What is a prenatal cell-free DNA (cfDNA) screening?
Prenatal cell-free DNA (cfDNA) screening is a blood test for pregnant women. During pregnancy, some of an unborn baby's DNA circulates in the mother's bloodstream. A cfDNA screening checks this DNA to find out if the baby is more likely to have Down syndrome or another disorder caused by a trisomy.
A trisomy is a disorder of the chromosomes. Chromosomes are the parts of your cells that contain your genes. Genes are parts of DNA passed down from your mother and father. They carry information that determines your unique traits, such as height and eye color.
People normally have 46 chromosomes, divided into 23 pairs, in each cell.
If one of these pairs has an extra copy of a chromosome, it's called a trisomy. A trisomy causes changes in the way the body and brain develop.
In Down syndrome, there is an extra copy of chromosome 21. This is also known as trisomy 21. Down syndrome is the most common chromosome disorder in the United States.
Other trisomy disorders include Edwards syndrome (trisomy 18), where there is an extra copy of chromosome 18, and Patau syndrome (trisomy 13), where there is an extra copy of chromosome 13. These disorders are rare but more serious than Down syndrome. Most babies with trisomy 18 or trisomy 13 die within the first year of life.
A cfDNA screening has very little risk to you and your baby, but it can't tell you for sure whether your baby has a chromosome disorder. Your health care provider will need to order other tests to confirm or rule out a diagnosis.
Other names: cell-free fetal DNA, cffDNA, non-invasive prenatal test, NIPT
