TPH1 and Stroke: On the other hand, the T/T-G/T and T/A-G/T genotypes of the same combinations diminished the risk of the disease more than 20-fold (p < 0.001) and more than twofold (p = 0.004), respectively Additionally, the presence of the T/T-C/C and T/A-C/A combined genotypes of the c.-1668T > A – TPH1 (rs623580) and c.-1449C > A – TPH2 (rs7963803) polymorphisms reduced the risk of stroke development, whereas the T/A-C/C and A/A-C/C genotypes were linked with an increased risk of the disease.