Apolipoprotein E (APOE = gene, apoE = protein) plays a central role in plasma lipoprotein metabolism and in lipid transport within tissues. The APOE shows a genetic polymorphism determined by three common alleles, APOE*2, APOE*3, APOE*4 and the product of the three alleles differs in several functional properties. APOE is involved in the development of certain pathological conditions. In particular, the APOE*4 allele is a risk factor for susceptibility to coronary artery disease (CAD) and Alzheimer's Disease (AD). In the present study we analyzed the APOE allele distribution in the world. The APOE*3 is the most frequent in all the human groups, especially in populations with a long‐established agricultural economy like those of the Mediterranean basin (0.849–0.898). The frequency of APOE*4, the ancestral allele, remains higher in populations like Pygmies (0.407) and Khoi San (0.370), aborigines of Malaysia (0.240) and Australia (0.260), Papuans (0.368), some Native Americans (0.280), and Lapps (0.310) where an economy of foraging still exists, or food supply is (or was until the recent past) scarce and sporadically available. The APOE*2frequency fluctuates with no apparent trend (0.145–0.02) and is absent in Native Americans. We suggest that the APOE*4, based on some functional properties it has and on its distribution among human populations, could be identified as a ‘thrifty’ allele. The exposure of APOE*4 to the contemporary environmental conditions (Western diet, longer lifespans) could have rendered it a susceptibility allele for CAD and AD. The absence of the association of APOE*4 with CAD and AD in Sub‐Saharan Africans, and its presence in African Americans, seems to confirm this hypothesis.

Background: Many studies have shown that estrogen replacement therapy may improve cognitive function in women and reduce the risk of Alzheimer’s disease (AD). Because most of the estrogen neuroprotective effect is mediated by receptors, we studied the associations between estrogen receptor α (ESR1) polymorphisms (PvuII and XbaI) and AD, and their interactions with apolipoprotein E (APOE) polymorphism and plasma levels. Methods: ESR1 genotypes and APOE plasma concentrations were determined in a sample of AD patients and controls. Results: ESR1 PP and XX genotypes were associated with an increased risk for AD only in males (OR = 3.6, 95% CI = 1.2–10.9) and conferred a relevant additional risk of AD to subjects also carrying APOE e*4 allele (OR = 13.3, 95% CI = 1.7–103.6). Mean APOE concentrations were lower in AD patients; the lowest levels were observed in male patients carrying PP and/or XX genotypes (p = 0.006) and in patients carrying PP and/or XX genotypes together with the e*4 allele (p = 0.003). In AD women, ESR1 PP and XX genotypes were also associated with lower MMSE values (p = 0.0007). Conclusion: The present data suggest that the involvement of ESR1 polymorphisms in AD onset is mediated by the regulation of apoE expression. ESR1 polymorphisms are also associated with a faster cognitive decline in the women AD patients.

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Several factors are believed to give rise to the late onset sporadic form of Alzheimer's disease (LOAD). We have studied the variation at the genes of three enzymes of the cholinergic system: acetylcholinesterase, butyrylcholinesterase, and choline acetyltransferase. The single nucleotide polymorphisms (SNPs) examined were: AChE rs2571598, BChE rs1355534, BChE rs1803274, and ChAT rs2177369. The sample for the case-control study was 471 LOAD patients aged 60 years or older, and 254 subjects with no neurodegenerative disorders as the control group. A significant difference in the genotype distribution between patients and controls was observed only for ChAT rs2177369, showing that the G/G genotype was to be considered a risk factor with respect to the G/A + A/A genotypes (odds ratio = 1.56; 95% Confidence Interval = 1.10-2.22; P = 0.01). Though indicating a significant association with AD onset, our results are far from definitive since contrast with the ones reported by other authors in a previous case-control study, and call for further investigations. Among patients, 171 took part in an observational study concerning the possible role of the genetic composition on the efficacy of treatment with Donepezil and Rivastigmine. We related the SNPs of the above cited genes with cognitive status measured by MMSE. Carrying an allele or a genotype of these SNPs does not seem to play a relevant role in the response to treatment with the two cholinesterase inhibitors, though some significant results were found associated with the AChE A/A genotype that had the best response when treated with Rivastigmine.

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