What Are the BRCA1 and BRCA2 Genes?

Genes are the units of genetic information that tell the cells of our bodies how to work and grow. Certain mutations to this genetic information can result in cells not working properly.

The breast cancer susceptibility genes 1 and 2, BRCA1 and BRCA2, have been linked to both breast and ovarian cancer risk. Every human being is born with 2 copies of each of the BRCA1 and BRCA2 genes: One copy of each gene comes from the mother, and one copy comes from the father.  Therefore, if someone’s mother or father has a BRCA1 or BRCA2 gene mutation, there is a 50% chance that they could receive a copy of that mutation as well.

 

BRCA1 and BRCA2 are tumour suppressor genes. This means that when working properly, these genes help to protect us from getting cancer. If a person inherits a BRCA1 or BRCA2 gene mutation from a parent, they have a higher chance of getting specific types of cancer. For example, this includes ovarian and breast cancer (click to learn more) in women and prostate and breast cancer in men. Even though an individual has a high chance of inheriting a gene mutation from a parent, not all individuals with a BRCA1 or BRCA2 gene mutation will develop cancer.

 

Type of Cancer

Risk in general population

Risk if have mutation in BRCA1 or BRCA2*

Breast Cancer

12%

40-70%

Ovarian Cancer

1.5%

10-40%

Prostate Cancer

17%

20-40%

*Individuals with a BRCA2 mutation may also have increased risks of developing male breast cancer, melanoma and pancreatic cancers.

Ovarian cancers that develop in women with a BRCA1 gene mutation usually happen at younger ages than in women with a BRCA2 gene mutation. For instance, ovarian cancer is often diagnosed before the age of 50 and as early as 35 years in women with BRCA1 gene mutations. Women with BRCA2 gene mutations are typically diagnosed with ovarian cancer after the age of 60. Overall, the average age of diagnosis of ovarian cancer in women with a BRCA1 or BRCA2 gene mutation is 48 years of age, compared to 63 years in the general population.

 

It is very important to identify high risk women with inherited BRCA1 or BRCA2 gene mutations so that ovarian cancer can be prevented. Genetic testing can determine if you have a BRCA1 or BRCA2 gene mutation.