An association of the e2 allele with aging may be explained by two hypotheses. First, the progressively increased frequency of the e2 allele with aging may have been a consequence of the disappearance in our selected healthy participants of the e4 allele, which is reported to be linked to a higher risk of age-related diseases and mortality. Notably, heterosis was observed when ACE genotypes were classified according to sex. In fact, a significant association of both I and D alleles was shown in Group 1-3 (sex-adjusted OR values = 1.581; 95% CI, 1.211-2.064 and 1.357; 95% CI, 1.048-1.759, respectively, for I and D alleles), Group 2 (sex-adjusted OR values = 0.753; 95% CI, 0.600-0.945 and 0.775; 95% CI, 0.628-0I.D. Crude Values Adjusted Values Crude Values Adjusted Values Group (N) p OR (95% CI) p OR (95% CI) p Crude OR (95% CI) p Adjusted OR (95% CI) Group 1 (n=292) 0.218 1.179 (0.907-1.533) 0.001 1.581 (1.211-2.064) 0.680 0.923 (0.630-1.351) 0.021 1.357 (1.048-1.759) Group 2 (n=629) 0.237 0.880 (0.712-1.088) 0.014 0.753 (0.600-0.945) 0.689 0.938 (0.684-1.285) 0.018 0.775 (0.628-0.956) Group 3 (n=270) 0.354 1.136 (0.867-1.487) 0.375 1.135 (0.858-1.503) 0.978 1.006 (0.674-1.500) 0.246 1.170 (0.897-1..527) Group 4 (n=153) 0..626 0..919 (0..656-1..288) .041 0..669 (0..455- .983) .547 .177(0..693-2..001 ) .010 .637( .453-.897 ) Centenarians(n=64) .550 .858( .519-1..418 ) .510 .192( .707-2..012 ) .423( .603-3..338 ) .005 2..135(1.253-3..636 ) Notes: OR - odds ratio; CI - confidence interval. 5. Shared Frequencies of Apolipoprotein E (ApoE) and Angiotensin-Converting Enzyme (ACE) Alleles in a Cohort of 1344 Healthy Elderly Persons and 64 Centenarians e2/D e4/I* Crude Values Adjusted Values Crude Values Adjusted Values Group (N) p OR (95% CI) p OR (95% CI) p OR (95% CI) p OR (95% CI) Group 1 (n=292) 0.450 1.170 (0.779-1.757) 0.353 1.274 (0.764-2.123) 0.228 1.275 (0.859-1.894) 0.031 1.690 Group 2 (n=629) 0.001 0.548 (0.381-0.789) 0.026 0.590 (0.371-0.940) 0.264 0..822( .583-1..159 ) .193 .743 Group 3 (n=270) 0..252 .762( .478-1..214 ) .932 .976( .557-1..710 ) .080( .959-2..122 ) .137(1..464 ) Group 4 (n=153) .006 1.919(1.209-3..044 ) .423 .724( .328-1..598 ) .910( .560-1..676 ) .224( .592 ) Centenarians(n=64) .0013..378(1..885-6..054 ) .0014..503(2.342-8..657 ) Not determined Not determined Notes: *No centenarian participants with e4/I were observed. OR - odds ratio; CI - confidence interval. Indeed, e4 has been defined as a frailty allele (30). The second hypothesis suggests that e2 could be a longevity-promoting allele, functioning independently from other ApoE alleles. This hypothesis is supported by our findings showing that the frequency of e3 did not change with advancing age, as would be expected if the e2 increase was due to e4 disappearance in the oldest age group. Indeed, an unchanged e3 allele frequency across age has been reported to be an important prerequisite in carrying out genetic association studies on aging (31). Considering a sample of healthy individuals, we greatly reduced the number of these variables. Alleles with age, were observed in Groups 1, 2, and 4. Heterosis occurs when heterozygotes show either a greater or lesser association with a phenotypic trait than do homozygotes or the wild type. Until now, this genetic phenomenon has not been described in ACE polymorphism and may proveAround the world, there have been several studies conducted on the relationship between genetics and aging. One such study was done by Louhija et al. (1995) which found that the apolipoprotein E phenotype is relatively lost in centenarians. Other studies have also found a decreased frequency of the apolipoprotein E epsilon allele from Northern to Southern Europe in Alzheimer's disease patients and centenarians (Panza et al., 1998), but some studies have shown no association between longevity and common variations in genes associated with cardiovascular risk (Bladbjerg et al., 1999). 

There has also been research on the interaction between different genetic mutations. For example, Isbir et al. (2004) found an interaction between apolipoprotein E and angiotensin-converting enzyme genotype in Alzheimer's disease. Additionally, Agerholm-Larsen et al. (2000) conducted a study on ACE gene polymorphism and ischemic heart disease, finding different allele frequencies between the North and South of Europe. 

Furthermore, there have been studies on risk factors for vascular dementia and cognitive decline in aging individuals. Solfrizzi et al. (2006) found that a high intake of monounsaturated fatty acids can protect against age-related cognitive decline, while Skoog (1998) reviewed various risk factors for vascular dementia. The Mini-Mental State examination is a practical method for grading cognitive state in patients (Folstein et al., 1975). 

In terms of methodology, there are various techniques for genotyping and analyzing genetic polymorphisms, including polymerase chain reaction and allele-specific oligonucleotide probes (Houlston et al., 1989), genotyping by one-stage PCR (Wenham et al., 1991), and sequence analysis (Emi et al., 1988). 

Overall, these studies provide insight into the complex relationship between genetics and aging.