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Genetic and Biological Nature
Down syndrome refers to the genetic condition under which an individual has 47 chromosomes instead of the accepted 46. The major cause of the syndrome is associated with the existence of extra copy of the 21st chromosome. This kind of Down syndrome is referred to Trisomy 21. The presence of extra chromosome leads to pathology of brain activity.
From a biological point of view, Down syndrome is considered the most frequent reason for human birth defects. However, there is no evident connection between parent’s activities before and during pregnancy and form of Down syndrome (U.S. National Library of Medicine n. p.). Any physical activity that a future mother can perform cannot influence the development of the disease.
Despite this, the probability of the emergence of Down syndrome is highly associated with the maternal age, particularly with teenage pregnancy. The occurrence of the deviation is also possible for the pregnant of older age. Consequently, genetic counseling should play a decisive role in defining the causes of Down syndrome.
Types of Tests Identifying Down Syndrome
There exist a great number of prenatal tests that can help to identify the presence of Down syndrome during pregnancy. They involve triple screen test, MSAFP test, cordocentesis/PUBS, and amniocentesis, first trimester screen, chorionic villus sampling, and the Quad test.
By means of triple screen test, it is possible to identify a maternal bond between mother and fetus (American Pregnancy Association, n. p.). The test also looks for such specific substances as Estriol, human chorionic gonadotropin (hCG), and alpha-fetoprotein (AFP). The test is a non-invasive procedure that is carried by means of blood test with low risk for a developing baby.
The triple screen test serves to identify Down syndrome in cases the level of AFP is low and the levels of hGG and estriol exceed the norm. The triple screen test is a safe procedure and no health risk is associated with it. Similar effect is produced by the Quad Test.
The Maternal Serum Alpha-Fetoprotein Screening (MSAFP) is carried out during the second trimester an it is also known as Alpha-Fetoprotein Test (AFP). The procedure allows to examine the level of AFP during pregnancy. It is performed as a part of triple screen test.
MSAFP identifies alpha-fetoprotein, which is found in amniotic fluid and fetal serum. The test does not pose any threats to health, except for the discomfort that a patient might feel during blood drawing.
Cordocentesis, also known as Percutaneous Umbilical Cord Blood Sampling (PUBS), examines fetus blood to identity fetal pathologies. The test is carried out by means of ultrasound that determines the location of umbilical cord’s insertion into the placenta.
The test can detect chromosome pathologies, such as Down syndrome and define any malformations of the fetus. Although, cordocentesis is recognized as a safe procedure, there is a potential risk of miscarriage that might occur one or two times for every hundred procedures.
Amniocentesis test is often chosen by parents who have genetic or inherited concerns and is used to predict if there are specific abnormalities. While carrying the procedures, the health professionals resort to ultrasound as a guide to define the safe needle location in the amniotic sac.
Just like PUBS, the amniocentesis test is used to discover chromosome abnormalities and genetic disorders, among which Trisomy 21 is the most common genetic pathology. The procedure can pose serious threats to health of a mother and a fetus.
The women can also take a test that combines both an ultrasound evaluation and a maternal blood test to detect risk for various chromosomal abnormalities, including Trisomy 21 and Trisomy 18. There are no serious risks and side effects linked to the First Trimester screen, except for the discomfort caused by drawing blood.
Parents should be ready for the probability for receiving abnormal results, but further testing can still define that the future baby does not have any pathology.
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Chorionic Villus Sampling (CVS) implies removal of chorionic villi cells of the placenta at the point of its attachment to the uterine wall. The procedure opens access to DNA of a potential father to compare it with the DNA of a future baby. The test also defines Down Syndrom by detecting chromosome abnormalities. No associated risk relate to this procedure.
In conclusion, because Down Syndrom has a genetic and biologic nature, the above-described tests can be efficient in detecting the genetic abnormalities. In particular, the test can also define different reasons and nature of the genetic pathology.
American Pregnancy Association. Prenatal Testing. 2012. Web.
U.S. National Library of Medicine. “Down Syndrome”. PubMed Health. 2012. Web.