Abstract 11001: Wnt/Planar Cell Polarity Pathway Mutations Are Over-Represented in Children with Concomitant Congenital Cardiac and Cleft Malformations

Abstract

Introduction: We have demonstrated a high association between cleft lip and/or palate (CL/P) and outflow tract congenital heart disease (CHD) in the pediatric population. Despite this strong phenotypic association, the molecular genetics underlying these concomitant disease processes remains unclear. Hypothesis: Genomic profiling of concomitant outflow tract CHD+CL/P patients will unravel mutations in signaling pathways with overlapping importance in heart and palatal development. Methods: Patients with outflow tract CHD+CL/P and no previously known genetic syndromes or positive chromosomal microarrays at our institution between January 2004 and December 2018 were identified. Whole exome sequencing was performed on blood specimens collected from patients and phenotypically normal parents. Gene ontology and pathway analysis of de novo variants identified in probands was performed using PANTHER and DAVID databases and reinforced with a primary literature search. Functional assessment of non-canonical Wnt signaling variants was performed through siRNA-knockdown and wound-healing assays in murine myoblasts. Results: De novo loss-of-function mutations were observed in all 17 probands, in a total of 28 genes. Five genes (18%) have previously been implicated in both heart and palate development (CHD7, MED12, NDST1, GRHL2, SMARCA4). Three genes (11%) were mutated in more than one proband (CHD7, CELSR3, SAPCD2). Gene ontology and pathway analysis of deleterious de novo variants predicted involvement in binding (n=11, 39%), gene-specific transcription (n=9, 32%), and molecular and transcriptional function (n=8, 29%). The Wnt pathway (n=14, 50%) was the most strongly enriched signaling pathway, mutated in 10 (59%) probands, followed by Semaphorin and Endothelin signaling (n=2 variants, 7.1%, each). Knockdown of Wnt/PCP genes SAPCD2, CELSR3, and CCDC88C disrupted myoblast cellular migration in vitro, validating the functionality of these gene candidates. Conclusion: Our study is the first to characterize the genomic profile of patients with concomitant outflow tract CHD+CL/P. Excess de novo mutations in genes involved in Wnt pathway signaling suggests that this pathway plays a crucial role in CHD+CL/P disease pathogenesis.