Human ependymomas reveal frequent deletions on chromosomes 6 and 9

Ependymomas are glial tumors of the brain and spinal cord. Genetic aberrations associated with the development of these tumors have not been fully identified yet. In previous cytogenetic and comparative genomic hybridization studies, multiple genomic imbalances in ependymomas were found, including partial or whole chromosome losses (1p, 4q, 6q, 9, 10, 11, 13, 16, 17, 19q, 20q and 22q). The aim of this study was to map particularly the commonly affected regions in ependymomas. Thirty-three pairs of matched normal and tumor specimens from ependymoma patients were genotyped using 34 polymorphic microsatellite markers distributed over 15 chromosomes. Loss of heterozygosity (LOH) was found in 26 of 33 tumors (78.8%). The most frequent LOHs were found on the long arms of chromosomes 6 (30.3%) and 9 (27.3%). LOH was also detected on 3p14 (13.3%), 10q23 (10.3%) and 11q (18.2%). Because of the high percentage of LOH on chromosome 6 and 9, we conclude that important tumor suppressor genes are situated on these two chromosomes.