ICAM2 and attention deficit-hyperactivity disorder: Several genes identified in DGE and pathway analysis are implicated in human ADHD and ND (ANK3, CALD1, CHRNA4, CHRNA7, CMTM8, DLG4, DUSP6, GNG3, GNG11, GRIK5, GRINA2, GRM5, ICAM2, KCNJ6, MAPK1, PRKAB1, PRKAG2, SNAP25, SYNPO, SYT1, VAMP2).