Three Nonsyntenic Regions on the Long Arm of Chromosome Independent Amplification and Frequent Co-Amplification of Updated Version

DNA amplification at 20qi3.2 is common in breast cancer, correlates with poor prognosis, and may reflect location of an important oncogene. Recently, other regions along 20q were also found to undergo amplifica tion. Here, amplification levels and patterns of co-amplification were analyzed by interphase fluorescencein situ hybridization at i4 locialong 20q in i46 uncultured breast carcinomas and i4 cell lines. Three regions were independently amplified in uncultured tumors: RMC2OCOOi region at 20q13.2 (highly amplified in 9.6% of the cases), PTPN1 region 3 Mb proximal (6.2%), and AIB3 region at 2Oqii (6.2%). Co-amplifications involving two or three of these regions were seen in ii of the 19 highly amplified tumors. The results suggest that three distinct nonsyntenic regions along 20q may be important and that complex chromosomal rearrangements underlie their frequent co-amplification in breast cancer.