Genetic disorders can be a difficult topic to talk about when it is not fully understood. Genetic disorders are also something that can be unpredictable and can change people's lives drastically. There are ranges of disorders going from physical to mental deficiencies, but all have lasting impacts on the people around them. As a parent, would you want to know if your child is going to have a genetic disorder? Would it impact your decision to keep the pregnancy or not? These are difficult questions that are brought about by genetic disorders and testing for them.
With increases in modern medicine and technology, genetic diseases are able to be detected with more efficiency than ever before. Common genetic disorders that are tested for are Trisomy 21, Trisomy 18, and Trisomy 13. These disorders are commonly known as Down Syndrome, Edwards Syndrome, and Patau Syndrome respectively. A karyotype is shown below for an individual with Trisomy 21.
Image of a karyotype that shows Trisomy 21.
Being able to detect for these disorders makes it so parents are able to be more informed on the condition of their baby. This testing also makes it so parents are able to plan for the future when it comes to having more children or not. Overall, prenatal genetic testing is something that is beneficial by allowing parents to make informed decisions.
Advancements in Genetic testing
Prenatal genetic testing is something that has been around for many years. It allows scientists and physicians to understand and detect any genetic diseases that newborns may have during fetal development. New methods of prenatal testing have been created in recent years to increase detection rates and lower false positive rates. This type of testing is called Prenatal cell free DNA genetic testing.
What is prenatal cell free DNA genetic testing?
Prenatal cell free DNA genetic testing was discovered in 1997 and these tests look directly into the fetal chromosomes to look for abnormalities. This means that any increases or decreases in the number of chromosomes, known as aneuploidy, that the fetus has will be detected through this test. Prenatal cell free DNA testing has been implemented more over the years as a replacement to the Quad Test which was previously used.
The implementation of the cell free DNA testing relies heavily on its ability to be more effective than previous methods. Efficiency is demonstrated by detection rates and false positive rates. Studies have been done to look at these differences and the overall result is that the cell free DNA testing has higher detection rates and lower false positive rates. Higher detection rates mean that of the people tested, positive results are indicated by the test at a higher percentage. Lower false positive rates are important because this ensures more trust in the testing as well as encourages more people to get prenatal testing done. Both of these factors are very important when it comes to choosing to have genetic testing done during pregnancy or not.
Why is testing important?
There are many forms of prenatal testing that are required by OBGYNs such as ultrasounds. Genetic tests are additions tests that are available and can be preformed to give additional information about the pregnancy and the condition of the mother and baby. Although these tests are optional, they can be recommended by physicians based on the type of pregnancy. It is also important to remember that these tests are not diagnostic tests but screening tests. This means that the physician will look for abnormalities in the chromosome number of the fetus but that does not diagnose a certain genetic disorder but instead detects for it. At this point, it raises the question of why parents would not choose to have prenatal cell free DNA genetic testing done. The simple answer is termination of the pregnancy.
Concerns
As with any other medical practice there are concerns and risks. When prenatal tests are run there is a chance that the results are positive and that the fetus is diagnosed with a physical or mental disorder. With the implementation of these tests, positive diagnoses can then lead to increases in pregnancy terminations. With this being said, prenatal genetic testing is still beneficial to patients in order to help plan for the future. Taking away the ability to get tested is more detrimental to society than the increase in the number of pregnancy terminations.
This infographic explains the difference between the Quad test and the Cell free DNA genetic testing, as well as the detection rates for both types of tests.
The reality is that prenatal genetic testing can be scary and unnerving for parents. Most people do not hope for these to be a positive result on the tests. No one likes leaving questions unanswered. We take comfort in knowing. In the world today, there are so many advancements in technology, especially medically, that are able to help answers those questions. Why wouldn't we take the chance to be as informed as possible? Prenatal genetic testing is one way that questions can be answered. So in the end, why not?
Sources:
(1) Controversies in implementing non‐invasive prenatal testing ... (n.d.). https://obgyn.onlinelibrary.wiley.com/doi/full/10.1111/aogs.14351
(2) Grace, M. R., Hardisty, E., Dotters-Katz, S. K., Vora, N. L., & Kuller, J. A. (2016, August). Cell-free DNA screening: Complexities and challenges of clinical implementation. Obstetrical & gynecological survey. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548289/#:~:text=In%201997%2C%20researchers%20identified%20what,samples%20collected%20from%20pregnant%20patients.
(3) Karyotype. Genome.gov. (n.d.). https://www.genome.gov/genetics-glossary/Karyotype
(4) professional, C. C. medical. (n.d.-a). Pregnancy genetic testing: What it is, options, benefits & risks. Cleveland Clinic. https://my.clevelandclinic.org/health/diagnostics/24136-pregnancy-genetic-testing
(5) professional, C. C. medical. (n.d.-b). Quad Marker Screen: Purpose, procedure & results. Cleveland Clinic. https://my.clevelandclinic.org/health/diagnostics/4698-pregnancy-quad-marker-screen
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