2.4. Statistical analysis

Weinberg Equilibrium using the Haploview program (Barrett, 2009; Barrett et al., 2005) and we did not find deviations of geno- type frequencies from HardyeWeinberg Equilibrium for any of the SNPs. To minimize population stratification, analysis was restricted to subjects of white ethnicity, resulting in the loss of 8 spouses (1%) and 5 relatives (0.2%) from the analysis. We used logistic regression procedures in generalized estimating equations to estimate the likelihood of carrying 1 or more APOE ε4 alleles, 1 or more APOE ε2 alleles, or 1 or more rs2075650 G alleles in TOMM40. Generalized estimating equations adjusts for the relatedness of the LLFS offspring and controls and for the possibility that the characteristics of family members are correlated by both shared genetics and shared environment, by treating family membership as a cluster. LLFS offspring were compared with spouse controls, adjusting for age, sex, level of education, and family membership (model A) and then adjusting for age, sex, level of education, family membership and a history myocardial infarction, hypertension, stroke, diabetes, and Parkinson’s disease (model B). In the offspring generation, only 2 people were reported as suffering from dementia, so we did not include dementia as a covariate for these analyses. SNPS inTOMM40 have been shown to be in linkage disequilibrium with the APOE ε4 allele and it has been suggested that rs2075650 might not have an

2.2. Eligibility and enrollment

The Family Longevity Selection Score (FLoSS) was developed by the LLFS study in order to rank longevity among families based on birth-year cohort survival probabilities of the proband and siblings (Sebastiani et al., 2009). On screening, a FLoSS of 7 or more was required for a family to be eligible. If a proband’s family was FLoSS- eligible, they also had to meet the following criteria: the proband

N. Schupf et al. / Neurobiology of Aging 34 (2013) 1287e1291

Table 2

independent effect on longevity (Deelen et al., 2011; Nebel et al., 2011; Sebastiani et al., 2012). To examine this possibility we repeated the analysis for TOMM40 including APOE in the model as a covariate, and also among those with the APOE ε3/ε3 genotype.

Likelihood of carrying the APOE ε4 allele and APOE ε2 allele by relative group

Participants At risk, ε4 Allele Odds ratio, Odds ratio, n (n, %) model Aa model Bb Likelihood of the APOE ε4 allele Offspring generation 2307 471 (20.4) 0.75 (0.6e0.9) 0.75 (0.6e0.9) Spouse controls 764 198 (25.9) 1.0 (reference) 1.0 (reference) Participants At risk, ε2 Allele Odds ratio, Odds ratio, n (n, %) model Aa model Bb Likelihood of the APOE ε2 allele Offspring generation 2307 415 (18.0) 1.5 (1.1e2.0) 1.5 (1.1e1.9) Spouse controls 764 101 (13.2) 1.0 (reference) 1.0 (reference)

3. Results

LLFS offspring and their spouse controls did not differ in mean age at assessment (60.5 vs. 60.9, respectively). The average number of years of education was slightly but significantly higher among LLFS offspring compared with spouse controls (12.6 vs. 12.1) (Table 1). LLFS offspring were also more likely to be female than spouse controls (57.7% vs. 47.3%) and less likely to have a history of hypertension (29.4% vs. 33.9%), but did not differ from spouse controls in the frequency of a history of myocardial infarction, history of stroke, diabetes, or Parkinson’s disease (Table 1).

a Model A adjusted for age, sex, level of education, and family membership. b Model B adjusted for age, sex, level of education, family membership, history of myocardial infarction, hypertension, stroke, diabetes, and Parkinson’s disease.

model, the relationship between offspring and the likelihood of G allele was attenuated (OR, 0.8; 95% CI, 0.6e1.1) (data not shown). Among those with the APOE ε3/ε3 genotype, the likelihood of carrying 1 or more G alleles remained 30% lower in offspring than in controls (OR, 0.7; 95% CI, 0.5e1.05), but the difference was not statistically significant.

Compared with spouse controls, the likelihood of carrying 1 or more ε4 alleles was 25% lower among LLFS offspring (odds ratio [OR], 0.75; 95% confidence interval [CI], 0.6e0.9), adjusting for age, sex, education, and family membership and did not change when the additional covariates were added to the model (Table 2, model A and model B). When the presence or absence of the G allele in rs2075650 of TOMM40 was added to the model, the relationship between offspring and the likelihood of G allele was attenuated (OR, 0.9; 95% CI, 0.7e1.2) (data not shown). Compared with spouse controls, the likelihood of carrying 1 or more ε2 alleles was 50% higher among offspring (OR, 1.5; 95% CI, 1.1e1.9), adjusting for covariates (Table 2, model A, model B).

4. Discussion

Overall, we found that the likelihood of carrying an APOE ε4 allele was lower and the likelihood of carrying an APOE ε2 allele was higher among LLFS family members in the offspring generation than among similarly aged spouse controls. These findings support the hypotheses that the absence of the ε4 allele and presence of the ε2 allele are associated with longevity. Adjustment for common

We confirmed findings from previous studies that rs2075650 in TOMM40 is in moderate linkage disequilibrium with the APOE ε4 allele (Fig. 1). Compared with spouse controls, the likelihood of carrying 1 or more G alleles was 30% lower among LLFS offspring (OR, 0.70; 95% CI, 0.6e0.9), adjusting for covariates (Table 3, model A, model B). When the APOE ε4 allele was added to the

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Table 1

Demographic characteristics