Based on these findings, our previous investigation further explored the genetic association between CHF and certain polymorphisms in histidine decarboxylase (HDC) gene, which encodes the only rate-limiting enzyme in histamine synthesis, and found that the HDC rs17740607 polymorphism decreased the enzyme activity of HDC, lowered the plasma histamine levels, and was significantly associated with CHF risk [6], which further strengthened the evidence of histamine involvement in CHF. The gene discussed is HDC; the disease is congestive heart failure.