Genomic rearrangements of hMSH6 contribute to the genetic predisposition in suspected hereditary non-polyposis colorectal cancer syndrome

摘要

>Methods: Out of 15 HNPCC or HNPCC-like patients who developed tumours with loss of hMSH6 protein expression, we selected three patients who still had no germline mutations after gene sequencing. Genomic DNA of these patients was analysed using PCR based relative quantification of hMSH6 fragments. Indicated exon deletions and amplifications were characterised by long range PCR and sequencing. >Results: Genomic rearrangements were identified in two of the three patients. Breakpoint analyses showed an Alu repeat mediated deletion of 13.0 kb affecting the promoter region, exon 1, and exon 2 in one patient, and a duplication of 4.9 kb containing 1.6 kb of the 3' end of exon 4 and exon 5, integrated into intron 5, in the other patient. >Conclusions: Although genomic rearrangements of hMSH6 only play a small role in the spectrum of all mutations predisposing to HNPCC, our results suggest that up to 10–20% of patients with hMSH6 negative tumours harbour germline rearrangements in this gene.