Loss of heterozygosity at locus F13B on chromosome 1q in human medulloblastoma.

Medulloblastoma is a primitive neuroectodermal tumor of the cerebellum with poorly understood pathogenesis. Previous studies have reported loss of heterozygosity (LOH) on chromosome arms 17p, 11p and 9q and cytogenetic abnormalities of chromosome 1 in medulloblastoma. We have used the polymerase chain reaction to amplify 10 microsatellites on the short arm and 8 microsatellites on the long arm of chromosome 1 to assess allelic loss in 22 medulloblastomas. Loss of heterozygosity (LOH) on chromosome 1 was found in 9 cases. Eight medulloblastomas (36%) showed an interstitial LOH on chromosome 1q. The common region of overlap was mapped between D1S 1604 and D1S237 and included the locus F13B in the chromosomal region 1q31-q32.1. An additional tumor had LOH in a proximal region of 1p, but did not exhibit LOH on 1q. None of the medulloblastomas exhibited LOH of the telomeric portion of chromosome 1p, which has been associated with several other human malignancies. Our data suggest the presence of a putative tumor suppressor gene located near the locus F13B on chromosome arm 1q that appears to be involved in the pathogenesis of medulloblastoma.