Nonrandom chromosomal imbalances in primary mediastinal B-cell lymphoma detected by arbitrarily primed PCR fingerprinting

We used arbitrarily primed polymerase chain reaction (AP-PCR) fingerprintin g to identify chromosomal imbalances in six primary mediastinal B-cell lymp homas (PMBLs). Seventy-four chromosomal imbalances were detected, consistin g of 49 sequence gains and 25 losses. Amplifications on chromosome X were s een in five cases, four of which involved the same chromosomal locus. Nonra ndom gains at the same locus were also identified on chromosomes 2 and 7 in four cases and on chromosomes 5, 9, and 12 in three cases. Five PMBLs were also analyzed by comparative genomic hybridization (CGH), which found chro mosome arm 9p amplification as the only nonrandom imbalance. Our data demon strate that chromosomal amplifications outnumber losses in PMBL. These main ly involve chromosomes 9 and X and may reflect more complex phenomena, such as translocations or other chromosomal rearrangements, as AP-PCR found coe xistent gains and losses on these chromosomes. Comparison between AP-PCR an d CGH suggests that anomalies affecting the same chromosomal regions may oc cur at much higher frequencies than expected by CGH, suggesting that genomi c amplifications are usually confined to DNA segments smaller than the mega base long segments required for detection in CGH. Modest increases in genet ic material may be as effective as higher-level amplifications when affecti ng sites where a proto-oncogene resides. (C) 1999 Wiley-Liss, Inc.