Chromosome 9 Deletion Mapping Reveals Interferon a and Interferon ß-1 Gene Deletions in Human Glial Tumors

We have applied restriction fragment length polymorphism analysis to a 30-member panel of primary glioma DNAs, which had been previ ously examined for loss of genetic information (C. D. James, E. Carlbom, J. P. Dumanski, M. Hansen, M. Nordenskjold, V. P. Collins, and W. K. Cavenee, Cancer Res., 48:5546-5551, 1988), to determine the frequency and sublocalization of loss of genetic information from chromosome 9. We have also utilized scanning densitometry for dosage determination of the 9p-localized Interferon a and Interferon ß-\ genes among these same tumors. Our results reveal the following: (a) for those cases in which loss has occurred, the region of common loss lies on the short (p) arm of the chromosome; (/») loss of genetic information from the short arm of chromosome 9 occurs frequently in glial tumors of intermediate (anaplastic, grade III) and high (glioblastoma, grade IV) histolÃ3gica!malig nancy (10 of 20 cases) but not in tumors of low (grade II) histolÃ3gica! malignancy (0 of 10 cases); (c) tumors with 9p deletions are hemior nullizygous for interferon ,J-1 and the Interferon a gene cluster; (d) cases of interferon nullizygosity occur exclusively among tumors of highest histolÃ3gica!malignancy (glioblastoma). These data, especially the deter mination of a region of nullizygosity, suggest proximity to or residence within a gene(s) whose function!s) is (are) critical to the suppression of the malignant evolution of glial tumors.