Genetic disorders - Family History Matters

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Your family history is so much more than where your ancestors came from. Genetic testingis more than figuring out you’re half German and a quarter Irish. Genetic testing provides insight into your genetic history, telling a story of your chromosomes and what could be hidden inside them. Visit: https://www.genomesmart.com/geno-blog/genetic-disorders---family-history-matters

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Genetic disorders - Family History Matters Your family history is so much more than where your ancestors came from. Genetic testing is more than figuring out you’re half German and a quarter Irish. Genetic testing provides insight into your genetic history telling a story of your chromosomes and what could be hidden inside them. The fact that you have blue eyes and sandy-blond hair and are five-feet tall like your mother is all thanks to your inherited makeup. But your family history also gives valuable insight into your health and more importantly your risk for certain diseases or conditions. Knowing what you could be at risk for also benefits your family’s health and any future children you may have. Certain cancers and diseases have a genetic component meaning if your parents have a genetic condition you are at risk for inheriting it as well. If your children or siblings have a disease or condition that may be genetically linked it’s possible you could be at risk for the same condition as well. First of all not all genetically inherited diseases will be passed down automatically. And second with the advances in scientific research it is now possible to find out if you are at risk for certain conditions and this technology is becoming easier to obtain. Genetic testing results can be confusing to interpret and it is always a good idea to work with a genetic counselor to help you understand your results and risks for certain genetically inherited cancers or diseases. The following is an overview of why your family history should matter and what your options are for screening for genetic disorders. Can cancer be inherited Most cancers are not actually inherited. In most cases a genetic mutation or change starts in one cell as it’s dividing and that mutation is present in every new cell that comes from that one. This is how cancer grows and divides within the body. The mutation isn’t present in egg or sperm cells so it’s not passed on from parent to child. This is the most common way cancer occurs in people. However there are some cancers that do have an inherited link. About 5-10 percent of cancers can come from a genetic mutation that was passed from parent to child according to the American Cancer Society. In fact when there is a distinct

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pattern of cancer in certain families this grouping is known as a family cancer syndrome. Family cancer syndrome Lynch syndrome is a type of family cancer syndrome. This is an inherited disorder that increases a person’s risks for certain cancers. Otherwise known as hereditary non-polyposis colorectal cancer or HNPCC Lynch syndrome increases a person’s risk of cancer in their lifetime most commonly colorectal and endometrial cancers as well as stomach small bowel urinary and brain. Lynch syndrome is caused by a mutation in any of the several mismatch repair genes — MLH1 MSH2 MSH6 PMS1 and PMS2. Hereditary breast and ovarian cancer HBOC syndrome is another example of a family cancer syndrome and the genetic mutation most people are aware of is that in the BRCA1 and BRCA2 genes. Mutations in one or both of these genes increase a person’s risk for developing breast and to a lesser degree ovarian cancer. 46-71 percent of women who have HBOC syndrome are at a higher risk of developing cancer than those who don’t have the syndrome. Li-Fraumeni syndrome is a rarer form of family cancer and can lead to types of cancer such as leukemia and sarcomas. People with this type of cancer syndrome also appear to have a higher risk of cancer after receiving radiation therapy. If you know you have Li-Fraumeni it’s best to avoid radiation whenever possible. Li- Fraumeni syndrome is caused by mutations in the tumor suppressor gene TP53. It is important to understand that not everyone with these gene mutations for family cancer syndrome will develop cancer. It simply means these mutations can be passed down from parent to child and puts you at an increased risk over the general population. It means with these mutations you could get certain cancers earlier in age than what is considered average and that cancer could be more aggressive than average.

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Are you at risk for a genetic disorder Your ethnicity Certain ethnicities are at a higher risk of having certain genetic disorders than others. For instance 1 in 40 women of Ashkenazi Jewish descent carries the BRCA gene mutation. African American men are at a higher risk for prostate cancer than non-white Hispanics. African Americans and people of Middle Eastern Asian and Mediterranean descent are at ahigher risk of sickle cell disease. Your ethnicity can determine your risk of inheriting particular disorders but that’s not always accurate. By this we mean that anyone could be at risk for a genetic condition and certain genetic disorders are not solely linked to a person’s ethnic background. More and more women who are pregnant or planning to become pregnant are being offered genetic screening tests regardless of their background. Lifestyle Diseases There are other conditions apart from cancer and serious diseases that can be inherited from your family. Certain lifestyle disease that could be caused by how you live your life can also have a genetic component. Heart disease could be linked to family history. A grouping of genes on chromosome 6 has been linked to Type 1 diabetes. Inheriting these genetic abnormalities can put you at greater risk for developing these diseases even if you take preventative measures such as exercise not smoking and eating healthy. Research is finding genetics and your family history plays a bigger role than once thought. Being a carrier of a genetic disorder Even if you do not pass down a genetic disorder itself you can still be a carrier. Carriers of genetic disorders have a genetic mutation in one of their two copies of a gene. It means you usually won’t show any signs of the disease but your future children will have a 50 percent chance of inheriting that genetic mutation as well. If your partner also is a carrier your child could inherit the mutated copies from both of you and therefore has a 25 percent chance of inheriting the actual disease.

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Genetic screenings for pregnancy There are a variety of testing methods available when it comes to screening for certain genetic disorders and understanding your risks of passing along a genetic condition to your child. These tests are usually done before and during pregnancy. Carrier screening Carrier screening can be done before during or after pregnancy but in order to prevent a future child from inheriting a certain condition screening is most beneficial before pregnancy begins. It is usually done by obtaining a blood sample from both parents and this can test for mutations that cause a variety of genetic conditions such as cystic fibrosis or sickle cell disease. Being a carrier of a genetic condition is not as concerning because in order for your child to have a recessively inherited disorder they would need to inherit both copies of a mutated gene one from each parent. Expanded carrier screening allows testing to be done for hundreds of genetic mutations that could cause disease. Preimplantation genetic diagnosis Thanks in part to advances in reproductive care it’s possible to perform testing on embryos to find out if their genetic material contains mutations that would put a future child at risk for certain conditions. Before any testing can begin an individual or couple will undergo thein vitro fertilization IVF process. Doctors will then take a few cells off each embryo and run genetic testing on them to see if their chromosomes contain any mutations. From there preimplantation genetic diagnosis PGD is performed. This is if you want to find out if your embryos have a certain genetic disorder that you may have passed on. For instance if you or a close family member has cystic fibrosis you have the option of having IVF with PGD testing on the embryos to see which ones carry the disease. Doctors look for genetic markers for a specific disease to see if that embryo has the disease or is a carrier for it. The unaffected embryos can then be selected and transferred back into the mother where she can be assured her future child will be free of the disease.

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If you or your partner are already pregnant there are options as well to find out if your child is at risk for certain genetic conditions. These are considered diagnostic tests and can include chorionic villus sampling CVS or amniocentesis and non- invasive prenatal screening NIPS. These tests look for abnormalities in chromosomes by either testing the fetal cells obtained through the mother’s abdomen via a needle or testing the fetal DNA that is present through the mother’s blood. What is the genetic testing process like Your decision to have testing At face value getting genetic testing seems to be an easy decision. Wouldn’t you want to know if something was concerning Don’t you want to know if you have a high risk of breast cancer because your mom and aunt have it There is a power that comes from knowledge but that knowledge also may be something you weren’t expecting. Therefore there is a lot of thought that needs to go into your decision to have genetic testing. Deciding to undergo testing is personal and it’s not right for everyone. After all once you know your results you can’t “unknow” them. This can bring on stress and anxiety as you figure out where you go from there. Likewise you may think a certain condition or cancer runs in your family and when you receive a negative result for those it can leave you feeling even more confused. It is important to spend some time deciding on whether or not you want to pursue testing and deciding which test is right for you. Sharing your results The testing process involves obtaining blood samples by a puncture in your arm. Many times insurances will cover genetic testing but it’s important to check with your specific insurance for what you would be responsible for. Testing results can take up to several weeks to come back. It is important to go over your results with a genetic counselor. They can help you interpret those results and determine if further testing is necessary. There may be

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others in your family who could benefit from genetic testing based on your own results. These family members would be your blood relatives. Your blood relatives are related to you by birth rather than by marriage. First degree relatives include a parent sibling or child. Second-degree relatives widen the circle and include grandparents aunts and uncles nieces and nephews and grandchildren. Finally third-degree relatives include cousins great-grandparents and great-grandchildren. The closer you are to another person the more genetic materials you share with them. You share more of the same genetic material with your mother or child than you do with a great aunt. our results are confidential to you and you can choose to share them with other family members. For example if you find out you have a BRCA gene mutation you can share that with your mother sister or child. They then could have their own testing to find out if they carry the BRCA mutation that would put them at higher risk of developing breast cancer. Since men with the BRCA2 mutation have an increased risk of developing prostate cancer the men in your family could benefit from knowing as well. Subsequent relatives who choose to get tested should have the same counseling since histories can differ slightly. For example if your mother went through genetic testing for her breast cancer and it was discovered she didn’t carry a BRCA mutation you would usually not need to be tested for BRCA as the mutation probably didn’t get passed on to you. A genetic counselor can help with this. Being proactive with your results Your decision to have testing Knowing you have a genetic condition passed down within your own family helps you to be proactive in managing the risk. One of the things you can do is to use the knowledge of a genetic mutation and incorporate it into your regular health care maintenance routine. If you know you have a mutation that increases your likelihood of certain cancers such as breast cancer you can talk with your doctor about having earlier and more high-tech mammograms. If you are a male with the BRCA2 gene mutation you

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may be a candidate for earlier prostate screenings. As stated above having a mutation only increases the risk of cancer not a guarantee you will get that cancer. However the benefit to early screenings is that if cancer were to occur it could be detected earlier than if you didn’t have genetic testing at all and were unaware of the mutation. This early detection can lead to earlier treatments and the goal is to prolong life expectancy and reduce complications. Sharing your results Some genetic conditions show up later in life such as Huntington’s disease. Disorders like this aren’t preventable and the knowledge of having a fatal condition can be hard to hear. Some people may be grateful to have the time to prepare and get their affairs in order. Others may regret finding out. One benefit to learning you have a condition such as Huntington’s is that you can take steps to prevent passing it on to your future children. This can be done by obtaining the testing as stated above. Other options for family-building include adoption or using a sperm or egg donor depending on which parent has the genetic condition. Limitations There are some limitations on what genetic testing can look for and its results. If you have a child you’ve adopted for instance you may not know his or her birth parents’ genetic history. Likewise you can’t have genetic testing done to see if your adopted children will inherit your genetic condition as they don’t share your genetic makeup. Another limitation to genetic testing due to family history is that not every mutation is able to be tested for. It is impossible to detect every single mutation and its potential disease it can cause. Therefore you still have the chance of having a genetic condition that hasn’t been discovered yet or one that your test didn’t or couldn’t include. Finally the information you receive is limited. You won’t be able to tell if you will get the disorder and show symptoms. You won’t know how severe the symptoms would be or how the disease will progress within you.

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Any two random people share 99.9 percent of their DNA but that 0.1 percent difference spread over the entire genome provides a large number of differences. Your family history plays an important role in determining your health and that of your family. GenomeSmart can help you decide whether you need to consider genetic testing and how to navigate the complex testing process.

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