| With the rapid development of society and industry,infection diseases almost have being in controled. But genetic diseases play a very sorrow role in our life. Not only for many families but also for the society. In a long time, human being had no way to resolve the serious probloms. After entrance in tne 20th centry, attribute to exploring of many new bio-medical technologies,such as cell biology,monoclone antibody,flow cyto ,especially the creation of nuclic amplication ,hybridization and recombination of gene,our researches on genetic diseases has got a big prograss.In tradition, all the prenatal diagnosis focused on the amniocenttesis and chorionic villus sampling. It is a long sought-after goal to replace invasive prenatal diagnositic methods and their inherent risks to the mother and the fetus with a nonivasive alternative. The isolation of fetal cells from the maternal circulation by Waknowska in 1969 represents a promising nonivasive approach to prenatal diagnosis. Now we have known the sorts ofall the fetal cells in maternal circunation. They are Lymphocytes, Granulocytes, Nucleated red blood cells, and Thophblast cells.Advances in molecular biology have provided new and sensitive tools for detecting and confirming the existence of fetal cells. However, because of the inconsistenct number of fetal cells found in maternal circulation,these techniques have not yet entered routine clinical practice.It is hoped that new methods of fetal cell enrichment,cell culture and automated microscopic scanning will improve the detection rate of fetal information.In 1997,Lo et al first demonstrate the presence of large amount of cell free fetal DNA in maternal circulating. Prompted by reports of large quantities of tumor DNA in plasma and serum from cancer patients. The results of subsequent studies showed that significant more fetal DNA is present in the plasma of pregnant women compared with the fetal DNA extracted from the cellular fraction of maternal blood. Our study was to explore the feasibility of detecting fetal genetic information in maternal peripheral blood cell and plasma. So as to development a series detecting procedures for the nonivasive prenatal diognosis for genetic diseases. At first, we used in-situ hybridisation (ISH) techniques with sex determing region (SRY) DNA probes on 22 placentaes (12 of them are from male fetus labore and 11 are from female fetus labore ).In order to identify the really informations of fetues and its cheracter of scattering in the placenta .Then we performed nest-PCR to amplify the special fragment ofSRY gene in 50 pregnant women peripheral blood cell and plasma. Our study demonstrated that in all the placental tissues of male fetues laboring, we got the stronger signals after ISH with SRY probes. But we could notfind any positive signal in the placentaes of female fetus laboring.After nest-PCR, Fetus-derived Y sequences were detected in 21(75%)of the 28 maternal blood cell and in 9(32%) of the maternal plasma samples, from women bearing male fetuses.Our study indicated that: detecting fetal DNA in pregnant women peripheral blood cell and plasma could be a feasible approach of non-invasive prenatal diagnosis. The main limitation at present appears to be the availability of uniquely fetal gene sequence that will identify the presence of fetal DNA in both male and female fetues. We must try our best to modify the detecting rate. So the noninvasive prenatal diagnosis will be applicated in a short time to the genetic diseases.
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