Progeria is a rare human genetic disease with many features suggestive of premature aging. Cultured progeric fibroblasts have previously been shown to have abnormalities in growth, DNA repair, Tissue Factor activity, Thermolabile protein, and HL-A expression. I plan to study a large number of progeric strains to find a reliable marker for progeric cells by various assays. The persistence of this defect will be examined using cocultivation to determine under what conditions it is reversible. This project may lead to information regarding human genetic disease and the nature of the aging process.