NAB2 and constipation disorder: In this study, GFs and their receptors, including pro-HB-EGF, VEGF121, PDGF-AA, NGFI-A-binding protein 2, FGF7, IGF-1, TGF-βRII, and VEGF sR2, causally associated with constipation were screened; the causal association between pro-HB-EGF and TGF-βRII and constipation was the most significant (p < 0.01).