Multi-omic analysis identifies a multi-step pathology in a case of multiple chorangioma syndrome in monochorionic twins.

BackgroundChorangiomas, benign proliferative capillary lesions in the placenta, occur in approximately 1% of births, typically as a solitary nodule. In rare cases, multiple nodules develop, posing risks of fetal heart failure, hydrops fetalis, and intrauterine death due to altered placental hemodynamics. Although genetic and hypoxic factors have been hypothesized to drive aberrant angiogenesis, definitive evidence has been lacking. We report on a unique case of multiple chorangiomas in half of a shared placenta in monozygotic, monochorionic diamniotic (MCDA) twins, providing an unprecedented opportunity to explore impacts that molecular variation has on chorangioma formation. ResultsWhole genome and bulk RNA sequencing supported identification of early embryonic or germline and somatic variation. It revealed a likely pathogenic heterozygous frameshift deletion in EPAS1, a hypoxia-sensing transcription factor, with an early embryonic or germline origin. This variant likely impaired placental oxygen regulation and angiogenesis through its impact on VEGF-related pathways. Deleterious somatic mutations in COL1A1, FBXO11, and TRIM71 were observed within the chorangioma-affected tissue, along with increased expression of Leptin and DNA damage signatures consistent with oxidative stress. In contrast, the unaffected twins placental territory showed a different pattern of pathogenic somatic variation with the presence of a known pathogenic variant in MUTYH and signs of repair deficiencies. These findings highlight the presence of predisposing events and distinct molecular processes within each domain of the shared placenta. We propose that these molecular events, combined with environmental factors intensified by the MCDA pregnancy, likely contributed to chorangioma development.. ConclusionsOur study provides novel insights into the molecular basis of multiple chorangioma syndrome. To our knowledge, this is the first molecular evidence implicating both germline and somatic genetic involvement in this condition. The identification of molecular signatures previously associated with malignancy suggests that chorangiomas may share pathways with oncogenic processes. These findings highlight the importance of considering both genetic and environmental interactions in placental pathologies, offering potential implications for understanding and managing complex vascular and placental conditions, including preeclampsia, intrauterine growth restriction, and fetal vascular malperfusion.