Ultrasensitive DNA Screening for Down Syndrome Offers Potential for Early Detection

MedicalResearch.com Interview with:

Zhiyong Zhang PhD Key Laboratory for the Physics and Chemistry of Nanodevices and  Department of Electronics Peking University Beijing China

Prof. Zhang

Zhiyong Zhang PhD
Key Laboratory for the Physics and Chemistry of Nanodevices
Department of Electronics
Peking University
Beijing China

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Down syndrome is caused by the presence of an extra 21st chromosome within the genome and is the most common birth defect (occurring in approximately 1 in 800 births). In the absence of a multiplexed quantitative diagnostic device, pregnant women have been examined with the ultrasound and the indirect biochemical markers (Alpha-fetoprotein, chorionic gonadotropin and free estriol) which are accompanied with a high misdiagnosis rate. And the diagnostic test (such as amniocentesis) following the wrong screening test results will bring harm to both the pregnant women and the fetuses.

Through PCR (polymerization chain reaction) amplification of the fetal DNA in the pregnant mother’s peripheral blood and fluorescence read-out, whole-genome sequencing (WGS)-based non-invasive prenatal testing (NIPT) sequences all the genomic DNA segments in parallel and quantitatively compares the percentage of different chromosomes, which increases the sensitivity for prenatal detection of Down syndrome. However, the complex instrumental setups and the resulted high processing cost present challenges for the large-scale application of WGS-based diagnosis at the point of care in the urban and rural areas of developing countries. Hence, beside the costly WGS method, there is an urgent need to develop a cost-effective NIPT biochip with simple instrumental setting, fast detection speed, high sensitivity, and programmable to multiple disease markers.

Taking advantages of we have developed a novel field effect transistor (FET) based biosensor that reveals a fast, ultra-sensitive, highly specific and cost-effective methods and someday can be used to detect fetal Down syndrome in NIPT.  Continue reading

Improved DNA Analysis Reduces False Positive Prenatal DNA Testing For Trisomy Conditions

MedicalResearch.com Interview with:

Professor Sir Nicholas Wald FRCP FRS Professor of Preventive Medicine Wolfson Institute of Preventive Medicine Barts and The London School of Medicine and Dentistry Queen Mary University of London London

Prof. Wald

Professor Sir Nicholas Wald FRCP FRS
Professor of Preventive Medicine
Wolfson Institute of Preventive Medicine
Barts and The London School of Medicine and Dentistry
Queen Mary University of London
London

MedicalResearch.com: What is the background for this study?

Response: Prenatal screening for Down’s syndrome (trisomy 21), Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13) by maternal plasma DNA analysis has an improved screening performance compared with conventional screening but is too expensive to be performed routinely and has a technical failure rate.

The aim of the study was to take advantage of the improved screening performance of the DNA analysis in conjunction with the existing methods thereby providing a seamless testing interface between the “old” and the “new” methods that would detect a larger proportion of affected pregnancies with a much lower false-positive rate, at a much reduced cost compared with universal DNA testing and with no failed tests. The novel approach was to conduct a conventional screening test using a screening cut-off level that identifies about 10% of women with the highest risks of having an affected pregnancy (much higher than in conventional screening) and then to perform a DNA test using a portion of the original blood sample collected for the conventional test. Progressing to the DNA test was automatic for these high risk women without their having to be recalled for counseling and a fresh blood sample (ie as a reflex response hence the term “reflex DNA screening”).

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