RESUMO
OBJECTIVE: To investigate BCL-6 gene mutations in B-cell non-Hodgkin lymphomas (B-NHL) and their implications in lymphoma pathogenesis. METHODS: Polymerase chain reaction (PCR) and direct DNA sequencing methods were used to identify mutations in the 5'-noncoding region of BCL-6 gene in 135 cases of B-NHL, 5 cases of T-NHL, 5 cases of nodular lymphocyte predominance Hodgkin's lymphoma (NLPHL) and 10 cases of reactive hyperplasia of lymph node. RESULTS: Mutations were identified in 6 cases of nodal DLBCL (27.3%), 4 cases of FL (22.2%), 4 cases of MALT lymphoma (22.2%), 4 cases of extranodal DLBCL (20.7%) and 2 cases of LRH (20%). No mutations were detected in T-NHL and NLPHL (P < 0.05). There were no significant differences in incidences of BCL-6 gene mutations between nodal and extranodal DLBCL (P > 0.05). All mutations were base substitutions and the frequency of single-base change was 0.14 x 10(-2)/bp approximately 0.68 x 10(-2)/bp. CONCLUSIONS: Mutations of the 5'non-coding region of BCL-6 gene may be involved in the pathogenesis and progression of B-NHL. Molecular demonstration of such mutations may provide a marker of lymphomas derived from the germinal center-related B cells.