The major genes with PVs in patients with colorectal cancer included the MMR genes MLH1, MSH2, PMS2, and MSH6, (accounting for 9% of patients with a PV), followed by APC, TP53, MUTYH, BARD1, ATM, and BRIP1. Patients presenting with polyposis tested positive for PVs in APC (4%), MUTYH (2%), PMS2 (2%), MLH1 (2%), TP53 (2%), and to a lesser extent in PTEN, SMAD4, and ATM. Among patients with gastric and other GI tract cancer, PV’s were found in CDH1, TP53, ATM, MSH2, and PMS2 genes (Table 2). Here, MRC1 is linked to polyposis.