Verifi Test – Non-invasive prenatal testing
Noninvasive prenatal testing, also known as “Verifi test”, is a genetic test that can detect chromosomal abnormalities such as Down syndrome, trisomy 18 and trisomy 13.
In this test, a blood sample is drawn from the mother, the blood is centrifuged, and the DNA is extracted from the sample. The lab can then check for the presence of chromosomal abnormalities.
The test can be performed as early as 10 weeks of pregnancy. From among the different tests, it allows the earliest identification of chromosomal abnormalities during the pregnancy.
When should I undergo the test?
The noninvasive prenatal testing can be undergone from the tenth week of pregnancy. It allows the earliest screening for birth defects from the different screening tests available.
Since it is considered an accurate test, there is no difference whether it is performed early during the pregnancy or in a later stage, and many doctors advise women in risk of chromosomal abnormalities to undergo the test.
The test is not as effective in the more advanced stages of pregnancy, since there are other tests such as CVS or amniocentesis that can provide more detailed information, depending on the stage of the pregnancy.
Who should undergo the test?
The prenatal testing is suitable for all pregnant women, but due to its high price it is usually recommended to women with a risk for chromosomal abnormalities.
Undergoing the test as early as 10 weeks allows women to know if the fetus suffers from a chromosomal abnormality at an early stage of their pregnancy, so they can plan the pregnancy accordingly.
Without non-invasive prenatal testing, the only way to detect chromosomal abnormalities is via invasive tests such as CVS (in week 11 – 13) or amniocentesis (after week 16). These tests will also give results regarding chromosomal abnormalities, but in a later stage.
The main risk factors for chromosomal abnormalities are a maternal age of 35 or older, abnormal results in nuchal translucency tests or triple screen tests (alpha-fetoprotein), abnormalities in an ultrasound test, and a family history of chromosomal abnormalities such as trisomies 21, 13 or 18.
Women with one of these risk factors are advised to take the prenatal testing according to their doctor’s instructions and the week of their pregnancy. Apart from that, the test is available to all women who wish to undergo it.
How does the test work?
In non-invasive prenatal testing, a single and simple blood test is drawn from the mother. The blood sample is sent to a laboratory where the fetal DNA is extracted – fragments of DNA that are released from the fetus into the mother’s bloodstream and can be identified with a unique biological calculation technology.
After the fetal DNA is extracted, it is analyzed in the laboratory for the different chromosomal abnormalities.
What diseases can the test detect?
The noninvasive prenatal testing identifies chromosomal abnormalities – genetic diseases that are a result of too many or too few chromosome copies. Cases of extra or missing chromosomes are also known as “aneuploidies”.
The most common chromosomal abnormality detected by the Verifi test is Down’s syndrome. Other abnormalities that can be detected are trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome).
In addition, a new version of the Verifi test can also screen sex chromosome abnormalities, such as Turner syndrome (girls with a missing x chromosome – one instead of two), and Klinefelter syndrome (boys with two x chromosomes instead of one).
Although sex chromosome abnormalities do cause certain disabilities, they usually do not cause serious diseases, such as the ones caused by trisomies 21, 18 and 13. In most cases, they do not cause intellectual disabilities or significant physical disabilities, and apart from fertility problems, people with these conditions can usually lead regular lives.
It should be noted that noninvasive prenatal testing does not screen for diseases caused by genetic mutations, but only for chromosomal abnormalities. For this reason, those at risk for genetic diseases other than the three trisomies should undergo more advanced genetic tests to isolate the relevant gene and check for mutations.
In cases of abnormalities in ultrasound tests and a suspicion of genetic diseases, the Verifi test is usually not enough on its own, and further, more thorough genetic testing is required.