FREQUENT LOSS OF CHROMOSOME-14 IN ATYPICAL AND MALIGNANT MENINGIOMA -IDENTIFICATION OF A PUTATIVE TUMOR PROGRESSION LOCUS

Formation of meningiomas has been associated with the loss of genetic material on chromosome 22. To approach the additional chromosomal even ts that underlie progression of these tumors to malignancy, we have ex amined several other chromosomal regions for loss of heterozygosity (L OH) in these tumors. Fifty-eight tumors, comprising 43 benign meningio mas, 11 atypical meningiomas and four malignant meningiomas, were exam ined. While the loss of chromosome 22 was seen in approximately half o f all these tumors, regardless of their malignancy, the most frequent chromosomal losses observed in the malignant and atypical tumors were on the long arm of chromosome 14. Thirty-nine tumors were informative for at least one of the three markers on chromosome 14 that we tested. Of these, 7/14 malignant and atypical tumors showed LOH in contrast t o only 1/25 benign tumors. Other loci that showed LOH in malignant tum ors, although at a much lower frequency, were on chromosomes 17p and 1 p, The high frequency of LOH for loci on chromosome 14q in atypical an d malignant tumors suggests the presence of a tumor progression gene a t this locus. In one of the malignant meningiomas heterozygosity was l ost at D14S13 and D14S16 but retained at the proximal marker D14S43 as well as the more distal marker D14S23. This suggests that an intersti tial deletion occurred in this tumor which should be useful for furthe r refining the position of the putative tumor progression locus.