پلی‌زومی

thumb|Human karyotype|karyogram, with annotated bands and sub-bands. It is a graphical representation of the idealized human [[diploid karyotype. It shows dark and white regions on G banding. Each row is vertically aligned at centromere level. It shows 22 homologous autosomal chromosome pairs, both the female (XX) and male (XY) versions of the two sex chromosomes, as well as the mitochondrial genome (at bottom left). ]] thumb|right|Trisomy 21 – Down syndrome, an example of a polysomy at chromosome 21 Polysomy is a condition found in many species, including fungi, plants, insects, and mammals,