DIFFUSE LARGE-CELL LYMPHOMAS EXHIBIT FREQUENT DELETIONS IN 9P21-22 AND 9Q31-34 REGIONS

We have previously identified deletions of 9p and 9q in a cytogenetic analysis of a large series of non-Hodgkin's lymphomas (NHLs), which su ggested loss of candidate tumor suppressor genes (TSGs). In order to d efine these deletions at the molecular level, we performed an LOH anal ysis of a panel of paired normal and tumor DNAs comprising 13 cases of diffuse lymphoma with a large cell component (DLLC) and 18 cases of B urkitt's lymphoma (BL), The loci tested comprised eight polymorphic pr obes mapped to 9p (D9S33, D9S25, IFNB, IFNA, IFNW, D9S126, D9S3, and D 9S19) and seven polymorphic probes mapped to 9q (D9S29, ASS, AKI, ABL, D9S10, D9S7, and D9S14). In this analysis, among cases informative fo r all loci in each subset, 5/13 (38%) DLLC and 4/18 (22%) BL showed LO H at 9p loci, whereas 5/13 (38%) DLLC and 3/18 (16%) BL showed LOH at 9q loci. Among the 9p loci partial homozygous or heterozygous losses w ere observed in 20-50% of informative cases of DLLC at D9S25, IFNB, IF NA, IFNW, D9S126, and D9S3, whereas in BL, losses at these loci ranged from 0% to 11%. Among the 9q loci, heterozygous losses were observed in >20% of informative cases of DLLC at D9S7 (23%) and D9S29 (27%), wh ereas no losses were seen at these two loci in BL. These data demonstr ate a high level of molecular deletion in DLLC, but not in BL, suggest ing that loss of one or more TSGs on chromosome 9 plays an important r ole in DLLC development. (C) 1995 Wiley-Liss, Inc.