TNFRSF21 and depressive symptom measurement: The TNFRSF21 gene has been found to be differentially expressed in PTSD [43, 44], including in postmortem brain samples in orbitofrontal cortex and dorsal anterior cingulate cortex regions [17], and genetic variants within this gene have emerged in genome-wide association studies of panic disorder [45] and depression [46, 47].