Jewish Health

Genetics and inheritance 2: BRCA mutations

Mutations on the BRCA1 and 2 genes can lead to an increased risk of developing breast cancer or ovarian cancer. These genes are inherited in an autosomal dominant manner; someone with the mutation has a 50% chance of passing on the mutation to their children. Three specific Founder Ashkenazi mutations have been found which together are ten times as common as BRCA mutations overall in the general population. An estimated 1 in 40 people of Ashkenazi Jewish descent carry one of these three mutations (Jewish Genetic Disorders 2010). These account for the majority of BRCA mutations in affected people from the Ashkenazi Jewish population. Because of this increased risk, women without a personal history of breast cancer, but with a history of cancer in their family and who are of Jewish descent should be referred for specialist genetic counselling and advice. If there is a known genetic mutation already identified, then a referral to a genetic specialist is advised. The genetic specialist will advise on whether and which testing should be considered. In addition the specialist clinic may consider whether any extra screening tests (such as mammograms or MRI) should be offered, and also whether any kind of preventative treatment might be considered, such as surgery or medications, to reduce the risk of developing breast cancer.
 
One woman described how after she found she carried an alteration (mutation) in the BRCA1 gene, she began to uncover other cancers in the family that she hadn’t previously known about' “the further you dig back, the more history you find”. A couple of people described how their physical likeness to one parent had made them convinced that they also must have inherited the faulty gene of that parent (though there is no scientific basis for such beliefs).
 
Those who had gone through genetic testing sometimes struggled to understand the risk statistics they were given for either developing or passing on a condition. Particularly in the case of breast cancer, which is common in the general population, the extra risk posed by having a known genetic mutation can be difficult to grasp. One woman who was diagnosed with breast cancer was not found to have any of the known Ashkenazi founder mutations causing breast cancer susceptibility, while another one was found to have the BRCA2 gene mutation despite being unaware of any family history of cancer.
For those who carried a cancer gene mutation (BRCA1 or 2), worries about passing the gene on to future generations were further compounded by worries about their own health. Even though a few of those who had tested positive for the cancer gene had already gone through and recovered from cancer, they knew that having the faulty gene put them at a high risk of further cancers developing.
 
Several women discussed their concern about their children inheriting the mutation from them. Their concerns also focused on when to tell their children and how much to tell them.


Last reviewed September 2015.
Last updated September 2015.

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