OP04.01: Chromosomal aberrations in fetuses with isolated muscular ventricular septum defects: a retrospective study and meta‐analysis

To investigate the association between prenatally detected isolated muscular ventricular septum defects (mVSD) and chromosomal aberrations. The study consisted of two parts: A retrospective study from the Greater Copenhagen Region of Denmark and a meta-analysis. The retrospective study included pregnancies with a due date between Jan 1st 2015 and Aug 31st 2023. Cases were retrieved from Astraia and assessed in their respective patient files to verify the presence of a VSD, the type of VSD, other malformations, and genetic test results. Isolated was defined as the absence of other structural malformations. PubMed and the Cochrane Database were searched for the meta-analysis. Studies were included if they entailed individual results for isolated mVSD. The meta-analysis was performed as a fixed-effect model with untransformed proportions and exact confidence intervals (CI) and included all cases of pathogenic genetic aberrations. A total of 2341 cases were retrieved, of which 365 had an isolated mVSD. Of those, 235 (64.4%) had had a genetic test performed prenatally. Five cases had genetic aberrations of which four were included in the analyses: two pathogenic aberrations associated with congenital heart defects (CHD), and two incidental, pathogenic findings (ichthyosis and Charcot-Marie-Tooth). One case had long QT-syndrome (LQTS) specifically tested for in the first trimester due to maternal LQTS and was not included in the analyses. Hence, the prevalence of genetic aberrations was 1.1% (4/365). For the meta-analysis, 322 papers were assessed, of which four studies were included + the present data. The meta-analysis included a total of 775 cases, with an overall prevalence of genetic aberrations of 0.51% (95% CI 0.01-1.01). This meta-analysis, incorporating new findings from The Capital Region of Denmark, indicates a 0.51% prevalence of genetic aberrations in fetuses with isolated mVSD, comparable to low-risk pregnancies without malformations.