Ashkenazi Jewish Women: Little-known Gene Mutations May Boost Breast Cancer Risk

Ashkenazi Jewish Women: Little-known Gene Mutations May Boost Breast Cancer Risk

Last Updated on July 27, 2017 by Joseph Gut – thasso

July 27, 2017 – Jewish women of Ashkenazi descent may be at risk for additional genetic mutations that increase their risk of breast cancer, according to a new study just published in JAMA Oncology. Researchers from University of Washington in Seattle found that around 4 percent of Ashkenazi Jewish women without well-known founder mutations in BRCA1 and BRCA2 genes have other mutations that may increase their risk for breast cancer.

Ashkenazi Jewish women

Founder mutations in BRCA1 and BRCA2 are responsible for about 10 percent of invasive breast cancers among Ashkenazi Jewish women, lead author Mary-Claire King and colleagues note in JAMA Oncology July 20, 2017.

According to the National Cancer Institute, between 1 in 400 and 1 in 800 people in the general U.S. population has one of these founders mutations – but that number increases to about 1 in 40 among Jewish women of Ashkenazi descent. In women who don’t carry one of these mutations, the risk of having another mutation that increases their risk of breast cancer was unknown so far.

For the new study, the researchers analyzed blood samples collected between 1996 and 2000 from 1,007 Ashkenazi Jewish women who were diagnosed with invasive breast cancer, who were being treated at one of 12 cancer centers near New York City, and who  were participants off the New York Breast Cancer Study (NYBCS), a longstanding cohort of Ashkenazi Jewish women with a primary diagnosis of invasive breast cancer.

In fact, genetic testing showed 903 women did not have founder mutations in their BRCA1 or BRCA2 genes. while 31women  (3.4%) carried a pathogenic mutation in another breast cancer gene (29 in the CHEK2 gene, and 1 each in the  BRIP1 gene and the NBN gene). Of all inherited predispositions to breast cancer in the NYBCS, 73.8% (104 of 142) were due to a BRCA1 or BRCA2 founder allele, 4.9% (7 of 142) to another BRCA1 or BRCA2 mutation, and 21.8% (31 of 142) to a mutation in another gene. Overall, 14.1% (142 of 1007) of Ashkenazi Jewish women with breast cancer in the NYBCS carried a germline mutation responsible for their disease: 11.0% (111 of 1007) in BRCA1 or BRCA2, and 3.1% (31 of 1007) in CHEK2 or another breast cancer gene. Of the 111 patients with BRCA1 or BRCA2 mutations, 57 (51.4%) had a mother or sister with breast or ovarian cancer and 54 patients (48.6%) did not.

The authors point out that about half of the women with these genetic mutations did not have a family history of breast cancer. So, making genetic counseling available only to women with a family history of breast cancer might miss about half of the women with mutations. Ashkenazi Jewish women, and of course any other women who have not been tested for genetic mutations tied to an increased risk of breast cancer should be offered testing for all mutations, they write. Under the condition that complete sequencing of all breast cancer genes is now straightforward and inexpensive, its use as the primary testing tool offers a uniform and comprehensive approach for women of all ancestries and precludes the need to consider additional testing for Ashkenazi Jewish women with negative results for only BRCA1 and BRCA2 founder alleles. This would constitute a great step forward in practicing theragenomic and personalized medicine aiming at applying individual treatment options to each single patient based on her/his underlying genetic outfit of a given disease, being breast cancer in the present case.

 

Ph.D.; Professor in Pharmacology and Toxicology. Senior expert in theragenomic and personalized medicine and individualized drug safety. Senior expert in pharmaco- and toxicogenetics. Senior expert in human safety of drugs, chemicals, environmental pollutants, and dietary ingredients.

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