BRCA Preimplantation Genetic Screening of Embryos at Increased Risk for Cancer
BRCA1 (BReast CAncer) and BRCA2 are human genes known as tumor suppressors. Harmful mutations of these genes can be linked to an increased risk of breast and ovarian cancer. In the U.S., between one in 400 – 800 people in the general population carry a BRCA mutation. Individuals with Ashkenazi Jewish background have an increased incidence; 1 in 40 may be affected with a BRCA1 or BRCA2 mutation. There are many variations in BRCA genes and not all changes confer the same risks. Some variants are harmless; others are known to be very harmful.
If you inherit a BRCA1 or BRCA2 harmful mutation, your lifetime risk of developing breast cancer is 60 to 80 percent, compared to about 13 percent in the general population. This translates to a five-fold increased risk for breast cancer. If you have a harmful BRCA1 mutation, you have a 30 to 45 percent lifetime risk of developing ovarian cancer. Cancer risks by age are shown in the table below. Overall, it has been estimated that inherited BRCA1 and BRCA2 mutations account for 5 to 10 percent of the total breast cancers and 10 to 15 percent of the total ovarian cancers among white women in the United States.
So who should be tested for the BRCA mutation? Family history may indicate the need for testing. According to U.S. Preventive Services Task Force, the likelihood of a harmful BRCA mutation is increased when:
- two first-degree relatives (mother, daughter, or sister) are diagnosed with breast cancer, one of whom was diagnosed at age 50 or younger
- three or more first or second-degree (grandmother or aunt) relatives diagnosed with breast cancer regardless of their age at diagnosis
- a first-degree relative with cancer diagnosed in both breasts
- a combination of two or more first- or second-degree relatives diagnosed with ovarian cancer regardless of age at diagnosis
- breast cancer diagnosed in a male relative
Patients diagnosed to be BRCA carriers are faced with complicated treatment decisions regarding both their own future risk of cancer as well as risk to their children. Some women are faced with the decision whether to proceed with surgically removing both breasts (mastectomies) and ovaries to reduce their cancer risks. If you are a carrier, your child has a 50% chance of inheriting the mutated BRCA gene. Male and female BRCA carriers may choose to proceed with genetic screening of their embryos (preimplantation genetic diagnosis or PGD). PGD permits transfer of embryos without the BRCA harmful mutations. The Fertility Centers of New England has extensive experience with PGD. Further information and counseling can be provided at an initial consultation with one of the Centers’ physicians.
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