Genes are short segments of DNA (deoxyribonucleic acid) found in chromosomes. DNA contains the instructions for building proteins. And proteins control the structure and function of all the cells that make up your body. Think of your genes as an instruction manual for cell growth and function.


There are two types of DNA changes:

  • Inherited DNA changes are passed down from parent to child. Inherited DNA changes are called germ-line alterations or mutations.
  • DNA changes that happen over the course of a lifetime, as a result of the natural aging process or exposure to chemicals in the environment, are called somatic alterations



BRCA1 and BRCA2 mutations may account for up to 10% of all breast cancers, or 1 out of every 10 cases. Women who have a BRCA1 mutation or BRCA2 mutation (or both) can have up to a 72% risk of being diagnosed with breast cancer during their lifetimes. Breast cancers associated with a BRCA1 or BRCA2 mutation tend to develop in younger women and occur more often in both breasts than cancers in women without these genetic mutations. In comparison, women with an abnormal BRCA1 gene have a 50% to 70% risk of developing breast cancer by age 70. Women with an abnormal BRCA2 gene have a 40% to 60% risk of developing breast cancer by age 70.

Women with a BRCA1 or BRCA2 mutation also have an increased risk of developing ovarian, colon, and pancreatic cancers, as well as melanoma.

High risk gene mutations

• PALB2: The PALB2 (partner and localizer of BRCA2) gene provides instructions to make a protein that works with the BRCA2 protein to repair damaged DNA and stop tumor growth. Research suggests that women with a PALB2 mutation have a 14% risk of developing breast cancer by age 50, but that risk jumps to 35% by age 70. And for those with a family history, the risk of breast cancer by age 70 is 58%.
• PTEN:. The lifetime breast cancer risk for women with a PTEN mutation is estimated at 25% to 50%, although some studies have reported a higher risk, at 77% to 85%. The average age at diagnosis is 38 to 50 years.
• TP53: The TP53 gene provides instructions to the body for making a protein that stops tumor growth. Inheriting an abnormal TP53 gene causes a higher-than-average-risk of breast cancer and a 54% risk of developing breast cancer by age 70. Also, women with this syndrome tend to develop breast cancer at earlier ages and may be more likely to have HER2-positive cancers.

The risk of getting any type of cancer in women with a TP53 mutation is up to nearly 100%. In men, it is up to 73%. This gender difference is mostly due to the high breast cancer risk in women.
Moderate to high risk gene mutations
• ATM:
• CDH1.
Moderate risk gene mutations
• NF1
• STK11