Genetics

 What are genes?

Every cell in your body contains genetic material, or genes.  Genes are the blueprints for your body.  They determine what color eyes you have and how tall you are. They also affect other functions of your body.  For example, they tell your body to repair tissue that has been injured and help a woman’s body to prepare for a growing baby during pregnancy.  Sometimes though, your genes do not work like they should.  This is due to an error in one or more of your genes, called a mutation.

Watson-Crick_double_helix

Mutations may be inherited or spontaneous.  Inherited mutations are those you were born with — a defective gene that one of your parents passed on to you at birth.  Spontaneous mutations are those that may occur in a single cell during the course of your life.  There are many ways a spontaneous mutation can happen.  However, scientists do not yet know exactly how, or if, these mutations are related to a woman’s lifestyle (diet, exercise, and reproductive patterns), chemical changes inside the body or exposure to environmental toxins, such as radiation or chemicals — or if these mutations can even be prevented.

Genes and breast cancer

Scientists have found two specific genes that are important in the development of breast cancer.  They are called BRCA1 and BRCA2.  Every woman has these genes, but some women have inherited a mutated form of one or both genes.  Inheriting a mutated form of BRCA1 or BRCA2 increases a woman’s risk of breast and ovarian cancer.  However, not all breast cancers are due to inherited mutations.

Inherited gene mutations, including mutations in BRCA1 and BRCA2, account for only about 5 to 10% of all cases of breast cancers, while most breast cancers are due to spontaneous gene mutations.  Mutations in BRCA genes are not only found in women.  Men also carry the abnormal genes, which may increase their risk of prostate cancer.  Men with a BRCA2 mutation also have an increased risk of breast cancer.

Who has mutations in BRCA1 and BRCA2?

The likelihood that you have mutations in the BRCA1 or BRCA2 genes is greater if one or more of the following statements is true for you:

  • You have been diagnosed with breast cancer before age 50
  • Your mother, sister, or daughter has had breast cancer before age 50 or ovarian cancer at any age
  • A woman in your family has had both breast cancer and ovarian cancer
  • A woman in your family has had breast cancer in both breasts
  • Your family is of Ashkenazi Jewish descent
  • There is male breast cancer in your family.

Remember, most women who get breast cancer do not have an inherited gene mutation in BRCA1 or BRCA2.  That is why it is important that every woman have mammograms as recommended, have clinical breast exams and perform monthly breast self-exams.

Can I find out if I have an inherited gene mutation?

Yes, you can. Women who have a family history of breast cancer are interested in being tested for an inherited gene mutation should be referred to a genetic counselor.  Genetic counselors are trained health professionals who can interpret a woman’s family history of breast and ovarian cancer as well as the results of genetic testing.  The steps a woman can expect to go through with the genetic counselor are:

  1. You will provide a thorough family history and the counselor will explain your individual risk.
  2. Pre-test counseling will be held to help you decide whether or not to proceed with genetic testing.  This step includes: an overview of the genetic test procedure, a review of the risk and benefits, such as cost, confidentiality and the potential knowledge that you carry the gene mutation, a discussion of what you will do with the information once you know the results, and a discussion of the emotional impact of this information, as well as implications for your family.
  3. A sample of your blood will be drawn for the test if you decide to proceed.
  4. The sample will be sent for testing.  Results usually take three weeks.
  5. The genetic counselor will explain the interpretation of the results.

Where can I get some testing?

If you are interested in genetic testing, you should talk to your doctor.  The doctor can refer you to a genetic counselor if one is available in your area.  If your doctor is not aware of a genetic counselor close to you, contact the National Cancer Institute or National Society of Genetic Counselors.  They can give you a referral to the health centers nearest you with genetic counselors on staff.  They can also provide additional information about BRCA1, BRCA2 and genetic testing.  Here is a list of several helpful organizations:

Susan G. Komen
1-877-GO-KOMEN
www.komen.org

American Cancer Society
1-800-ACS-2345
www.cancer.org

Facing Our Risk of Cancer Empowered 
1-866-824-7475
www.facingourrisk.org

National Cancer Institute 
1-800-4-CANCER
www.cancer.gov

National Society of Genetic Counselors, Inc.
1-312-321-5163
www.nsgc.org