PRENATAL CF-DNA TESTING FOR DOWN SYNDROME AND OTHER CHROMOSOMAL ANEUPLOIDIES: CLINICAL OUTCOME, BASED ON A ONE-BRAND CF-DNA TEST IN SLOVENIA

Darija Strah1, Uršula Reš Muravec 2, Faris Mujezinović3, Petra Ovniček4, Janez Bernik5

1. Strah Diagnostic Centre, Domžale, Slovenia 2. Dravlje Health Centre, Ljubljana, Slovenia 3. University Medical Centre Maribor, Maribor, Slovenia 4. University of Maribor, Faculty of Medicine, Maribor, Slovenia 5. University of Ljubljana, Faculty of Pharmacy, Ljubljana, Slovenia

Objectives: The use of prenatal cf-DNA testing as Results: Of total 497 pregnant women on which a highly accurate screening method for aneuploid- cf-DNA testing was performed, 365 (51.1 %) were ies is bringing the most radical changes to the field of advanced maternal age. 551 (79%) had prior of fetal medicine. Currently, amniocentesis still rep- screening tests. 114 (16.4 %) were at high risk for resents a gold standard for prenatal diagnosis of T21, T18 or T13, based on prior screening test re- chromosomal abnormalities. First commercial cf- sults. 14 of total 18 high risk cf-DNA cases (includ- DNA tests in Slovenia were performed at the end ing 10 cases of T21, 1 case of T13, 1 case of X0 and of 2012. 2 cases of XXY) were confirmed by fetal karyotyp- ing. 3 cases (1 T18, 1 T13 and 1 X0) turned out to be Methods: We present the joint test results of pre- false positive. 1 woman with high cf-DNA test result natal cf-DNA testing from majority private outpa- for T13 aborted before karyotyping. There were no tient clinics and one public health Department of false negative cases reported. perinatology over the last 3 years (from 5. 2. 2013 until 17. 2 .2016). In our study, 497 pregnant women In general, cf-DNA testing had 100 % sensitivity from 10th to 33th week of pregnancy were includ- and 99.4 % specificity, PPV turned out to be 82.4% ed. All samples were analyzed in clinical laboratory for all aneuploidies. Regarding only T21, sensitivity – the ISO/IEC 17025-certified clinical laboratory of and specificity were 100 %. Repeat blood sampling BGI-Shenzhen, China. was required in 17 cases (redraw rate = 2.44 %).

Conclusions: Our results confirmed that prenatal cf-DNA testing represents highly accurate approach for advanced screening of most common aneuploidies. However, we must be aware of false positive tests, resulting in unnecessary anxiety, causing more harm than good.

Contact: Darija Strah, [email protected], 00386 41 330 501