Additionally, the increased risk of DD occurrence was associated with the T/T‐C/A combined genotype of c.‐173A>T—TPH1 and c.‐1449C>A—TPH2 (rs10488682 versus rs7963803); however, the T/A‐C/C genotype decreased the risk depression occurrence. The gene discussed is TPH2; the disease is major depressive disorder.