Stability of BAT26 in tumours of hereditary nonpolyposis colorectal cancer patients with MSH2 intragenic deletion

摘要: Colon cancers arising in most patients with hereditary nonpolyposis colorectal cancer (HNPCC) show microsatellite instability (MSI). BAT26, a quasimonomorphic polyA stretch located just 3' of MSH2 exon 5, is considered the sensitive and specific marker MSI. A total 10 HNPCC families large intragenic deletions, encompassing 5 intron identified by multiplex ligation-dependent probe amplification (MLPA) were included this study. The deletions under study del1-16, del1-8, del1-7, del1-6, del3-6, detected 3, 1, 2, 1 families, respectively. Although all examined from these developed unstable tumours, 13/19 MSI-H tumours (68 %) surprisingly showed stability BAT26. By MLPA sequence analyses BAT26-stable we demonstrated that wild-type allele was somatically inactivated an identical deletion, complete loss 5/BAT26 sequences at tumour DNA level. We could infer apparent BAT26 due to absence target sample, which results exclusive contaminant normal DNA, containing single copy stable sequence. Identification subset MSH2-related are not recognized analysis indicates should never be used alone for rapid MSI screening tumours. Moreover, our findings indicate context strongly suggestive presence deletion.