Association Analysis of Variants of and With Hirschsprung Disease Susceptibility in Han Chinese and Functional Evaluation in Zebrafish

Hirschsprung disease (HSCR) has a higher incidence in children with Down syndrome (DS), which makes trisomy 21 a predisposing factor to HSCR. and are close together on the HSCR-associated critical region of chromosome 21. Common variants of and rare variants of were implicated to be associated with sporadic HSCR. However, the submucosal neuron defect of DS mouse model could not be rescued by normalization of . We aimed to explore the contribution of and to the development of the enteric nervous system (ENS) and HSCR susceptibility. We genotyped 133 tag single-nucleotide polymorphisms (SNPs) in and gene region in 420 HSCR patients and 1,665 controls of Han Chinese. Expression of and homologs was investigated in the developing gut of zebrafish. Overexpression and knockdown of the homologs were performed in zebrafish to investigate their roles in the development of ENS. Two SNPs, rs430255 ( = 0.0052, = 1.36, 95% CI: 1.10-1.68) and rs2837756 ( = 0.0091, = 1.23, 95% CI: 1.05-1.43), showed suggestive association with HSCR risk. Common variants in were not associated with HSCR risk. We observed , , and expression in the developing gut of zebrafish. Knockdown of , , and caused a reduction of enteric neurons in the hindgut of zebrafish. Overexpression of and had no effects on neuron number in the hindgut of zebrafish. Our results suggested that common variation of contributed to HSCR risk in Han Chinese. The dysfunction of both and caused defects in enteric neuron, indicating that and might play functional roles in the occurrence of HSCR. These novel findings might shed new light on the pathogenesis of HSCR.