Telomere lengths of TPP2-deficient lymphocytes and granuloyctes. (A) Exemplary fluorescence-activated cell sorter plot of the flow- fluorescence in situ hybridization analysis: human lymphocytes, granulocytes, and cow thymocytes were discriminated by forward scatter (FSC) and LDS 751 staining. (B) Telomere lengths were determined by subtracting telomere-Alexa-Fluor 488 intensity of stained from the unstained lymphocytes of the patient (P1) or the healthy carrier sister. Cow thymocytes with known telomere length were used as an internal control and to calculate telomere lengths in kilobases. Absolute telomere lengths of lymphocytes (C) and granulocytes (D) of the patient, his sister, and 2 patients with DKC are shown in the context of age-dependent percentiles (black lines: 99th, 50th, and 1st percentile, dotted lines: 75th and 25th percentile).