The past year has seen widespread confirmation that the epsilon 4 allele of the apolipoprotein E gene is a major risk factor for Alzheimer's disease. The epsilon 4 allele also appears to correlate with life expectancy. This allele has been found to be present in over 50% of Alzheimer patients, regardless of whether or not they have a family history of dementia. It is not yet clear how the epsilon 4 allele mediates its actions; however, recent evidence suggests that apolipoprotein E4 may be responsible for the accelerated formation of beta-pleated amyloid from soluble beta-amyloid peptide, as is seen in the neuritic plaques of Alzheimer patients, as well as interacting with intraneuronal microtubular transport mechanisms.