Non-Hodgkin's lymphoma (NHL) is the most common malignancy referred to our institute which is the largest tertiary referral cancer centre in Saudi Arabia, The proportion of follicular low grade NHL appears to be extremely small in this population (<5% of all NHL). To date, there is no data available regarding any correlation between bcl-2 gene rearrangement and different cell types of nodal and extranodal NHLs in Saudi patients. We used a sequential polymerase chain reaction (PCR) technique to determine the frequency of bcl-2/J(H) recombination occurring via the major breakpoint region (mbr) in 16 GI tract NHLs including 4 MALT lymphomas and 13 follicular (nodal) NHLs. The results showed only 2/13 (15%) nodal follicular NHLs with bcl-2/J(H) fusion DNA whereas 9/16 (56%) of the extranodal NHLs with at least 2 of them exhibiting MALT characteristics were positive for the bcl-2 gene rearrangement. A breakdown of the proportion of extranodal NHLs of different cell types showing bcl-2 rearrangement via mbr was as follows: 5/8 diffuse large non-cleaved cell (DLNCC), 1/3 diffuse small cleaved cell (DSCC), 1/1 follicular small cleaved cell (FSCC) and 2/4 MALTs. The PCR amplified bcl-2/J(H) fusion DNA from 5 randomly selected tumors (2 MALTs, 1 DLNCC, 1 DSCC and 1 nodal follicular lymphoma) were cloned and sequenced. All 5 of them showed different bcl-2/J(H) N-regions confirming the clonality of each tumor sample. The data indicating a very low incidence of bcl-2 translocation in nodal follicular NHLs and a surprisingly high incidence of it in extranodal NHLs are intriguing, and quite contrary to the findings in Western patients. These unusual observations warrant further studies and may suggest that different genetic events are involved in the development of extranodal NHLs including MALT and follicular center-cell NHLs in Saudi patients.

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