TPH1 and Stroke: Moreover, we found that the T/T-T/A, C/C-T/A, C/C-A/A genotypes of c.975-7T > C– KAT2 (rs1480544) and c.-1668T > A – TPH1 (rs623580) increased the risk of stroke about threefold (p = 0.016), fourfold (p < 0.001) and 27-fold (p < 0.001), respectively.