With the advancement of new DNA analysis technologies, prenatal screening tests are also refining. Today, just a drop of maternal blood to check if the fetus suffers from Down's syndrome or other genetic abnormalities. Instead, other tests should be done before conceiving and identifying possible mutations that are dangerous to the offspring.
What are the genetic tests that are changing the world of prenatal screening?
Free circulating fetal DNA testing
Maternal blood also contains a certain amount of cells from the fetus. By recovering these it is possible to analyze its DNA in the first weeks of gestation. These tests are safe for both mom and baby and have a high level of reliability.
Free fetal DNA tests are used to identify common chromosomal abnormalities, such as Down's syndrome. They are especially recommended for older couples and give a much earlier response to traditional tests. Nevertheless, in case of a positive result, it is advisable to use the amniocentesis, too.
Widened bearer screening
In the past, the history was the only way to test for the presence of genetic diseases in the family. Even today it is a key element in deciding whether and which genetic tests to perform. The tests also focused on a particular set of abnormalities. This made it impossible to identify any variants linked to different pathologies.
Extended bearer screening is a wide-ranging genetic test that identifies variants of over 100 diseases. To do just that, you need a blood sample for each couple member. If the same anomaly emerges in both, then there is the risk that the offspring will manifest the disease. It is estimated that this is about 5% of the couples who undergo screening.
Sequencing the Exam
In some rare cases, ultrasonography reveals malformations in the fetus that can not be diagnosed with traditional genetic testing. Sequencing of the next generation is focused on developmental and health related genes. For this reason it is also useful for assessing the health of the fetus and can provide a diagnosis in 30% of the cases.
Unlike invasive prenatal diagnosis, this requires amniocentesis. Even though it has a minimal risk, it is possible to intervene immediately at birth.