Sammons determined that some resistant weeds have as many as 160 extra copies of a gene called EPSPS. (technologyreview.com)
The prevailing theory for decades has been that extra copies of genes on a specific area of chromosome 21, known as the Down syndrome critical region (DSCR), cause the mental and physical features of Down syndrome. (sciencemag.org)
Human beings have several extra copies of the gene for the starch - digesting enzyme. (gorillaprotein.com)