Sunday, March 3, 2024

What Are The 3 Types Of Cancer Genes

Which Cancers Are Genetic

Cancer 101 | National Geographic

People commonly wonder which cancers are genetic. As of now, some of the cancers are better identified as genetic cancer, although these cancers can occur as sporadically too. This needs to take into consideration, the family history of cancer and perform necessary tests. It is important to perform special tests in family members, to infer if they have the gene of interest or not.

Here are some instances of cancers commonly found as genetic cancer:

  • Adrenal cortical tumors

Note: Stomach, colon, pancreas, esophagus, lung, and gonadal germ cells cancers in some cases have been reported also for genetic cancers.

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 .

How Faulty Genes Lead To Cancer

Our genes pick up mistakes that happen when cells divide. These mistakes are called mutations. Mutations can happen throughout our lives, during natural processes in our cells. Or they can happen because of other factors such as:

  • tobacco smoke
  • high energy radiation, such as x-rays
  • ultraviolet radiation from the sun
  • some substances in food
  • chemicals in our environment

Sometimes people inherit certain faulty genes from their parents. This can give them an increased risk of cancer.

It is usual for cells to repair faults in their genes. When the damage is very bad the cell may self destruct instead. Or the immune system may recognise them as abnormal and kill them. This helps to protect us from cancer.

Sometimes mutations in important genes cause a cell to no longer understand instructions. The cell can start to multiply out of control. It doesn’t repair itself properly, and it doesn’t die when it should. This can lead to cancer.

There are 4 main types of genes involved in cell division. Most tumours have faulty copies of more than 1 of these types. You can read more about the 4 types below.

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Tumor Suppressor Genes And Hereditary Cancer

According to the American Cancer Society, inherited cancer syndromes account for between 5% and 10% of cancers, but studies suggest the percent of cancers that can be attributed to these genes may be much higher. Genetic screening is now available for several of these syndromes, but in many cases, a genetic predisposition cannot be found with testing. In this case, it’s very helpful for people to work with a genetic counselor who may be able to understand more about risk based on family history.

Tumor Suppressors: The Retinoblastoma Gene

9 Main Causes of Cancer Which Should Be Avoided

The retinoblastoma gene encodes a protein that acts by altering the activity of transcription factors. By interacting with transcription factors, Rb is able to indirectly control gene expression. In addition to this function, Rb and closely related proteins have several other less well documented activities. Ultimately, Rb and its relatives contribute to the control of the cell division process. 107

The RB1 gene is mutated in many types of cancer. One of the best studied is retinoblastoma, a cancer of the eye from which the gene got its name. The disease is often found in young children. Two different forms of retinoblastoma have been differentiated.

  • The sporadic form of the disease can affect anyone and is dependent on genetic changes aquired during the lifetime of the affected individual.
  • The familial form of the disease results when affected individuals inherit a defective copy of the gene from one of their parents. In these individuals every cell contains one normal and one defective copy of the gene.108

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What Do Brca1 And Brca2 Genetic Test Results Mean

BRCA1 and BRCA2 mutation testing can give several possible results: a positive result, a negative result, or a variant of uncertain significance result.

Positive result. A positive test result indicates that a person has inherited a known harmful variant in BRCA1 or BRCA2 and has an increased risk of developing certain cancers. However, a positive test result cannot tell whether or when the tested individual will develop cancer. Some people who inherit a harmful BRCA1 or BRCA2 variant never develop cancer.

A positive test result may also have important implications for family members, including future generations.

  • Both men and women who inherit a harmful BRCA1 or BRCA2 variant, whether or not they develop cancer themselves, may pass the variant to their children. Each child has a 50% chance of inheriting a parents variant.
  • All blood relatives of a person who has inherited a harmful BRCA1 or BRCA2 variant are at some increased risk of having the variant themselves. For example, each of that persons full siblings has a 50% chance of having inherited the variant as well.
  • Very rarely, an individual may test positive for a harmful variant not inherited from either parent. This is called a de novo variant. Such a variant is one that arose in a germ cell of one of the parents and is present in all the cells of the person who grew from that cell. The children of someone with a de novo variant are at risk of inheriting the variant.

What A Positive Result Means

If your predictive genetic test result is positive, it means you have a faulty gene that raises your risk of developing cancer.

It does not mean you are guaranteed to get cancer your genes only partly influence your future health risks. Other factors, such as your medical history, lifestyle and your environment, also play a role.

If you have one of the faulty BRCA genes, there is a 50% chance you will pass this on to any children you have and a 50% chance that each of your siblings also has it.

You may want to discuss your results with other members of your family, who may also be affected. Staff at the genetics clinic will discuss with you how a positive or negative result will affect your life and your relationships with your family.

You can read more about BRCA1 and BRCA2 in the beginner’s guide to BRCA1 and BRCA2 produced by The Royal Marsden NHS Foundation Trust.

Insurance companies cannot ask you to disclose the results of predictive genetic tests for the majority of policies, but this may change in the future.

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Syndromes Of Genetic Cancers:

Cancer in parent , close relatives at each side of the family separately or sibling, should be more cause for concern to detect whether it is genetic or acquired. Certain things should be existing in family history that could be concluded as family cancer syndrome after due genetic test, such as:

  • Many cases of an uncommon or rare type of cancer .
  • Cancers occurring at younger ages than usual
  • More than one type of cancer in a single person
  • Cancers occurring in both of a pair of organs
  • More than one childhood cancer in a set of siblings

Who Is At Risk Of Inherited Cancers

Oncogenetics – Mechanism of Cancer (tumor suppressor genes and oncogenes)

There is a difference between familial cancers and inherited cancers. Familial cancer is used to describe a situation in which more members of a particular family are diagnosed with a type of cancer than would be statistically expected, but its not known why hereditary and lifestyle causes separately or together may contribute to the high incidence in the family. In contrast, the term inherited cancer is used to refer to familial cancers in which a genetic cause has been identified.

The children of parents with an inherited cancer genetic mutation have a 50 percent chance of also having the mutation. If you have several family members who had cancer or some family members with cancer at a relatively young age talk to your doctor about genetic testing for yourself and your family.

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Are Harmful Variants In Brca1 And Brca2 More Common In Certain Racial/ethnic Populations Than Others

Yes. The likelihood of carrying an inherited mutation in BRCA1 or BRCA2 varies across specific population groups. While the prevalence in the general population is about 0.2%0.3% , about 2.0% of people of Ashkenazi Jewish descent carry a harmful variant in one of these two genes and the variants are usually one of three specific variants, called founder mutations. Other populations, such as Norwegian, Dutch, and Icelandic peoples, also have founder mutations .

Different racial/ethnic and geographic populations also tend to carry different variants in these genes. For instance, African Americans have BRCA1 variants that are not seen in other racial/ethnic groups in the United States . Most people of Ashkenazi Jewish descent in the United States who carry a BRCA variant have one of three specific variants . In the Icelandic population, a different variant in BRCA1 is common among those who inherit a mutation in BRCA1.

Genetic Testing And Analysis

Genes were grouped based on their penetrance and inheritance type . Five specific variants or variant types were considered as having a different penetrance or inheritance pattern compared to the typical pathogenic variants in the respective genes: APC p.Ile1307Lys having low penetrance , CHEK2 p.Ile157Thr having uncertain penetrance , EGFR loss-of-function variants having autosomal recessive inheritance for neonatal ectodermal dysplasia with severe skin defects and gastrointestinal dysfunction and uncertain risk for lung cancer , FH p.Lys477dup having AR inheritance for fumarate hydratase deficiency with uncertain risk for hereditary leiomyomatosis and renal cell cancer , and VHL p.Arg200Trp having AR inheritance for Chuvash polycythemia and uncertain risk for von Hippel-Lindau syndrome . Confidence intervals were calculated based on sample sizes using the Wilson/Brown method.

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Which Cancers Are Genetic & What Is A Genetic Cancer Know The Symptoms Genes Related To Genetic Cancer

So far, gathered from the latest data as collected and assimilated by World Health Organization it is revealed that during 2015, cancer was the cause of death of 8.8 million people across the world. Nearly 1 in 6 deaths was due to cancer. The number of new cancer cases expected to rise to 22 million within the next two decades. There are a lot of researches around the fact of family history of cancer. You may be interested to know what cancers are genetic.

Want To Learn More Check Out These Genome Medical Resources

A common genetic signature has been discovered among three cancer prone ...
Want to learn more? Check out these Genome Medical resources

CancerGenetics

Learn more about the link between cancer and genetics from the experts at Genome Medical. Find out answers to questions like is cancer genetic?

ReproductiveGenetics

Genome Medical offers reproductive genetic counseling, genetic test recommendations and long-term reproductive health planning to women and couples starting a family.

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Genome Medical offers pediatric medical genetics counseling, genetic test recommendations, and long-term pediatric care planning for a wide range of childhood genetic conditions.

What is Genetic Testing?

Genome Medical offers pharmacogenomics counseling, genetic test recommendations and long-term care planning to custom-tailor your medications and dosages based on your genetic makeup.

What is Genetic Counseling?

Learn more about what genetic counseling is and which genetic counseling programs are right for you or your family, answered by Genome Medicals genetic experts.

Cancer Genetics

Learn more about the link between cancer and genetics from the experts at Genome Medical. Find out answers to questions like is cancer genetic?

Reproductive Genetics

Genome Medical offers reproductive genetic counseling, genetic test recommendations and long-term reproductive health planning to women and couples starting a family.

Pediatric Genetics

What is Genetic Testing?

What is Genetic Counseling?

Genetics 101

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Hereditary Breast And Ovarian Cancer Syndrome

In some families, many women develop breast cancer and/or ovarian cancer. Often these cancers are found in women who are younger than the usual age these cancers are found, and some women might have more than one cancer . This is known as Hereditary Breast and Ovarian Cancer syndrome .

Most often, HBOC is caused by an inherited mutation in either the BRCA1 or BRCA2 gene.

The risk of breast and ovarian cancer is very high in women with mutations in either BRCA1 or BRCA2, but it tends to be higher with BRCA1 mutations. Along with breast and ovarian cancer, this syndrome can also lead to fallopian tube cancer, primary peritoneal cancer, male breast cancer, pancreatic cancer, and prostate cancer, as well as some others. Male breast cancer, pancreatic cancer, and prostate cancer can be seen with mutations in either gene, but are more common in people with BRCA2 mutations. In the US, mutations in the BRCA genes are more common in people of Ashkenazi Jewish descent than in the general population.

Because breast cancer is rare in men, men with this cancer are often offered genetic counseling and testing for BRCA mutations. Although having a mutation is less likely to affect a mans future health than it is a womans, it can affect his risk of some cancers, such as prostate and pancreatic cancer. It can also be helpful for a mans close relatives to know that he has a mutation and that they might be at risk.

Inherited Genes And Cancer Types

  • Most cancers are not linked to inherited faulty genes.

  • If you have an inherited faulty gene it increases your risk of developing certain types of cancer.

  • Some faulty genes increase the risk of more than one cancer type.

  • Faulty BRCA1 and BRCA2 genes increase the risk of developing breast, ovarian, pancreatic and prostate cancer.

Most cancers are not linked to inherited faulty genes . Only around 5 in every 100 cancers diagnosed are linked to an inherited faulty gene.

This information is aboutsome of the inherited faulty genes that can increase your risk of developing cancer. Faulty genes are also called gene mutations.

Its important to remember that these conditions are rare. Most cancers develop because of a combination of chance and our environment, not because we have inherited a cancer gene fault. Talk to your GP if you have a strong family history of cancer. Or if you think you could have inherited any of these faulty genes.

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What Are Brca1 And Brca2

BRCA1 and BRCA2 are genes that produce proteins that help repair damaged DNA. Everyone has two copies of each of these genesone copy inherited from each parent. BRCA1 and BRCA2 are sometimes called tumor suppressor genes because when they have certain changes, called harmful variants , cancer can develop.

People who inherit harmful variants in one of these genes have increased risks of several cancersmost notably breast and ovarian cancer, but also several additional types of cancer. People who have inherited a harmful variant in BRCA1 and BRCA2 also tend to develop cancer at younger ages than people who do not have such a variant.

A harmful variant in BRCA1 or BRCA2 can be inherited from either parent. Each child of a parent who carries any mutation in one of these genes has a 50% chance of inheriting the mutation. Inherited mutationsalso called germline mutations or variantsare present from birth in all cells in the body.

Even if someone has inherited a harmful variant in BRCA1 or BRCA2 from one parent, they would have inherited a normal copy of that gene from the other parent . But the normal copy can be lost or change in some cells in the body during that persons lifetime. Such a change is called a somatic alteration. Cells that dont have any functioning BRCA1 or BRCA2 proteins can grow out of control and become cancer.

What Are The Benefits Of Genetic Testing For Brca1 And Brca2 Variants

Mutations (Updated)

There can be benefits to genetic testing, regardless of whether a person receives a positive or a negative result.

The potential benefits of a true negative result include a sense of relief regarding the future risk of cancer, learning that one’s children are not at risk of inheriting the family’s cancer susceptibility, and the possibility that special check-ups, tests, or risk-reducing surgeries may not be needed.

A positive test result may allow people to make informed decisions about their future health care, including taking steps to reduce their cancer risk.

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Generation And Assessment Of Nomogram

According to results of the univariate Cox regression and the multivariate Cox , we considered patients age, tumor T stage, and risk score as independent risk factors with a prognostic value and generated a nomogram with these independent risk factors in colon cancer . The AUC of the nomogram for 1-, 3-, and 5-year OS was all > 0.780 in the TCGA cohort . Similarly, the calibration plots of the nomogram for 1-, 3-, and 5-year OS were consistent with the predictions .

Fig. 7

Generation and assessment of Nomogram. A, B Identifying independent risk factors of clinical characteristics for worse OS by univariate and multivariate Cox regression. C Nomogram based on age, tumor T stage, and risk scores. D The ROC curves for 1-, 3- and 5-year OS of colon cancer patients in the nomogram. E The calibration curves for 1-, 3- and 5-year OS

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