L. Carotenuto

Gene/longevity association studies at four autosomal loci ( REN, THO, PARP, SOD2 )

The possibility that four loci (REN, THO, PARP, SOD2) are associated with longevity was explored by comparing the genotypic pools of subjects older than 100 years with those of younger subjects matched for sex and geographic area (northern and southern Italy). The markers (all located within the respective gene) were HUMREN4; HUMTHO1; HUMPARP (gt)845nt; SOD2(C/T)401nt. In order to reduce the number of genotypes, multiallelic polymorphisms were recoded as diallelic according to allele size and frequency patterns (small: S, and large: L, alleles). A significant loss of LL homozygous genotypes was found at the THO locus in male but not in female centenarians with respect to matched controls. On the other hand no significant difference was found between case/control genotypic frequencies at REN, PARP, SOD2 loci. The latter loci therefore do not affect inter-individual variability in life expectancy (at least in terms of qualitative variants associated with the tested markers). However, the data is consistent with an association between the THO locus and longevity.

Age‐related changes of the 3′APOB‐VNTR genotype pool in ageing cohorts

The analysis of seven different age cohorts (697 individuals from 10 to 109 years old) revealed age‐related changes in the 3′APOB‐VNTR genotype pool. By recoding the 3′APOB‐VNTR alleles into three size‐classes (small, S, 26–34 repeats; medium, M, 35–39 repeats; large, L, 41–55 repeats), an age‐related convex trajectory of the frequency of SS homozygotes was found. The frequency of SS in the genotype pool increased from the group aged 10–19 years (3.06±1.74%) to that aged 40–49 years (8.51±4.07%). Then it declined reaching the minimum value in centenarians (1.58±0.90%). The observed trajectory is in agreement with that expected by assuming crossing of mortality curves relevant to subgroups of individuals having different genotypes.

The study of APOA1, APOC3 and APOA4 variability in healthy ageing people reveals another paradox in the oldest old subjects

The genes coding for apolipoprotein A1 (APOA1), apolipoprotein C3 (APOC3) and apolipoprotein A4 (APOA4) are tandemly organised within a short region on chromosome 11q23‐q24. Polymorphisms of these genes have been extensively investigated in lipoprotein disorders and cardiovascular diseases, but poorly investigated in healthy ageing. The aim of this study was to describe possible modifications of the APOA1, APOC3, and APOA4 gene pool by cross‐sectional studies carried out in a healthy ageing population whose ages ranged from 18 to 109 years (800 subjects, 327 males and 473 females, free of clinically manifested disease, and with emato‐chemical parameters in the norm). APOA1‐MspI‐RFLP (−75 nt from the transcription starting site), APOC3‐SstI‐RFLP (3′UTR, 3238 nt), and APOA4‐HincII‐RFLP (Asp127/Ser127) were analysed according to age and sex. A significant age‐related variation of the APOA1 gene pool was observed in males. An analysis of the allele average effect exerted by APOA1‐MspI‐RFLP A/P alleles (Absence/Presence of the restriction site) on lipidemic parameters in 46–80 year old males showed that allele A decreased, while allele P significantly increased, serum LDL‐cholesterol. Unexpectedly, the P allele was over‐represented in the group of the oldest old subjects, thus giving evidence of another “genetic paradox of centenarians”.

Genes and longevity: a genetic-demographic approach reveals sex- and age-specific gene effects not shown by the case–control approach (APOE and HSP70.1 loci)

Association analyses between gene variability and human longevity carried out by comparing gene frequencies between population samples of different ages (case/control design) may provide information on genes and pathways playing a role in modulating survival at old ages. However, by dealing with cross-sectional data, the gene-frequency (GF) approach ignores cohort effects in population mortality changes. The genetic-demographic (GD) approach adds demographic information to genetic data and allows the estimation of hazard rates and survival functions for candidate alleles and genotypes. Thus mortality changes in the cohort to which the cross-sectional sample belongs are taken into account. In this work, we applied the GD method to a dataset relevant to two genes, APOE and HSP70.1, previously shown to be related to longevity by the GF method. We show that the GD method reveals sex- and age-specific allelic effects not shown by the GF analysis. In addition, we provide an algorithm for the implementation of a non-parametric GD analysis.

Spatial Analysis and Surname Analysis: Complementary Tools for Shedding Light on Human Longevity Patterns

Starting from the observation that human longevity patterns show regional variations, we applied Spatial Analysis (using the Geographic Information System) and Surname Analysis to highlight the effect of the population genetic structure on such patterns. The study was carried out in Calabria, a southern Italian region which is characterized by a wide variability of geographic features (high mountains and deep valleys which created geographic isolates in the past). We identified three zones of high longevity: a male and a female longevity zone were located near the town of Cosenza (northern Calabria), while a male longevity zone was located in a mountainous and quite isolated part of the province of Reggio Calabria (southern Calabria). The latter zone was characterized by the lowest Female/Male ratio in nonagenarians observed to date. By applying surname analysis (Fishers alpha) we found a significant negative correlation between surname abundance and index of longevity, showing that this isolated zone of male longevity presents a high level of inbreeding. On the whole, the results showed the effectiveness of spatial analysis in revealing geographical longevity patterns, and highlighted the importance of the population genetic structure in shaping such patterns.

EcoRI-RFLP of the Apo B gene : a study in a sample group from south Italy

EcoRI restriction analysis at codon 4154 of the Apo B gene was performed in a sample of 90 subjects from southern Italy (sample S), using total blood cell DNA amplified by PCR. A group of 46 subjects from northern Italy (sample N) was also investigated for comparison. Southern Italians showed an incidence of the R2 allele (absence of the cutting site) twice as high as that found in northern Italians (48 v. 21 %). By ASPCR the mutation which abolishes the restriction site was confirmed as being G→A at the first base of the 4154 codon of the Apo B gene (Glu→Lys) in both S and N samples. By studying the variability of cholesterolaemia among different EcoRI genotypes in the S sample, it was estimated that the average effect of the R2 allele is to lower serum cholesterol by 8‐5 mg/dl.

Population Genetics of VNTR Markers (TPO and 3’APOB Loci) in the Mediterranean Area (Albania, Greece and Italy)

The use of hypervariable markers in population genetic studies indicated that different ethnic groups can show distinguishing features of allele frequencies, even though the range of DNA fragment size is almost the same (1). It is not clear, however, how much efficient are these markers in distinguishing populations of the same major ethnic group.