Apolipoprotein E4: an allele associated with many diseases

Apolipoprotein E (apoE) was discovered as a plasma protein involved in lipo protein metabolism. ApoE is synthesized by the liver and is also made local ly in the brain. There are three common variants of apoE, resulting from co mmon genetic variation, called E2, E3 and E4. The E3 allele is the most pre valent form, and the proportion of the three alleles differs between popula tions. Epidemiological studies have found that the E4 allele is associated with decreased longevity, increased plasma cholesterol levels and increased prevalence for cardiovascular disease and particularly for Alzheimer's dis ease. The apoE polymorphism also affects response to head trauma, cognitive decline upon ageing and several other disorders. Thus, common genetic vari ation in the apoE gene may be associated with successful ageing.