A genetic association among autism and the TrkB gene (Correia et al., 2011), abnormal blood BDNF levels in children with autism (Nelson et al., 2001; Miyazaki et al., 2004; Connolly et al., 2006; Iughetti et al., 2011), and increased BDNF protein expression in postmortem brain tissue of autistic individuals (Perry et al., 2001; Garcia et al., 2012) suggests that BDNF/TrkB signaling plays a role in the pathophysiology of autism. This evidence concerns the gene BDNF and autism.