Chromosome 22q allelic losses at microsatellite loci in human astrocytic tumors.

Common regions of deletion(s) on chromosome 22q and the correlations between loss of heterozygosity and patient survival were analysed in 18 deoxyribonucleic acid samples from astrocytic tumors (3 astrocytomas, 5 anaplastic astrocytomas, and 11 glioblastomas) and matched normal brain tissues. The polymerase chain reaction products using five microsatellite markers were electrophoresed on polyacrylamide gels and the ethidium bromide stained bands were photographed. Loss of heterozygosity was observed in 14 (74%) of 19 samples, with similar incidences in astrocytomas, anaplastic astrocytomas, and glioblastomas (67%, 80%, and 82%, respectively). The locus D22S300 (q12.1-q13.1) was most frequently involved, with loss of heterozygosity in eight (80%) of 10 informative glioblastomas at this locus. Increased loss of heterozygosity during tumor progression or recurrence was seen in two patients at the D22S300 (q12.1-q13.1) and TOP1P2 (q11.2-q13.1) loci. No correlation between loss of heterozygosity on chromosome 22 and the postoperative survival was found. These findings suggest that loss of heterozygosity on chromosome 22q probably occurs quite frequently in astrocytic tumors. The chromosome segment 22q12.1-q13.1, around the D22S300 locus, may be the common region of deletion in glioblastomas.