Joris Deelen |25-06-2014 | Genetic and biomarker studies of human longevity
The aim of this thesis was to identify novel lifespan regulating loci that influence human longevity and population mortality. To this end, we performed two genome-wide association studies, one of long-lived individuals from the family-based Leiden Longevity Study (LLS) and an extended one of long-lived individuals from multiple cohorts of European descent. Using the latter, we identified two genome-wide significant loci, the TOMM40/APOE/APOC1 locus and an intergenic locus on chromosome 5q33.3. In addition, our gene set analysis with the LLS data showed that genetic variation in genes involved in the insulin/IGF-1 signaling and telomere maintenance pathways is associated with human longevity. Since our genetic studies identified a limited number of longevity loci, we additionally examined whether leukocyte telomere length (LTL) could be used as a biomarker of healthy aging. We showed that LTL meets three of the four criteria for a biomarker of healthy aging in the LLS, i.e., LTL changes with chronological age and is associated with health, in this case immune-related parameters, and prospective mortality. To identify novel longevity loci, future research may benefit from a better definition of the healthy aging phenotype, combining study designs, and the use of novel methods and technologies, such as next-generation sequencing.