BIOL 1F25 Lecture Notes - Lecture 20: Tumor Suppressor Gene, Melanoma, Mutation Rate
Document Summary
In some cases (5-15%), cancer appears to be inherited. What is really inherited is an increased risk for cancer due to the inheritance of a mutated allele of a tumour suppressor gene. Not all individuals who inherit such an allele will develop cancer, because the remaining mutations must still occur and in some individuals, this will never happen. Probability of six mutations occurring in a single cell: The chance of six mutations accumulating in a single cell and producing cancer is about 10-42. With 1014 cells in our body, cancer shouldn t be able to happen/ occur. Possible explanation: the mutation rate increases during the very early stages of cancer development. One of the first mutations occurs in a gene that is involved in dna repair. Evidence for probability of cancer changing with time: Frequent occurrence of large and numerous changes in chromosome structures. Some inherited, familial forms of cancer: defects in repair of damaged dna.