Estimating the sex-specific HRR on human survival showed that the female carriers of haplotype G-C-T had longer survival duration than the non-carriers (HRR=0.550; p=0.015) (Table 3), while all other haplotypes failed to reach the significance level. Fig. (3) (left), shows that the estimated frequency of the G-C-T haplotype goes up with increasing age indicating the beneficial effect of the haplotype. On an average, female carriers of the G-C-T haplotype live about one year longer than non-carriers [Fig. (3), right]. Similar to the genotype-based analysis, no haplotype displays a significant effect on male survival.

39    T carriersnon-carriers97 98     96Age   —iGu9594oo2 Oo @ o nn + mn - °- oso Ss os oso Ss 36 os cs os oleansAge 2 wo ° oo °o ooo o ire} ~ 7 ooo So ° o o oS“bad adAjojdeH

Fig. (3). Frequency (left) and survival (right) of G-C-T haplotype carriers in females over the follow-up ages.

3. Estimated Relative Risks of the Frequent Haplotypes* over the Three Loci in Females

Haplotype Frequency Risk p-value AAT 0.379 1.481 0.115 AGT 0.027 2.266 0.180 GCT 0.358 0.550 0.015 AAC 0.230 1.148 0.589

*The first position in the haplotypes corresponds to the marker in gene HSPA1B, second in HSPA1A, and third in HSPA1L.

longitudinal cohort design for studying relative risk of haplotypes and genotypes on human survival in a cohort of individuals born in Denmark in the year 1905 [21].

In our study we found that the female carriers of genotype HSPA1A-AA survived for a shorter duration than the non-carriers. Our result is consistent with the observations of Altomare et al. from a case-control study done on Italian subjects where they found that the frequency of allele A was unfavorable for female longevity [11]. However, the current survival study, being performed on a cohort, is more powerful to show this association. HSPA1A (- 110A>C) SNP is present in the promoter region of the gene, 3’ upstream of the heat shock element (HSE). Favatier et al. [27] had observed that this SNP does not affect the binding of heat shock factor with the HSE and hence may not affect the synthesis of Hsp. In another recent study it was shown that the reporter constructs containing the -110A allele cloned into the luciferase reporter plasmid drove marginally higher transcriptional activity of HSPA1A as compared with the -110C allele in both control and heat shocked cells [28], proposing that this polymorphism may be a functional one. Since we have observed a significant association of this SNP with female survival, the mechanisms involved in this association need to be further explored.

A group of nonagenarians, born in year 1905, and from whom DNA was collected in the year 1998, when they were 93 years old, were genotyped for polymorphisms in the three HSP70 genes. Thus we could study if, over the years, the carriers of one genotype/ haplotype survived better or worse than the non-carriers. Nona- genarians form an ideal group on which such follow-up studies can be performed. A large degree of heterogeneity with respect to physical and cognitive functioning can be expected among them. Nonagenarians are also better representative of the older population than a group of rare and selected centenarians. A follow up study of this age group can shed light on the aging processes among extremely old individuals. It has also been found in the Danish 1905 cohort that the selection pressure that an individual has to face in order to survive from ages 92 to 100 is comparable to the selection pressure faced in order to survive from ages 0 to 92 (http://www.mortality.org). So even if we cannot use a younger cohort for studying the survival, the use of an older group such as nonagenarians can be a good representative of the general popu- lation [21].

In the current study we also observe that female carriers of genotype HSPA1B-AA survive for a shorter duration as compared to the non-carriers. This synonymous SNP is present at position 1267, in the coding region of HSPA1B. We had recently observed

= HSPA

A = HSPA

B = HSPA

L = Heat Shock Response = Major Histocompatibility = Single Nucleotide Polymorphism

that a high level of linkage disequilibrium (LD) exists between HSPA1A-A and HSPA1B-A (D’=1) [14]. This is consistent with our present observation where we see that carriers of both the alleles, HSPA1A-A and HSPA1B-A, are shorter survivors. Because HSPA1B (1267A>G) is not a functional variation, it remains to be seen how the negative association of this allele with human survival is manifested at the biofunctional level.

Because longevity is a complex trait, statistical approaches that take into account a group of genetic variants (haplotypes) are crucial in mapping genes that modulate human survival. In our analyses on the association of haplotypes on human survival, we observed that the female carriers of haplotype G-C-T were longer survivors as compared to the non-carriers. Our current results are consistent with our earlier observations of haplotype survival analysis, in the cross-sectional study design (manuscript in pre- paration). Moreover in the cross-sectional study design we had also seen that allele HSPA1L-T was favourable, whereas allele HSPA1L- C was unfavourable for female longevity. From the current results on the 1905 cohort individuals, we see that allele HSPA1L-T is defined in the haplotype G-C-T which is shown to have longer survival duration for females. We also observed a trend towards shorter survival duration of the carriers of HSPA1L-C as compared to the non-carriers (Table 2).

REFERENCES

and ageing: Mechanisms and applications. Cell Biol Int

;

-

Rattan SI. Aging intervention, prevention, and therapy hormesis. J Gerontol A Biol Sci Med Sci

;

:

-

Rattan SI. Increased molecular damage and heterogeneity as basis of aging. Biol Chem

;

:

-

Rattan SI. Hormesis in aging. Ageing Res Rev

;

:

-

Soti C, Csermely P. Molecular chaperones and the aging Biogerontology

;

:

-