Editing Genetic variation (section)

== Forms ==
Genetic variation can be divided into different forms according to the size and type of genomic variation underpinning genetic change.
Small-scale sequence variation (<1 kilobase, kb) includes [[base-pair substitution]] and  [[indels]].<ref name="scher">{{cite journal |author=Lars Feuk, Andrew R. Carson & Stephen W. Scherer |title=Structural variation in the human genome |journal=Nature Reviews Genetics |volume=7 |pages=85–97 |date=February 2006 |doi=10.1038/nrg1767 |pmid=16418744 |issue=2|s2cid=17255998 }}</ref>
Large-scale [[structural variation]] (>1 kb) can be either [[copy number variation]] ([[Deletion (genetics)|loss]] or [[Gene duplication|gain]]), or [[chromosomal rearrangement]] ([[Chromosomal translocation|translocation]], [[Chromosomal inversion|inversion]], or Segmental acquired [[uniparental disomy]]).<ref name="scher" /> Genetic variation and recombination by transposable elements and endogenous retroviruses sometimes is supplemented by a variety of persistent viruses and their defectives which generate genetic novelty in host genomes.
Numerical variation in whole [[chromosome]]s or [[genome]]s can be either [[polyploidy]] or [[aneuploidy]].