Given that the proBDNF/p75NTR/sortilin pathway and the mBDNF/TrkB pathway acts in an opposing way in the pathogenesis of alcohol dependence, we then analysed the relative ratio of lymphocyte proBDNF (detected by western blot) to the serum mBDNF protein level (detected by ELISA assay) in both alcohol dependence group and control groups. This evidence concerns the gene BDNF and alcohol dependence.