Genetics and brain injury: Apolipoprotein E

Apolipoprotein E (apo E) is a lipoprotein produced by astrocytes and microglia and has a proposed role in transporting lipids to injured neurons. There are three known isoforms of apo E, coded for by the APOE epsilon 2, APOE epsilon 3, and APOE epsilon 4 genes. The APOE epsilon 4 genotype has been implicated as a risk factor for Alzheimer's disease. Recent studies have suggested that APOE epsilon 4 may influence the central nervous system's response to injury. This article presents an overview of the relationship between apo E, Alzheimer's disease, and head injury and reviews recent studies implicating APOE epsilon 4 as a possible genetic determinant in recovery from head injury.