Alleles and genotypes of three polymorphic sites at the IL-1 cluster were estimated in the group of people described above. Neither IL-1b nor IL-1Ra plasma levels showed any relationship with genotypes at the IL-1b locus (F=0.448, d.f.=2, P=0.64) or with carriers of allele 2 at the IL-1Ra locus (F=2.197, d.f.=1, P=0.141).

4. Discussion

3.1. IL-1 cluster genotype and allele frequency distributions

In a large sample of 1131 subjects, ranging from 20 to 102 years of age, no significant age-related changes of allele, genotype and haplotype frequency distributions of the IL-1 cluster polymorphisms were found. These results are in agreement with those recently published in nonagenarian Finnish subjects (Wang et al., 2001); indeed, it is remarkable that in these two genetically different populations (Finnish and Italians), the gene cluster distributions are quite similar.

The genotype and allele frequency distributions were estimated in a total of 1131 subjects from 20 to 102 years old. To perform a comparative analysis, the whole sample was divided into three age groups: young subjects (19-65 years old; 688 individuals, 210 females and 478 males), elderly subjects (65-99 years old; 309 individuals, 149 females and 160 males) and centenarians (>99 years old; 134 individuals, 94 females and 40 males). Table 1 shows the genotype frequency distributions of the IL-1a (-889 locus), IL-1b (-511 locus), and the IL-1Ra VNTR locus in the three groups described above. Within each group, the genotype distributions were consistent with those predicted by the HWE (P<0.05). No significant difference in the genotype frequency distributions was observed when the sexes were analyzed together (Table 1) or separately (data not shown). The analysis of the difference in the three groups of allele frequency distributions was also not significant (Table 2) even when the sexes were analyzed separately (data not shown). The frequency distribution of the three loci haplotypes was estimated in the three age groups by means of maximum likelihood estimation algorithm (Table 3). Again, no significant differences were detected.

3.2. IL-1Ra and IL-1b plasma levels during aging

IL-1Ra plasma levels were assessed in a group of 130 unrelated randomly selected subjects (71 females and 59 males) ranging from 20 to 102 years of age. Fig. 1 shows that IL-1Ra plasma levels showed a significant age-related increase.There are many errors in this text, and it is difficult to understand the meaning. Could you please provide more context or information about what this text is about?The following text appears to be a list of references related to genetics and disease. As such, there is no need to process the text.