CYTOGENETIC EVIDENCE FOR A CHROMOSOME-22 TUMOR SUPPRESSOR GENE IN EPENDYMOMA

Although ependymomas comprise 5-10% of pediatric brain tumors, consistent cytogenetic aberrations have not been identified in these neoplasms. We report karyotypes for two ependymomas. A predominantly well-differentiated ependymoma contained several numerical chromosome aberrations, including monosomy 22. In contrast, an anaplastic ependymoma had a more complex karyotype that included loss of one chromosome 22 homologue and a balanced translocation at q13.3 in the remaining 22 homologue. These findings suggest the location of an ependymoma tumor suppressor gene on the long arm of chromosome 22.