Edwards syndrome: what are the characteristics of this chromosomal abnormality?
Pregnancy brings about many physical and psychological changes in a woman. Pregnant women, who are carrying their baby, should take care of their own health and that of the baby by performing all medical checkups and seeing their gynecologist to choose together which prenatal test to perform, such as the fetal DNA test.
The gynecologist knows the health status of each woman, so she is able to indicate which examinations are most appropriate to perform. Screening and prenatal diagnosis tests can be performed during pregnancy. Screening examinations are very important to detect the percentage of risk that the fetus may be affected by chromosomal abnormalities.
These include the trisomies, namely Edwards Syndrome, Down Syndrome and Patau Syndrome. The incidence rate of these chromosome number 1-related abnormalities increases if the pregnant woman is older than 35 years old.
What’s Edwards Syndrome
The Edwards syndrome, also called Trisomy 18, which occurs in about 1 in 8 thousand newborns 2 , is the second most common chromosomal abnormality, after Down syndrome.
It is a chromosomal abnormality with an ominous prognosis. Survival does not go beyond the first few weeks, although in some cases it exceeds the first year of age 3 . Conception, in most cases, ends in miscarriage 3 .
Clinically, the child has certain features, such as facial dysmorphia, small mouth, dysmorphic ear pinnae, narrowed eyelid, mental retardation and cardiac abnormalities 3 .
Prenatal screening tests are essential to be able to detect the possible presence of a chromosomal abnormality such as Trisomy 18. Expectant mothers can choose the prenatal screening test that best suits their needs, taking into account gestational period, reliability rate, and when information about fetal health is desired.
DNA testing when it can be done
From the 10th week of pregnancy, fetal DNA testing can be performed, which consists of a simple blood draw. It is a state-of-the-art test that analyzes fetal DNA fragments in maternal blood to detect the possible presence of the major trisomies, several chromosomal abnormalities and major microdeletions.
Between 11 and 13 weeks, the Bi Test can be performed, along with an ultrasound examination called nuchal translucency, with 85 percent reliability. The Tri Test, on the other hand, can be performed between the 15th and 17th weeks of pregnancy and achieves a reliability rate of about 60 percent.