Antenatal Investigation of Fetuses With Complex Congenital Heart Defects Using multiOMICS

Overview

This study will use multiOMICS study on fetuses with complexe congenital heart defects (CHD) to identify etiological epigenetic factors of these cardiac malformations, related to environmental factors during pregnancy.

Congenital heart defects (CHDs) are a very heterogeneous group of heart diseases in terms of embryonic mechanisms, phenotypes and aetiologies. In isolated forms, genetic causes are identified in only 19% of cases, linked to chromosomal abnormalities (8%) or gene variants (11%). Environmental causes such as infection, exposure to toxic substances or ingestion of teratogenic substances may also favour the onset of MCC. Although in the majority of cases the aetiology remains unknown, the discovery of MCC in the ante-natal period almost systematically leads to a genetic aetiological work-up using amniotic fluid for karyotype, Array-CGH and, more recently, exome analysis. With regard to environmental causes, recent data in the literature report a link between environmental exposures (occupational, extra-occupational or medicinal) and congenital anomalies. Objectives: The low percentage of genetic abnormalities and toxic factors identified as causal in patients with non-syndromic CHD prompts a search for more complex causes such as epigenetic modifications linked to an interaction between genes and environmental factors. Methods: The multi-omics study approach, using high-throughput sequencing technologies (exome, RNASeq, methylSeq), provides a wealth of information on cellular and/or tissue signaling pathways in response to exposure. Integrated analysis of transcriptomes and methylomes has demonstrated the occurrence of combined defects in gene expression and methylation following toxic exposure. The period of CHD formation during embryonic development prompts us to look for epigenetic modifications during prenatal period, as close as possible to the pathophysiological mechanisms leading to this malformation. Expected results: the multi-omics analysis applied to fetuses with non-syndromic complex CHD, combined with the characterization of occupational and non-occupational environmental exposures, will enable us to extend the etiological search for these malformations, to identify biomarkers linked to the occurrence and severity of these malformations and gain a better understanding of the pathophysiological mechanisms linked to CHD. In the longer term, this study will serve as a basis for large-scale studies to enable the development of prevention policies, based on exhaustive, multicenter cohorts. In addition, multi-omics studies could identify gene markers, by exome, transcriptome and/or methylome, which could then be studied in a targeted manner.

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