Key News in Family Medicine February 13, 2019 (10 of 13)

According to the Centers for Disease Control and Prevention, Down syndrome is the most common conbad anomaly; it occurs once in 700. However, traditional non-invasive prenatal testing for the disease is unreliable or carries risks to the mother and the fetus. Researchers have developed a novel sensitive biosensor that could potentially be used to detect Fetal Down Syndrome DNA in the blood of pregnant women. They report their results in the ACS journal Nano Letters.

Characterized by varying degrees of intellectual and developmental problems, Down syndrome is due to the presence of an extra copy of chromosome 21. To screen for this condition, pregnant women may undergo ultrasound or indirect biomarker testing blood, but the misdiagnosis rates are high. Amniocentesis, in which doctors insert a needle into the uterus to collect amniotic fluid, provides a definitive diagnosis, but the procedure poses risks for both the pregnant woman and the fetus. The emerging method of whole genome sequencing is very accurate, but it is a slow and expensive process. Zhiyong Zhang and her colleagues wanted to develop a rapid, sensitive and cost-effective test to detect high levels of chromosome 21 DNA in the blood of pregnant women.

The researchers used biosensor chips with field effect transistors based on a single layer of molybdenum disulfide. They attached nanoparticles of gold to the surface. On the nanoparticles, they immobilized probe DNA sequences capable of recognizing a specific chromosome 21 sequence. When the team added chromosome 21 DNA fragments to the sensor, they linked to the probes, which caused a drop in the electrical current of the device. The biosensor could detect DNA concentrations as low as 0.1 fM / L, which is much more sensitive than other field-effect transistor DNA sensors. The researchers say that the test could possibly be used to compare the levels of chromosome 21 DNA in the blood with those of another chromosome, such as 13, to determine if there are any copies additional suggesting that a fetus is suffering from Down syndrome.