XBP1 and bipolar disorder: For example, 10 genes among the 16 confirmed genes (Cacng2, Dnajc3, Dusp4, Gpc6, Mbp, Nov, Phf21b, Atxn10, Xbp1, and Zfyve28) have their human orthologs located within a 10 Mb region flanking the linkage markers for bipolar disorder [30], and thus merit further study.