OR, Odds ratio; CI, confidence interval.

in the long-lived men as compared to the control men (0.22). The crude OR for the probability of surviving to age 90 years or older or not associated with the PPARG Pro/Ala genotype, calculated only for the men, was 0.248 (95% CI 0.065–0.954), indicating that carrying the PPARG Pro/Ala genotype could limit survival to 90 years or older in men. Conversely, no difference in PPARG Pro12Ala genotype frequencies was observed between the long-lived and the control women.

Logistic regression analysis was then applied to the female sample to correctly evaluate the effect of the FSHR 680 Ser/ Ser genotype on longevity after adjusting for other covari- ates. In the analysis, the dependent variable was having survived to age over 90 years or not. Together with the FSHR 680 Ser/Ser genotype, the other explanatory variables were the estrogen receptor-a (ESR1) and aromatase (CYP19) ge- notypes that, in a previous study on the same sample, were observed to promote longevity in both men and women.21

Logistic regression analysis was then applied to the male sample to better evaluate the effect of PPARG genotypes on longevity after entering as further co-variates the CYP19 and ESR1 genotypes, as well as an index of the fertility level (number of children > 3 [population median value]) or not. The fertility level was included in the model because we observed in a previous study involving the same sample an association between the PPARG Ala allele and a significantly higher number of children only for the men.23 The analysis (Table 3) confirmed that carrying the PPARG Ala allele may preclude survival to more than 90 years of age (PPARG Pro/Ala genotype adjusted OR= 0.13), and that this associ- ation is independent of the other co-variates entered into the model. The influence of ESR1 on survival was present, al- though only marginally significant, while CYP19 genotypes and fertility level did not appear to have an effect on sur- vival. No significant interaction was observed between the PPARG Pro/Ala genotype and fertility level.

FSHR is known to play a crucial role in fertility. In a previous study22 on the women of the present sample (not selected for fertility disorders), however, we observed that the FSHR Asn680Ser genotypes were not associated with a differential fertility (mean number of children/FSHR geno- types analysis of variance [ANOVA] p= 0.30); therefore, no index of fertility level was included in the logistic analysis. The analysis (Table 2) indicates that the FSHR 680 Ser/Ser genotype is significantly associated with surviving to more than 90 years of age (FSHR 680 Ser/Ser: adjusted OR= 4.21). Accordingly, together with the ESR1 polymorphism, the FSHR 680 polymorphism may be assumed to be an inde- pendent determinant of longevity. The influence of the CYP19 genotypes on survival to older ages was not apparent in the present analysis.

Published data on longevity genes with a gender-specific action were then collected (Table 4), and the studies were reviewed. For gene variants. the nomenclature used by the authors was reported and the dbSNP ID number was added for completeness in some cases.

In the total sample, the distribution of the observed PPARG genotype frequencies agreed with those expected according to Hardy–Weinberg equilibrium (p =0.93), and the PPARG Pro allele frequency was 0.942 –0.01. Table 1 also reports the distribution of PPARG Pro12Ala genotypes in the long-lived and the controls. A significant decrease (p= 0.03) in PPARG Pro/Ala genotype frequency (0.06) was observed

Discussion

In the present study, we searched for a possible asso- ciation between FSHR and PPARG polymorphisms and longevity by means of a follow-up study. The study design chosen for the present investigation aimed to avoid the ‘‘cohort effect’’ observed in association studies on human longevity where the control sample is often composed of younger subjects belonging to birth cohorts too distant from those of the long-lived and having thus experienced different social and environmental influences.24,25 Further- more, while ‘‘younger’’ control life span is unknown, the present control group was certainly composed of non-long- lived subjects. Our findings seem to indicate that the FSHR and PPARG genes are both involved in determining lon- gevity in a gender-specific way, albeit with an opposite sign.

Variable OR 95% CI p value FSHR680 Ser/Ser genotype 4.21 1.10–16.1 0.036 ESR1 PP genotype 3.48 1.11–10.9 0.033 CYP19 T carrying genotypes 1.23 0.48–3.14 0.67

OR, Odds ratio; CI, confidence interval.

Table Genes with a Potential Gender-Specific Influence on Life Span Determination 4.