Molecular and cytogenetic analysis of chromosome 9 deletions in 75 malignant gliomas.

A deletion mapping analysis of chromosome 9 has been performed on a series of 75 samples derived from malignant gliomas. A total of 27 tumors displayed different deletions for the loci studied (D9S1, NRASLI, D9S18, IFNA, and IFNBI). In most instances, losses involving the markers located on the short arm of chromosome 9 were observed, and only two samples were characterized by losses of the short and long arms. Either partial or complete homozygous deletions of IFN genes were observed in 15 cases, and 12 other samples showed hemizygous deletions for these genes. The results show that the 9p abnormalities are not exclusive to high-grade astrocytic tumors, as some low-grade samples (two astrocytoma grade II and six oligodendrogliomas) displayed this anomaly which, in a few instances, was the sole abnormality detected.