Your body is made up of trillions of cells. Each cell has a core structure (nucleus) that contains your chromosomes.
Each chromosome is made up of tightly coiled strands of deoxyribonucleic acid (DNA). Genes are segments of DNA that determine specific traits, such as eye or hair color. You have more than 20,000 genes.
A gene mutation is an alteration in your DNA. It can be inherited or acquired during your lifetime, as cells age or are exposed to certain chemicals. These changes in your DNA can result in genetic disorders.