First, we review mechanisms by which the DNA exonuclease TREX1 negatively regulates the cytosolic DNA sensor cGAS and its downstream effector STING, and we propose a model of TREX1-mediated DNA damage and cellular senescence that implicates age-related, inducible TREX1 expression in the context of genetic disease and inflamm-aging. The gene discussed is TREX1; the disease is hereditary disease.