Figure 1.

Examples of numerical chromosome instability (CIN) and structural CIN. A schematic depicting examples of the types of karyotypic changes associated with either numerical CIN (N-CIN) or structural CIN (S-CIN). Note that to accurately define CIN within a given population requires multiple distinct karyotypes to be identified as a single aberrant karyotype only defines a state, and not a rate. For illustrative purposes, the starting diploid cell (center) only contains three pairs of chromosomes (i.e., a partial karyotype). N-CIN involves whole chromosome gains or losses, including both small-scale changes that result in aneuploidy, as well as large-scale polyploidization events. S-CIN includes partial chromosome deletions, amplifications, inversions, or translocations (ranging in size from single genes to entire chromosome arms). These different classes of N-CIN or S-CIN are often combined to produce complex karyotypes that evolve over time. However, techniques for evaluating CIN typically only detect a subset of these karyotypic changes.