Copy number gain at 12q12-14 may be important in the transformation from follicular lymphoma to diffuse large B cell lymphoma

The purpose of this study was to identify novel areas of genomic copy numbe r change associated with transformation from follicular lymphoma (FL) to di ffuse large B cell lymphoma (DLBL). DNA was extracted from tumour cells mic ro-dissected from paraffin embedded tissue sections in 24 patients with FL and subsequent transformation to DLBL and 18 patients with de novo DLBL. Tu mour DNA was compared to reference DNA using comparative genomic hybridizat ion. Abnormalities common to all 3 groups were gains on chromosomes 4q, 5q, 7q, 11q and X and losses on 3p, 8p and 10q. Copy number changes seen in bo th transformed and de novo DLBL and not seen in FL were gains on 20 and los ses on 1q, 15q and Xq. Gains on 2q, 6p, 7p and 17q and losses on 5p and 8q were specific to transformed DLBL cases. Gain on 12q12-14 was found in 52% of the transformed DLBL cases and was never seen in its follicular counterp art. Patterns of genomic copy number change associated with specific clinic al events in NHL have been demonstrated and suggest that gains on 2q, 6p, 7 p, 12q and 17q and losses on 50 and 8q may be important in the transformati on from low to high-grade disease. (C) 2001 Cancer Research Campaign.