In contrast, we did not observe any significant differ- ences in the distribution of the apoB Xba I alleles between the centenarians and the younger Finnish populations (Table 2). Previous studies on several pop- ulations have suggested that the XI allele may be a genetic marker for increased risk of atherosclerotic vascular disease.4244 The underlying mechanism is un- known and may involve a linkage disequilibrium be- tween the XI allele and a putative atherosclerosis- promoting functional change in the apoB gene or its immediate vicinity. However, this linkage may not be present in all populations, since our previous study showed only an insignificantly higher frequency of the XI allele in Finnish patients with angiographically con- firmed coronary constrictions compared with patients with other cardiac diseases but no angiographic evi- dence of atherosclerosis (61% versus 54%).35

Acknowledgments

This study was conducted under a contract with the Finnish Life and Pension Insurance Companies and was additionally supported by grants from the Finnish Academy of Sciences, the Sigrid Juselius Foundation, the Paavo Nurmi Foundation, and the Ragnar Ekberg Foundation.

The higher frequency of the apoC-III 52 allele among the centenarians than among the younger Finns (Table 2) was a somewhat unexpected finding. We have previ- ously detected the 52 allele in approximately 60% of Finnish patients with severe primary hypertriglyceri- demia but in only 16% (P<.001) of healthy normolipi- demic subjects.21 Furthermore, it occurs in 23% of Finnish patients with coronary disease, among whom those with high serum triglyceride levels seem to carry the 52 allele more often than those with normal triglyc- eride levels (43% versus 12%; P<.05).21 We also found a significant association between the 52 allele and high serum LDL cholesterol levels in young Finns aged 9 to 21 years.17 Collectively, these earlier data and our present findings suggest that the apoC-III 52 allele may constitute a genetic marker for a severe and relatively rare form of hypertriglyceridemia among Finns, which does not, however, influence life expectancy to any significant extent at the population level.

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Previous studies on Finns have shown that both the apoE e4 and the apoB X2 allele are associated with serum total and LDL cholesterol levels that are signif- icantly higher than average in childhood11-17'45 and adulthood.818 In our centenarians we found a similar although statistically nonsignificant association between the presence of one or other of these alleles and high serum cholesterol levels in centenarians (Table 4). When the alleles at both loci were taken into account, the association between a high serum cholesterol level and apoE e4 plus apoB X2 reached statistical signifi- cance (Figure). This result is similar to that observed in a younger sample of the Finnish population.45 Our data suggest that the cholesterol-elevating effects of the apoE e4 allele and apoB X2 allele are lifelong.