Health

What Genes Affect Breast Cancer?

Overview.

About 5% to 10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child.

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. Changes or mistakes in the DNA are like typographical errors. They may provide the wrong set of instructions, leading to faulty cell growth or function. In any one person, if there is an error in a gene, that same mistake will appear in all the cells that contain the same gene. This is like having an instruction manual in which all the copies have the same typographical error.

There are two types of DNA changes: those that are inherited and those that happen over time. 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.Some DNA changes are harmless, but others can cause disease or other health issues. DNA changes that negatively affect health are called mutations.

BRCA1 and BRCA2 genetic mutations.

Most inherited cases of breast cancer are associated with mutations in two genes: BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two).

Everyone has BRCA1 and BRCA2 genes. The function of the BRCA genes is to repair cell damage and keep breast, ovarian, and other cells growing normally. But when these genes contain mutations that are passed from generation to generation, the genes don’t function normally and breast, ovarian, and other cancer risk increases. BRCA1 and BRCA2 mutations may account for up to 10% of all breast cancers, or 1 out of every 10 cases.

Having a BRCA1 or BRCA2 mutation doesn’t mean you will be diagnosed with breast cancer. Researchers are learning that other mutations in pieces of chromosomes — called SNPs (single nucleotide polymorphisms) — may be linked to higher breast cancer risk in women with a BRCA1 mutation as well as women who didn’t inherit a breast cancer gene mutation.

Women who are diagnosed with breast cancer and have a BRCA1 or BRCA2 mutation often have a family history of breast cancer, ovarian cancer, and other cancers. Still, most people who develop breast cancer did not inherit a genetic mutation linked to breast cancer and have no family history of the disease.

You are substantially more likely to have a genetic mutation linked to breast cancer if:

▪️You have blood relatives (grandmothers, mother, sisters, aunts) on either your mother’s or father’s side of the family who had breast cancer diagnosed before age 50.

▪️There is both breast and ovarian cancer on the same side of the family or in a single individual.

▪️You have a relative(s) with triple-negative breast cancer.

▪️There are other cancers in your family in addition to breast, such as prostate, melanoma, pancreatic, stomach, uterine, thyroid, colon, and/or sarcoma.

▪️Women in your family have had cancer in both breasts.

▪️You are of Ashkenazi Jewish (Eastern European) heritage.

▪️You are Black and have been diagnosed with breast cancer at age 35 or younger.

▪️A man in your family has had breast cancer.

▪️There is a known abnormal breast cancer gene in your family.If one family member has a genetic mutation linked to breast cancer, it does not mean that all family members will have it.

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.

Women with a BRCA1 or BRCA2 mutation also have an increased risk of developing ovarian, colon, and pancreatic cancers, as well as melanoma.Men who have a BRCA2 mutation have a higher risk of breast cancer than men who don’t — about 8% by the time they’re 80 years old. This is about 80 times greater than average.

Men with a BRCA1 mutation have a slightly higher risk of prostate cancer. Men with a BRCA2 mutation are 7 times more likely than men without the mutation to develop prostate cancer. Other cancer risks, such as cancer of the skin or digestive tract, also may be slightly higher in men with a BRCA1 or BRCA2 mutation.

Preliminary research suggests that a BRCA2 mutation in children and adolescents may be linked to a higher risk of non-Hodgkin lymphoma. Lymphoma is cancer of the lymph system.

Other genes that can affect breast cancer.In addition to BRCA and BRCA2, there are other genes that can increase your risk of developing breast cancer if you inherit a mutation.

These genes include :

▪️CDH1. Mutations in CDH1 put you at a higher risk of developing hereditary diffuse stomach cancer (gastric cancer). This mutation also increases your risk of lobular breast cancer.

▪️PALB2. This gene partners with the BRCA gene in your body. People with mutations in the PALB2 gene are 9.47 timesTrusted Source more likely to develop breast cancer than people who don’t have that mutation.

▪️PTEN. This is a gene that regulates cell growth. A PTEN mutation can cause Cowden syndrome, a condition that increases your risk of developing benign and cancerous tumors, like those found in breast cancer.

▪️TP53. Mutations in TP53 can lead to Li-Fraumeni syndrome, a condition that predisposes your bodyTrusted Source to several different types of cancer, including breast cancer and brain tumors.

Reference:

Genetics/https://www.breastcancer.org/risk/factors/genetics

What Genes Affect Breast Cancer?/https://www.healthline.com/health/breast-cancer/breast-cancer-gene

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