A gene variant is a permanent change in the DNA sequence that makes up a gene. This type of genetic change used to be known as a gene mutation, but because changes in DNA do not always cause disease, it is thought that gene variant is a more accurate term. Variants can affect one or more DNA building blocks (nucleotides) in a gene.

Genomic variation refers to DNA sequence differences among individuals or populations. Some variants influence biological function (such as a mutation that causes a genetic disease), while others have no biological effects.

The differences among human genomes are called genomic variants. A person’s set of genomic variants is part of what makes them unique. Other factors (such as diet, environment, lifestyle and social context) also contribute to a person’s uniqueness.