A genetic disorder is a health problem caused by abnormalities in the genome. They are heritable, and may be passed down from the parents' genes to their children and to later generations. If a genetic disorder is present from birth, it is described as a congenital defect. Some defects only show up in later life.

The mutation responsible can occur spontaneously before the embryo develops, or it can be inherited from parents who are carriers of a faulty gene.