POLD1 and mismatch repair cancer syndrome 1: Tumor exome sequencing performed in the MMR-deficient colon cancer developed by the POLD1 c.230delC (p.Pro77Leufs*92) carrier revealed that ~85% of the signatures’ contribution corresponded to MMR deficiency and no representation of POLE/D1-associated signatures (Fig. 4; Supplementary Table S7).