CHRNA3 and schizophrenia: In healthy subjects, the effects of the rs1051730 and rs1317286 polymorphisms of the CHRNA3 gene on PPI were described by a linear trend (CC>CT>TT and AA>GA>GG, accordingly), while a significant quadratic trend was observed in patients with schizophrenia with regard to the maximum values of PPI in CT/GA heterozygotes (Petrovsky et al., 2010).