Abnormalities of chromosome 22 in human brain tumors determined by combined cytogenetic and molecular genetic approaches.

Southern blot hybridization studies were performed on a panel of 130 blood/tumor samples from brain neoplasms including all major histologic subtypes: 50 meningiomas, 18 neurinomas, 56 gliomas, and six others. To detect abnormalities involving chromosome 22, polymorphic probes were used to analyze eight loci located in this chromosome: D22S9, IGLV, D22S20, D22S32, MB, PDGF-B, D22S80, and D22S171. Loss of heterozygosity (LOH) was observed in 40 cases including monosomy, terminal, and interstitial deletions, which suggest the location of recessive tumor genes in certain chromosome 22 subregions (22q11.3-q12 in neurinomas and meningiomas, and 22q13 in malignant gliomas). Cytogenetic studies were performed in parallel on the same tumors, in most instances corroborating the presence of abnormalities for chromosome 22. Nevertheless, discrepancies between the cytogenetic and molecular findings were observed in several cases, suggesting that the use of both methodologies in combination might provide key information on the incidence and extent of the abnormalities involving chromosome 22 in human brain tumors.