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Genetic instability is a hallmark of cancer cells, and occurs when genes required for genomic maintenance are inactivated. It emerges that altering just one of the two copies of certain genes can drive genetic instability in yeast.
Cancer is a disease of uncontrolled cell division that is fuelled by genetic instability — a state in which cells acquire mutations at an abnormally high rate. When normal cells are transforming into cancer cells, a common early event is the acquisition of mutations in a type of gene called a tumour-suppressor gene. If both of the two copies of a tumour-suppressor gene are inactivated in a cell, this decreases genomic stability and aids the acquisition of other cancer-initiating mutations. Writing in Nature, Coelho et al.1 report their studies in budding yeast (Saccharomyces cerevisiae), which indicate that, frequently, the disruption of just one copy of certain genes can be sufficient to trigger genetic instability.