In contrast to normal middle-aged individuals, a 48-year-old woman (PD47703) treated for Hodgkin lymphoma with chlorambucil and procarbazine at age 10 years and bendamustine at age 47 years showed multiple independent clonal expansions carrying ‘driver’ mutations in the DNA damage response gene PPM1D (Fig. 5c). This evidence concerns the gene PPM1D and Hodgkins lymphoma.