MACROD2 and attention deficit-hyperactivity disorder: There is a large body of evidence for associations of intronic variants in MACROD2 with complex psychosocial, neurological, and psychiatric traits, including: attention deficit hyperactivity disorder [45, 46], morningness (being a morning person) [47], risk-taking behavior [48], eating disorders [49], autism [50–52], and bipolar disorder [52, 53].