RET and Hirschsprung disease: Moreover, several GWAS have shown an epistatic combined effect of SNPs of NRG1 and RET, highlighting the potential interplay between common variants of NRG1 and RET in the genetic etiology of HSCR(Phusantisampan et al., 2012; Gui et al., 2013; GunadiKapoor et al., 2014; GunadiIskandar et al., 2019).