Gene

A gene is a section of the genetic material or deoxyribonucleic acid (DNA) in a cell. Genes, alone or in combination, determine what features (genetic traits) people inherit from their parents, such as blood type, hair color, eye color, and other characteristics, including risks for certain diseases.

Many genes together make up chromosomes. Changes (mutations) in genes or chromosomes may be undetectable or may cause genetic diseases, such as hemophilia or sickle cell disease. Genetic problems may also increase the risk for some conditions, such as heart disease and juvenile idiopathic arthritis.

Gene changes can be passed from parents to children. Diseases that run in families are often caused by genetic changes. A person may be born with a certain genetic makeup that makes them susceptible or at risk for a certain condition.