LOSS OF ALLELES IN BRAIN-TUMORS - DISTRIBUTION AND CORRELATIONS WITH CLINICAL COURSE

Gliomas (n = 44) and meningiomas (n = 24) of different grades of malig nancy were analysed for allele losses at loci on chromosomes 10, 13, 1 7 and 22. Deletions of genetic material on these chromosomes occurred in gliomas without being restricted to any histological entity. The fr equency of chromosome-10-specific allele losses increased significantl y with the age of the patients and with the grade of malignancy of the tumours. Deletions of chromosome 10 material were associated with a p oor prognosis, The glioblastomas of patients aged over 70 years lacked the loss of the entire chromosome 10, even in tumours with EGFR gene amplification. Deletions at loci of chromosomes 13, 17 and 22 were obs erved in 18-32% of all gliomas, independent of grade of malignancy, pa tients' age, EGFR gene amplification and clinical course. Only chromos ome-22-specific allele losses were found preferentially in gliomas of female patients, Loss of chromosome 22 alleles in 44% was the only mut ation detected in meningiomas. This occurred independently of grade of malignancy and biological factors.