Abstract
Objective To assess the additive value of prenatal chromosomal microarray analysis (CMA) for
all indications and the likelihood of detecting pathologic copy number variations
(CNVs) based on specific indications.
Methods A retrospective analysis was performed on amniocentesis and chorionic villi sampling
results obtained between 2010 and 2014 in a single institution. A total of 3,314 consecutive
patients undergoing invasive genetic testing for different indications were offered
CMA in addition to standard karyotype. The prevalence of pathologic CNVs was compared
between patients with low-risk indications and those with high-risk indications. Likewise,
the prevalence of pathologic CNVs among patients with different sonographic abnormalities
was calculated and compared with the low-risk group. Chi-square and Fisher exact tests
were used for statistical analysis.
Results The prevalence of pathologic CNVs was significantly higher in patients with high-risk
indications and specifically those with sonographic abnormalities, compared with the
low-risk group (2.8 and 5.9% vs. 0.4%, respectively; all p < 0.05).
Conclusion Prenatal CMA detected clinically relevant CNVs in fetuses with a normal karyotype.
Major structural malformations and nuchal translucency (NT) ≥ 3.0 mm are associated
with the highest risk for a CMA abnormality. Nevertheless, the prevalence of pathologic
CNVs in the low-risk population was high enough (1:250) to consider genetic counseling
in this group.
Keywords
chromosomal microarray - genetic counseling - karyotype - prenatal diagnostic test