Changes in genes other than BRCA1 and BRCA2 are also associated with breast cancer. While many of these abnormal genes are much less common and don't seem to increase risk as much as abnormal BRCA1 and BRCA2 genes, research is on-going and we’re learning much more about the role these genes may play in increasing risk.
- ATM: The ATM gene helps repair damaged DNA. DNA carries genetic information in cells. Inheriting two abnormal copies of this gene causes the disease ataxia-telangiectasia, a rare disease that affects brain development. Inheriting one abnormal ATM gene has been linked to an increased rate of breast cancer in some families because the abnormal gene stops the cells from repairing damaged DNA.
- CDH1: The CDH1 gene makes a protein that helps cells bind together to form tissue. An abnormal CDH1 gene causes a rare type of stomach cancer at an early age. Women with an abnormal CDH1 gene also have an increased risk of invasive lobular breast cancer.
- CHEK2: The CHEK2 gene also provides instructions for making a protein that stops tumor growth. Li-Fraumeni syndrome also can be caused by an inherited abnormal CHEK2 gene. Even when an abnormal CHEK2 gene doesn't cause Li-Fraumeni syndrome, it can double breast cancer risk.
- MRE11A: Along with the RAD50 and NBN genes, the MRE11A gene forms the MRN complex, which helps repair DNA damage in cells. An abnormal MRE11A gene is linked to ataxia-telangiectasia-like disorder, a rare disease that affects brain development. The disease also weakens the immune system and increases cancer risk.
- NBN: Along with the MRE11A and RAD50 genes, the NBN gene forms the MRN complex, which helps repair DNA damage in cells. An abnormal NBN gene causes Nijmegen breakage syndrome, a condition that causes slow growth in infancy and early childhood. People with Nijmegen breakage syndrome are shorter than average, have a higher risk of several types of cancer, including breast cancer, and many other health problems. Of the three genes in the MRN complex, researchers think that an abnormal NBN has the strongest link to breast cancer.
- p53 (also called the TP53 gene): The p53 gene provides instructions to the body for making a protein that stops tumor growth. Inheriting an abnormal p53 gene causes Li-Fraumeni syndrome, a disorder that causes people to develop soft tissue cancers at a young age. People with this rare syndrome have a higher-than-average-risk of breast cancer and several other cancers, including leukemia, brain tumors, and sarcomas (cancer of the bones or connective tissue).
PALB2: The PALB2 gene is called the partner and
localizer of BRCA2. It provides instructions to make a protein that
works with the BRCA2 protein to repair damaged DNA and stop tumor
growth. Research published in 2014 found that an abnormal PALB2 gene
increases breast cancer 5 to 9 times higher than average, almost as high
as an abnormal BRCA1 or BRCA2 gene. Women with an abnormal PALB2 gene
have a 14% risk of developing breast cancer by age 50 and a 35% risk of
developing breast cancer by age 70. In comparison, women with an
abnormal BRCA1 gene have a 50%-70% risk of developing breast cancer by
age 70. Women with an abnormal BRCA2 gene have a 40%-60% risk of
developing breast cancer by age 70.
Inheriting two abnormal PALB2 genes causes Fanconi anemia type N, which suppresses bone marrow function and leads to extremely low levels of red blood cells, white blood cells, and platelets. People with Fanconi anemia also have a higher risk of several other types of cancer, including kidney cancer and brain cancer.
PTEN: The PTEN gene helps
regulate cell growth. An abnormal PTEN gene causes Cowden syndrome, a
rare disorder in which people have a higher risk of both benign (not
cancer) and cancerous breast tumors, as well as growths in the digestive
tract, thyroid, uterus, and ovaries.
In 2015, an abnormal version of the SEC23B gene also was linked to Cowden syndrome. The SEC23B gene also helps regulate cell growth. Because this discovery is so new, there is not a test available for an abnormal SEC23B gene.
- RAD50: Along with the MRE11A and NBN genes, the RAD50 gene forms the MRN complex, which helps repair DNA damage in cells. An abnormal RAD50 gene has been linked to a higher risk of breast cancer in some families because the abnormal gene stops the cells from repairing damaged DNA.
- RECQL: The RECQL gene provides instructions for making RecQ helicases. RecQ helicases are enzymes that help cells fix DNA damage. Research suggests that Polish and French-Canadian women with an abnormal RECQL gene have a much higher than average risk of breast cancer compared to women of the same ethnicities who don’t have an abnormal RECQL gene. Other studies have found that mutations in the RECQL gene are associated with a higher risk of several cancers, including larynx, brain, and pancreatic cancer.
- RINT1: The RINT1 gene, also called RAD50 interactor 1, helps regulate cell division. Besides breast cancer, an abnormal RINT1 gene is linked to Lynch-syndrome cancers: cancer of the colon, rectum, stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain, ovaries, lining of the uterus, and skin.
Genetic testing for abnormal ATM, CDH1, CHEK2, MRE11A, NBN, p53, PALB2, PTEN, RAD50, RECQL, or RINT1 genes
Finding out whether you have an inherited abnormal gene requires a special test, and the results are separate from the results in your pathology report. A genetic counselor may order testing for an abnormal ATM, CDH1, CHEK2, MRE11A, NBN, p53, PALB2, PTEN, RAD50, RECQL, or RINT1 gene if it's determined from your personal or family history that these tests are needed. Right now, there is not a test for an abnormal SEC23B gene.
Read about steps you can take to lower your risk of a future breast cancer if you test positive for one of the above gene mutations.