Patients with traumatic brain injury (TBI) are at an increased risk of developing chronic neurodegenerative diseases, including Alzheimer's disease (AD) [2], an association thought to be related to several factors, including altered production and clearance of apolipoprotein E (ApoE) and amyloid-β (Aβ) [3, 4]. The gene discussed is APOE; the disease is early-onset autosomal dominant Alzheimer disease.