Overview
Genetic testing involves studying the chemical language, or DNA, that controls your body’s functions. Genetic testing can reveal genetic anomalies that may result in illness or disease.
While genetic testing can be used to provide important medical information, it also has limitations. Just because someone is genetically predisposed to develop a specific disease, it does not always mean they will develop that disease. On the one hand, negative results don’t necessarily mean that you won’t already have the disorder.
Talking to your doctor about what you would do with the results of genetic screening is an important first step in the process.
DNA sequencing.
When genetic testing has failed to provide a clear diagnosis, but a genetic etiology is still suspected, some facilities offer genome sequencing—a process for analyzing the DNA of your blood.
Everyone has a unique genome, which includes the DNA in all of their genetic material. This genetic testing can potentially help identify genetic features of your health. Most of this testing is done by focusing on only the protein-encoding exome.
Why it’s done.
Genetic tests are used for various purposes including determining risk, screening for diseases, and sometimes prescribing treatment. The types of genetic testing done for different reasons
Diagnostic tests: If a person has symptoms of a disease caused by genetically caused mutations, genetic testing reveals whether the person is genetically predisposed to the disorder. Genetic testing is critical in confirming diagnoses of cystic fibrosis or inheritable diseases like Huntington’s disease.
Screening and diagnostic testing: If you or a family member has a genetic condition, genetic testing may show a risk of early onset of a condition. This type of test may be useful for determining whether someone is at risk of developing certain types of cancer.
Environmental testing: If you already have a family history of a genetic disorder or you belong to a group that has a higher risk of a genetic disorder, you may want to have genetic testing before having children. Expanded carrier screening can detect genes associated with various genetic diseases and can identify if you and your partner are carriers of genetic diseases.
Pharmacogenetics If a particular health condition or disease is present, genetic testing may reveal the ideal medication and dosage that will work best.
Abortion testing: In a pregnancy test, it is possible to detect problems with the baby’s genes. Down Syndrome and Trisomy 18 (also known as Turner Syndrome) are two common genetic disorders that are tested for as part of prenatal testing. Tests that can be done to determine the blood’s markers or use of invasive testing like amniocentesis. Newer DNA testing like maternal blood tests look at babies’ DNA via their mother’s blood tests.
Newborn testing: The most utilized form of genetic testing is. In the United States, newborns are routinely tested for a variety of genetic and metabolic conditions. This type of genetic testing is important because it enables effective care and treatment to begin right away when there is an inherited disorder.
Preimplantation testing: Also called Preimplantation Genetic Testing; this alternative reproductive method may be used in situations where in vitro fertilization is not possible. The embryos are tested for chromosomal anomalies. Conceived embryos are implanted in the uterus with the hope of resulting in a pregnancy.
Risks:
Determining someone’s genome has little physical risk. Body fluid tests have very little risk.
How You Prepare:
When considering genetic testing, collect as much medical history about your family as possible. Then, examine your personal and family medical history with a genetic counselor to better understand your genetic risks. Ask questions and bring up issues with the testing methods being proposed. We also cover what you would do, depending on the test results.
If you plan on testing for a genetic disorder that runs in your family, you should notify your family members of the potential testing results. Before undergoing testing, ask family members how they would respond to the results and how it would affect them.
What you can Expect:
In order for us to review your application, we will need to have a sample of your blood, skin, amniotic fluid or other tissue sent in for analysis.
Blood test: A member of your health care team draws a blood sample from your arm using a needle. The blood sample is taken by pricking your baby’s heel for newborn testing.
Stool swab. For some evaluations, people take a swab sample from inside their mouth to do genetic testing.
Amnio: In this prenatal genetic test, a small membrane is removed from your abdomen and replaced with a thin needle through which amniotic fluid is removed for testing.
Chorionic villus sampling: For this pregnancy test, the doctor extracts a sample from a baby’s umbilical cord. For some women, the sample can be obtained through a tube (catheter) inserted in the vagina or through the abdomen and uterus through a thin needle.
Results:
The length of time a genetic test takes will change depending on the type of test ordered, and the provider.
Positive Results:
A positive genetic test means the change that was being tested for was found. The steps that you will take after receiving a positive genetic test result will vary depending on the reason for the testing.
If the purpose is to:
To make a diagnosis, a positive test result will help in determining the right treatment, and management plan.
Your doctor can determine if you carry a gene that could cause a disease in your child, and if so, what your child’s risk of developing the disease is. The results of the genetic testing can be used to inform decisions on family planning.
Knowing your positive test doesn’t necessarily mean that you will ultimately get the disorder. If you have an aggressive form of breast cancer, you’re at high risk of developing it in your lifetime, but you’re not guaranteed to get it. However, in certain diseases, like Huntington’s, having a mutated gene provides a higher risk of developing the disease.
Talk to your doctor about an accurate interpretation of a test result. You can improve your lifestyle in ways that are known to help prevent a disease, even if you have a genetic predisposition for the disease. Results may also help you make treatment decisions, family planning decisions, career decisions and insurance coverage decisions.
Negative Results:
Failure by the test to detect a mutated gene is reassuring but does not mean that the person doesn’t have the disorder. The accuracy of genetic tests varies based on the purpose of the test and whether it determines whether someone has a gene mutation that they already have.
Even if you never have the disease, you could still be at risk of getting it in the future. The majority of females who develop breast cancer do not have a genetic predisposition to breast cancer (BRCA1 or BRCA2). Genetic testing may not always identify the genetic defects.
Inconclusive Results:
An incidental test of a gene may not provide useful information about that gene. Genes vary precisely, and sometimes these differences do not impact your health. It is sometimes difficult to distinguish the gene that causes a disease from the gene that caused a harmless variation. The changes are newly emerging variants that could seem important. In cases where follow-up testing is not sufficient, periodic reviews of the gene may be necessary.
Genetic counselling:
Even if you receive a negative result, talk to a genetic specialist or genetic counselor at ANRA about any health-related questions or concerns you may have. This will help you to better understand the results and how they may apply to you.