The Long and the Short of It: What Everyone Should Know About BRCA!
- There is a 1 in 40 risk of carrying genes known to increase the risk of serious genetic cancers (the BRCA genes) in people with Ashkenazi Jewish heritage.
- It is just as important for men to get tested as it is for women – BRCA genes are better known for their role in breast and ovarian cancers, but they also significantly increase the risk of many other cancers that affect both men and women
- The best time to get tested is when you are young and healthy – testing for BRCA in your 20s and 30s provides you with many options to prevent and manage your risk of genetic cancer before it strikes
- Testing is quick, simple, easy and cheap (or free in many cases!) – testing involves a saliva or blood test and is often covered by MSP, depending on your family history
- All people with Jewish heritage should consider getting tested – just because there is not a strong history of cancer in your family, doesn’t mean you aren’t at risk, only half of all carriers have the history of cancer in the family that would indicate the presence of a BRCA gene
What is BRCA?
BRCA is actually a general term for BRCA1 and BRCA2, two important genes in the human genome. They were discovered by geneticists in 1990 and found to play a significant role in preventing the development of breast cancer, which is how they received the name BRCA (BR for breast, CA for cancer; sometimes pronounced “brak-ah”), sometimes called Hereditary Breast Ovarian Cancer Syndrome (HBOC).
They are “tumor suppressor proteins” which normally control cell growth and cell death. These genes are important because they also help repair normal and abnormal damage that affects our DNA throughout our lives. Everyone (regardless of gender) has two copies of these genes in the DNA of every cell in their bodies. People are called carriers of BRCA1 or BRCA2 when they carry one normal and one abnormal or mutated copy of either one of these genes. That means that one copy of the genes functions normally to help suppress potential tumor development, while the other does not.
What does it mean to be a BRCA1 or BRCA2 carrier?
Having two copies of normally functioning genes is very helpful, because if one gene mutates spontaneously, the other copy can act as a backup and keep everything functioning as it should, while the body repairs the mutation. People who are carriers of BRCA1 or BRCA2 only have one functioning copy of these genes, which means if the other copy mutates spontaneously, there is a a higher risk of it leading to the development of a tumour. Possible causes of mutated genes in life include chemical, physical, or biological environmental exposures, or chance errors during cell replication. This is why carrying a mutated copy of BRCA1 or BRCA2 is not a guarantee that the person will develop cancer. It just means that they have a higher risk of developing cancer than people who have two normal copies of these genes.
What are the cancer risks for BRCA1 or BRCA2 carriers?
This is not a simple question and the answer depends on whether you are biologically male (XY) or female (XX), your age, what specific type of mutation you have, and many other factors. Generally speaking, carriers of BRCA1 and BRCA2 may be at increased risk of developing the following cancers:
- Breast cancer (high risk in women; small, but increased risk in men)
- Ovarian cancer (in women only)
- Prostate cancer (in men only)
- Pancreatic Cancer
- Several other cancers including endometrial, laryngeal, colorectal, gastric cancers and lymphoma
BRCA carriers are also at higher risk of developing cancer at a younger age on average and the cancers that develop can often be more aggressive and resistant to treatment. Knowing your carrier status is powerful information. It can help you take preventative measures and can help your doctors identify the best course of action for you in the case that you do develop a genetically-linked cancer. It also provides important information for your family, as this gene could be carried by other family members and can be passed on to your children.
What is the BRCA risk for people with Ashkenazi Jewish background?
In the general (non-genetically Jewish) population, estimates vary but the risk of carrying a BRCA mutation is approximately 1/500-1/1000. In people of Ashkenazi Jewish descent, the risk is about 10 times greater than in the general population – about 1 in 40 or 2.5% of Ashkenazi Jews. Most carriers in the Ashkenazi Jewish population carry one of three specific mutations of BRCA1 or BRCA2. About 90% of carriers carry either BRCA1 185delAG, BRCA1 5382insC, or BRCA2 6174delT. Knowing which mutation you have as a carrier is important for understanding your specific risk profile for various cancers. For instance, female carriers of BRCA 2 6174delT are at a significantly lower risk of developing breast cancer than carriers of the other founder mutations.
What if my family is not religious or I’m not ‘fully’ Jewish? Does this change my risk?
The increased risk of carrying BRCA1 or BRCA2 is a Jewish (genetic) heritage issue, not a religious issue. People who carry these gene mutations may not be actively affiliated in any way with Judaism. Of course, coming from a mixed background will decrease the chances that you might have inherited these genes, but it will not eliminate the risk. Anyone who believes they may have parents, grand-parents or even great-grandparents of Ashkenazi Jewish descent should discuss the possibility of genetic testing with their family doctor or another trusted health professional.
Can I pass BRCA1 and BRCA2 on to my kids?
We receive one copy of our genes from our mothers and one copy from our fathers. Because BRCA carriers have two copies of BRCA1 and BRCA2 genes (one normal and one mutated), carriers have a 50/50 chance of passing on a copy of these genes to their children. This is why it may be important for anyone to know their carrier status, regardless of their biological gender. Not only are men who are carriers at increased for cancers like aggressive prostate or pancreatic cancers, but they can also pass on these genes on to their daughters or their sons.
Why is the risk higher for people with Ashkenazi Jewish heritage?
The BRCA mutations found in the Ashkenazi Jewish population are called the “founder mutations” resulting from something called the “founder effect”. In the field of genetics, “founders” are a small group of people who tended to procreate in isolation. When a population is isolated over many generations, specific genetic mutations can become more common in the population. The founder effect in the Jewish population is also likely linked with important events that shrunk the Jewish population over history, such as the Holocaust. This is called a “bottlenecking effect”.
Today’s Ashkenazi Jewish population are the descendants of a small group of founders from Eastern Europe, of whom one or more members must have carried the specific mutations we now see in the BRCA1 and BRCA2 genes. This information has practical meaning when it comes to genetic testing because some laboratories now offer “ethnic-specific” mutation panels. Rather than searching through the entire gene every time a person is tested, in some cases, laboratories can instead first look for specific mutations based on a person’s ethnic background.