mutant

Mutant is a term used in biology to describe an organism or allele that differs from the wild-type due to a genetic mutation. A mutant can be a gene variant at a single site or a larger genetic change, and the phenotype may range from subtle to visible. Mutations arise spontaneously during DNA replication or are caused by environmental mutagens such as radiation or chemicals. When the mutation occurs in germ cells, it can be inherited; in somatic cells, it affects only the individual.

Mutations are classified by their type and effect. Common classes include point mutations, insertions, deletions, duplications, inversions, and larger chromosomal rearrangements. Most mutations are neutral or deleterious, but some are beneficial and can introduce new traits that natural selection can act upon.

Mutations drive genetic diversity, underpinning evolution and adaptation. They can alter traits such as coloration, metabolism, or disease susceptibility. Examples include the sickle-cell mutation in humans, which can confer malaria resistance in carriers; lactose tolerance arising from regulatory changes that maintain lactase production; and antibiotic resistance in bacteria arising from mutations in target genes. Not all changes are visible; many are molecular.

In popular culture, the term mutant is often used to describe fictional individuals with extraordinary powers due to genetic changes, as seen in various media. In scientific contexts, researchers emphasize genotype and phenotype, and prefer precise language such as allele variant or mutant allele.