A DETAILED PHYSICAL AND TRANSCRIPTIONAL MAP OF THE REGION OF CHROMOSOME-20 THAT IS DELETED IN MYELOPROLIFERATIVE DISORDERS AND REFINEMENT OF THE COMMON DELETED REGION

Acquired deletions of the long arm of chromosome 20 are the most commo n chromosomal abnormality seen in polycythemia vera and are also assoc iated with other myeloid malignancies. Such deletions are believed to mark the site of one or more tumor suppressor genes, loss of which per turbs normal hematopoiesis. A common deleted region (CDR) has previous ly been identified on 20q. We have now constructed the most detailed p hysical map of this region to date-a YAC contig that encompasses the e ntire CDR and spans 23 cM (11 Mb). This contig contains 140 DNA marker s and 65 unique expressed sequences. Our data represent a first step t oward a complete transcriptional map of the CDR. The high marker densi ty within the physical map permitted two complementary approaches to r educing the size of the CDR. Microsatellite PCR refined the centromeri c boundary of the CDR to D20S465 and was used to search for homozygous deletions in 28 patients using 32 markers. No such deletions were det ected. Genetic changes on the remaining chromosome 20 may therefore be too small to be detected or may occur in a subpopulation of cells. (C ) 1998 Academic Press.