While a role for the BDNF peptide and its receptor, TrkB, have been well established in auditory fear conditioning (Rattiner et al., 2004; Choi et al., 2010; Andero et al., 2011), additional insight into the epigenetic mechanisms regulating the BDNF pathway and its role in PTSD have been investigated by a number of groups. Here, NTRK2 is linked to post-traumatic stress disorder.