Abstract
Aging studies can be facilitated by refocusing from longevity phenotypes to their proxies (intermediate phenotypes). Robust selection of the intermediate phenotypes requires data on such phenotypes and life span measured in the same individuals, which is not always the case in aging studies. A promising approach is to select intermediate phenotypes using information on longevity measured in related individuals. We evaluated feasibility of this approach focusing on 32 geriatric diseases as potential intermediate phenotypes of longevity assessed in the Longitudinal Study of Aging Danish Twins. Our analyses reveal that geriatric diseases measured in some family members can predict life span in the other family members both individually and cumulatively ensuring that this approach for selection of intermediate phenotypes is feasible. The cumulative-trait approach is more promising for such studies compared with the individual-trait approach. Heritable health dimensions contributing to a decrease of life span have sex-insensitive and sex-specific components.