ALLELIC STATUS OF 1P, 14Q, AND 22Q AND NF2 GENE-MUTATIONS IN SPORADICSCHWANNOMAS

Schwannomas are common benign tumours of schwann cell origin, frequent ly found in patients with neurofibromatosis type 2 (NF2). Inactivation of the NF2 tumour suppressor gene appears to be a molecular event res ponsible for the development of up to 60% of cases, but no data are av ailable on other superimposed secondary or alternative molecular abnor malities in those schwannomas lacking NF2 gene inactivation. We analys ed 23 sporadic schwannomas for mutations in the NF2 gene and for the a llelic status at Ip, 14q and 22q, as alterations of these genomic regi ons appear to be related to tumour progression in meningiomas, another NF2-associated neoplasm. Nine samples displayed allelic losses for ma rkers on chromosome 22, and deletions at Ip were detected in two. No c ase showed losses for 14q. Three tumours displayed NF2 gene mutations, at exons 2, 7 and 12. Our results confirm that inactivation of the NF 2 gene is a primary event in schwannoma development, and provide data suggesting that allelic loss at Ip may contribute to the pathogenesis of a small subgroup of this histological tumour type.