The novel finding in our study is that after controlling for age, which is necessary when considering the potential differences in age of onset of inherited malignancies, the presence of a germline alteration in any of the five DNA repair genes studied (ATM, BRCA1/2, CHEK2, PALB2) was not associated with a higher prevalence of CH, except in aggregate among women with breast cancer. Here, ATM is linked to cyclic hematopoiesis.