Subtelomeric analysis of pediatric astrocytoma: subchromosomal instability is a distinctive feature of pleomorphic xanthoastrocytoma.

Astrocytic neoplasms are genetically heterogeneous; however a low frequency of genomic changes has been found in juvenile pilocytic astrocytoma (PA) in molecular studies. Concerning pleomorphic xanthoastrocytomas (PXA), recent studies have given heterogeneous results for chromosomal alterations. We studied the subtelomeric regions of 19 primary astrocytoma tumors. Results were near normality for the PA group with relative scarcity of chromosomal imbalances, except for the duplication of 3pter in 4/15 and deletion of 21qter in 5/15 of them. In contrast, a specific profile was observed in the 4 PXA tumoral samples. This involved 3pter, 14qter and 19pter duplication and 4qter, 6qter, 9qter, 13cen, 17pter, 18qter and 21qter deletion. Our results indicate that the chromosomal and genetic aberrations in PXAs differed from those typically associated with the diffusely infiltrating astrocytic and oligodendroglial gliomas. These genetic differences would likely contribute to the more favorable behavior of PXAs and may be helpful for molecular differential diagnosis of pediatric cerebral tumors.