A blood test will show chromosomal abnormalities of the fetus
Down's disease can be diagnosed by the mother's blood
According to a study by Kypros Nicolaides from King's College London, when studying about a thousand British women, DNA testing showed a risk of developing trisomy 21 (Down syndrome), 18 (Edwards syndrome) or 13 (Patau syndrome) of less than 0.01%. In the other 11 cases, the risk for trisomy 21 was more than 99%, and for trisomy 18 and 13 – less than 0.01%. In five cases, the risk of trisomy 18 and 13 was 99 and 34%, respectively.
The risks were assessed by examining maternal blood serum for the amount of pregnancy-associated protein A (RARP-A) in combination with beta-chorionic gonadotropin at 10 weeks of pregnancy. Chorionic villi were examined in 16 out of 17 cases, and in 15 of them cytogenetic analysis confirmed fetal abnormalities.
Positive data were obtained on the high sensitivity and specificity of a non-invasive method for detecting fetal chromosomal abnormalities using cell-free fetal DNA (cff-DNA diagnostics) obtained from the blood of a pregnant woman. The method is a serious alternative to existing methods of prenatal diagnosis of congenital fetal pathologies.
Laboratory tests conducted in thousands of patients using these two methods at 10 weeks of pregnancy had a lower false positive result than the combined test that was conducted between 11 and 13 weeks of pregnancy using ultrasound and blood tests for maternal hormones. Both methods, and the study of fetal DNA and the combined test revealed the presence of trisomies, but the frequency of obtaining a false positive result was 0.1 and 3.4%, respectively.
The average age of the patients was 36.7 years (from 20.4 to 48.8), the average weight was 62.3 kg. Pregnancy was spontaneous in 861 cases (85.7%), after in vitro fertilization in 117 cases (11.6%) and after taking ovulation-stimulating drugs in 27 cases (2.7%).
Thus, the researchers showed that serum screening at 11-13 weeks revealed abnormalities in 98% of cases, without the use of invasive technologies that can be dangerous for both mother and fetus. Scientists are going to achieve the best results using a combination of screening of the pregnant woman's blood serum for the main biomarkers with cff-DNA diagnostics, with simultaneous ultrasound examination, which can give almost 100 percent accuracy in determining the possibility of genetic abnormalities in fetal development.
Articles by Nikolaides and his colleagues Implementation of maternal blood cell-free DNA testing in early screening for aneuploidies and First-trimester content screening for trisomy 21 by biomarkers and maternal blood cell-free DNA testing are published in the electronic version of the journal Ultrasound in Obstetrics & Gynecology.
Portal "Eternal youth" http://vechnayamolodost.ru18.06.2013