Table 1. Characteristics of Study Populations

p Value Offspring vs Control Probands Offspring Controls p Value N ¼ 118 N ¼ 228 N ¼ 78 Probands vs Controls* y z Female 74 50 63 .10 .06 .06 y 98.0 (0.3) 68.0 (0.5) 75.6 (1.2) ,.0001 ,.0001 ,.0001 range, y 95–106 50–92 51–94 lg/mL 17.0 (0.8) 12.8 (0.5) 12.5 (0.8) .01 .75 .02 kg/m2 22.4 (0.3) 26.3 (0.3) 25.3 (0.4) ,.0001 .11 .59 fat, % 25.2 (0.8) 29.2 (0.5) 30.8 (0.9) ,.0001 .13 .58 mg/dL 177 (3.0) 206 (2.8) 196 (4.4) .0007 .08 .14 mg/dL 116 (4.4) 154 (6.8) 119 (5.8) .39 .009 .005 mg/dL 114 (3.3) 116 (2.4) 114 (4.3) .97 .79 .75 mg/dL 56.7 (1.7) 61.1 (1.2) 61.3 (2.1) .02 .94 .66 LDL particle size, % of total 73.7 (2.1) 62.4 (2.0) 56.2 (3.6) .003 .13 .03 HDL particle size, % of total 61.6 (1.3) 51.3 (1.1) 51.9 (1.8) .009 .76 .99 circumference, inches 37.5 (0.3) 34.5 (0.2) 35.0 (0.2) ,.0001 .36 .06 diastolic, mmHg 139 (2), 74.3 (1) 135 (1.4), 79.3 (0.7) 138 (1.9), 77.6 (1) .85, .02 .4, .04 .17, .16 mg/dL 111 (3) 92.9 (2.2) 92.9 (3.1) ,.0001 .77 .99 syndrome, % of total 23 16 13 .017 .50 .25

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Notes: Data are expressed as mean (standard error [SE]). Crude means are shown. Triglycerides, which were not normally distributed, were ln-transformed for analysis but presented as untransformed raw values for presentation. Metabolic syndrome was defined based on the National Cholesterol Education Program (NCEP), Adult Treatment Panel III (ATP III) criteria. *p values between probands and controls adjusted for BMI and sex (adiponectin, cholesterol [mg/dL], triglycerides [mg/dL], LDL [mg/dL], HDL [mg/dL], Large LDL particle size [% of total], Large HDL particle size [% of total]), waist circumference [inches], BP-systolic, diastolic [mmHg], Glucose [mg/dL], metabolic syndrome [% of total]).

*p values between probands and controls adjusted for BMI and sex (adiponectin, cholesterol [mg/dL], triglycerides [mg/dL], LDL [mg/dL], HDL [mg/dL], Large LDL particle size [% of total], Large HDL particle size [% of total]), waist circumference [inches], BP-systolic, diastolic [mmHg], Glucose [mg/dL], metabolic

zp values between offspring and controls adjusted for age, sex and BMI (adiponectin, cholesterol [mg/dL], triglycerides [mg/dL], LDL [mg/dL], HDL [mg/dL], large LDL particle size [% of total], large HDL particle size [% of total], waist circumference [inches], BP-systolic, diastolic [mmHg], glucose [mg/dL], metabolic

BMI ¼ body mass index; LDL ¼ low-density lipoprotein; HDL ¼ high-density lipoprotein.

correlations for metabolic syndrome-associated traits (i.e., blood pressure, HDL, LDL, triglycerides, glucose, waist circumference, and HDL and LDL particle sizes) were adjusted for age, sex, and BMI (Table 2).

correlated, whereas waist circumference was negatively correlated with adiponectin levels (Table 2). Glucose, LDL levels, and blood pressure showed no significant correlation with adiponectin levels.

Low adiponectin levels have been associated with meta- bolic syndrome (33); this relationship held in our control and offspring groups. The mean difference in adiponectin levels between persons with and without metabolic syn- drome was 3.18 lg/mL (p ¼ .011). This difference was observed in both offspring and in controls, and the effect size was similar in each group (p ¼ .56 for interaction effect), suggesting that the biological action of adiponectin to protect from metabolic syndrome is similar in offspring (with higher adjusted adiponectin levels) who are expected to be genetically enriched for longevity compared to con- trols. The relationship between adiponectin levels and meta- bolic syndrome was significant in both sexes but stronger among men (women: 13.5 6 1.2 vs 16.6 6 0.6, p ¼ .02; men: 7.7 6 1.2 vs 11.5 6 0.5, p ¼ .004).

Before analysis, genotypes were checked for Mendelian consistency where possible by comparing probands–off- spring pairs. Mendelian errors were resolved or removed before analysis. Allele frequencies were calculated by gene counting. All SNPs conformed to Hardy–Weinberg expect- ations. We evaluated the association between SNP genotype and phenotype (adiponectin levels) under the additive and dominant genetic models using multiple regression. Statis- tical analyses were performed using Stata 9.2 (Stata Corp., College Station, TX) and SAS 9.1 (Cary, NC).

R ESULTS

The phenotypic characteristics of exceptionally long-lived probands, their offspring, and unrelated controls are shown in Table 1. Adiponectin levels are known to be associated with age and BMI (a surrogate for body fat), and these relationships held in our sample (Figure 1 and Table 2). As previously described (31,32), women had significantly higher adiponectin levels than did men in the combined sample (15.6 6 0.49 vs 11.6 6 0.58 lg/mL; p , .0001, adjusted for age at recruitment and BMI. Furthermore, adiponectin levels were correlated with some serum lipid levels (Table 2), for example, Spearman correlation coefficients for triglycerides and HDL with adiponectin levels were (cid:2)0.19 (p ¼ .0005) and 0.23 (p , .0001), respectively. Lipoprotein particle sizes were positively

We hypothesized that if increased adiponectin levels are heritable and are related to genes that promote longevity, we would expect to find greater adiponectin levels in the offspring of long-lived probands than in controls. In unadjusted analysis, adiponectin did not differ between the offspring and control groups [mean 6 SE 12.8 6 0.5 vs 12.5 6 0.8 lg/mL (p ¼ .75)] (Table 1). However, after adjustment for BMI, age, and sex, adiponectin levels were significantly higher in the offspring group than in the control group (adjusted mean difference 2.28 lg/mL, p ¼ .02). To avoid concerns about mortality selection, we also analyzed

Table 2. Univariate Correlations Between Adiponectin Levels and Other Metabolic Syndrome-Related Traits for All 424 Participants