Gain of 1q and loss of 22 are the most common changes detected by comparative genomic hybridisation in paediatric ependymoma

Ependymomas are the third most common brain tumour in the paediatric popula tion. Although cytogenetic and molecular analyses have pinpointed deletions of chromosomes 6q, 17, and 22 in a subset of tumours, definitive patterns of genetic aberrations have not been determined. In the present study, we a nalysed 40 ependymomas from paediatric patients for genomic loss or gain us ing comparative genomic hybridisation (CGH). Eighteen of the tumours (45%) had no detectable regions of imbalance. In the remaining cases, the most co mmon copy number aberrations were loss of 22 (25% of tumours) and gain of I q (20%). Three regions of high copy number amplification were noted at 1q24 -31 (three cases), 8q21-23 (two cases), and 9p (one case). Although there w as no association with the loss or gain of any chromosome arm or with benig n versus anaplastic histologic characteristics, the incidence of gain of 7q and 9p and loss of 17 and 22 was significantly higher in recurrent versus primary tumours. This study has identified a number of chromosomal regions that may contain candidate genes involved in the development of different s ubgroups of ependymoma. (C) 2001 Wiley-Liss, Inc.