ALLELIC LOSS AT 1P AND 19Q FREQUENTLY OCCURS IN ASSOCIATION AND MAY REPRESENT EARLY ONCOGENIC EVENTS IN OLIGODENDROGLIAL TUMORS

The molecular mechanisms underlying the genesis and progression of oli godendroglial tumors are poorly understood, since only restricted info rmation on loss of heterozygosity from isolated cases is available. Th e commonest alterations appear to invoke deletion of 1p and 19q, while loss of heterozygosity for 9p, chromosome 10 or epidermal growth fact or receptor gene amplification have been described in single tumors. W e have applied restriction fragment length polymorphism analysis to 14 loci covering chromosome 1 and 7 loci on chromosome 19 in a series of 25 tumors with an oligodendroglial component to determine precisely t he participation of these suppressor genes in the genesis of tumors. T wenty-two and 19 of the 25 samples displayed LOH at 1p and 19q, respec tively, and both anomalies were detected in association in 17 samples, including low- and high-grade oligodendrogliomas as well as mixed oli go-astrocytomas. Our findings suggest that inactivation of tumor suppr essor genes located on 1p and 19q represent cooperative alterations oc curring at early stages of oncogenic transformation of oligodendroglia l neoplasms. (C) 1995 Wiley-Liss, Inc.