Genome-wide search for loss of heterozygosity in Burkitt lymphoma cell lines.

The molecular biological characteristics of Burkitt lymphoma (BL), in addition to the presence of the Epstein-Barr virus (EBV) in some forms, relies on well-characterized alterations, such as MYC translocations and TP53 inactivations. To ascertain the number and location of other genome alterations, we used 191 polymorphic markers in a genome-wide search for loss of heterozygosity (LOH) in 31 Burkitt lymphoma cell lines and their normal counterparts. We were able to distinguish two types of altered allelic patterns: a bona fide LOH profile, indicative of deletion (LOH), and a profile indicative of increased dosage (ID). The former type was most frequent at chromosome arm 17p, most likely indicating TP53 gene inactivation. Increased dosage at 1q was found almost exclusively in non-EBV cell lines (P < 0.00004) and correlated well with karyotypic abnormalities affecting region 1q21-25. Our results suggest that a gene important for BL pathogenesis is located in region 1q21-25 and that the activation of this gene mimics the effects of EBV.