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Background: Apolipoprotein E (apo E) is a protein associated with plasma lipoproteins. Apo E polymorphism has been related to significant modifications of lipoprotein profile, as well as to the incidence of different pathologies including cardiovascular disease, Alzheimer's disease, and vascular dementia. Furthermore, it was proposed that apo E polymorphism might be involved in the aging selection process.Objective: The purposes of the present study were the following: (1) to evaluate apo E polymorphism in 'successful' and 'unsuccessful' aging, defined as the absence or presence of disability and severe chronic diseases (mainly cardiovascular disease and dementia), respectively; (2) to evaluate the impact of apo E polymorphism on plasma lipids in very old individuals free of or affected by disability.Methods: 253 Italian subjects including 100 free-living healthy octo- and nonagenarians, 62 disabled octo- and nonagenarians, and 91 healthy adult controls, all matched for origin were studied. Apo E phenotypes were determined by PhastSystem (Pharmacia). Lipoprotein parameters (total cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, lipoprotein (a), and apoprotein A-I and B) were measured by standardized methods. ADL were evaluated by the Katz index.Results: The frequency of sigma2, sigma3, and sigma4 alleles was 0.062, 0.887, and 0.051 respectively in the entire sample; no differences in alleles distribution were found between the three groups. When the subjects were divided according to the E type (E2 type: E2/E2 and E2/E3; E3 type: E3/E3; E4 type: E3/E4 and E4/E4), no differences in lipoprotein parameters emerged, but a trend toward higher total and LDL-cholesterol from the E2 to the E4 type was observed. The sigma4 allele had a raising effect, while sigma2 had a lowering effect on total cholesterol levels, but these effects were much less profound in the disabled octo- and nonagenarians.Conclusions: We conclude that (1) the frequency of the sigma4 allele is very low in this sample of subjects from central Italy; (2) no differences emerged in sigma4 distribution between healthy and disabled octo- and nonagenarians, and adult controls; the very low frequency of sigma4 allele might contribute to this finding; (3) our data do not support the hypothesis of a possible association between apo E polymorphism and longevity or disability in this population. [ABSTRACT FROM AUTHOR]