In the case of the c.-1493G > C – IDO1 (rs10089084) and c.*456G > A– KAT1 (rs10988134) combined genotypes, we found that G/G-G/G and G/G-G/A were associated with a more than fourfold increase of the stroke risk, while the C/C-G/G combined genotype of the same polymorphisms was associated with an increase of this risk by about 10 times (p < 0.001). Here, IDO1 is linked to Stroke.