Prenatal Diagnosis Center, Taizhou Hospital, Wenzhou Medical University, Zhejiang, China.
Medical Research Center, Taizhou Hospital, Wenzhou Medical University, Zhejiang, China.
BMC Med Genomics. 2020 Jul 6;13(1):96. doi: 10.1186/s12920-020-00751-8.
Non-invasive prenatal testing (NIPT) has been established as a routine prenatal screening to assess the risk of common foetal aneuploidy disorder (trisomy 21, 18, and 13). NIPT has high sensitivity and high specificity, but false positive and false negative results still exist. False negative NIPT results involving Down syndrome are rare, but have a high clinical impact on families and society.
We described a case of a foetus that tested "negative" for trisomy 21 (Z-score was 0.664) by NIPT based on the semiconductor sequencing platform (SSP). The foetal fraction of cell-free DNA was 16.9%; this percentage was much larger than the threshold of 4% for obtaining accurate NIPT results. However, postnatally, the newborn was diagnosed with Down syndrome with the 46,XY,der(21;21)(q10;q10),+ 21 karyotype.
We presented a case of false negative NIPT results, which may occur through biological mechanisms rather than poor quality, technical errors or negligence. It is imperative for clinical geneticists and their patients to understand that NIPT is still a screening test.
非侵入性产前检测（NIPT）已被确立为一种常规的产前筛查方法，用于评估常见胎儿非整倍体疾病（21 三体、18 三体和 13 三体）的风险。NIPT 具有高灵敏度和高特异性，但仍存在假阳性和假阴性结果。涉及唐氏综合征的假阴性 NIPT 结果较为罕见，但对家庭和社会具有较高的临床影响。
我们描述了一例基于半导体测序平台（SSP）的 NIPT 检测结果为“阴性”的唐氏综合征胎儿（Z 评分 0.664）。游离 DNA 的胎儿比例为 16.9%；这个比例远大于获得准确 NIPT 结果的 4%的阈值。然而，新生儿出生后被诊断为唐氏综合征，核型为 46,XY,der(21;21)(q10;q10),+21。
我们提出了一例假阴性 NIPT 结果的病例，这可能是由于生物学机制而非质量差、技术错误或疏忽导致的。临床遗传学家及其患者必须认识到，NIPT 仍然是一种筛查试验。
