Mutation of the 5' noncoding region of the BCL-6 gene in low-grade gastric lymphoma of the mucosa-associated lymphoid tissue.

BCL-6 gene rearrangement and hypermutations were investigated in four Hong Kong Chinese patients with low-grade gastric lymphoma of the mucosa-associated lymphoid tissue (MALToma). The former was studied by Southern analysis and the latter by the technique of polymerase chain reaction and denaturing gradient gel electrophoresis. BCL-6 gene rearrangement was not detectable in any of the four cases. However, mutations at both the E1.11 and E1.12 segments of the 5' noncoding region of the BCL-6 gene were found in two patients. This preliminary observation suggests that the mutations of the 5' noncoding region of the BCL-6 gene rather than gene rearrangement may be playing a more important role in the tumorigenesis of low-grade gastric MALToma. Further confirmation of this finding by studying a larger number of patients will be required.