Establishment and application of median serum markers for second trimester screening in Qingdao region / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To establish the median of serum markers for second trimester screening in Qingdao region and to assess the influence of median correction on the performance of screening.</p><p><b>METHODS</b>Maternal serum alpha-fetoproteins (AFP), human chorionic gonadotrophin, free beta subunit (β -HCG) and unconjugated oestriol (uE3) were assayed for prenatal screening of 18 188 singleton pregnancies at 15-20(+ 6) weeks gestation from January 2009 to July 2010. The median of serum markers was calculated based on above results and applied for risk estimation in screening for fetal aneuploidy from August 2010 to March 2011. The screening performance, specified in terms of detection rates (DRs), false positive rates (FPRs) and odds of being affected given a positive result (OAPR) were compared between the two groups. The risks of 45 affected pregnancies detected during the study were estimated with both Caucasian and corrected medians.</p><p><b>RESULTS</b>The average level of AFP in local pregnancies was similar to that of the Caucasian population, whilst β -HCG and uE3 were respectively 11% and 33% higher than those of Caucasians. The multiple of median (MoM) value was between 0.94 and 1.02 for the dataset based on the corrected median. At a cut-off of l in 270, FPR has decreased from 5.2% to 4.9%, and DR of Down syndrome has increased from 60% to 69.2%, and OAPR has increased from 1:79 to 1:59 when evaluating risk based on the corrected median. For the 45 affected pregnancies, three Down syndrome pregnancies could be missed because their risk estimates were lower than the cut-off level based on Caucasian median.</p><p><b>CONCLUSION</b>It is useful to establish and apply population and laboratory-specific medians in order to improve the performance of prenatal screening and diagnosis.</p>

Evaluation of Down's syndrome screening methods using maternal serum biochemistry in the second trimester pregnancy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To provide basis for selecting the suitable method of Down's syndrome biochemical screening in the second trimester pregnancy.</p><p><b>METHODS</b>A total of 30 547 singleton pregnancies between 14 and 20(+ 6) weeks of pregnancy were collected and analyzed for maternal serum alpha-fetoproteins (AFP) and human chorionic gonadotrophin, free beta subunit (beta-HCG) with or without unconjugated estriol (uE3). The screening risks were calculated using the software Lifecycle. The detection rates and the cost of per Down's syndrome detected were calculated and compared. And four different methods were compared in a series of 64 serum samples from Down's syndrome pregnancies.</p><p><b>RESULTS</b>(1) Among the 64 affected cases, the detection rate of Down's syndrome was improved no matter in the double test (DT) or in the triple test (TT) if software Lifecycle (LC) was used to evaluate risks. And it was not suitable to evaluate risks with software 2T-Risks in the triple tests. (2) In the cohort of 30 547 singleton pregnancies, the detection rate of Down's syndrome with project DT-LC, which was double test using AFP and free beta-HCG together with software Lifecycle, and project TT-LC, which was triple test using AFP, free beta-HCG and uE3 together with software Lifecycle, was 56.25% and 57.14%, respectively. The former project was better because it decreased the false positive rate at a lower running cost.</p><p><b>CONCLUSION</b>The DT-LC is an effective screening strategy for second trimester detection of fetal Down's syndrome in mainland China.</p>