C4B and leukemia: Interestingly, CH mutations in PPM1D were found to be depleted in patients with P/LP germline mutations in DNA damage response (DDR) genes like ATM, CHEK2, and TP53. Furthermore, patients with solid tumors carrying both P/LP germline mutations and CH mutations, along with mosaic chromosomal alterations, may be at heightened risk for developing secondary leukemias.