title: Infrequent occurrence of microsatellite instability in sporadic and familial breast cancer.
abstract: Microsatellite instability was analysed in 93 primary breast tumours at 13 chromosomal loci frequently altered in breast cancer. RER (replication errors) were observed at a low (5%) frequency in sporadic, familial and hereditary breast tumours, as well as in breast tumours from patients with multiple primary cancers. Our study suggests that the RER+ phenotype is rare in breast tumours, and that breast cancer is not included in the hereditary non-polyposis colon cancer (HNPCC) syndrome. Moreover, the RER+ tumours revealed an atypical pattern of microsatellite alteration as compared with those usually seen in HNPCC tumours. In agreement with the findings in HNPCC tumours, all RER+ breast tumours were diploid, although having a similar frequency of allelic imbalance as RER- tumours. Thus, mismatch repair deficiency is rare in breast cancer, is most likely caused by somatic mutations, and possibly in a set of DNA repair genes different from that involved in the HNPCC syndrome.
authors.affiliation: Department of Oncology, University Hospital, Lund, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Jönsson
authors.forename: O
authors.initials: O
authors.lastname: Johannsson
authors.forename: A
authors.initials: A
authors.lastname: Borg
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics; D005260:Female; D006801:Humans; D018895:Microsatellite Repeats / Q000235:genetics*; D009378:Neoplasms, Multiple Primary / Q000235:genetics; D017422:Sequence Analysis, DNA