Analysis of the 10q23 chromosomal region and the PTEN gene in human sporadic breast carcinoma

We examined a panel of sporadic breast carcinomas for loss of heterozygosit y (LOH) in a 10-cM interval on chromosome 10 known to encompass the PTEN ge ne. We detected allele loss in 27 of 70 breast tumour DNAs. Fifteen of thes e showed toss limited to a subregion of the area studied. The most commonly deleted region was flanked by D 10S215 and D10S541 and encompasses the PTE N locus. We used a combination of denaturing gradient gel electrophoresis a nd single-strand conformation polymorphism analyses to investigate the pres ence of PTEN mutations in tumours with LOH in this region. We did not detec t mutations of PTEN in any of these tumours. Our data show that, in sporadi c breast carcinoma, loss of heterozygosity of the PTEN locus is frequent, b ut mutation of PTEN is not. These results are consistent with loss of anoth er unidentified tumour suppressor in this region in sporadic breast carcino ma.