| The most frequent fetal chromosomal aberrations involve chromosomes 21, 18, 13, X and Y. Aneuploidy or alterations in copy number of these five chromosomes account for about 80% of clinically significant chromosomal aberrations diagnosed in the prenatal period. The traditional karyotyping is the"gold standard"test of chromosomal disease, but it is labour-intensive and the results are usually not available for 2 weeks or more. QF-PCR (Quantitative Fluorescent Polymerase Chain Reaction) can detect common numerical abnormality with few hours, it has advantages of fast, accurate, lowcost, hypersensitivity, high specific and automatic mode of operation. This technique has already been widely used in many prenatal centers. This thesis compared the results between the QF-PCR and cytogenetic analyis in 1870 prenatl samples, analysis the consistency of the two methods in order to evaluate the detection of aneuploidies by QF-PCR in rapid prenatal diagnosis application.Objection1. To investigate the fast reporting , sensitivity, specificity ,accuracy and feasibility of QF-PCR in rapid prenatal diagnosis of common aneuploidies .2. To investigate the superiority and limitations of QF-PCR in rapid prenatal diagnosis of common aneuploidies . 3. To evaluate the clinical application of QF-PCR in rapid prenatal diagnosis when prenatal tests are performed for indications such as positive Down syndrome screening , Advanced Maternal Age and Abnormal Ultrasound Findings. to investigate whether karyotype can be replaced by QF-PCR for these indications.Methods1. subjects: it selected 1870 cases of prenatal samples whose prenatal tests are performed for indications such as positive Down syndrome screening , Advanced Maternal Age and Abnormal Ultrasound Findings. these samples were all from guangzhou women and children's hospital from Nov.2007 to Apr.2010.2. Samples were tested by karyotype analysis and the results of postpartum followup were recorded.3. Using 23 short tandem repeats located on chromosomes 13, 18, 21, X and Y, the total samples were analysed by QF-PCR.4. the results were analysis by the software of computer SPSS 16.0 and the results of these two methods were compared.Results1. Karyotyping results : the results were obtained 2 to 3 weeks after the sample collection; 1823 (97.49%)samples were sucsessfully analysed by karyotypes , among those 1732 cases were normal, 91 cases were abnormal. Including 73 cases of aneuploidies, they were 40 cases of trisomy 21, 19 cases of trisomy 18, 4 cases of trisomy 13, 6 cases of 45,X, 1 cases of 47,XYY, 1 cases of 47,XXX, 2 cases of 69,XXX,7 cases of mosain ,2 cases of rob 21 and other 9 cases of structural abnomalities.2. QF-PCR results :The results of QF-PCR were obtained within 24-48 hours of sample collection. 1863 (99.63%)samples were sucsessfully analysed by QF-PCR , among those 1787 cases were normal, 76 cases were abnormal. they were 40 cases of trisomy 21, 19 cases of trisomy 18, 4 cases of trisomy 13, 6 cases of 45,X, 1 cases of 47,XYY, 1 cases of 47,XXX, 2 cases of 69,XXX . 1 case of 46xy,der(14:21)(q10,q10) ,+21 and one case of 46XX,der(14;21)(q10;q10),+21 turned out to be trisomy 21. another case of 47,XXY[47]/46,XY[3] mosain turned out to be 47,XXY。3. The QF-PCR test is more rapidly.The results obtained by QF-PCR were consistent with that of cytogenetic studies in 99.18% of the samples. It can detect all aneuploidies involving chromosomes 21, 18, 13, X and Y in prenatal diagnosis and can detect 83.52% of all the abnormalities.No false positive result was found. The false negative rate is 0.82%. Only a small cases of mosain and structural abnomalities can not be detected.4. It can detect 86.05%, 50.00% and 87.50% of all the abnormalities differently when prenatal tests are performed for indications such as positive Down syndrome screening, Advanced Maternal Age and Abnormal Ultrasound Findings. When these two methods were compared, the first part has no statistic discrepancy while the other two has statistic discrepancy .Conclusions1. The rapid QF-PCR test can detect all aneuploidies involving chromosomes 21, 18, 13, X and Y in prenatal diagnosis speedly, correctly, economically and effectively,Without no false positive result, The Sensitivity and specificity was 100%. It is the first select method for rapid prenatal diagnosis of aneuploidies.2. The prominent advantage of QF-PCR is fast reporting within 24 to 48 hours and earlier relief of anxiety during waiting for the results of karyotyping.3. It can not detect aneuploidies involving chromosomes apart from 21, 18, 13, X and Y. when comes to mosain and structural abnomalities, the detection rate is very low. |
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