Telomere length in study participants and individual CFUs from CH carriers. (A) Telomere length in donors and recipients, respectively, as measured by MM-qPCR and depicted as T/S ratio. (B) Telomere length difference between individual donor-recipient pairs translated into years of premature ageing. (C) Telomere length in individuals with or without CH based on donor or recipient status. (D) Schematic outline demonstrating experimental workflow for identification of wild-type and mutated CFUs by Sanger sequencing followed by telomere length measurement using MM-qPCR. (E) Telomere length in individual wild-type or CH mutation–positive CFUs (single individuals affected by CH, upper panel; donor-recipient pairs with mutations in both donor and recipient, lower panel). Mann-Whitney test was used to calculate statistical significance.