XPA and progeroid syndrome: Indeed, not only CR or mutant dwarf mice but also progeroid XpdTTD mice, which have a milder TC-NER defect than Csbm/m;Xpa−/−, Ercc1−/− and Ercc1−/Δ−7 mice, are protected from tumorigenesis and despite showing segmental progeria in a variety of tissues they show a number of paradoxically improved histopathologic changes related to a CR-like phenotype in other tissues such as lower incidence and/or severity of de-myelination of the peripheral nerve, cataract, thyroid follicular distension, pituitary adenomas and ulcerative dermatitis [34].