In vascular tissue, for instance, the ADBR2 receptor regulates vasodilation and in healthy myocardium it regulates chronotropic and inotropic responses to endogenous and exogenous adrenergic agents (Brodde and Michel, 1999). The Arg16Gly and Gln27Glu polymorphisms are both associated with vasodilator responsive- ness (Brodde, 2008b) and thus can be connected with cardiovas- cular events. Prior studies, however, are not in agreement on which specific variants of these polymorphisms are associated with enhanced vasodilation (Brodde, 2008b). Our findings are in line with earlier epidemiologic studies that support the protective effect of the Glu27 allele on risks of MI, as documented both in longitudinal population-based studies (e.g., the Cardiovascular Health Study (Heckbert et al., 2003)) and in case–control studies (e.g., Sala et al., 2001).

Thus, the derived Gln27 allele was selected during evolution because of its favorable role for certain (unknown) conditions beneficial for the early life. However, this advantageous effect appears to be not relevant for the oldest-old ages—which follows from the change of the favorable role of the Gln27 allele to an unfavorable one (Fig. 3). This unfavorable role is the result of a survival disadvantage for carriers of the derived Gln27 allele and, respectively, a survival advantage for carriers of the ancestral Glu27 allele associated with the late-life health conditions. Given unknown forces driving the evolutionary advantage of the Gln27 allele (that deserves further exploration), the entire biochemical mechanism relevant to the observed opposite genetic effects at different ages is unclear. It is clear, however, that in part it should be related to cancer- and CVD-specific pathways (discussed in the previous section). It is worth noting that these finding are in line with an apparently antagonistic effect of genetic variants of the ADRB2 gene on hypertension (Bao et al., 2005) and cognition (Bochdanovits et al., 2009) in early and late life with some indications on a putative role of the white matter integrity in the splenium (Penke et al., 2010).

both fibroblast and endothelial cells proliferation (Iaccarino et al., 2005) and has been linkedto inhibitingcellular immunityin cancer (Uotila, 1996). Recent studies also suggest a novel molecular pathway involving ADRB2 in the process of malignant transfor- mation. This pathway is associated with repression of the ADRB2 gene expression by a Polycomb group protein (EZH2) that promotes prostate cells invasion (Thompson, 2007; Yu et al., 2007). Dysregulation of EZH2 has previously been linked to a number of cancers, including melanoma, lymphoma, breast and prostate cancers (Bracken et al., 2003; Varambally et al., 2005; Visser et al., 2001; Yu et al., 2007). Recent studies have also demonstrated a potential mechanism connecting behavioral stresses and certain types of cancer that includes ADRB2 mediated activation of the tumor cell cAMP-protein kinase A signaling pathway (Thaker et al., 2007). Epidemiological case–control studies have shown that carriers of the ADRB2 Glu27 allele could be protected against breast cancer (Huang et al., 2001) and that the Gly16 allele could be protective against lung cancer (Wang et al., 2006), which is broadly in line with our finding of favorable effect

Our results also add to the discussion on replication of genetic associations in independent samples. Replication is sometimes viewed as a ‘‘gold standard’’ in the era of genome-wide association studies given relevant statistical and technological issues (McCarthy et al., 2008; Ziegler et al., 2008). Only a few candidate

 (B)       (D)Glu?”             ge 2> gae eae |= 8RK & 2von VonQQ es [an: i —es | 2 ~. a8Cc©oO2>N~~SSVvnalS =a  01uomodold0.80.60.40.2Gin??NND.zDNID.Ud 2UIDGin? Glu?”NS.2NID,nid.2UI9.uld2ID.°

Fig. 4. Proportions of carriers of the Gln27Gln, Gln27Glu, and Glu27Glu genotypes in different samples. (A) The entire sample (All) and a subsample of young-old individuals (aged <65 years at the end of follow up in the year 2007. (B) Samples of short-lived (LS  ae 72 years) and long-living (LS > 72 years) individuals. LS denotes life span. (C) Samples of short-lived individuals as in (B) but with history of cancer (Yes) and without it (No). (D) The same as in (B) but for cut-off at 83 years. Bars show 95% confidence interval.

phenotypes. This is in line with increasingly recognized sensitivity of the effect of common polymorphisms to local environment or/ and genetic heterogeneity (Zintzaras et al., 2008). The latter factors can even selectively alter the effect of specific polymorphisms not affecting the others even if they are in the same gene and are in modestly strong LD (Kulminski et al., 2010)).

longevity-associated genes, among many others, have been replicated thus far in two or more human studies, including APOE (see e.g., Christensen et al., 2006; Salvioli et al., 2006), CETP (Barzilai et al., 2003; Koropatnick et al., 2008), and FOXO3A (Flachsbart et al., 2009; Willcoxet al., 2008a). The question is if lack

Replication in independent samples implies that the effects of the respective genetic variants can: (i) have smaller chances of being an artifact of a particular procedure (e.g., technology, genotyping, sampling, etc.), (ii) be weakly sensitive to population heterogeneity and, consequently, have a stronger systemic component, and (iii) have strong but the same-type sensitivity to population heterogeneity in all studied samples. Therefore, lack of replication might be informative, because this could indicate differences in sensitivity to population heterogeneity in different samples, i.e., provide clues on factors affecting possible discor- dance.