The long arm of chromosome 17 is a frequent target of allelic losses at multiple sites during breast cancer formation and progression. Several genes linked to breast carcinomas have been mapped on this chromosome such as BRCA1, NME and erbB2 genes. The aim of this work was to delineate a deletion map on chromosome 17q and to examine the role of loss of heterozygosity (LOH) during breast tumor development and progression looking for correlation between LOH on 17q and various histopathological parameters. A series of 71 human mammary carcinomas and the corresponding peripheral blood lymphocytes has been studied for loss of heterozygosity at 6 different polymorphic loci on chromosome 17q. 46 out of 71 (65%) tumors showed LOH on 17q. A positive correlation was found between allelic loss for BRCA1 flanking markers and young age at diagnosis. The absence of estrogen receptors was more frequently observed in tumors with deleted BRCA1 flanking markers.

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