common exonic SNPs were found. The two SNPs most strongly associated with longevity, FOXO3A rs1935949 and rs4946935, lie in intron 3, 1.7 kb from the intron–exon boundary of the 3¢UTR, but not in an area of evolutionary conservation (Fig. 2D).

We observed a borderline effect of sex on the FOXO3A rs1935949 SNP association with longevity, suggesting a stronger effect of female sex (OR = 0.72, 95%CI = 0.52–0.99, P = 0.049), as also seen when comparing the odds ratio for association with longevity between the mixed-sex (OR = 1.24, 95%CI = 1.09–1.41) and female-only subsets (OR = 1.35, 95%CI = 1.15–1.57). When restricted to female subjects, the association of FOXO3A rs1935949 and rs4946935 with longev- ity in the meta-analysis achieved statistical significance (adjusted P-values were 0.0093 and 0.019 respectively).

Interaction analyses

We included four SNPs in the replication genotyping that were not individually associated with longevity in SOF, but had a significant association with longevity in interaction analyses with another SNP. Two IGFBP5 SNPs (rs3770472 and rs11575134) had significant interactions with GHR SNP rs2940935 in SOF (both P < 0.00004); these interactions appeared to replicate in the AJC study (P = 0.012 for rs3770472 and 0.026 for rs11575134), but not in the CHS cohort. SNP rs1009728 was included in the replication genotyping because of a significant interaction with a SNP in PIK3R1, but this latter SNP could not be genotyped in the replication cohorts.

Next, we evaluated the association with longevity for the repli- cated SNPs in a genotypic model (Table 4). For AKT1 rs3803304, theassociation with longevity appeareddrivenbythe minorallele homozygous genotype (CC). Subjects homozygous for the minor allele were underrepresented among long-lived cases (OR = 0.41–0.5, P = 0.00016 in the meta-analysis). A single allele did not confer a significant effect (P = 0.12), suggesting a recessive effect, with homozygosity for the minor allele decreasing the probability of longevity. For the two FOXO3A SNPs, the effect appeared to be consistent with a multiplicative model; the proba- bility of surviving to exceptional longevity increased with each additionalcopyoftheminorallele.Resultsweresimilarwheneval- uated in women only (rs1935949: CT, OR = 1.33 (1.08–1.63), P = 0.067;TT,OR = 1.82(1.25–2.65),P = 0.0017).

Association of lifespan-associated SNPs with cause- specific mortality

We evaluated associations of the longevity-associated SNPs with reported cause of death in SOF and CHS (Table 5). AKT1 rs3803304 was associated with deaths due to cardiovascular disease and deaths from noncardiovascular, noncancer causes. The FOXO3A SNP rs4946935 was associated with cardiovascular causes of death in SOF and with noncardiovascular, noncancer other causes of death in CHS. The FOXO3A SNP rs1935949 was associated with cardiovascular and cancer causes of death in SOF, and with other causes of death in CHS.

Follow-up of significant findings in AKT1 and FOXO3A

Complete coverage (at r2 > 0.8) of common variation in both AKT1 and FOXO3A based on HapMap Caucasians (CEU) has been achieved (Fig. 2A, Fig. S1).

Discussion

We have comprehensively evaluated common variants in 30 genes in the insulin/IGF1 signaling pathway for their

The longevity-associated AKT1 rs3803304 SNP is not in LD with any other HapMap SNPs (Fig. 2A). Therefore to follow-up,