Discussion

Our work shows that women carriers of C282Y mutation are at a higher frequency among the elderly compared with control women. These data suggests that this poly- morphism plays a role in determining lifespan, at least in the Sicilian generation under study (see below).

the HFE mutation pattern of high-risk groups and of gen- eral population, showing that the HFE gene mutations are more frequent in north than in south Italy.13,20,24,31,32 However, in our study, in young controls, the prevalence of C282Y (and of S65C) gene mutations was surprisingly low. On the other hand, the frequencies observed by our- selves are in agreement with those recently reported in a large sample of the population from southern Italy (0.15%, 18.6% and 0.15%, for C282Y, H63D and S65C respectively),13 being the C282Y mutation the lowest yet reported for a population of European origin. Inciden- tally, in our population it seems to have little, if any diag- nostic relevance (our unpublished observations). Similar results have been obtained in Greece.19

Several findings point out that gender is a major vari- able in the genetics of longevity and suggest as a working hypothesis that men and women follow different stra- tegies to reach longevity.42–46 Present data indicates that C282Y allele distribution is different in elderly women in respect to controls, but not in elderly men. Even if the small number of sample elderly males might not allow the identification of significant differences, these data seem to suggest that possession of C282Y allele, known to be associated with an increase of iron uptake,3,4,6,9 sig- nificantly increases only in women the possibility to reach longevity. In this respect, it has to be remembered that for the generation of elderly people under study life- style, including diet, was quite different for men and women. For instance, in Sicily, like in other pre-industrial countries, a lot of pregnancies (and abortions) were yet the rule for the women born at the beginning of the last century and the their diet consisted mainly in iron-poor grains, vegetables and fruits (if any), whereas meat was highly uncommon and in any case put aside for men and children.41,47 Thus, it is to be taken into account that gene variants representing a genetic advantage for one gender might not be automatically relevant for the other gender

in successful ageing. It is intriguing that HFE mutations have been suggested to be involved in unsuccessful age- ing too. In fact, in Alzheimer disease (AD) patients carry- ing the H63D allele had a mean age at onset of 72 years vs 77 years of those who were homozygous for the wild- type allele. Thus, it seems that H63D mutations may anticipate sporadic late-onset AD clinical presentation in susceptible individuals.33 In another study, in patients with familial AD (FAD) C282Y and H63D mutations were over-represented in men and under-represented in women with FAD.34 Thus, the possibility that HFE mutations are important new genetic risk factors for AD should be pursued further.

Regarding the biological significance of HFE hetero- zygous status, this phenotype was recently defined.35,36 The mean serum iron concentrations, ferritin levels and transferrin-saturation values were higher in hetero- zygous subjects than in normal ones, as were mean hae- moglobin levels and mean corpuscular volume. The prevalence of iron deficiency anaemia was lower in women who carried HFE mutations. Concerning then the significance of iron in immune responses, a delicate bal- ance exists inside the host cell. Too much iron down- regulates microbicidal effector mechanisms and favours the growth of the pathogen, whereas too little iron is inhibitory to the induction of antimicrobial processes.37 However, it is undeniable the importance of iron in the regulation of immune responses.7,8

In conclusion, present data showing the relevance of C282Y for womens survival to late age, adds another piece of evidence to the complex puzzle of genetic and environmental factors involved in control of lifespan expectancy in humans.

Materials and methods

Subjects

One hundred forty-one unrelated healthy Sicilians ran- domly selected were studied: 106 young controls (age range from 22 to 55 years; 40 men and 66 women) and 35 elderly subjects (age range from 91 to 105 years; seven men and 28 women). Reported age was verified by researching archival records in the City Hall and/or Church registries, paying attention to the concordance between reported age and personal chronologies (age of marriage, age of military service for males, age of first and last pregnancy for women, age of children, among others). Written informed consent for enrolling in the study and for personal data management had been pre- viously obtained from all the subjects according to Italian laws. Blood specimens were collected in tripotassium − ° EDTA sterile tubes, immediately stored at 70 C and in a further time processed for HFE genotyping. Genomic DNA extraction was carried out according to Miller et al48 − ° and stored at 20 C for the HFE gene analysis.

The role of genetics in determining lifespan is complex. On the basis of results obtained from the population- based Scandinavian Twin Registries,38,39 a maximum of around one-third of the variance of ‘longevity’ is attribu- table to genetics. However, the real contribution of the genetics to human longevity has not yet been sufficiently addressed. Therefore, the role of genetics in longevity might be much higher than predicted.2

As pointed out by Shachter et al40 two strategies can be exploited to identify genes that influence human lifespan, ie sibling pair analysis or case-control studies. In a case- control study, allele and genotype frequencies at poly- morphic marker loci (for instance HFE gene) are com- pared between a long-lived group and a control group