Prenatal and postnatal chromosomal microarray analysis in 885 cases of various congenital heart defects

Purpose: This study aimed to evaluate the prevalence of clinically significant (pathogenic and likely pathogenic) variants detected by chromosomal microarray (CMA) tests performed for prenatally and postnatally detected congenital heart defects. Methods: A retrospective evaluation of CMA analyses over a period of four years in a single tertiary medical center was performed. Detection rate of clinically significant variants was calculated in the whole cohort, prenatal vs. postnatal cases, and isolated vs. non-isolated CHD. This rate was compared to previously published control cohorts, and to a theoretical detection rate of noninvasive prenatal testing (NIPS; 5 chromosomes). Results: Of the 885 cases of CHD, 111 (12.5%) clinically significant variants were detected, with no significant difference between the 498 prenatal and the 387 postnatal cases (10.8% vs. 14.7%, p = 0.08). In both groups, the detection rate was significantly higher for non-isolated vs. isolated CHD (76/339 = 22.4% vs. 35/546 = 6.4%, respectively, p < 0.05). The detection rate was higher than the background risk in both groups, including cases of postnatal isolated CHD. 44% of abnormal findings in the prenatal setting would be detectable by NIPS. Conclusion: CMA should be performed for both prenatally and postnatally detected CHD, including postnatal cases of isolated CHD, while NIPS can be considered in specific scenarios.