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Kids First: The Genomic Architecture of Hirschsprung Disease (HSCR)


Hirschsprung disease (HSCR) is a male biased developmental disorder associated with a lack of innervation of the gastrointestinal tract. Genetic studies have been instrumental in understanding its multifactorial inheritance, high heritability, syndromic associations, and genetic heterogeneity with variable penetrance and expressivity. At least 24 genes and 9 loci with pathogenic alleles (PAs) are known to underlie HSCR pathogenesis and explain 62% of its population attributable risk (PAR). Despite this heterogeneity, there is functional unity in HSCR: ~53% of HSCR PAs disrupt RET and EDNRB signaling in the developing enteric nervous system (ENS) in which 11 genes comprising a gene regulatory network control RET and EDNRB gene expression. We propose to identify the remaining 30% PAR by studying 857 unrelated HSCR cases, their 125 affected and 1,446 unaffected firstdegree relatives by whole genome sequencing to increase statistical power of gene discovery through improved detection of all types of coding and regulatory PAs. HSCR arises from cell autonomous defects in enteric neural crest cell precursors (ENCCs) affecting their proliferation, differentiation and migration in the ENS, functional studies that will guide our detection of novel genes.