Defining the Smallest Common Region of Chromosome l7p that is Deleted in Sporadic Breast Tumors.

The most distal region of chromosome 17p between 17p13.3 and the telomere have been found to be independently deleted in several breast tumors. The overall goal of this project is to produce a physical mapping resource which would allow the identification of genes important in breast carcinogenesis. A major obstacle in the way of further study of this region has been the paucity of polymorphic markers localized to it. This problem has been approached by the construction of a microdissection library of this region. In brief, microclones dissected from 17pter were PCR-amplified with degenerate primers UN1, the product subsequently biotynilated and used in FISH experiments to confirm localization. A second round of amplification led to direct cloning into pAMP UDG vector. After transformation of E. coli with the recombinant plasmids, colonies containing inserts are selected by X-gal bluewhite color selection. The microclone library was analyzed by FISH analysis on human metaphase chromosomes and hybridized to Cot-1 DNA. Every Cot-1 negative clone was hybridized to a gridded chromosome 17 cosmid library, and one positive cosmid form each hybridization was identified. The identification of cosmids in this area is an important first step towards the isolation of markers.