Researchers have developed a new non-invasive blood test that can diagnose Down syndrome in unborn babies more accurately and much earlier than the tests that are currently available.
Down syndrome is a condition where the baby possesses an extra chromosome, apart from the regular 46 chromosomes. This additional chromosome affects the normal development of the body and brain. According to Centers for Disease Control and Prevention (CDC), nearly 6,000 babies in the country are affected by the disorder. Children with Down syndrome experience both physical problems and intellectual disabilities. According to the CDC, these children will benefit from therapies such as speech, occupational and physical therapy.
Though tests are currently available to detect the genetic disorder, they can be carried out only between the 11th and 13th weeks of pregnancy. These tests include both non-invasive methods like ultrasound screen and hormonal analysis of the blood, and invasive tests like collecting cell samples from the placenta and amniocentesis (chorionic villus sampling). However, according to experts, the invasive methods pose a risk to the pregnancy and can lead to miscarriages.
Researchers from King's College London based their findings on previous studies that have highlighted the sensitive nature of a fetal cell free (cf) DNA, present in mother's blood.
Kypros Nicolaides and colleagues confirmed accuracy of the cfDNA testing on more than 1,000 pregnant women at 10 weeks of pregnancy. They found that the blood test was able to detect trisomies 21, 18, and 13 more accurately than the tests currently available, with the cfDNA testing providing wrong results only 0.1 percent of the time, compared to 3.4 percent by the tests done at 12 weeks.
According to the researchers, pregnant women, who are at higher risks, can be easily detected through this fetal DNA analysis and can be further confirmed with an ultrasound scan at 12 weeks. It can also eliminate the need of spending huge amounts on invasive methods, and can avoid around 300 miscarriages caused by invasive tests every year, The Telegraph reported.
"This study has shown that the main advantage of cfDNA testing, compared with the combined test, is the substantial reduction in false positive rate. Another major advantage of cfDNA testing is the reporting of results as very high or very low risk, which makes it easier for parents to decide in favour of or against invasive testing," Nicolaides said in a University news release.
The results of the study have been reported in the journal Ultrasound in Obstetrics & Gynecology.
