MtDNA haplogroups observed in southern Italy are shown in Table 4. The overall frequency distributions were not significantly different between centenarians oidP=( and controls either in males (P 0.980) or in females aksP=( (P 0.273). Furthermore, no association was evident between longevity and specific mtDNA haplogroups.

TABLE 3. MtDNA haplogroups observed in samples of northern Italians of different agesa

Females Males Controls Centenarians Controls Centenarians     (n 74) (n 83) (n 51) (n 26) Haplogroups Abs. Rel. Abs. Rel. Abs. Rel. Abs. Rel. H 27 365 (56) 28 337 (52) 24 471 (70) 13 500 (98) I 3 41 (23) 2 24 (17) — — — — J 5 68 (29) 11 133 (37) 1 20 (19) 6 231 (83) K 4 54 (26) 4 48 (24) 2 39 (27) 2 77 (52) T 9 122 (38) 12 145 (39) 4 78 (38) — — U 15 203 (47) 12 145 (39) 12 235 (58) 1 38 (38) V — — 4 48 (24) 1 20 (19) 1 38 (38) W 2 27 (19) 2 24 (17) 2 39 (27) — — X 2 27 (19) 2 24 (17) 1 20 (19) 1 38 (38) Others 7 95 (34) 6 72 (28) 4 78 (38) 2 77 (52)

a Controls: 20- to 75-year-old individuals; median age of males 44 years, median age of females 39 years. Centenarians: individuals over 100 (x1 years old. Abs. and Rel. indicate absolute and relative ( 1000) haplogroup frequencies with standard error in parentheses. P values refer to heterogeneity tests between controls and centenarians performed by permutations (18).

Females Males Controls Centenarians Controls Centenarians     (n 76) (n 67) (n 74) (n 36) Haplogroups Abs. Rel. Abs. Rel. Abs. Rel. Abs. Rel. H 26 342 (54) 29 433 (61) 31 419 (57) 15 417 (82) I 1 13 (13) 3 45 (25) 3 41 (23) 3 83 (46) J 2 26 (18) 4 60 (29) 5 68 (29) 2 56 (38) K 9 118 (37) 5 75 (32) 6 81 (32) 4 111 (52) T 9 118 (37) 4 60 (29) 7 95 (34) 2 56 (38) U 8 105 (35) 8 119 (40) 11 149 (41) 5 139 (58) V 3 39 (22) 5 75 (32) 1 14 (14) 1 28 (27) W 4 53 (26) 1 15 (15) 2 27 (19) — — X 2 26 (18) 4 60 (29) 3 41 (23) 1 28 (27) Others 12 158 (42) 4 60 (29) 5 68 (29) 3 83 (46)

a Controls: 20- to 75-year-old individuals; median age of males 34 years, median age of females 33 years. Centenarians: individuals over 100 (x1 years old. Abs. and Rel. indicate absolute and relative ( 1000) haplogroup frequencies with standard error in parentheses. P values refer to heterogeneity tests between controls and centenarians performed by permutations (18).

DISCUSSION

tain gene depends on the physiological background in which the gene is expressed. Since the age-related physiological scenario changes in males and females differently, the effect of mtDNA variability on suc- cessful aging and longevity could vary between sexes. On the other hand, life expectancy is significantly higher in females than in males (gender effect). It may be that in order to attain longevity, males more than females need particularly protective mtDNA types.

We wanted to test whether the analysis of mtDNA haplogroups is able to reveal any association between mtDNA inherited variability and longevity. The ap- proach was a comparative analysis between the mtDNA pool of healthy centenarians and that of younger people matched for sex and geographic area.

Let us consider the results obtained in northern Italian males. Not only was the overall frequency distribution different between cases and controls, but the frequency of a specific haplogroup (J) was notably higher in centenarians than in controls, although both groups had been sampled from the same population. Since case/control matching had been carefully checked (the ancestry of both cases and controls in the specific geographic area had been verified as far as maternal grandmothers), bias caused by long-range mobility occurring in Italy in the last century could be excluded. Likewise, since both centenarians and controls had been collected in very large geographic areas of northern Italy, effects caused by genetic drift could be excluded too. The existence of a true positive association between inherited mtDNA variants and long life expectancy is therefore likely in males of this geographic area.

As for the second question, consider that groups are categories defined on the basis of mutations shared among different Therefore, each haplogroup encompasses many lotypes, and its composition is defined by the of the population (22). The different results tained in northern and southern Italy are not unexpected if we consider that northern southern Italian populations have different as well documented by both historical and studies (23). In any case, longevity could be through various strategies, according to various pools and environments. The latter emphasizes the importance of having rapid cheap genetic markers, such as haplogroups, to the role of mtDNA on longevity in various tions from various geographic areas. In this regard, should be noted that the Mt5178A mutation in Japanese centenarians (12) is included in the haplogroup, extremely frequent in Asia but absent in Europe (22).

This finding raised two questions: 1) Why were these phenomena not observed in females? 2) Why were these phenomena not observed in southern Italy?

As to the first question, different findings in males and females have already been observed in gene/ longevity association studies (20, 21). This is not unexpected if we consider that longevity is a multi- factorial trait where the phenotypic effect of a cer-

These data show that, at least in males from a well-defined geographic area, not only the haplo- group frequency distribution is different between centenarians and younger people, but also a specific haplogroup (J) is significantly more frequent in

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