Genotype x age interaction, and the insulin-like growth factor I axis in the San Antonio Family Heart Study: A study in human senescence (Texas)

This dissertation approaches human senescence from a statistical genetic perspective and works with data provided by the San Antonio Family Heart Study (SAFHS). It is shown how statistical genetics provides a logical foundation for traditional approaches to studying human senescence. For analytic tractability, the insulin-like growth factor I (IGF-I) axis is adopted as the main physiological system of interest. In theory, however, the statistical genetic approach used in this research can be applied to any physiological system. Working from within the statistical genetic framework, the basic model therein is improved upon and extended to include genotype x age interaction. Genotype x age interaction was found to be important in the overall behavior of the IGF-I axis in the SAFHS. The statistical genetic, biomedical and evolutionary implications of this finding are explored. The theory of genotype x age interaction is then extended to include mitochondrial effects, which are known to play important roles in human senescence. Lastly, the findings of this dissertation research are summarized.