the young sample, with a decrease in I:I and an increase of I:D with age. Since ACE allele frequencies were no different in the elderly men compared to the young sample, we derived genotypes in the young group from the allele frequencies on the basis of expectations ac- cording to Hardy-Weinberg equilibrium. These geno- types were not significantly different to the observed genotypes in the elderly men. However, the role of ACE in survival into old age is supported by finding different observed genotype distributions in elderly men and women, with males having a reduction of I:I. No significant differences in ACE allele or genotype fre- quencies were found in the young boys and girls (boys: DD(cid:30)38%, ID(cid:30)39%, II(cid:30)23%; girls: DD(cid:30)35%, ID(cid:30)42%, II(cid:30)42%).

3.2. ACE

ACE allele frequencies were not significantly different for any of the comparisons of the elderly and young populations (Table 3). Genotype frequencies were not significantly different in elderly females and the young population. However, ACE genotype frequencies were significantly different in the elderly men compared to

3.3. MTHFR

The 677C-T transition was analysed in the elderly and young populations (Table 4). All comparisons failed to show differences in either genotype or allele frequency distributions between the elderly and young

ACE allele and genotype frequencies for the Alu insertion:deletion (I:D) polymorphism in the young population and in elderly men and elderly women

Young Elderly men Elderly women No. (%) RR (95% CI) No. (%) RR (95% CI) Allele I 172 (43%) 78 (39%) 1.0 160 (47%) 1.0 D 224 (56%) 122 (61%) 1.20 (0.85–1.69) 180 (53%) 0.86 (0.64–1.15) Genotype I:I 46 (23%) 12 (12%) 1.0 43 (25%) 1.0 I:D 80 (40%) 54 (54%) 2.59 (1.26–6.71) 74 (44%) 0.99 (0.59–1.67) D:D 72 (36%) 34 (34%) 1.81 (0.85–3.85) 53 (31%) 0.79 (0.46–1.36)

The number of alleles or genotypes are indicated with proportions in parentheses. Genotype frequencies in elderly men were significantly different to those in the young sample ((cid:120)2(cid:30)7.15, 2 d.f., PB0.05) and those of the elderly women ((cid:120)2(cid:30)7.07, 2 d.f., PB0.05).

MTHFR allele and genotype frequencies for the 677 C-T mutation in the young population and in elderly men and elderly women

Young Elderly men Elderly women No. (%) RR (95% CI) No. (%) RR (95% CI) Allele C 262 (67%) 122 (62%) 1.0 234 (65%) 1.0 T 130 (33%) 74 (38%) 1.22 (0.85–1.74) 128 (35%) 1.10 (0.80–1.52) Genotype CC 91 (46%) 36 (37%) 1.0 73 (40%) 1.0 CT 80 (41%) 50 (51%) 1.58 (0.94–2.67) 88 (49%) 1.37 (0.89–2.11) TT 25 (13%) 12 (12%) 1.21 (0.55–2.66) 20 (11%) 1.00 (0.51–1.94)

The number of alleles or genotypes are indicated with proportions in parentheses. No significant differences were observed between young and elderly populations.

nonagenarians) [4]. Our sample may have been biased towards healthy survivors, since a proportion of our cohort refused assessment, or were too confused to give consent for DNA analysis. However, those who pro- vided samples are more likely to live longer and there- fore this bias is unlikely to have reduced the power of our analysis of genes associated with longevity. These studies were designed so that the elderly and young populations were carefully regionally matched, in order to avoid regional variations in genotype frequencies. This is important especially when examining loci genes like apo E, where allele frequencies vary greatly in different populations [5]. The similar allele and geno- type frequencies observed at the APC (see Section 2) and MTHFR loci confirm this assumption.

groups. Similar proportions of all populations were homozygous for the mutation.

4. Discussion

Our data support previous observations that apo E:apo C-I and ACE genotype frequencies differ in elderly and young populations, suggesting a role for these genes in human longevity. The effects associated with these genes may be different for males and fe- males, since apo E:apo C-I genotypes were only differ- ent in elderly women, while ACE genotypes were only different in elderly men. Furthermore, ACE genotypes were significantly different in elderly men and elderly women but not in young boys and girls.

Apo E genotypes have been previously examined in centenarians, nonagenarians and octogenarians [3–5]. The female-specific apo E genotype frequency differ- ence in our elderly individuals was initially considered to be equivocal, since this result was not significant when the observed genotypes of the elderly women were compared to those in the young group computed from their allele frequencies, according to expectations of Hardy-Weinberg equilibrium. However, the female

Our study analysed DNA from 282 individuals over 84 and 200 individuals aged younger than 17 years. This sample is not large enough to rule out weak genetic associations, like the putative effect of the 677C-T MTHFR mutation. However, our elderly sam- ple was of a similar size to that of Schachter et al. (325 centenarians) [3] and larger than those of Davignon et al. (236 octogenarians) [5] and Kervinen et al. (95