PRDM1 and neoplasm: More interestingly, a random sampling weighted on the size of the annotated protein domains demonstrated that deleterious mutations were significantly enriched in the PR domain of PRDM1, PRDM5, PRDM6, PRDM8, PRDM9, PRDM12 and PRDM13. Frequent mutations disrupting the PR domain in tumor samples would be a mechanism for removing the tumor suppressor function of the PR-plus isoform in favor of the oncogenic PR-minus form.