What do DNA test results mean?

A genetic test, also known as a DNA test, is a type of medical test that determines changes in chromotypes, genes or proteins. Genetic test results can confirm or exclude genetic diseases, help identify a person at risk of development, the ability to transmit genetic disorders to the next generation, determine blood DNA. More than 1,000 DNA tests are currently in use and are still being developed.

Genetic testing plays an important role in determining the risk of developing certain diseases as well as screening for diseases and sometimes treating them. Different types of genetic tests will be performed in different specific cases such as:

• Diagnosis of the disease. If the person has symptoms of a disease that may be caused by the patient's genetics or DNA, sometimes also known as a mutation gene, genetic testing can detect if the disease is caused by a genetic mutation. For example, genetic testing can be used to confirm the diagnosis of cystic fibrosis (CF) or Huntington's disease.
• Predictive and presymptomatic tests. If a healthy person has a family history of a genetic disease, genetic testing before the person has symptoms can show how at risk of contracting that genetic disease. For example, this type of test is useful for determining the risk of certain types of colorectal cancer.
• Carrier testing. If a person has a family history of a genetic disorder – such as sickle cell anemia or cystic fibrosis – or that person belongs to a group of people at risk of a specific genetic disorder then he or she may choose to have a genetic test before having children. The substance screening test can detect genes associated with a variety of diseases, genetic mutations, and can determine if the person and their fiancé are people with the same mutation gene or genetic disease.
• Pharmacokiny. If a person has a special health condition or suffers from a certain disease, this type of genetic testing can help determine what kind of drug and dosage it is, it will be most effective and beneficial for that person.
• Pre-production testing. If the maternity is pregnant, tests can detect some type of abnormality in the fetal gene. Down syndrome and trisomy syndrome 18 are two genetic disorders that are usually pre-bio-screened. Accordingly, to detect these diseases, it is done by looking at indicators in the blood or by invasive tests such as amniotic punctures. Nowadays, blood tests from mothers are used to find free DNA from pregnancy (cffDNA – cell free fetal DNA).
• Newborn screening. This is the most common type of genetic test. In the United States, all states require babies to be tested for genetic and transgender disease abnormalities. This type of genetic test is important because if the results show that the child has disorders such as congenital incalypinal incalypilation, sickle cell disease, or phenylketonuria (PKU), then the care and treatment of the child can be done immediately.
• Pre-implantation genetic testing (PGT) is a technique used in biomedy to identify genetic abnormalities in embryos (less common than the polar body of eggs) produced through in vitro fertilization.
• DNA testing (DNA testing, DNA testing) is a type of molecular biology test through the analysis of gene data for a specific purpose such as the results of blood DNA tests, personal identification, finding lost relatives,… This somewhat special type of test is not too new in Vietnam because it has long been used in criminal science to track down perpetrators, confirm or deny a biological evidence, identify victims …

In general, DNA testing carries little physical risk for the person who needs to perform it. Specimens such as oral mucosal cell samples, blood samples, hair (root) legs (hair, antennae), nails (legs), umbilical cord … there is almost no risk. However, pre-maternity tests such as amniotic punctures or thorny biopies or spine bios (CVS ) are at risk of miscarriage.

Genetic testing may also be at risk of emotional, social, and financial damage. The person who needs to do it best should discuss all the risks and benefits of DNA testing with a doctor, medical genetics or genetic advisor before taking it.

Before performing a DNA test, gather as much information as possible about your family's medical history. Then, talk to your doctor or a genetic advisor about your and your family's medical history so that they better understand the risk of the disease and what kind of disease it is for themselves and the next generation.

If you want to get tests for genetic disorders in your family, you should consider discussing whether to do it with your family member. Having these conversations before the test can tell us how your family is feeling with the DNA test results and how the DNA test results affect them.

Not all health insurance policies pay for DNA testing. So, before doing so, check with your insurance provider to see what tests will be covered.

Depending on the type of test, a sample of the person's blood, skin, amniotic fluid or other tissue will be collected and sent to the laboratory for analysis.

• Blood samples. Medical staff will take samples using needles and take intravenous blood on the arms of the person who needs to be tested. For newborn screening tests, blood samples will be taken by injection into the baby's heel.
• Sample of oral mucosal cells. For some tests, a sample of oral mucosa is taken from the inside of the cheek of the person who needs a DNA test.
• Invasive fetal DNA testing is also known as a traditional DNA test amniotic puncture method. Samples used for testing are cells taken from amniotic fluid. This method must be supported by a specialist in order to avoid the risks affecting the fetus.
• A placenta bios or a prickly bios (CVS: Chorionic Villus Sampling) is a medical technique that takes a cell sample that is the membrane that surrounds the embryo also known as a thorn.

5.1. Positive result

If the genetic test result is positive, it means that the person has a genetic disease. The next steps after receiving a positive result will depend on the reason for the DNA test. If the purpose is:

• Diagnosing a specific disease or health condition that tests for DNA will help your doctor determine the appropriate treatment and management plan.
• Find out if you carry the pathogenic gene to transmit to your child, and if a DNA test is positive, your doctor, medical genetics, or genetic advisor can help you determine your child's risk of actually developing the disease. The test results can also provide information to consider when you and your spouse make a decision about how to have a baby later.
• Determining if the person may have a certain disease but testing positive does not necessarily mean that the person will have the disorder. For example, having a breast cancer gene (BRCA1 or BRCA2) means that the person is at increased risk for breast cancer at some point in life, but that does not mean that the person will have breast cancer for sure. However, with some other diseases, such as Huntington's disease, the mutation of the gene is sure to eventually develop.

Talk to your doctor about what a positive result means for yourself and your family. In some cases, patients may have lifestyle changes that can reduce the risk of developing the disease, even if there are genes that make them more susceptible to the disease. DNA test results can also help the person make choices related to treatment, family planning, career, and insurance.

5.2. Negative results

A negative result means that the mutation gene is not detected by testing, which can be reassuring, but it is not a 100% guarantee that the person will no longer be sick from a genetic mutation. The accuracy of DNA tests to detect mutation genes varies, depending on the conditions examined and whether the genetic mutation was previously identified in a family member.

Even without a mutable gene, that doesn't necessarily mean that the person will never get sick. For example, the majority of people with breast cancer do not have a breast cancer gene (BRCA1 or BRCA2). In addition, genetic testing may not be able to detect all genetic defects.

5.3. Unknown results

In some cases, genetic testing may not provide useful information about the gene you want to test. Everyone has variations in the gene and often these variants do not affect the health of the person. But sometimes it can be difficult to distinguish between pathogenic genes and harmless gene variants. In these situations, a follow-up test or a periodical evaluation of the gene over time will be essential for early detection of real pathogenic gene mutations later on.

Article reference source: Mayoclinic.org; ghr.nlm.nih.gov