Many breast cancers are associated with mutations in the BRCA1 gene. Explain the difference between sporadic and

familial breast cancer caused by this gene at a molecular level.



What will be an ideal response?


ANSWER: In order to develop breast cancer from a mutation in the BRCA1 gene, both copies of the gene
must be mutated. In sporadic breast cancer, the cell originally has two normal copies of the
gene, but over time, a mutation arises in one copy and then the other. In familial cancer, an
individual inherits one normal copy of the gene and one mutant copy. Therefore, a cell only
needs to acquire a mutation in the one normal copy of the gene for cancer to develop.

Biology & Microbiology

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