Prenatal diagnosis study using array comparative genomic hybridization for genotype-phenotype correlation in 772 fetuses.

Objective: The aim was to evaluate the main indications for prenatal diagnosis, the prevalence of abnormal copy number variations (CNVs), correlate them with clinical findings, analyze the prevalence of VUS, report the rare variants found and additionally highlight the clinical importance of microarray-based comparative genomic hybridization (aCGH) in prenatal diagnosis.

Study Design: We retrospectively analyzed a cohort of 772 fetuses with indication for genetic study in two tertiary hospitals, in a 9-years-period, using aCGH.

Results: Our results demonstrated 8.3 % (6.4-10.5 %, 95 % CI) detection rate of pathogenic CNVs. Within this group, the main indication was structural malformations (57 %) mainly involving central nervous system, skeletal and cardiac systems. Pathogenic results in cases with multiple malformations were higher than in cases with isolated anatomical system malformations showing statistical significant differences (p < 0.001). The second indication where we found more pathogenic CNVs was increased nuchal translucency (5-6.4 mm). In fact, the rate of pathogenic CNVs did not show significant differences between structural and non-structural malformations (p > 0.001), highlighting the relevance of genetic study by aCGH also in cases with no structural malformations. A total of 217 fetuses with CNVs classified as VUS were identified, mainly involving chromosomes X, 1 and 16.

Conclusion: Our findings demonstrate 4.9 % (4.2-5.6 %, 95 % CI) increased in the diagnostic yield using aCGH compared to the use of conventional karyotype alone, confirming that the aCGH can improve the accuracy of prenatal diagnosis. Our survey provides a full genotype-phenotype analysis that can be clinically useful for the classification of variants in the context of prenatal setting, helping to provide a better reproductive genetic counselling.