MRC1 and cancer: Tessier-Cloutier et al reported an undifferentiated colonic carcinoma with SMARCA4, MLH1, and PMS2 loss.17 There is great variability in MMR status among SMARCA4-deficient carcinomas in the GI tract with reports of tumors in the small intestine and stomach.9 An analysis of the TCGA Pan-Cancer Atlas showed 14.7% of any gastric cancer with any SWI/SNF alteration had MSI.20 Therefore, it appears that MMR deficiency is not mutually exclusive with SMARCA4 loss and should not preclude the classification as a SMARCA4-UT.