Mutational analysis of INI1 in sporadic human brain tumors

The INI1/SMARCB1/hSNF5 gene on chromosome 22 is frequently mutated in rhabd oid tumors. An association of INI1 mutations with allelic losses on chromos ome 22 supports a classical tumor suppressor mechanism. Several brain tumor entities including astrocytomas, glioblastomas and ependymomas are charact erized by allelic losses on chromosome 22. In the present study we examined a series of 200 brain turners by Single-strand conformation polymorphism a nalysis and direct sequencing for paint mutations in INI1. In addition, all tumors were analyzed for homozygous deletions spanning both exons 3 and 8 of INI1. No mutations or homozygous deletions were detected in astrocytomas , glioblastomas, oligodendroglial tumors, neurinomas or medulloblastomas. H owever, a point mutation could be identified in the single case of plexus c arcinoma. Our data suggest that INI1 mutations are involved in the pathogen esis of plexus carcinoma; however, INI1 alterations are not a frequent even t in the majority of brain tumor entities.