Association of Copy Number Variants With Specific Ultrasonographically Detected Fetal Anomalies

OBJECTIVE: To evaluate the association of other-than-common benign copy number variants with specific fetal abnormalities detected by ultrasonogram. METHODS: Fetuses with structural anomalies were compared with fetuses without detected abnormalities for the frequency of other-than-common benign copy number variants. This is a secondary analysis from the previously published National Institute of Child Health and Human Development microarray trial. Ultrasound reports were reviewed and details of structural anomalies were entered into a nonhierarchical web-based database. The frequency of other-than-common benign copy number variants (ie, either pathogenic or variants of uncertain significance) not detected by karyotype was calculated for each anomaly in isolation and in the presence of other anomalies and compared with the frequency in fetuses without detected abnormalities. RESULTS: Of 1,082 fetuses with anomalies detected on ultrasound scan, 752 had a normal karyotype. Other-than-common benign copy number variants were present in 61 (8.1%) of these euploid fetuses. Fetuses with anomalies in more than one system had a 13.0% frequency of other-than-common benign copy number variants, which was significantly higher (P<.001) than the frequency (3.6%) in fetuses without anomalies (n=1,966). Specific organ systems in which isolated anomalies were nominally significantly associated with other-than-common benign copy number variants were the renal (P=.036) and cardiac systems (P=.012) but did not meet significance after the adjustment. CONCLUSIONS: When a fetal anomaly is detected on ultrasonogram, chromosomal microarray offers additional information over karyotype, the degree of which depends on the organ system involved. LEVEL OF EVIDENCE: : II.