Four of 6 cases with > 5 SNV + Indel/Mb and germline variations in MLH1, MSH2, MSH6, PMS2, POLE or POLD1 belonged to Myeloid Predominant, suggesting higher levels of immune infiltration in patients with biallelic Mismatch Repair Deficiency (bMMRD) syndrome. Here, MLH1 is linked to mismatch repair cancer syndrome 1.