An accurate screening method for Down

Recently, the University of California, San Francisco (UCSF) researchers have proposed a new method, between 10-14 weeks of pregnancy blood test, a comparable standard non-invasive screening techniques to more effectively diagnose Down syndrome and the other two less common chromosomal abnormalities. The study followed nearly 16,000 pregnant women, pregnancy outcomes, using cell-free DNA blood test correctly identified all fetuses with Down's syndrome (38), Down syndrome is a cognitive disorder associated with disease, increase the risk of several diseases. Researchers by neonatal screening, prenatal or postnatal genetic analysis confirmed these diagnostic results. The present study focuses on the float in maternal blood fraction of fetal DNA. With a molecular "Copy" technique (known as polymerase chain reaction) amplification of DNA and sequenced, so that the relative amount of DNA can be compared between each chromosome.

When the same acceptance criteria for screening pregnant women, the 38 fetuses among them 30 are marked with Down syndrome. Including blood screening for chromosomal defects related hormones and proteins were identified, along with the back of the neck in neck pleated ultrasonic liquid, if one has Down syndrome implies excessive. The average age of the pregnant woman is 30 years old, about a quarter more than 35 years of age, these women have traditionally been considered to have a high risk and invasive prenatal testing for them, such as amniocentesis. The incidence of Down syndrome misdiagnosis relatively low. The standard screening method is recognized can lead to a lot of false positives, the use of cell-free DNA tool is much less false positives. With this new method only have nine false positives, but with 854 times the standard screening rule of false positives. Meanwhile, the researchers found the Recombinant human Apolipoprotein C-III http://www.cusabio.com/Recombinant-Protein/Recombinant-human-Apolipoprotein-C-III-11030819.html in the study population, no DNA screening accuracy is still more than the other standard screening methods. In 10 cases of trisomy 18 (also known as Edwards syndrome), a cell-free DNA techniques to determine the nine cases, there is a false positive. Using standard screening methods were identified eight cases, there are 49 false positives. For Trisomy 13 (also known as trisomy), cell-free DNA testing to identify the two cases, and mark a false positive, while the standard screening method identified only one case, marking 28 false positives.

Although these findings suggest that cell-free DNA screening is superior to standard procedures, but the study highlights the need to pay attention. "Standard Filter" to determine a wide range of abnormal cell-free DNA detection screening for less. Down syndrome cases including more than 50 percent of aneuploidy (abnormal number of chromosomes caused by). Furthermore, there is an unusually high number of aneuploidy in 488 pregnant women, their plasma samples failed because of an insufficient number of fetal DNA contained or incalculable, or sequencing to detect failure or high variance, which will lead to the results difficult to interpret . Approximately 2.7% of these fetuses fetal chromosomal abnormalities, including those with abnormal cell-free DNA techniques have not been found. This is significantly higher than the overall prevalence of 0.4 group. Because the study included the failure queue, the detection rate of cell-free DNA screening tools are low.