PPM1D and neoplasm: Interestingly, these two patients also lacked mutations in TP53 and PPM1D. To further investigate this observation, we analyzed a larger cohort of published data [21] and found that the number of clones in a tumor sample was lower in H3.1-mutant cases with marginal significance (median 4.5 in H3.1 versus 6.0 in H3.3-mutant patients, p value = 0.056).