INVESTIGATION OF GENETIC ALTERATIONS ASSOCIATED WITH THE GRADE OF ASTROCYTIC TUMOR BY COMPARATIVE GENOMIC HYBRIDIZATION

Comparative genomic hybridization (CGH) is a technique that allows the detection of losses and gains in DNA copy number across the entire ge nome, We used CGH to study the genetic alterations that occur in prima ry astrocytomas, including 14 glioblastomas (GEM), 12 anaplastic astro cytomas (AA), and 7 low-grade astrocytomas (LGA). The average numbers of total aberrations in GEM, AA, and LGA were 9.7, 5.4, and 4.0, respe ctively. The average number of DNA sequence losses in GEM was signific antly higher than that in AA or LGA (P < 0.01). Frequently altered reg ions (> eight cases) observed in all grades of astrocytoma were 7p13-p 12 (gain), 7q31 (gain), 8q24.1-q24.2 (gain), 9p21 (loss), 10p12-p11 (l oss), 10q22-qter (loss), 13q21-q22 (loss), and 20q13.1-q13.2 (gain). L oss of 9p, 10p, or 10q, and the gain or amplification of 7p, were obse rved frequently in GEM (64%, 57%, 64%, and 50% of cases, respectively) . Frequent alterations found In AA were losses of 9p, 10q, and 13q, an d gains of Iq, chromosome 7, 11q, and Xq, Whereas 7p13-p11 amplificati on occurred exclusively in cases with the lass of all or part of chrom osome 10, this change never occurred in cases having an increase in co py number of 8q, which was the most frequent change observed in LGA (f our of seven cases), These results may indicate that an increase in co py number of 8q is an important event in GEM, with a genetic pathway, which is distinct from that in GEM with 7p amplification. (C) 1998 Wil ey-Liss, Inc.