Emerging biomarkers such as NfL, S100B, tau, and NSE provide valuable insights into axonal injury and post-traumatic neurodegeneration, supporting a pathophysiological continuum between acute TBI and chronic neurodegenerative disorders, including Alzheimer’s disease and chronic traumatic encephalopathy (CTE). The gene discussed is S100B; the disease is early-onset autosomal dominant Alzheimer disease.