This study by Sotiriadis et al. (Prenatal Diagnosis, 2017) sought to calculate the proportion of pathogenic results that would be picked up by array comparative genomic hybridization (aCGH) compared to NIPS.
Comparative Retrospective Study
This study included 2,779 fetuses that underwent invasive prenatal diagnosis using aCGH, with indications including large NT, standard 1st and 2nd trimester screening, fetal anomalies, maternal age, personal or family history of genetic issues, patient request or other (e.g. infection). Patients who were referred for screen positive NIPS were excluded. The investigators assumed a simulated NIPS panel comprised of common aneuploidies, trisomies 21, 18, 13, but also sex chromosome aneuploidies including monosomy X, 47, XXX, 47, XYY, and 47, XXY. NIPS would detect 28.0% (95% CI 14.3-47.6) of detectable aCGH pathogenic results for NT between 95th to 99th centile, 14.3% (95% 5.0-34.6) for NT > 99th centile, 34.2% (95% CI 21.1-50.1) for high-risk first-trimester results, 52.4% (95% CI 32.4-71.7) for second-trimester markers and 50.0% (95% CI 26.8-73.2) for advanced maternal age. Overall, the rate of aCGH pathogenic/likely pathogenic results was 5.0% of which 44.0% (95% CI 36.0-52.2) would have been missed by NIPS alone. This paper yet again reinforces the fact that NIPS is a screening test only and, particularly in the age of aCGH, approximately half of pathogenic findings detectable with invasive testing will be missed.
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