Apolipoprotein E in Southern Italy: protective effect of epsilon 2 allele in early- and late-onset sporadic Alzheimer's disease.

Apolipoprotein E (apoE) polymorphism was evaluated in 81 sporadic late onset Alzheimer's disease (LOAD) patients, 28 sporadic early-onset Alzheimer's disease (EOAD) and 92 sex- and age-matched healthy controls from Apulia, Southern Italy. ApoE genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism method. The frequency of apoE epsilon 4 allele was significantly higher in EOAD patients than in the control group, but not in LOAD patients. Furthermore, EOAD patients carrying epsilon 4 allele had lower age at onset of AD symptoms (about 4. 5 years). In the whole sample, epsilon 4 was associated to AD by an odds ratio of 2.14, while it increased up to 6.55 in < 65 years old subjects. Finally, in both < 65 and > or = 65 subgroups of subjects, epsilon 2 played a protective role against the development of AD. It is concluded that the geographic decreasing trend of epsilon 4 allele and the age at onset may influence the association of apoE polymorphism with sporadic AD in a Southern Italian sample.