errors thus suggesting that these are real associations and not artifacts.

To further test the generalizability of these results to other independent groups, we evaluated these associations in the AJCS and the JCS, using a combination of proxy SNPs typed with the Affymetrix platforms and SNPs in Table 3 typed with more traditional techniques (See methods). Table 4 summa- rizes the results of the replication study of 4 of the 5 SNPs and one additional proxy SNP is in Table 5. None of these SNPs in ADARB1 replicates the results in the NECS and SICS samples although the significant association of the SNP rs17004734 that is within 2Kb from rs414743 is consistent with the presence of longevity associated variants in the region. Because the SNPs used in the NECS and SICS are chosen to best capture the genetic variations of Caucasians from the HapMap, they may not be the correct choice for this founder population and indeed Figure 1 shows a different pattern of LD in ADARB1 in the AJCS subjects. All ADARB1 SNPs in Table 3 and two additional proxy SNPs were genotyped in the JCS subjects and Tables 6 and 7 summarize the results. The last three SNPs in Table 6 show effects that are consistent with the NECS and SICS subjects but do not reach statistical significance, even when the data from the three studies are aggregated. Figure 3 shows the posterior densities of the ORs for the three rare SNPs that are suggestive of association but would need much larger sample sizes to reach statistical significance. The association of two proxy SNPs for rs2838816 in Table 7 is again consistent with the presence of longevity

Association of ADARB1 with Exceptional Longevity

We examined the associations of 31 SNPs in ADARB1 in the NECS and SICS samples using recessive and dominant models with Bayesian logistic regression [32]. The details of the statistical analysis are in the Methods and the significant results are summarized in Table 2 that provides the physical positions and allele frequencies derived from the HapMap for these SNPs, and Table 3 (rows 14–15). Five SNPs in ADARB1 are strongly associated with extreme old age in the NECS, and the association of SNP rs414743 remains significant even after imposing stringent corrections for multiple comparisons (Bayesian signif- icance ,0.05/145 = 0.00035 where 145 is the overall number of SNPs included in this analysis). The five SNPs tag one region of strong linkage disequilibrium (LD) of the gene (Figure 1). None of the SNPs reached statistical significance in the SICS although the three SNPs rs2838809, rs2838810 and rs2838816 exhibited consistent associations in terms of odds ratios and allele frequencies and, when the NECS and SICS data were combined, the three SNPs remained statistically significant. These three SNPs have extreme minor allele frequencies in the NECS centenarians (MAF,0.01), while the allele frequencies in the controls are very close to referent allele frequencies from the HapMap (Table 3). Figure 2 displays the scatter plot of genotype intensities generated from BeadStudio that rules out genotyping

Table 2. Summary of selected SNPs.

Risk versus Row SNP Chr position referent alleles CEPH JPT 1 rs10903420 10 1333726 AA v AG/GG 0.327 0.058 2 rs1007147 10 1341088 AA v AG/GG 0.312 0.091 3 rs2805562 10 1357514 AA v AG/GG 0.15 0.058 4 rs884949 10 1361610 AA v AC/CC 0.124 0 5 rs2805533 10 1374633 AA/AG v GG 0.77 0.92 6 rs2387653 10 1397826 AA v AG/GG 0.097 0 7 rs2805535 10 1450432 AA v AG/GG 0.699 0.151 8 rs2805543 10 1454892 AA v AG/GG 0.46 0.105 9 rs3898610 10 1474759 AA v AG/GG 0.841 0.686 10 rs1533484 10 1481339 AA/AG v GG 0.442 0.791 11 rs2676192 10 1495474 AA v AG/GG 0.301 0.419 12 rs2387952 10 1657365 AA v AG/GG 0.69 0.616 13 rs17294019 10 1659347 AA/AG v GG 0.196 0.012 14 rs3788157 21 45335136 AA v AG/GG 0.63 0.65 15 rs414743 21 45336503 AA/AG v GG 0.47 0.31 16 rs2838809 21 45445866 AA v AG/GG 0.009 0 17 rs2838810 21 45447751 AA/AG v GG 1 1 18 rs2838816 21 45454470 AA v AG/GG 0.009 0

List of 18 SNPs —13 in the gene ADARB2 (10p15.3) and 5 in the gene ADARB1 (21q22.3) — that are associated with exceptional longevity with either dominant or recessive models. The table reports a sequential number for easy identification in the other tables and figures (column 1), the SNP identifier from dbSNP (column 2), chromosome and physical position from the human genome NCBI Build 36.3 (columns 3 and 4), the risk versus referent alleles that were associated with exceptional longevity using dominant and recessive models (column 5), the frequencies of the risk allele in the HapMap CEPH and JPT. Note that several of alleles in the Japanese group have allele frequencies that change substantially from the CEPH, and the SNPs in rows 4 and 6 become monomorphic. doi:10.1371/journal.pone.0008210.t002