Progressive telomeric shortening in acquired AA. Telomere loss, expressed as distance in kilobases (TRF^O-E) from the age-appropriate point on the normal regression line of TRF against age, is plotted against months since presentation with idiopathic AA. (A) Patients with active AA, with persistent cytopenia (n = 40; ⧫), showing significant correlation between TRF loss and disease duration (r = −.685; P < .0001). The slope of the regression line, shown as a solid line (95% confidence band shown as dotted lines), predicts a loss of 216 bp per year, in addition to the normal age-related loss. (B) Patients with fully recovered blood counts (n = 20; ○), showing lack of correlation between telomere loss and interval since diagnosis.