Beyond the Curtains: Identification of the Genetic Cause of Foetal Developmental Abnormalities Through the Application of Molecular Autopsy

<b>Background</b>: Foetal structural abnormalities can be detected in approximately 3% of all pregnancies and frequently remain without a genetic diagnosis. This study aims to apply an integrated approach with the final goal of providing a molecular diagnosis in the challenging Italian setting of early termination of pregnancy. <b>Methods</b>: In a cohort of 86 foetuses, <i>post-mortem</i> dysmorphological examination, radiological assessments, and molecular autopsy through Whole-Exome Sequencing-WES-analysis were performed. <b>Results</b>: Forty-two foetuses were phenotypically classified as presenting a single major malformation (i.e., central nervous system, skeletal, urogenital, or cardiac anomalies, or fluid accumulation), while 44 foetuses presented multiple malformations and/or dysmorphic features. Overall, WES provided a diagnostic yield of 26.7%; additionally, seven Variants of Uncertain Significance (VUS) potentially liked to the foetal phenotype were identified. The highest detection rate was achieved for foetuses presenting a single major urogenital (50%) or skeletal (42.9%) malformation, followed by foetuses presenting multiple malformations (27.3%). Peculiar results of particular interest were (1) the identification of two splicing variants (within the <i>INPPL1</i> and <i>RHOA</i> genes), functionally characterised through minigene assay, which contributed to evaluate their pathogenicity, and (2) the identification of a novel de novo missense <i>ZNF292</i> variant (NM_015021.3:c.6325A>C p.(Ser2109Arg)) in a foetus affected by corpus callosum hypoplasia. The <i>ZNF292</i> gene is associated with the Intellectual developmental disorder, autosomal dominant 64 and this finding represents the first report of prenatally detected anomalies of the central nervous system in a foetus carrying a <i>ZNF292</i> variant. <b>Conclusions</b>: This study underlines the diagnostic utility of an integrated approach to achieve a precise genetic diagnosis for structural foetal abnormalities, thus providing families with precise recurrence risk estimations and detailed options about future pregnancies. Additionally, a systematic implementation of this strategy could be crucial to better characterise new variants and discover new genes involved in embryonic and foetal development.