本篇報導旨在探討臨床上使用SNP-based NIPT檢測胎兒22q11.2缺失症候群(狄喬治症)的準確度表現。共收集21,948件臨床個案進行22q11.2缺失症候群 篩檢，並追蹤每個高風險個案後續的臨床結果 95位個案22q11.2缺失症候群檢測結果為高風險，61位(64.2%)經過診斷(48位接受產前侵入性檢查、11位為產後確診、2件為自然流產物質檢查)，11位(18.0%)為真陽性；50位為偽陽性(82.0%)，陽性預測率PPV為18.0%；若加上尚 未追回確診結果的34位個案，整體陽性預測率估計介於11.6–47.4%。真陽性個 案中僅有81.8%具有超音波異常，而偽陽性個案亦有18%在超音波檢查中發現異 常狀況。另外兩位高風險個案顯示產婦疑似22q11.2缺失症候群，其中一位經過 確認診斷證實為22q11.2缺失症候群患者；另一位個案具有22q11.2缺失症候群 家族病史。有3位產婦因22q11.2缺失症候群篩檢高風險結果而中止妊娠，其中 兩位經過確診為真陽性個案。
Objectives To evaluate the performance of a singlenucleotide polymorphism (SNP)-basednon-invasive prenatal test (NIPT) for the detection of fetal 22q11.2 deletion syndrome in clinical practice, assess clinical follow-up and review patient choices for women with high-risk results.
Methods In this study, 21 948 samples were submitted for screening for 22q11.2 deletion syndrome
using a SNP-based NIPT and subsequently evaluated. Follow-up was conducted for all cases with a
Results Ninety-five cases were reported as high risk for fetal 22q11.2 deletion. Diagnostic testing results were available for 61 (64.2%) cases, which confirmed 11 (18.0%) true positives and identified
50 (82.0%) false positives, resulting in a positive predictive value (PPV) of 18.0%. Information regarding invasive testing was available for 84 (88.4%) high-risk cases: 57.1% (48/84) had invasive
testing and 42.9% (36/84) did not. Ultrasound anomalies were present in 81.8% of true-positive and 18.0% of false-positive cases. Two additional cases were high risk for a maternal 22q11.2 deletion;
one was confirmed by diagnostic testing and one had a positive family history. There were three pregnancy terminations related to screening results of 22q11.2 deletion, two of which were confirmed as true positive by invasive testing.
Conclusions Clinical experience with this SNP-based non-invasive screening test for 22q11.2 deletion syndrome indicates that these deletions have a frequency of approximately 1 in 1000 in the
referral population with most identifiable through this test. Use of this screening method requires the availability of counseling and other management resources for high-risk pregnancies. 2015 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the
International Society of Ultrasound in Obstetrics and Gynecology.