A 35-year-old man undergoes gastrectomy for gastric carcinoma. Gross examination of the resected stomach reveals diffuse thickening without a discrete mass lesion. Microscopic exam shows an infiltration of signet-ring cells dispersed singly. Family history reveals that his father had a similar cancer at a young age. What gene is most likely to be mutated in this patient and his father?

- Mutation in CDH1, the gene encoding the cellular adhesion protein E-cadherin. - E-cadherin mutations account for a significant propoion of familial gastric cancers and Lobular carcinoma of the breast. OTHER OPTIONS: - APC is mutated in the majority of colorectal adenocarcinomas & intestinal type of gastric cancer. - MSH2 and PMS2 are both mismatch repair genes are mutated in Lynch syndrome - p53 is mutated in Li Fraumeni syndrome.