Microsatellite instability in gastric MALT lymphomas and other associated neoplasms

Background: Microsatellite instability (MSI), caused by a reduced efficacy of the DNA mismatch repair (MMR) machinery, represents a type of genomic in stability frequently detected in HNPCC spectrum cancers and in a subset of sporadic carcinomas. The involvement of MSI in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) has never been conclus ively investigated. In this study, we tested the presence of MSI in tumor s amples of patients harboring both MALT lymphomas and other types of maligna ncies. Materials and methods: We examined 10 microsatellite loci (D3S11, D3S1261, D3S1265, D6S262, D6S193, BAT-26, BAT-25, D17S250, APC, D2S123) out of a tot al of 34 primary tumors from 14 patients with MALT lymphomas and one or mor e additional neoplasms. The patients' MSI results were also tested for an a ssociation with a positive family history of cancer. Results: MSI, defined by the presence of microsatellite alterations in more than 40% of the examined loci, was scored negative in all tumors studied, and pedigree analysis failed to identify any condition of familial cancer a mong the patients examined. Conclusions: The present study suggests that defects in DNA mismatch repair do not contribute significantly to the molecular pathogenesis of MALT lymp homas and associated neoplasms.