PARP1 and post-traumatic stress disorder: Further TDA mapping of TBI severity, PTSD Checklist-Civilian Version (PCL-C), and GOS-E outcome measures revealed that among patients lacking visible damage on CT scans, a time-dependent increase in functional impairment was predicted by the presence of the A/T SNP of PARP1, a gene associated with cellular stress and injury response signaling pathways.