BRCA Mutations Underestimated in Asian American Women
by Sue Friedman and Cara Scharf
Not all ethnic groups carry the same risks for inherited diseases. People of African American descent, for example, are at much higher risk for sickle-cell anemia, and people of Jewish background have a higher likelihood of Tay-Sachs disease. We also know that people of Eastern European Jewish descent are 10 times more likely to carry a BRCA mutation than individuals of other ethnic backgrounds. Much less is known, however, about the prevalence of BRCA mutations in other minority groups in the U.S.
Genetic testing for hereditary breast and ovarian cancer is not always a simple, straightforward test, and not everyone will benefit from genetic testing. Meeting with a genetics counselor is an important step to determine whether cancer in a family is hereditary. Counselors use preestablished computer prediction models to estimate a person’s chance of carrying a BRCA mutation and to determine who should be tested. Yet a new study published by researchers from the U.S. and Canada suggests that existing models underestimate the prevalence of BRCA mutations in Asian American women.
Details of the study
Researchers studied BRCAPRO and Myriad II, two models widely used by genetics experts to estimate the likelihood of a mutation within a group of people. Using test information from 200 Asian American women, the researchers ran both models and compared the results with a control group of 200 non-Jewish Caucasian women who had known BRCA mutations. As expected, the models accurately predicted the number of non-Jewish Caucasian women who had a BRCA mutation. But in the Asian American group, both models were well off the mark: Forty-nine Asian women tested positive for a BRCA mutation, while the BRCAPRO model predicted only 25 and the Myriad II model predicted just 26 women.
How can we interpret the findings?
Since the BRCAPRO and Myriad II models often play an important part in determining whether a person will benefit from testing or not (and may determine whether insurance will pay for testing), inaccurately predicting the number of Asian Americans with mutations may mean that testing is recommended for this community less often than it should be. This denies individuals the opportunity to obtain an accurate estimate of their genetic risk for developing breast and ovarian cancer. The study suggests that a more effective model is needed for estimating the risk for a BRCA mutation in Asian American women. In the meantime, Asian American women who believe they may be at higher risk should consult with a cancer genetics expert.
Cara resides in Philadelphia and works as an editorial intern. She plans to attend graduate school for journalism, and aspires to work one day for National Public Radio.
Kurian AW, et. al. Performance of BRCA1/2 mutation prediction models in Asian Americans. Journal of Clinical Oncology, 2008; 26(29):4752-4758.
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