Fibroblasts derived from various progeroid syndromes have been shown to have a reduced replicative capacity compared to normal cells; such syndromes include WS, ATR-SS, AT and HGPS (Davis and Kipling 2009; Tivey et al. 2013a; Davis et al. 2005; Tivey et al. 2013b). The gene discussed is ATR; the disease is Werner syndrome.