TPH2 and depressive symptom measurement: In the case of c.803+221C>A—TPH1 (rs1800532) and c.‐844G>T—TPH2 (rs4570625), the C/A‐G/G combined genotypes were associated with the risk of depression higher by nearly four times (P < 0.001), while the C/A‐G/T combined genotypes of the same polymorphism combination decreased this risk by more than three times (P < 0.001).