MCTP1 and Behcet disease: Our evidence identifies the striatum as a point of convergence between three of our candidate genes, MCTP1, RXRG, and TNR. The striatum is a relevant brain region in BD, since the diagnostic symptoms of mania include increased risk-taking and deficits in goal regulation (Johnson, 2005; Goodwin and Sachs, 2010), and the striatum is involved in both of these (Balleine and O'Doherty, 2010; Bartra et al., 2013; Mason et al., 2014).