease type B.
However, researchers have determined that the underlying defect in types A and B involves variants in the SMPD1 gene and deficiency of the enzyme acid sphingomyelinase, which does not occur in NPC. Niemann-Pick disease types A and B are now considered a distinct disorder called acid sphingomyelinase deficiency.