Genetic variation

Genetic variation is the difference in DNA sequence among individuals or populations. It provides the inherited diversity on which evolution and many forms of biological adaptation depend.

Mutation: A change in the DNA sequence of a genome. Mutations create new sequence variants that can add to genetic variation.
DNA sequence: The ordered series of nucleotide bases in a DNA molecule. Sequence is the level at which genetic variants differ.
Genome-wide association study: A study that tests genetic variants across many genomes for statistical association with a trait or disease. These studies use population variation to identify regions associated with traits.
Evolution: The change in heritable characteristics of populations across generations. Changes in genetic variation underlie evolutionary change across generations.
Heritability: A population statistic describing how much observed trait variation is associated with genetic differences under specified conditions. Heritability estimates depend on the variation present in a particular population and environment.
Genetic recombination: The exchange or rearrangement of genetic material that produces new combinations of DNA sequences. Recombination reshuffles existing variants into new combinations.
Allele: One of two or more versions of a DNA sequence at a particular genomic location. Alleles are the alternative sequence forms whose differences make up variation.
Pharmacogenomics: The study of how genetic differences influence responses to medicines. Inherited variants can help explain why people respond differently to the same drug.
Heterozygote advantage: A form of natural selection in which individuals with two different alleles have higher fitness than either homozygote. This mechanism can maintain multiple variants in a population.
Missing heritability: The gap between estimated genetic contributions to a trait and the effects explained by identified genetic variants. Many measured genetic differences do not yet account for all estimated inherited influence.

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