PPM1D and cyclic hematopoiesis: The CH-associated mutations identified included no advantageous mutations reported in aging-associated human CH1,2,31, such as DNMT3A, TET2, ASXL1, TP53, JAK2, and PPM1D, nor mutations described in CH cases treated with cancer radiotherapy12; therefore, the mutations identified in this study may not directly contribute to promoting CH.