Hereditary ovarian cancer is most commonly caused by a mutation in either the BRCA1 or BRCA2 gene. Some mutations in other genes are also known to be associated with an increased risk of ovarian cancer however scientists have not yet found all of the genes associated with an increased risk.
What are the BRCA1 and BRCA2 genes?
The BRCA1 and BRCA2 genes were discovered in the mid-1990s in families that had a lot of cases of breast cancer (BReast CAncer genes). A mutation in the BRCA1 or BRCA2 gene accounts for the majority of hereditary ovarian cancer.
About 10-15 per cent of women who develop ovarian cancer have a mutation in either their BRCA1 or BRCA2 gene.
BRCA1 and BRCA2 genes are protective against cancer. However, mutations can occur or be inherited in these genes which can increase the risk of developing breast cancer (for both men and women) and increase the risk of developing ovarian cancer from two per cent (among women generally) to 30-50 per cent for BRCA1 and 10-25 per cent for BRCA2 gene mutations.
It is important to note that not everyone who inherits a mutation in the BRCA1 or BRCA2 gene will develop cancer, but it does increase the risk.
Which other gene mutations put me at risk?
Mutations in the BRCA1 and BRCA2 genes account for the majority of hereditary ovarian cancer cases. However, mutations in other genes can also increase risk of ovarian cancer:
- Lynch Syndrome (also known as hereditary non-polyposis colorectal cancer or HNPCC) is a type of bowel cancer predisposition which is linked to mutations in one of the genes MSH2, MLH1, MSH6 and PMS2. A woman with a mutation in one of these genes has an estimated nine to 12 per cent chance of developing ovarian cancer at some point during her lifetime. The chance of developing cancer of the stomach, liver, kidney, bladder, skin and brain can also be increased by a mutation in one of the Lynch Syndrome genes.
- Mutations in RAD51C and RAD51D genes can increase a woman’s risk of ovarian cancer. However these mutations are very rare. Women carrying a RAD51D mutation have about a 10 per cent risk of developing ovarian cancer by the time they reach the age of 80.
- Mutations in the STK11 gene may also increase the risk of developing ovarian sex cord-stromal tumours – a different type of ovarian cancer. Mutations in this gene cause Peutz-Jeghers syndrome, which is an extremely rare condition estimated to affect one in 100,000 people. People with Peutz-Jeghers syndrome have an 18 per cent risk of developing gynaecological cancers by the age of 70.
- Mutations in the BRIP1 (FANCJ) gene increase the risk of ovarian cancer from approximately two per cent to six per cent. It is estimated that two women in every 2000 carry a mutation in their BRIP1 (FANCJ) gene. There is currently no routine test available to check for mutations in the BRIP1 (FANCJ) gene.
Mutations in different genes carry different increases in risk. A clinical geneticist (a doctor who specialises in genetics) or a genetic counsellor will be able to give you a more accurate and personalised risk assessment.
This information focuses on the BRCA1 and BRCA2 gene mutations as this is what is most commonly tested for at the moment. Testing is currently in development for a number of other genes.
Find out more
- Getting tested - what should I consider before having a genetic test?
- What is a genetic test and what are the possible results?
- What is the impact of the different results for me and my family?
- I have a BRCA1 or BRCA2 gene mutation – what now?
- What are the implications for a family member with a BRCA gene mutation?
- Further sources of support
The information on this page is approved by the Information Standard scheme to ensure that it provides accurate and high-quality information.
Last reviewed: July 2016
Next review: June 2019