BDNF and depressive symptom measurement: In summary, this study demonstrates that SNPs of the microRNA146a gene at rs2910164, ACE2 gene at rs2285666 and the SGK1 gene at rs1743963 and rs1763509, and the SNPs at the 5-HTTLPR and BDNF gene loci are associated with the onset of comorbid depression in coronary heart disease.