The G/G-A/T and G/G-T/T genotypes of c.-1493G>C – IDO1 (rs10089084) and c.-173A > T – TPH1 (rs10488682) caused an increase of the risk of stroke, whereas the C/C-A/T and C/C-T/T genotypes of the same combined polymorphisms brought about a reduction of this risk. Here, IDO1 is linked to stroke disorder.