Rsearch On The Improved Method Of Sample Processing In Non-invasive Prenatal For Pregnant Women

Early prenatal screening of pregnant women can analyze the fetal disease in early pregnant stage,so as to realize the early treatment of the fetus,or choose to terminate the pregnancy,and reduce the burden of serious fetal diseases in society and families.The population of fetuses suffering from genetic diseases and birth defects in China is relatively high.The popularization of prenatal screening is of great social significance.However,the current clinical prenatal testing techniques have major limitations.For example,the testing methods are traumatic.As a result,the false positive rate is high and the detection range is narrow.It is urgent to develop new prenatal testing techniques to fill these shortcomings.In recent years,the discovery of fetal cf DNA has created a precedent for non-invasive prenatal screening.By enriching the free fetal DNA contained in the peripheral blood of pregnant women,non-invasive detection of fetal genetic information can be achieved,which is of great significance.The content of fetal cf DNA in the blood of pregnant women is low.At the same time,the cf DNA o f pregnant women can also interfere with the detection of fetal DNA.How to efficiently enrich fetal cf DNA and reduce the impact of maternal cf DNA is the key in improving the sensitivity and accuracy of non-invasive prenatal screening.Our research group has developed a noval magnetic nanoparticles with high-performance.By modifying its surface,it can achieve high-efficiency separation and extraction of cf DNA.It has been proved that this new magnetic nanoparticles can separate short DNA fragments from l ong DNA fragments with high resolution.According to reports,we have found that the fetal cf DNA is shorter than the maternal cf DNA.Therefore,based on the high-resolution enrichment effect of this new type of magnetic nanoparticle material,we designed and optimized a method aimed at the enrichment of fetal cf DNA,and used in the analysis of clinical non-invasive prenatal early screening.This subject first designed a two-step enrichment workflow for short cf DNA fragments based on two types of magnetic nanoparticles,and proved the principle in a simulation system.The feasibility of this method was verified by analyzing the results of DNA fragment distribution.Subsequently,the two-step screening method was used to screen and enrich the short cf DNA fragm ents in plasma samples of pregnant women,and the enrichment results were analyzed in clinical samples.Finally,according to the enrichment results,the enrichment workflow was optimized,and a new screening mehod with higher recovery rate and better separation efficiency was obtained.Through the research work of this subject,we innovatively designed and optimized a new short DNA fragment screening technology,successfully achieved the screening and enrichment of fetal cf DNA,and provided sample support for the analysis and detection of downstream fetal genetic information.It has advantages and great application value in the sample processing of pregnant women.