Germline PMS2 mutation screened by mismatch repair protein immunohistochemistry of colorectal cancer in Japan |
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| Authors: | Kokichi Sugano Takeshi Nakajima Shigeki Sekine Hirokazu Taniguchi Shinya Saito Masahiro Takahashi Mineko Ushiama Hiromi Sakamoto Teruhiko Yoshida |
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| Affiliation: | 1. Department of Genetic Medicine and Services, National Cancer Center Hospital, Tokyo, Japan;2. Oncogene Research Unit/Cancer Prevention Unit, Tochigi Cancer Center Research Institute, Utsunomiya, Japan;3. Department of Endoscopy, National Cancer Center Hospital, Tokyo, Japan;4. Molecular Pathology Division, National Cancer Center Research Institute, Tokyo, Japan;5. Division of Pathology and Clinical Laboratories, National Cancer Center Research Institute, Tokyo, Japan;6. Division of Genetics, National Cancer Center Research Institute, Tokyo, Japan |
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| Abstract: | Germline PMS2 gene mutations were detected by RT‐PCR/direct sequencing of total RNA extracted from puromycin‐treated peripheral blood lymphocytes (PBL) and multiplex ligation‐dependent probe amplification (MLPA) analyses of Japanese patients with colorectal cancer (CRC) fulfilling either the revised Bethesda Guidelines or being an age at disease onset of younger than 70 years, and screened by mismatch repair protein immunohistochemistry of formalin‐fixed paraffin embedded sections. Of the 501 subjects examined, 7 (1.40%) showed the downregulated expression of the PMS2 protein alone and were referred to the genetic counseling clinic. Germline PMS2 mutations were detected in 6 (85.7%), including 3 nonsense and 1 frameshift mutations by RT‐PCR/direct sequencing and 2 genomic deletions by MLPA. No mutations were identified in the other MMR genes (i.e. MSH2, MLH1 and MSH6). The prevalence of the downregulated expression of the PMS2 protein alone was 1.40% among the subjects examined and IHC results predicted the presence of PMS2 germline mutations. RT‐PCR from puromycin‐treated PBL and MLPA may be employed as the first screening step to detect PMS2 mutations without pseudogene interference, followed by the long‐range PCR/nested PCR validation using genomic DNA. |
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| Keywords: | Colorectal cancer immunohistochemistry Lynch syndrome mismatch repair gene
PMS2
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