Results

Genotype success was 100% for rs2267668, rs6949152, and rs1937, 99.7% for rs8192678, and 99.2% for rs12594956. Parallel genotyping results showed 100% concordance be- tween the two laboratories. All genotype distributions met Hardy–Weinberg equilibrium in both the control and the centenarians’ group ( p > 0.05), except for TFAM Ser12Thr (rs1937) in the centenarians’ group ( p < 0.001). Figures 1 and 2 show the allele and genotype frequencies, respectively, in the two study groups. When studying men and women together in the two cohorts, we found no significant between-group differences (all p > 0.1), except for the ge- notype frequency of rs1937 (v2 = 11.440, p = 0.003), with no

Discussion

The polymorphisms we studied have been associated with several health/disease phenotypes, many of which are re- lated to mitochondrial function, notably the variant Ser allele of the PPARGC1A Gly482Ser (rs8192678) variation is asso- ciated with risk of type 2 diabetes,19(cid:2)22 insulin resistance,23 obesity,24,25, dyslipidemia,29 hypertension,26(cid:2)28 and low aer- obic fitness.30 Yet, we found no association of genetic

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FIG. 1. Allele distribution of the study polymor- phisms. No between-group differences were found. PPARD, Proliferator-activated receptor delta; PPARG- C1A, peroxisome proliferator-activated receptor c coactivator 1a; NRF, nuclear respiratory factor; TFAM, mitochondrial transcription Factor A.

FIG. 1. Allele distribution of the study polymor- phisms. No between-group differences were found. PPARD, Proliferator-activated receptor delta; PPARG- C1A, peroxisome proliferator-activated receptor c coactivator 1a; NRF, nuclear respiratory factor; TFAM, mitochondrial transcription Factor A.

FIG. 2. Genotype distribution of the study polymor- phisms. (*) p =0.003 for the between-group difference. PPARD, Proliferator-activated receptor delta; PPARG- C1A, peroxisome proliferator-activated receptor c coac- tivator 1a; NRF, nuclear respiratory factor; TFAM, mitochondrial transcription Factor A.

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FIG. 2. Genotype distribution of the study polymor- phisms. (*) p =0.003 for the between-group difference. PPARD, Proliferator-activated receptor delta; PPARG- C1A, peroxisome proliferator-activated receptor c coac- tivator 1a; NRF, nuclear respiratory factor; TFAM, mitochondrial transcription Factor A.

variants in the PPARD-PPARGC1A-NRF-TFAM pathway and extreme longevity. We only found a marginal associa- tion for the TFAM Ser(G)12Thr(C) (rs1937) polymorphism when studying the two sexes together or only men sepa- rately, with no representation of the CC genotype in the control cohort versus a total frequency of *3% in centenar- ians, included among them the oldest person in Europe until September, 2012 (disease-free man, aged 111 years). Inter- estingly, the frequency of the CC genotype in our centenar- ians’ cohort was above that previously reported for control European cohorts, with a virtual absence of the CC genotype, e.g., 0% in adolescents of both genders from Argentina (Eu- ropean descent),46 0.7% in Russian men and women,47 1.0% in European (German, Swiss, Italian) men and women (0% in men),39 and 1.8% in Spanish men and women.36

(Ser12Thr) in the sequence of the mitochondrial signal pep- tide TFAM48; and (2) the putative role of this gene. The TFAM gene, located at 10q21, encodes the key protein re- sponsible for replication and transcription of mitochondrial DNA and protects cells against oxidative stress, the latter being involved in the development of disease phenotypes, notably neurodegenerative disorders.49,50 TFAM knockout mice exhibit depletion of mtDNA and abolished oxidative phosphorylation,51 whereas heart-specific TFAM gene knockout mice display a progressive heart phenotype with depletion of mtDNA and an accompanying severe decline of respiratory chain enzyme activities and decreased mito- chondrial adenosine triphosphate (ATP) production.52 Wre- denberg et al.53 reported accumulation of abnormally appearing mitochondria, progressively deteriorating respi- ratory chain function, and reduced muscle-force production in muscle fibers of mice with skeletal muscle-specific dis- ruption of the TFAM gene. In contrast, over-expression of this gene in cardiac myocytes is associated with a two-fold

The rs1937 variation in TFAM could affect disease phe- notypes and thus, at least partly, longevity owing the fact that: (1) This polymorphism could be of relevant functional significance, because it predicts an amino acid change

treme longevity, at least in the Spanish population, yet a marginal association could exist for the TFAM Se12Thr (rs1937) polymorphism, with a certain survival benefit ex- isting for the rare, low-risk CC genotype. More research is needed on other genetic variants potentially associated with maintenance of mitochondrial function.

increase in the number of mtDNA copies and elevated ATP production.54