Common regions of deletion on chromosome 22q12.3-q13.1 and 22q13.2 in human astrocytomas appear related to malignancy grade

Approximately 30% of human astrocytomas have been reported to display allel ic loss of the long arm of chromosome 22, suggesting the presence of a chro mosome 22q astrocytoma suppressor gene. To define the most likely location for this putative tumor suppressor, we performed deletion mapping on 141 tu mors using 16 chromosome 22q microsatellite markers. Allelic loss of 22q wa s observed in 2/12 (17%) of astrocytomas, 9/29 (31%) of anaplastic astrocyt omas, and 38/100 (38%) of glioblastomas, consistent with a role for chromos ome 22q loss in astrocytoma progression as well as formation. Twenty-two tu mors exhibited allelic loss at every informative locus, consistent with los s of the entire arm of 22q. Twenty-seven tumors showed partial deletions, w ith one common region of deletion at 22q12.3-q13.1 between markers D22S280 and D22S282, and a second candidate region at 22q13.2 near the marker D22S1 170. For the proximal candidate region, the incidence of allelic loss was s imilar between grades; for the distal locus, the incidence increased with g rade, raising the possibility that the distal locus is involved in a later stage of astrocytoma tumorigenesis.