PDE4D and bipolar disorder: First, we examined the effect of a) six novel variants shown here to exert an effect in cis on DISC1 expression b) three common missense variants R264Q (rs3738401), L607F (rs6675281) and S704C (rs821616), c) the 3 SNPs, rs1538979, rs821577 and rs821633, reported to show interplay conferring ‘risk’, ‘neutral’ and ‘protective’ effects on schizophrenia and bipolar disorder [10] and d) variants previously reported as associated with schizophrenia or related psychotic traits in European cohorts for the DISC1 interactors NDE1, NDEL1, PDE4B and PDE4D.