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Chromosomal instability (CIN) is a type of genomic instability in which chromosomes are unstable, such that either whole chromosomes or parts of chromosomes are duplicated or deleted. The unequal distribution of DNA to daughter cells upon mitosis results in a failure to maintain euploidy (the correct number of chromosomes) leading to aneuploidy (incorrect number of chromosomes). In other words, the daughter cells do not have the same number of chromosomes as the cell they originated from. These changes have been studied in solid tumors, which may or may not be cancerous. CIN is a common occurrence in solid and haematological cancers, especially colorectal cancer. Although many tumours show chromosomal abnormalities, CIN is characterised by an increased rate of these errors. ==Criteria for CIN definition== *As chromosome instability refers to the rate that chromosomes or large portions of chromosomes are changed, there should be comparisons between cells, or cell populations rather than looking at cells individually in order to determine chromosome instability. These differences should be examined statistically as well.〔 *The rates in the cell population being tested should be compared to a reference cell population. This is especially true in low phenotype chromosomal instability,〔 where the changes are subtle. *The number of cell divisions undergone by a cell population should be related to the rate of chromosomal change.〔 *A chromosomal instability assay should measure not only whole chromosome change rates, but also the partial chromosomal changes such as deletions, insertions, inversion and amplifications to also take into account segmental aneuploidies.〔 This provides a more accurate determination of the presence of chromosome instability. *The results from polyploid and diploid cells should be identified and separately recorded from one another. This is because the fitness cost (survival to next generation) of chromosomal instability is lower in polyploid cells, as the cell has a greater number of chromosomes to make up for the chromosomal instability it experiences.〔 *Polyploid cells are more prone to chromosomal changes, something that should be taken into account when determining the presence and degree of chromosomal instability 〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Chromosome instability」の詳細全文を読む スポンサード リンク
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