Objective: To estimate the incremental yield of detecting copy number variants (CNVs) by genomic microarray over karyotyping in fetuses with increased nuchal translucency (NT) diagnosed by first-trimester ultrasound.
Methods: This was a systematic review conducted in accordance with PRISMA criteria. We searched PubMed, Ovid MEDLINE and Web of Science for studies published between January 2009 and January 2015 that described CNVs in fetuses with increased NT, usually defined as ≥ 3.5 mm, and normal karyotype. Search terms included: fetal or prenatal, nuchal translucency or cystic hygroma or ultrasound anomaly, array comparative genomic hybridization or copy number variants, with related search terms. Risk differences were pooled to estimate the overall and stratified microarray incremental yield using RevMan. Quality assessment of included studies was performed using the Quality Assessment tool for Diagnostic Accuracy Studies (QUADAS-2) checklist.
Results: Seventeen studies met the inclusion criteria for analysis. Meta-analysis indicated an incremental yield of 5.0% (95% CI, 2.0-8.0%) for the detection of CNVs using microarray when pooling results. Stratified analysis of microarray results demonstrated a 4.0% (95% CI, 2.0-7.0%) incremental yield in cases of isolated NT and 7.0% (95% CI, 2.0-12.0%) when other malformations were present. The most common pathogenic CNVs reported were 22q11.2 deletion, 22q11.2 duplication, 10q26.12q26.3 deletion and 12q21q22 deletion. The pooled prevalence for variants of uncertain significance was 1%.
Conclusion: The use of genomic microarray provides a 5.0% incremental yield of detecting CNVs in fetuses with increased NT and normal karyotype.
Keywords: copy number variants; cystic hygroma; genomic microarray; increased nuchal translucency; prenatal diagnosis.
Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.