Along the same line, recent data from in vivo [11C]PBR28 positron emission tomography (PET) brain imaging of the 18-kDa translocator protein (TSPO), a biomarker of microglia activity in humans [191], demonstrate lower rather than higher TSPO availability in prefrontal-limbic regions in PTSD patients [186]. The gene discussed is TSPO; the disease is post-traumatic stress disorder.