Novel insights into the genetic landscape of congenital heart disease with systems genetics.

We recently conducted a large-scale mouse mutagenesis screen and uncovered a central role for cilia in the pathogenesis of congenital heart disease (CHD). Though our screen was phenotype based, most of the genes recovered were cilia-related, including genes encoding proteins important for ciliogenesis, cilia-transduced cell signaling, and vesicular trafficking. Also unexpected, many of the cilia related genes recovered are known direct protein-protein interactors, even though each gene was recovered independently in unrelated mouse lines. These findings suggest a cilia-based protein-protein interactome network may provide the context for congenital heart disease pathogenesis. This could explain the incomplete penetrance and variable expressivity of human CHD, and account for its complex non-Mendelian etiology. Supporting these findings in mice, a preponderance of cilia and cilia related cell signaling genes were observed among de novo pathogenic variants identified in a CHD patient cohort. Further clinical relevance unfolded with the observation of a high prevalence of respiratory cilia dysfunction in CHD patients. This was associated with increased postsurgical respiratory complications. Together these findings highlight the importance of cilia in CHD pathogenesis and suggest possible clinical translation with instituting pulmonary therapy to improve outcome for CHD patients undergoing congenital cardiac surgeries.