Chromosome breakpoint at 17q11.2 and insertion of DNA from three different chromosomes in a glioblastoma with exceptional glial fibrillary acidic protein expression.

A glioblastoma that retained glial fibrillary acidic protein (GFAP) in culture has a break in the long arm of chromosome 17 at band 17q11.2. DNA inserted at this breakpoint came from chromosome bands 3p21, 3q23, 16q11.2, and 22q11.2. These chromosome fragments were inserted in band 17q11.2 proximal to the neurofibromatosis-1 (NF-1) gene and neu (HER2; erbB2) oncogene loci. The glioblastoma also contained a reciprocal translocation between 16p12 and 20p12. These structural abnormalities, previously undescribed in gliomas, were demonstrated by high-resolution chromosome banding, microdissection, and fluorescence in situ hybridization (FISH). Numerical changes typical of glioblastoma were present: gain of chromosome 7 and losses of chromosomes 10, 13, and 22. The complex chromosome origin of DNA inserted in this glioma chromosome is described. The association of two infrequent events in this single glioblastoma line, this complex insertion and retention of GFAP expression, is not likely to be a chance occurrence. It raises the possibility of an association between the two events.