"Basically, when you look at different types of cells, such as fibroblasts, which form connective tissue, or epithelial cells, from saliva, you see general correlations within a person. If telomeres are up for one cell type, they're up for others overall."
Elizabeth Blackburn is an Australian-American molecular biologist whose work on telomeres and telomerase transformed cell biology research. She shared the 2009 Nobel Prize in Physiology or Medicine.