Frequency of bcl-2 gene rearrangement in B-cell Non-Hodgkin's lymphoma

Abstract

Objective: The objective of the study was to determine the frequency of bcl-2 gene rearrangement in B-cell Non-Hodgkin's lymphoma (NHL) and identify different breakpoints of bcl-2 gene.

Methods: Thirty cases of B-cell lymphoma (including 8 cases of follicular lymphoma, 19 cases of diffuse large B-cell lymphoma and 3 cases of T-cell rich B-cell lymphoma) were included in the study. Good quality of DNA was extracted in 4 cases from formalin fixed paraffin embedded tissue and in 26 cases from fine needle aspirate. The polymerase chain reaction was done for major break point region (mbr), minor cluster region (mcr) and intermediate cluster region (icr) of the bcl-2 gene.

Results: The bcl-2 gene rearrangement was identified in 23.3% of B-cell lymphoma, 50% of follicular lymphoma, 15% of diffuse large B-cell lymphoma and no bcl-2 rearrangement was identified in any of the T-cell rich B-cell lymphomas. Further analysis showed the icr breakpoint in 16.7% of B-cell lymphoma, 37.5% of follicular lymphoma and 10.5% of diffuse large B-cell lymphoma. Involvement of the mbr breakpoint was found in 6.7% of B-cell lymphoma, 12.5% of follicular lymphoma, and 5.3% of diffuse large B-cell lymphoma. Involvement of the mcr breakpoint was not seen in any of the cases.

Conclusion: The bcl-2 gene rearrangement is quite frequent in follicular lymphoma, followed by diffuse large B-cell lymphoma. The commonest breakpoint in present series is icr followed by mbr. This indicates that primers for bcl-2 gene must include icr primer, whenever the bcl-2 gene is being evaluated for B-cell NHL in this part of the world and this might reduce the variability of frequency of bcl-2 gene rearrangement within and between different regions.