CSNK1E and bipolar disorder: Perhaps the most convincing evidence so far has emerged from bipolar disorder with some evidence of association with period homolog 3 (Drosophila) (PER3), ARNTL[36], basic helix-loop-helix family, member e40 (BHLHE40), casein kinase 1, epsilon (CSNK1E), and CLOCK[40].