What Gene Mutation Causes Breast Cancer

Combinations Of Polymorphisms In Different Genes

One study examined the four polymorphisms in the CYP1A1 gene and the GSTM1 and GSTT1 polymorphisms. None of these polymorphisms, either separately or combined, was associated with increased breast cancer risks. Others analysed a combination of the m2 polymorphism in the CYP1A1 gene and the GSTM1 polymorphism and again no associations were found. One study examined the m1 polymorphisms in the CYP1A1 gene and the polymorphisms in the CYP17 and COMT genes. The presence of at least two putative high risk genotypes was associated with an increased risk of breast cancer .

In conclusion, in a few studies with small sample sizes, combinations of polymorphisms were examined.

How Do Certain Genes Affect Breast Cancer

Cancer is a health condition that can be caused by changes to your genes. Your genes carry instructions that tell the proteins in your cells how to behave.

When your genes cause proteins and cells to develop in abnormal ways, it can become cancer. This can happen because of a gene mutation.

Its possible to be born with certain gene mutations. This is called an inherited mutation. Somewhere between 5 to 10 percent of breast cancers are currently thought to be hereditary. Your genes may also mutate later in life due to environmental or other factors.

A few specific mutations can play a role in developing breast cancer. Affected genes tend to be ones that control things like cell growth and the DNA in your reproductive organs and breast tissue.

BRCA1 and BRCA2 genes typically make proteins that can repair your DNA when it gets damaged, particularly in your breasts and ovaries. When these genes are mutated, it can cause abnormal cell growth. These cells can then become cancerous.

About

People born with a penis and who have the BRCA2 mutation have an increased risk of developing male breast cancer.

Your risk for having BRCA1 or BRCA2 mutations may be higher if you have:

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:

Ovarian Cancer And Other Cancers

BRCA1 and BRCA2 mutations increase a womans risk of ovarian cancer, pancreatic cancer and melanoma .

BRCA1/2 mutations may also increase the risk of other cancers . However, data are limited and these topics are still under study.

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Common Breast Cancer Mutations

Researchers have identified several key gene changes linked to breast cancer. Some of these pose a high risk, while others seem to be less significant.

BRCA1 and BRCA2

The BRCA1 and BRCA2 inherited gene mutations are the most common cause of hereditary breast cancer. Mistakes in these genes account for up to 10% of all breast cancers. BRCA mutations also raise your chances for ovarian cancer, pancreatic cancer, and, in men, prostate cancer. A BRCA mutation may raise your chances of colon cancer. Women with a BRCA1 or BRCA2 mutation have up to a 72% chance of breast cancer during their lifetime.

PALB2

Normally, the PALB2 gene makes a protein that works with the BRCA2 gene protein to repair damaged DNA and stop tumor growth. But defects in the gene can lead to a higher likelihood of breast cancer. Some studies suggest that women with a PALB2 mutation have a 14% chance of breast cancer by age 50 and a 35% chance by age 70.

PIK3CA

HER2

The HER2 gene makes a protein called HER2 . This protein is found on the surface of all breast cells and that helps them grow. If the HER2 gene malfunctions and makes too many copies of itself, it tells cells to make too much HER2 protein. This causes the cells to grow out of control.

PTEN

TP53

CDH1

Researchers have discovered many other genes related to breast cancer.

Changes in the following genes may also raise your chances:

• BARD1

Understanding Your Risk Of Breast Cancer

Several breast cancer risk assessment tools have been developed to help a woman estimate her chance of developing breast cancer. The best studied is the Gail model, which is available on the National Cancer Institutes website at www.cancer.gov/bcrisktool. After you enter some personal and family information, including race/ethnicity, the tool provides you with a 5-year and lifetime estimate of the risk of developing invasive breast cancer. Because it only asks for information about breast cancer in first-degree family members and does not include their ages at diagnosis, the tool works best at estimating risk in women without a strong inherited breast cancer risk. For some women, other ways of determining the risk of breast cancer may work better. For example, women with a strong family history of breast cancer risk should consider talking to a genetic counselor.

It is important to talk with your doctor about how to estimate your personal risk of breast cancer and to discuss risk-reducing or prevention options .

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What Is A Gene

Each persons DNA contains the code used to build the human body and keep it functioning. Genes are the small sections of DNA that code for individual traits. For example, someone with naturally red hair has a gene that causes his or her hair to be red.

All inherited traits are passed down through genes. Each person has two copies of every gene: one gene from each parent. Since each parent passes down exactly half of their genes to each child, any of the parents genetic traits has a 50% chance of being passed on to their offspring.

Breast Cancer And Genetic Testing

At the current time, testing is available for BRCA gene mutations, as well as mutations ATM, CDH1, CHEK2, MRE11A, MSH6, NBN, PALB2, PMS2, PTEN, RAD50, RAD51C, SEC23B, and TP53, with this area expected to expand dramatically in the near future.

Having these tests available, however, raises many questions. For example, who might have hereditary breast cancer and who should be tested? What should you do if you test positive for one of these genes?

Ideally, any testing should be done only with the guidance and help of a genetic counselor. There are two reasons for this.

One is that it can be devastating to learn that you carry a mutation that may increase your risk, and the guidance of someone who is aware of recommended management and screening is invaluable.

As noted earlier, some mutations confer a high risk and others a much lower risk. Some mutations might be of more concern earlier in life , whereas others might not require early screening. A genetic counselor can help you learn about what is currently recommended with regard to screening for your particular mutation while taking into account any other risk factors you might have.

The other reason genetic counseling is so important is that you may have a significant risk of developing breast cancer even if your tests are negative. There is much yet to learn, and a genetic counselor can help you look at your family history to see if you may carry a high risk despite negative testing, and plan screening accordingly.

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The Role Of Brca Genes

Genes, which are inside each cell in your body, are made of DNA molecules. They are a blueprintcoding for the proteins that your body builds. BRCA genes are normal genes that function as tumor suppressor genes. Each of your cells contains two copies of the BRCA1 gene and two copies of the BRCA2 gene .

Normal BRCA genes code for proteins that prevent cancer growth, especially breast cancer and ovarian cancer. Specifically, these proteins are responsible for repairing cancer-causing damage to DNA in your cells.

You may hear some people refer to these by spelling out “B-R-C-A mutations” or by saying “braca mutations.”

What Does Palb2 Stand For

PALB2 stands for Partner And Localizer of BRCA2 or PAL of BRCA2 for short. The PALB2 gene normally codes for a protein that interacts with the protein made by the BRCA2 gene. Together, the proteins make up part of the repair pathway that fixes DNA damage in cells. A mutation in any of these DNA repair genes prevents abnormal genes in cells from being fixed or eliminated, and those cells may grow uncontrollably to form tumors.

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Screening For Other Cancers

People with a BRCA1 or BRCA2 mutation are not usually offered screening for other cancers. This is because:

• the risk of other cancer types linked to BRCA1 or BRCA2 mutations is usually much lower than for breast cancer in women
• regular screening tests cannot prevent these cancers
• there is no clear evidence that screening tests for these cancers are good at finding cancer early when it is more treatable.

Sometimes screening for other cancer types is offered as part of a research trial. Taking part in a research trial is completely up to you. Your doctor or nurse can explain the possible risks and benefits of taking part.

What Is Hereditary Breast And Ovarian Cancer

A diagnosis of Hereditary Breast and Ovarian Cancer Syndrome is considered when there are multiple cases of breast cancer and/or ovarian cancer on the same side of the family. The chance that a family has HBOC increases in any of these situations:

• 1 or more women are diagnosed at age 45 or younger

• 1 or more women are diagnosed with breast cancer before age 50 with an additional family history of cancer, such as prostate cancer, melanoma, and pancreatic cancer

• There are breast and/or ovarian cancers in multiple generations on the same side of the family, such as having both a grandmother and an aunt on the fathers side both diagnosed with these cancers

• A woman is diagnosed with a second breast cancer in the same or the other breast or has both breast and ovarian cancers

• A male relative is diagnosed with breast cancer

• There is a history of breast cancer, ovarian cancer, prostate cancer, and/or pancreatic cancer on the same side of the family

• Having Ashkenazi Jewish ancestry

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Brca1 And Brca2 Mutations And Treatment Strategies For Breast Cancer

Inês Godet

Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, USA

Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, USA

E-mail :

Daniele M. Gilkes

Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, USA

Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, USA

DOI: 10.15761/ICST.1000228

Figures & Data

Are There Preventative Measures Women Can Take

Breastcancer.org recommends that women who are aware they have a genetic mutation linked to breast cancer consider implementing the following preventive measures to lessen the risk:

• Keep weight in a healthy range
• Engage in a regular exercise program
• Avoid smoking
• Consider reducing or eliminating alcohol
• Eat a nutrient-rich diet

More aggressive preventative strategies may include:

• Begin screening for hereditary breast cancer at an earlier age, depending on a woman’s family history
• Hormonal therapies
• A prophylactic mastectomy, or surgical removal of the healthy breasts

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Familial Atypical Multiple Mole Melanoma Syndrome

FAMMM is a syndrome that increases your risk of developing melanoma skin cancer. People with FAMMM tend to have large numbers of moles or moles that are unusual. They also have at least one close relative with a diagnosis of melanoma. A close relative is a parent, brother or sister, or child.

Scientists think that FAMMM is linked to a fault in the CDKN2A gene. It may also increase your risk of developing pancreatic cancer. But doctors need more research to find out for sure.

Finding The Missing Heritability

The breast cancer genes identified thus far explain only about 30% of the heritability, which is the proportion of the phenotypic variance that can be attributed to genetic variation. There are several possible sources for the missing genes, and this is a subject of intense argument and ongoing research.

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Other Cancer Risks For People With Hboc

Anyone with mutations in the BRCA2 gene may be at an increased risk of other types of cancer, including melanoma and pancreatic, stomach, esophageal, and bile duct cancers.Mutations in other genes may be associated with an increased risk of developing breast and other cancers, including the Li-Fraumeni syndrome , Cowden syndrome, and others. The pattern of cancers in the family is often a clue to the specific gene that may explain the hereditary cancer for that family. Multigene panels are available for people with a strong personal and family history of cancer. Multigene panel tests include BRCA1 and BRCA2 and many other genes that increase the risk of breast, ovarian, and other cancers. If your BRCA1 and BRCA2 test was negative, then you may or may not have mutations in other genes. A newer type of testing, called next generation sequencing, massively parallel sequencing, or deep sequencing, has made testing for multiple genes at the same time faster and less expensive. If a genetic mutation is found, this could explain the cancers in a specific family and provide information about who is at risk and the appropriate types of monitoring and prevention/risk reduction methods.

Who Should Consider Genetic Counseling And Testing For Brca1 And Brca2 Variants

Anyone who is concerned about the possibility that they may have a harmful variant in the BRCA1 or BRCA2 gene should discuss their concerns with their health care provider or a genetic counselor.

Tests are available to see if someone has inherited a harmful variant in BRCA1 and BRCA2. However, testing is not currently recommended for the general public. Instead, expert groups recommend that testing be focused on those who have a higher likelihood of carrying a harmful BRCA1 or BRCA2 variant, such as those who have a family history of certain cancers. Testing can be appropriate for both people without cancer as well as people who have been diagnosed with cancer. If someone knows they have a mutation in one of these genes, they can take steps to reduce their risk or detect cancer early. And if they have cancer, the information about their mutation may be important for selecting treatment.

Before testing is done, a person will usually have a risk assessment, in which they meet with a genetic counselor or other health care provider to review factors such as which of their relatives had cancer, what cancers they had, and at what ages they were diagnosed. If this assessment suggests that someone has an increased risk of carrying a harmful BRCA1 or BRCA2 gene variant, their genetic counselor can discuss the benefits and harms of testing with them and order the appropriate genetic test, if the individual decides to have genetic testing .

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Genetic Counseling And Testing For Breast Cancer Risk

Some people inherit changes in certain genes that increase their risk of breast cancer . Genetic testing can look for mutations in some of these genes. While it can be helpful in some cases, not everyone needs to be tested, and each person should carefully consider the pros and cons of testing. Its very important to understand what genetic testing can and cant tell you before these tests are done.

Challenges In Understanding Cancer Genetics

Researchers have learned a lot about how cancer genes work. But many cancers are not linked with a specific gene. Cancer likely involves multiple gene mutations. Moreover, some evidence suggests that genes interact with their environment. This further complicates our understanding of the role genes play in cancer.

Researchers continue to study how genetic changes affect cancer development. This knowledge has led to improvements in cancer care, including early detection, risk reduction, the use of targeted therapy, and survival.

Further studying cancer genetics may help doctors find better ways to:

• Predict a persons risk of cancer

• Diagnose cancer

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Inherited Vs Acquired Gene Mutations

When talking about mutations, it’s important to distinguish between inherited and acquired gene mutations.

Acquired or somatic gene mutations have received a lot of attention in recent years, as these mutations cause changes that drive the growth of cancer. Targeted therapies, drugs that target specific pathways related to these changes, have significantly improved the treatment of some cancers such as lung cancer.

Acquired mutations, however, are not present from birth, but rather, are formed any time after birth in the process of a cell becoming a cancer cell. These mutations affect only some cells in the body. They are not inherited from a parent, but rather “acquired” as the DNA in cells is exposed to damage from the environment or as a result of the normal metabolic processes of the body.

Inherited, or germ-line mutations, in contrast, are genetic changes that people are born with, and that are passed down from one or both parents. These mutations affect all the cells of the body. It is these inherited mutations that can increase the chance that a person will develop cancer, and account for what is known as hereditary or familial breast cancer.

What Other Cancers Are Linked To Harmful Variants In Brca1 And Brca2

Harmful variants in BRCA1 and BRCA2 increase the risk of several additional cancers. In women, these include fallopian tube cancer and primary peritoneal cancer , both of which start in the same cells as the most common type of ovarian cancer. Men with BRCA2 variants, and to a lesser extent BRCA1 variants, are also at increased risk of breast cancer and prostate cancer . Both men and women with harmful BRCA1 or BRCA2 variants are at increased risk of pancreatic cancer, although the risk increase is low .

In addition, certain variants in BRCA1 and BRCA2 can cause subtypes of Fanconi anemia, a rare syndrome that is associated with childhood solid tumors and development of acute myeloid leukemia . The mutations that cause these Fanconi anemia subtypes have a milder effect on protein function than the mutations that cause breast and ovarian cancer. Children who inherit one of these variants from each parent will develop Fanconi anemia.

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