[Progression-associated gene regions in astrocytomas: a candidate locus on chromosome 19q]

A study was carried out to examine whether genetic loci which have been shown to exhibit loss of heterozygosity in gliomas are involved in the process of malignant progression from low grade astrocytomas to anaplastic variants. We have analyzed 18 well differentiated astrocytomas WHO grade II (A II) and 26 anaplastic astrocytomas WHO grade III (A III) for loss of heterozygosity (LOH) on chromosomes 1p, 1q, 9p, 9q, 10p, 10q, 11p, 13q, 17p, 19p, 19q and 22q and for amplification of the EGFR receptor. A PCR-based assay with microsatellite repeat sequences was employed for the detection of polymorphisms on silver-stained polyacrylamide gels. LOH on 9p was seen in 1/18 (6%) informative cases of A II and 4/25 (16%) informative cases of A III. LOH on 17p was observed in 10/17 (53%) informative cases of A II and 15/28 (54%) informative cases of A III. LOH on 19q was detected in 2/18 (11%) informative cases of A II and in 12/26 (46%) informative cases of A III. Thus, the majority of chromosomal regions examined in this study do not appear to play a role in malignant progression of astrocytomas. LOH 17p is a frequent event in astrocytoma but has not been detected at a higher incidence in anaplastic variants. However, a putative tumor suppressor gene on chromosome 19q emerges as an interesting novel candidate for a progression-associated gene in human astrocytic gliomas.