GENE AMPLIFICATION IN NON-HODGKINS-LYMPHOMA

Among 426 consecutively ascertained and karyotypically abnormal non-Ho dgkin's lymphoma (NHL) tumours, cytological evidence for gene amplific ation in the form of homogeneously staining regions (HSRs) was encount ered in nine cases of large cell diffuse lymphoma (LC-DL). The mean ag e of patients with HSRs was 62.9 years and four died within a year of diagnosis. To identify candidate gene(s) amplified in these tumours, w e performed a Southern blot analysis of tumour DNA using probes for 23 known protooncogenes and the multidrug resistance gene, PGY1. Besides a two-fold implication of the BCL2 gene in two cases, no evidence for overt amplification of any of the genes assayed was found. To confirm DNA amplification in these specimens we performed the DNA in-gel rena turation assay. Evidence for presence of amplified DNA fragments was o btained in four of seven specimens. These results suggest amplificatio n of a novel gene(s). To our knowledge, this is the first formal study of gene amplification in a large consecutively ascertained series of fresh lymphoma biopsies.