CHEK2 and malignant colon neoplasm: The majority of those positive results were in well-established colon cancer genes: MLH1, MSH2, MSH6, PMS2, EPCAM, MUTYH, APC, PTEN, and STK11. However, 28.2% (35/124) were observed in genes considered nonclassical for gastrointestinal cancers: BRCA1, BRCA2, CHEK2, ATM, PALB2, BRIP1, and RAD51D. BRCA1/2 alone accounted for 9.7% (12/124) of positive variants identified in individuals diagnosed with colon cancer.