MOLECULAR-GENETIC STUDIES IN MEDULLOBLASTOMAS - EVIDENCE FOR TUMOR-SUPPRESSOR GENES AT THE CHROMOSOMAL REGIONS 1Q31-32 AND 17P13

Background Medulloblastoma represents a common primitive neuroectoderm al tumor of the cerebellum the molecular pathogenesis of which has not been identified, Previous cytogenetic observations disclosed aberrati ons of chromosome 1 and 17 in medulloblastomas. In the present study. we have molecularly characterized the affected chromosomal segments. P atients and methods A panel of microsatellites on chromosomes 1 and 17 was used to assess allelic loss in 30 medulloblastomas and to charact erize putative tumor suppressor loci. Results 36% of the medulloblasto mas showed an interstitial loss of heterozygosity (LOH) on chromosome 1q. The common region of overlap was mapped between D1S1604 and D1S237 and included the locus F13B in the chromosomal region 1q31-q32.1. Non e of the MBs exhibited LOH of the telomeric portion of chromosome Ip w hich has been associated with several other human malignancies. 47% of the tumors showed LOH on chromosome 17p with a common region of overl ap at 17p13.3. The lissencephaly gene 1 (LIS-1) was excluded as a cand idate gene in this region. Conclusion Our data strongly suggest the in volvement of putative tumor suppressor genes Located on the chromosome arms 1q and 17p in the molecular pathogenesis of medulloblastoma.