Accordingly, the effects of IGF-IR and PIK3CB polymor- phisms on IGF-I plasma levels were assessed by means of a general linear model ANOVA, including age, sex, IR (HOMA), and BMI as covariates (Table 2). The analysis re- vealed lower free IGF-I plasma levels in IGF1R A(cid:5) subjects ves\~ | (AG and AA genotypes) than in A (GG genotype) subjects  “yrs[+7    (2.95 2.62 vs. 2.21 2.34 ng/ml; F 6.56; P 0.011) as well as in PIK3CB T(cid:5) individuals (TT and TC genotypes) com-

The gene polymorphism due to a T to C transition located 359 bp upstream from the starting codon of PIK3CB (chromosome 3q22.3, GI: 5453894) was analyzed by the allele refractory method. In each of two separate PCR mixes, an allele-specific primer and an allele-nonspecific   primer were used as follows: T allele, 5 -CATTGATTCAAATTCAA- wer3)     5'- CATAA-3 and 5 -GAAAAACTCAGC CTAAGAAGC-3 ; C allele, 5 - GTTTATTCAGATGTCAAATATC-3(cid:3) and 5(cid:3) -CAAGAGTAA GTCAG-

Free IGF-1 (ng/mL)204060Age (years) 120

TABLE 2. General linear model analysis with plasma levels as dependent variable (n ANE ©= 496)

TABLE 1. Plasma IGF-I levels in the study population (n 

IGF-I plasma levels IGF1R (G/A) polymorphism GG 2.95 tl 2.61 AG 2.34   2.41 AA 1.94   2.17 IRS-1 (G/A) polymorphism GG 2.56 tl 2.46 GA 1.95   2.92 AA 0.50   a PI3KCB (T/C) polymorphism TT 2.19 I+ 2.05 TC 2.24   2.37 CC 3.02   3.10 FOXO1A (T/C) polymorphism TT 2.49 I+ 2.56 TC 2.37   2.27 CC 7.81 Le  a

F P Age 5.52 (cid:6)0.05 BMI 1.54 NS Sex 0.08 NS IR (HOMA)a 9.25 (cid:6)0.05 IGF1R genotypeb 9.92 (cid:6)0.01 PIK3CB genotypec 7.59 (cid:6)0.01 IGF1Ra PI3KCB 3.87 (cid:6)0.05 NS, Not significant. R2   0.133. a Back log transformed. b Calculated as A(cid:5) vs. A(cid:4). c Calculated as T(cid:5) vs. T(cid:4).

(median age, 99 yr; 74.3% vs. 72.7% for females; 25.7% vs. Ay 4>

As expected (17, 18), long-lived people had lower BMI (23.1 I+ ¢5 3.7 vs. 25.2 I+¢ 2.8 kg/m2; P a< 0.001), lower fasting plasma glucose (5.02  1.48 vs. 5.63 i+ / 1.37 mmol/ml; P ro<   ney 0.001), lower plasma insulin (7.36 4.36 vs. 8.99 3.56   mU/liter; P 0.001), lower IR (HOMA) degree (1.70 1.08 ape  vs. 2.33 1.38; P 0.001), and lower plasma free IGF-I    plasma levels (1.89 2.42 vs. 2.75 2.38; P 0.005) than young people. These data confirm that subjects more than 85 yr of age have peculiar metabolic and anthropometric characteristics

IGF1R (G/A) polymorphism: GG vs. AG vs. AA; F  3.83, P   0.02; IRS-1 (G/A) polymorphism: P on \> =] NS; PI3KCB (T/C) polymorphism: TT vs. TC vs. CC; F yaa’ 3.01, P  0.05; FOXO1A (T/C) polymorphism: P  NS. NS, Not significant. a

   pared with T (CC genotypes) individuals (2.22 2.22 vs. I+ ¢se    3.02 3.11; F 6.017; P 0.015). Inasmuch as the interaction eek ayxX. (IGF-IR PIK3CB) was significant, a univariate two-factor general linear model ANOVA was performed, which re-  Ti vealed that IGF-IR/PIK3CB A /T individuals had the high- est IGF-I levels in the population; this was independent of \-/   + age and gender (A /T vs. all other groups, 4.25 4.03 vs. alm vi ae 2.17 2.31; t 3.63; p 0.005). All other comparisons adj among IGF-IR/PIK3CB genotype combinations were not sig- nificant (Fig. 2).

The genotype frequency distributions at IGF-IR, PIK3CB, IRS-1, and FOXO1A loci in young people and long-lived people were studied in the two groups. Carriers of the A vel‘ue allele (A subjects) at the IGF-IR locus were more repre- sented among long-lived people than in young people (Table 3). No significant differences were found when PIK3CB, IRS-1, and FOXO1A gene polymorphisms were examined. Differences in genotype combinations were also tested by ‘YP an weQt /  combining IGF-IR A and A carrier status with R /R

The entire sample was then divided into two subgroups characterized by the same gender proportion, designated young people (median age, 60 yr) and long-lived people

Plasma IGF-1 levels (ng/mL)-A+/T+n=131A+/T-n=45A-/T+n=84 A-/T-n=20

T+ /  carrier status at the IRS-1 locus, C /C status at the PI3KCB   locus, and C /C carrier status at the FOXO1A locus. IGF- +/   IR/PI3KCB-A /T carriers increased from 43.5% to 54.5%, in long-lived people ((cid:1)2  4.382; df   1; P phat> 0.036), and A(cid:4) /T(cid:4) individuals dropped from 9.3% to 5.5%; this latter change was not significant ((cid:1)2 wank 1.763; df mee 1; P ee 0.184). No significant changes were found as far as the remaining ge- notype combinations were concerned (data not shown).

is evidence that centenarians, the best example of successful aging, have lower plasma IGF-I levels (14, 15). Interestingly, caloric restriction, the most reproducible intervention to ex- tend animal life span (28), substantially reduces plasma free IGF-I levels (29, 30).