difference did not reach statistical significance. In order to evaluate a possible interaction between GSTT1 deletion and p53 gene polymorphisms, we calculated the combined genotype frequencies in the two groups (Table 2). We found a statistically significant difference in the frequency of the GSTT1 deletion and certain p53 genotypes: the absence of any p53 polymorphisms and of GSTT1 deletion, and the simultaneous presence of the three p53 polymorphisms and of the GSTT1 deletion, were much more frequent in young subjects than in centenarians (41.5% versus 26.9% and 8.8% versus 3.8%, respectively). Combinations of p53 genotypes and GSTM1 or CYP1A1*2 were not differently distributed in the two groups (data not shown). The absence of any p53 polymorphisms and of both GSTT1 and GSTM1 deletion was 22.5% in controls and 13.5% in centenarians, while simultaneous presence of the three p53 polymorphisms and of the double deletion of both GSTT1 and GSTM1 was 4.8% in controls and was not found in centenarians (x2 (cid:4)26.8, p(cid:4)0.04). / /

We studied the frequency of several gene polymorphisms in a population of in order to understand the mechanisms of ageing.

2. Combined genotype frequencies in centenarians and healthy controls.

Centenarians Controls (n(cid:4)66) (n(cid:4)150) / / p53 P53 16 bp p53 Msp1 codon 72 duplication GSTT1 n % n % G/G G/G Wild type Present 14 26.9 61 41.5 G/G G/G Wild type Deleted 8 15.4 14 9.5 G/G G/G Polymorphic Present 2 3.8 3 2.0 G/G G/G Polymorphic Deleted 1 1.9 1 0.7 G/G G/C(cid:2)C/C Wild type Present 4 7.7 19 12.9 / G/G G/C(cid:2)C/C Wild type Deleted 4 7.7 1 0.7 / G/A(cid:2)A/A G/G Wild type Present 0 0.0 0 0.0 / G/A(cid:2)A/A G/G Wild type Deleted 0 0.0 0 0.0 / G/A(cid:2)A/A G/C(cid:2)C/C Wild type Present 2 3.8 0 0.0 / / G/A(cid:2)A/A G/C(cid:2)C/C Wild type Deleted 0 0.0 1 0.7 / / G/A(cid:2)A/A G/G Polymorphic Present 0 0.0 0 0.0 / G/A(cid:2)A/A G/G Polymorphic Deleted 0 0.0 0 0.0 / G/G G/C(cid:2)C/C Polymorphic Present 0 0.0 0 0.0 / G/G G/C(cid:2)C/C Polymorphic Deleted 0 0.0 0 0.0 / G/A(cid:2)A/A G/C(cid:2)C/C Polymorphic Present 15 28.8 34 23.1 / / G/A(cid:2)A/A G/C(cid:2)C/C Polymorphic Deleted 2 3.8 13 8.8 / /

The main finding of this study was the presence of a significantly lower of certain combined genotypes in centenarians, such as GSTT1 deletion/ 16 bp duplication, and GSTT1 deletion/p53 Msp1 polymorphism. A possible for these findings is that loss of function in GSTT1 allows the of a large amount of activated carcinogens, which are known to several types of DNA damage such as DNA adducts. In addition, in p53 are known to affect DNA repair and genome stability et al. 2000). Subjects with both GSTT1 deletion and p53 polymorphisms therefore have greater exposure to carcinogens and reduced DNA repair and thus are at increased risk for cancer. This mechanism could also explain the pattern of deletion of the two phase II genes GSTM1 and GSTT1 together p53 polymorphisms was very rare, or even absent, in our population of The deletion of two glutathione transferases would amplify the effect described above. Case(cid:1)control studies have shown an increased / of lung cancer associated with the GSTs1 and p53 double variants (Liu et al. Miller et al. 2002). It is possible that the effect of the combined genotypes is than the sum of the independent effects, even though the genes are not on same biological pathways; multiple variants may interact in a unique way and a biological effect for which individual variants may have poor predictive (Kinzler and Vogelstein 1997).

No data was available on the past environmental exposure in this population; however, it is likely that environmental conditions were very different at the beginning of the century, when this population was young and active, than nowadays. Our study included a large number of female centenarians, whose reproductive life included more children than younger females, and this could be a contributing factor to longevity.

Metabolic gene polymorphisms and p53 mutations in healthy centenarians

Another possible explanation for our findings is that both metabolic genes and p53 act on pathways related to cell ageing and death. It is known that p53 acts on apoptosis and cell senescence. It is possible that the accumulation of oxidative processes, such as those found in the presence of deletion of the GSTs genes, could increase the mechanisms of cell senescence and death associated with p53 polymorphisms. In this case, certain composite genetic patterns would represent a generic mechanism of protection against ageing, not just against the development of chronic diseases. Since cancer is not the only disease responsible for a short survival, it is possible that the genes included in our study could also be relevant to

One aspect that needs to be underlined is that our study indicates that combinations of polymorphisms in several different classes of genes need to be studied when looking at the processes of carcinogenesis or ageing. The pathways we explored by looking at some candidate genes are probably very complex and involve several other gene families. Large samples of healthy centenarians are needed in order to study multiple pathways and several gene polymorphisms at once. In conclusion, it is likely that longevity is related to a very complex genetic trait as well as to certain environmental exposures.

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