Low incidence of BCL-6 gene alterations for diffuse large B-cell lymphomas in Taiwan Chinese

BACKGROUND. In Western populations, rearrangement of the BCL-6 gene can be identified in 20-40% of patients with diffuse large B-cell lymphoma (DLBCL). Analysis of the BCL-6 gene has revealed the presence of point mutations or small deletions in 70% of DLBCL tumors; however, few studies have investigated BCL-6 gene alteration in patients with non-Hodgkins lymphoma (NHL) of Chinese descent. METHODS. Samples from 135 Taiwanese patients with NHL were examined (28 samples of T-cell NHL and 107 samples of B-cell NHL; 59 samples from patients with DLBCL) for gene rearrangement and mutation of the BCL-6 proto-oncogene using Southern blot analysis and single-strand conformation polymorphism (SSCP) followed by sequence analysis. RESULTS. BCL-6 rearrangement and point mutations were found in 14.8% of patients (n = 20) and in 7.4% of patients (n = 10), respectively. All BCL-6 gene alterations occurred in patients with B-cell NHL, and none occurred in patients with T-cell NHL. Among the 59 patients with DLBCL, BCL-6 gene rearrangements were identified in 10 patients (16.9%), and mutations were identified in 8 patients (13.6%), with the BCL-6 mutation occurring independent of the BCL-6 rearrangement. The incidence of BCL-6 gene rearrangement and mutations in patients with extranodal DLBCL was 9.5% (2 of 21 patients) and 23.8% (5 of 21 patients), respectively. Univariate analysis and multivariate logistic regression found no association between BCL-6 gene alternations and clinical characteristics, including extranodal tumors in patients with DLBCL, and no association between the BCL-6 alterations and prognosis was found. CONCLUSIONS. The incidence of BCL-6 alterations was lower in Taiwanese patients with DLBCL compared with Western populations, and BCL-6 gene alterations showed no prognostic significance in patients with DLBCL.