DRD2 and post-traumatic stress disorder: After applying a combination of general linear models and machine learning-driven topological data analysis (TDA) to explore relationships among variables contained within the TBI-CDE, the authors reported enrichment of COMT Val158Met, along with five other gene variants (DRD2, PARP1, and three ANKK1 SNPs), in a subset of mTBI participants with PTSD diagnoses and worsening Glasgow Outcome Scale—Extended (GOS-E) scores from three to 6 months post-injury.