Relatively large sections of the DNA are sometimes deleted or repeated one or more times, such that in those sections of DNA, the number of copies of the section varies between individuals (rather than, for example, a single DNA base differing between individuals, as in SNPs).
So far, copy number variation has not commonly been used in MR owing to a) the majority of natural variation in humans taking the form of SNPs, 2) genotyping technology being principally designed to assay SNPs and 3) a relative paucity of robustly associated copy number variants with phenotypes of interest.
- Wain LV, Armour JA, Tobin MD. Genomic copy number variation, human health, and disease. Lancet 2009;374:340-50.
- Thapar A, Cooper M. Copy number variation: what is it and what has it told us about child psychiatric disorders? J Am Acad Child Adolesc Psychiatry 2013;52:772-4.