Statistical analysis (Pearson's chi-squared test) demonstrated that observed and expected frequencies of allele identity between centenarian and sibs were not significantly different for HLA-DQA1* and DQB1* alleles.

Genes that contribute to human longevity are a powerful tool in mapping very strong effects of genes.10 Mapping of less effective but contributing genetic variation necessitates a larger sample.10 On the other hand, the sample size allowed the evaluation of DQA* or DQB1* allele sharing among centenarians and 85-year-old sibs. Nine of twenty-four sibs shared two HLA-DQA1* and 8/24 shared two HLA-DQB1* alleles with centenarians, but statistical analysis demonstrates that the observed and expected frequency of allele identity between centenarian and sibs was not significantly different both for HLA-DQA1* and DQB1* loci, suggesting that genetic settlement at the HLA DQ region is indifferent regarding longevity.

In conclusion, present and previous results5,16 seem to support the hypothesis that genes involved or associated with HLADQ-DR haplotypes have a marginal influence, if any, in determining human longevity.

ACKNOWLEDGMENTS 
The authors are grateful to Dr. Alessandra Errigo for help in patient recruitment and blood sample processing. The Gruppo di Studio sull'Immunosenescenza coordinated by Professor C. Caruso was funded by grants from MIUR, Rome (ex 40%, to C.C. and D.L.; ex 60% to G.C. and G.C.R.). The collaboration between this group and the Istituto Nazionale di Riposo e Cura per Anziani was enhanced by a cooperation contract (longevity and elderly disability biological markers). Professor C. Franceschi was funded by MIUR, Rome (PROCESSED TEXT: No changes needed. This is likely an email address.