Published in:
01-12-2009
Determination of splice-site mutations in Lynch syndrome (hereditary non-polyposis colorectal cancer) patients using functional splicing assay
Authors:
Hiromu Naruse, Noriko Ikawa, Kiyoshi Yamaguchi, Yusuke Nakamura, Masami Arai, Chikashi Ishioka, Kokichi Sugano, Kazuo Tamura, Naohiro Tomita, Nagahide Matsubara, Teruhiko Yoshida, Yoshihiro Moriya, Yoichi Furukawa
Published in:
Familial Cancer
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Issue 4/2009
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Abstract
Lynch syndrome (hereditary non-polyposis colorectal cancer) is an inherited disease caused by germ-line mutation in mismatch repair genes such as MLH1, MSH2, and MSH6. The mutations include missense and nonsense mutations, small insertions and deletions, and gross genetic alterations including large deletions and duplications. In addition to these genetic changes, mutations in introns are also involved in the pathogenesis. However, it is sometimes difficult to interpret correctly the pathogenicity of variants in exons as well as introns. To evaluate the effect of splice-site mutations in two Lynch syndrome patients, we carried out a functional splicing assay using minigenes. Consequently, this assay showed that the mutation of c.1731+5G>A in MLH1 led to exon15 skipping, and that the mutation of c.211+1G>C in MSH2 created an activated cryptic splice-site 17-nucleotides upstream in exon1. These aberrant splicing patterns were not observed when wild type sequence was used for the assay. We also obtained concordant results by RT-PCR experiments with transcripts from the patients. Furthermore, additional functional splicing assays using two different intronic mutations described in earlier studies revealed splicing alterations that were in complete agreement with the reports. Therefore, functional splicing assay is helpful for evaluating the effects of genetic variants on splicing.