| ObjectiveTo establish a short tandem repeats (STR) sequence detection technique using the real-time fluorescence quantitative polymerase chain reaction (PCR). To evaluate the efficacy of the detection technique in the prenatal diagnosis of Down's Syndrome (DS) and the effect of the technique on the psychological status of the pregnant women who receive prenatal diagnostic operation.MethodsThe amniotic fluid samples were collected from 37 fetus with DS and 131 non-DS fetus who were diagnosed using the standard cytogenetic method. We detected three STR sequences by real-time fluorescence quantitative PCR, using D21sl411 and D21s1259 on chromosome 21 as detection loci, D19s222 on chromosome 19 as the control locus, and SYBR(?) Greenâ… as fluorescent dye. Four pairs ofâ–³Ct values were analysed between the DS group and the non-DS group.Using Zung's Self-Rating Depression Scale, the psychological status of pregnant women was investigated before prenatal diagnostic operation, at the 3rd day after operation and prior to the report of cytogenetic results, respectively.244 patients were only informed the results of standard cytogenetic study between the 14th and the 28th day after operation (the group without rapid diagnosis),126 patients were additionally offered the results of STR-PCR diagnosis at the 3rd day after operation (the group with rapid diagnosis). The effect of the rapid diagnostic technique application on the psychological status of the pregnant women was evaluated.Results1,The mean value and the 95% confidence interval ofâ–³Ct1411 andâ–³Ct1259 were positive in non-DS group, while they were negative in DS group. The 95% confidence intervals did not overlap between the two groups.2,The difference ofâ–³Ct1411 between the DS group and non-DS group was greatly significant (t1411=12.088, P1411=0.000). The difference ofâ–³Ct1259 between two groups was significant too(t1259=13.884, P1259=0.000). 3,The area under the ROC curve was 0.929 when using D21s1411 as STR marker. The sensitivity and specificity were 91.9% and 84% when the cut-off value ofâ–³Ct1411 was 0.1327. While the area under the ROC curve was 0.985 when using D21s1259 as STR marker. The sensitivity and specificity were 100% and 97.7% when the cut-off value ofâ–³Ct1259 was-0.2016.4,The mean value of Zung score in the group without rapid diagnosis before prenatal diagnostic operation, at the 3rd day after operation and prior to the report of cytogenetic results were 0.411,0.405 and 0.417, respectively. The mean value of Zung score prior to the report of results was significantly higher than that at the 3rd day after operation (t=-2.217, P=0.027). The incidence rate of depression at the 3rd day after operation was 7.79%. The rate prior to the report of cytogenetic results increased to 10.25%. The anxiety and depression of the pregnant women worsen during the long period of waiting for the results.5,The mean value of Zung score in the group with rapid diagnosis before prenatal diagnostic operation, at the 3rd day after operation and prior to the report of cytogenetic results were 0.376,0.358 and 0.350, respectively. The mean value of Zung score at the 3rd day after operation and prior to the report of cytogenetic results were significantly lower than that before operation (t= 2.117, P= 0.035; t= 3.088, P= 0.002). The incidence rate of depression at the 3rd day after operation was 7.14%.The rate prior to the report of cytogenetic results decreased to 4.76%.6,The mean value of Zung score in the group with rapid diagnosis were significantly lower than that in the group without rapid diagnosis before operation, at the 3rd day after operation and prior to the report of cytogenetic results (t= 4.734, P= 0.000; t= 6.963, P= 0.000 and t= 10.151, P= 0.000). The anxiety and depression of pregnant women was improved obviously in the group with rapid diagnosis.Conclusions1,The psychological stress of pregnant women worsened and the incidence rate of depression may increase during the long period of waiting for the cytogenetic results. It is necessary to establish a rapid prenatal diagnostic technique to improve the anxiety and depression of pregnant women. 2,The detection of the two STR sequences (D21s1411 and D21s1259) on chromosome 21 from amniotic fluid samples by real-time fluorescence quantitative PCR technique can effectively diagnose DS. The detection rate was greater than 91%.3,The diagnostic value of STR sequences of D21s1259 was greater than that of D21s1411.4,The STR locus on chromosome 19 (D19s222) was suitable for control genes.5,The detection technique by real-time fluorescence quantitative PCR using SYBR(?) Greenâ… as fluorescent dye was simple, economical and reliable.6,The application of rapid diagnostic technique may improve the psychological status of pregnant women and decrease the incidence rate of depression during the period of waiting for the cytogenetic results.
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