The condition in which an organism is made up of cells that contain different numbers of chromosomes. Aneusomy is widespread in flowering plants possessing B chromosomes (q.v.). In animals, the term generally refers to a diploid organism with subpopulations of aneuploid, somatic cells. The term aneusomy has been misused in the recent literature of human cytogenetics to refer to a genetic imbalance within a chromosome pair. For example, an individual heterozygous for a deficiency including one or more genes is hemizygous for those genes on the normal homolog. To call such an individual a segmental aneusomic is confusing, since aneusomy traditionally implies mosaicism. See aneuploidy.
Subjects: Genetics and Genomics.