TO IDENTIFY THE GENETIC FACTORS: Family and twin studies showed that longevity results from the interaction of genetic and environmental factors. Despite progress the performed made in the study of animal models highlighting some interesting metabolic pathways, characterization of genetic factors remains difficult in human beings. Two genetic approaches are currently available: association studies and sib-pair analyses. ASSOCIATION STUDIES: The first method is based on the comparison of polymorphism repartitions on candidate genes in two matched populations of old people and young controls. SIB-PAIR ANALYSES: The second requires genotyping of brothers and/or sisters on a set of highly polymorphic markers, in order to identify new candidate regions on the genome. APOE: Until now, the only gene that remains clearly associated with longevity is the Apolipoprotein E gene.