目的:评估在非侵入性产前检测(NIPT)中通过纯化的超顺磁性珠对无细胞胎儿DNA(cffDNA)的改良富集方法的效率。
方法:选取2017年12月至2022年9月在海淀区妇幼保健院接受NIPT的26252例孕妇,随机分为常规组(n=10573)和改良富集组(n=15679)。然后使用常规和改进的技术对cffDNA进行筛选和富集,分别。对NIPT检测到的高危孕妇进行侵入性产前诊断。所有女性都接受了妊娠结局的随访,并在片段大小方面比较了两种方法的检测功效,cffDNA的浓度,重复检测率,和临床实验室检查指标。
结果:修饰富集组的无细胞DNA文库主峰的片段大小明显低于常规组[267(264,269)bpvs.294(292,296)个基点,P<0.01],而cffDNA的浓度明显更高[21.86%(17.61%,26.36%)与9.08%(6.87%,11.87%),P<0.01]。此外,重复检出率(0.740%与2.02%,X2=83.90,P<0.01)和检测失败率(0.006%vs.0.057%,P<0.05)改良富集组明显低于常规组。两种高危人群的联合阳性预测值(PPV)(64.3%vs.76.1%)和低风险(35.3%与45.5%)改良富集组的孕妇略低于常规组,尽管没有检测到显著差异。在常规组的高危孕妇中,有1例21三体假阴性,改良富集组未发现假阴性病例。
结论:改良的cffDNA筛选富集技术显著提高了cffDNA的相对浓度,降低了NIPT的漏检率和重复检出率,显着降低了由于低浓度的cffDNA而导致的假阴性病例的发生率,大大提高了NIPT的整体检测效能。
OBJECTIVE: To assess the efficiency of modified enrichment method for cell-free fetal DNA (cffDNA) through purified superparamagnetic beads during non-invasive prenatal testing (NIPT).
METHODS: A total of 26 252 pregnant women undergoing NIPT at the Maternal and Child Health Care Hospital of Haidian District from December 2017 to September 2022 were recruited and randomly assigned into the conventional group (n = 10 573) and the modified enrichment group (n = 15 679), who were then subjected to the screening and enrichment of the cffDNA using a conventional and a modified technique, respectively. High-risk pregnant women detected by NIPT were subjected to invasive prenatal diagnosis. All women were followed up for their pregnancy outcomes, and the detection efficacy of the two methods was compared in terms of fragment size, concentration of cffDNA, duplicate detection rate, and indices of clinical laboratory tests.
RESULTS: The fragment size of the main peak of the cell-free DNA library of the modified enrichment group was significantly lower than that of the conventional group [267 (264, 269) bp vs. 294 (292, 296) bp, P < 0.01], while the concentration of cffDNA was significantly higher [21.86% (17.61%, 26.36%) vs. 9.08% (6.87%, 11.87%), P < 0.01]. In addition, the duplicate detection rate (0.740% vs. 2.02%, X2 = 83.90, P < 0.01) and detection failure rate (0.006% vs. 0.057%, P < 0.05) in the modified enrichment group were significantly lower than those of the conventional group. The combined positive predictive value (PPV) in both high-risk (64.3% vs. 76.1%) and low-risk (35.3% vs. 45.5%) pregnant women from the modified enrichment group was slightly lower than those from the conventional group, though no significant difference was detected. There was one false negative case for trisomy 21 among the high-risk pregnant women from the conventional group, and no false negative case was found in the modified enrichment group.
CONCLUSIONS: The modified technique to screen and enrich the cffDNA has significantly enhanced the relative concentration of cffDNA and reduced the failure and duplication detection rate of NIPT, which has significantly reduced the incidence of false negative cases due to the low concentration of cffDNA, and greatly increased the overall detection efficacy of NIPT.