APOE and early-onset autosomal dominant Alzheimer disease: The APOE ε4 allele is associated with an increased risk of Alzheimer's disease, exacerbation of disability in multiple sclerosis, and a higher incidence of late‐onset post‐traumatic seizures in individuals with moderate to severe brain injuries.[8] The APOE gene encodes the APOE protein, which is primarily produced by astrocytes in the brain.[7, 9] Chen et al.