Question

BRCA1 (BReast Cancer gene 1) and BRCA2 (BReast Cancer gene 2) are genes that produce proteins that help repair damaged DNA Everyone has two copies of each of these genes-one copy inherited from each parent BRCA1 and BRCA2 are sometimes called tumor suppressor genes. People who inherit harmful variants in one of these genes have increased risks of several cancers-most notably breast and ovarian cancer but also several additional types of cancer. Why do people who inherit harmful variants in either BRCA1 and BRCA2 have increased risks of several cancers? Explain

Answer 1

BRCA1 and BRCA2 are genes that code for proteins that repair DNA, so if one of these is defective, DNA is not repaired properly, increasing the number of mutations in the DNA, which is the cause of cancer.

As is mentioned in the question one copy is inherited by each parent, so when one of the parents is a carrier the offspring has a 50% chance to inherit the mutation, now the fact that someone inherits a defective copy does not imply that necessarily will develop cancer however their chances increase, for example, a woman with a defective copy will have 55% to 72% chances to develop cancer meanwhile a woman with both healthy copies has 13% chances.