HUMBIO 3A Lecture Notes - Lecture 38: Tumor Suppressor Gene, Brca1, P53
20 Dec 2019
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Loss of function mutations (recessive) - you need two of these mutations (two mutant alleles) for someone to have the phenotype of missing the protein. These tend to involve cell checkpoints (losing checkpoints), and the checkpoints help to limit over-cell proliferation. Just having a single allele is generally enough to prevent the mutant phenotype. Gain of function mutations (dominant) - these tend to involve pathways/proteins that already promote cell growth, promoting growth even more. Note that these mutations are less likely to be inherited or passed down because they are prohibitively detrimental. Since gain of function mutations are dominant, having just one mutated allele in a cell can be enough to give a cancer phenotype. In families, there is a trend of dominant inheritance patterns for cancer- related phenotypes, but the mutations themselves are recessive. If you hav one genetically inherited mutant allele (p53 mutations, brca1 and 2 mutations, etc.
