Brief Article Open Access
Copyright ©2010 Baishideng. All rights reserved
World J Gastroenterol. Aug 14, 2010; 16(30): 3847-3852
Published online Aug 14, 2010. doi: 10.3748/wjg.v16.i30.3847
Germline mutation analysis of hPMS2 gene in Chinese families with hereditary nonpolyposis colorectal cancer
Xia Sheng, Heng-Hua Zhou, Xiao-Yan Zhou, Xiang Du, Tai-Ming Zhang, San-Jun Cai, Wei-Qi Sheng, Da-Ren Shi
Xia Sheng, Xiao-Yan Zhou, Xiang Du, Tai-Ming Zhang, Wei-Qi Sheng, Da-Ren Shi, Department of Pathology, Shanghai Cancer Center, Fudan University, Shanghai 200032, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Heng-Hua Zhou, Department of Pathology, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
San-Jun Cai, Department of Abdominal Surgery, Cancer Center, Fudan University, Shanghai 200032, China
Author contributions: Sheng X and Zhou HH contributed equally to this work, participated in the treatment of patients, analyzed the data, performed the research and wrote the manuscript; Zhou XY, Du X, Sheng WQ and Shi DR participated in the treatment of patients, collected the data and designed the research; Cai SJ participated in the treatment of patients, collected the data; Zhang TM contributed to the new reagents/analytic tools.
Supported by The Initiation Fund for Prominent Young Researchers of Shanghai Medical College, Fudan University
Correspondence to: Wei-Qi Sheng, MD, PhD, Associate Professor, Department of Pathology, Shanghai Cancer Center, Fudan University, 270 Dong An Road, Shanghai 200032, China. shengweiqi2006@yahoo.com.cn
Telephone: +86-21-64175590 Fax: +86-21-64046008
Received: March 25, 2010
Revised: May 21, 2010
Accepted: May 28, 2010
Published online: August 14, 2010

Abstract

AIM: To study the germline mutation of hPMS2 gene in 26 unrelated Chinese hereditary nonpolyposis colorectal cancer (HNPCC) probands and to fulfill the screening strategy for HNPCC in Chinese.

METHODS: Genomic DNA was extracted from the peripheral blood. To avoid the interference of pseudogene in detection of the remaining 11 exons (exon 1-5, 9, 11-15), long-range polymerase chain reaction (PCR) was conducted to amplify the complete coding region of hPMS2 gene firstly. Then 1/8 of the PCR products were used as template to amplify the individual exon respectively and DNA sequencing was done. Direct DNA sequencing of the conventional PCR products of exon 6, 7, 8 and 10 of hPMS2 gene was performed. The same analysis was made in 130 healthy persons without family histories of HNPCC to further investigate the pathological effects of the detected missense mutation.

RESULTS: One HNPCC proband fulfilled Bethesda guidelines and was found to carry the germline mutation of hPMS2 gene, which has not been reported in Chinese HNPCC families. It was a missense mutation at c.1532C>T of exon 11. It was detected in three controls as well with an occurrence rate of 2.3% (3/130). Since it could not be found in the PMS2-single nucleotide polymorphism (SNP) database, this missense mutation is a new SNP unreported up to date. Meanwhile, 260 reported SNPs of hPMS2 gene were detected in the 26 HNPCC probands. The 2nd and 5th exons were probably the hot SNP regions of hPMS2 gene in Chinese HNPCC families involving 53.1% of all reported SNP.

CONCLUSION: The germline mutation of hPMS2 gene may be rare in Chinese HNPCC families. The 2nd and 5th exons are hot SNP regions of hPMS2 gene.

Key Words: Hereditary nonpolyposis colorectal cancer, hPMS2, Missense mutation, Single nucleotide polymorphism, Colorectal cancer



INTRODUCTION

Hereditary nonpolyposis colorectal cancer (HNPCC), or Lynch syndrome, is an autosomal dominantly inherited disease with cancer-susceptibility. Perhaps it is the most common cause of hereditary colorectal cancer, accounting for 5%-10% of the total colorectal cancers worldwide[1-3]. People inheriting this predisposition are at a particularly high risk of developing colorectal cancer with an early age of onset[3,4]. The affected patients always carry germline mutations in DNA mismatch repair (MMR) genes, mostly in hMLH1, hMSH2, and hMSH6[5,6]. Less commonly, mutations in other MMR genes are present. We analyzed the abnormalities of hMSH2/hMLH1/hMSH6 genes in a series of Chinese HNPCC families fulfilling different clinical criteria. We studied germline mutation, large genomic variations of the entire coding regions of the three genes and methylation of hMLH1 promoter in 58 Chinese HNPCC probands, in which 24 fulfilled Amsterdam criteria (AC)[7], 15 fulfilled Japanese criteria (JC)[8] and 19 met Bethesda guidelines (BG)[7]. The total detected gene abnormality rate was only 53.4% (31/58), including 29 cases of germline mutation and 2 cases of methylation of hMLH1 promoter[9-14]. So the aberrant MMR genes other than hMSH2/hMLH1/hMSH6 are suspected to be involved in Chinese HNPCC.

In order to accomplish our serial studies of Chinese HNPCC, we detected hPMS2 germline mutation in 26 Chinese HNPCC families by long-range polymerase chain reaction (LR-PCR)-based sequencing in this study, and evaluated this manner in the molecular genetics screening of Chinese HNPCC.

MATERIALS AND METHODS
Materials

Twenty-six unrelated HNPCC probands registered from January 1998 to October 2005 at the Department of Abdominal Surgery in Shanghai Cancer Center were retrieved. Five of them fulfilled AC, 10 fulfilled JC and the remaining 11 fulfilled BG. Germline abnormalities of MSH2/MLH1/MSH6 were excluded in all the 26 probands by PCR-based sequencing. Ten milliliter peripheral blood was collected from each proband for genomic DNA preparation. The peripheral blood samples of 130 healthy volunteers without any family history of hereditary disease or development of colon cancer in early age were obtained for control. The informed consents were signed by all the probands and volunteers before blood drawing. This study was approved by the Medical Ethical Committee of Shanghai Cancer Center, Fudan University. The whole procedures of the study were in accordance with the international rules and regulations.

DNA extraction

Genomic DNA was extracted from the peripheral blood using the QIAGEN (Hilden, Germany) DNA extraction kit and following the manufacturer’s instructions. Concentrations of the genomic DNA were determined by an ultraviolet spectrophotometer (Beckman, DU640 type).

PCR amplification and DNA sequencing

LR-PCR (exon 1-5, 9, and 11-15): Since exon 1-5, 9, and 11-15 of hPMS2 genes were severely hampered by the presence of multiple pseudogenes with highly similar sequences. LR-PCR was conducted to preferentially amplify hPMS2 gene and avoid the interference of the pseudogenes.

Four overlapping sets of primers were designed to amplify the complete coding region of hPMS2 gene by LR-PCR[15,16] (Table 1). The LR-PCR amplification profile is also shown in Table 1. Then 1/8 of the four LR-PCR products were used as template to amplify the 11 exons (exon 1-5, 9, 11-12 and 13-15) individually. The primer sequences are listed in Table 2.

Table 1 Primer sequences of long-range polymerase chain reaction.
Primer nameSequence (5’-3’)Size (bp)Exon
LRPCR1
ForACGTCGAAAGCAGCCAATGGGAGTT9964Exon 1-5
RevCTTCCACCTGTGCATACCACAGGCT
LRPCR2
ForGGTCCAGGTCTTACATGCATACTGT9440Exon 9
RevCTGACTGACATTTAGCTTGTTGACA
LRPCR3
ForGCGTTGATATCAATGTTACTCCAGA8812Exon 11, 12
RevAGTAGTCAGGGTAAAACATTCCAGT
LRPCR4
ForAAAATTAGTCAGACTTGATGGTGTG9804Exon 13-15
RevCCTTCCATCTCCAAAACCAGCAAGA
Table 2 Primer sequences and polymerase chain reaction condition of individual exon of hPMS2 gene.
ExonPrimer sequence (5’-3’)Size (bp)AT (°C)CN
1M13F-ACGTCGAAAGCAGCCAATGGGAGTT4756628
M13R-CAGGTAGAAAGGAAATGCATTCAGT
2M13F-ACAGTGTTGAGTCATTTCCCACAGT4556628
M13R-TTCTTAGCATAACACCTGCCTGGCA
3M13F-TAGTCTGGGCTAGTAAATAGCCAGA7056835
4M13R-TATGACTTAGATTGGCAGCGAGACA
5M13F-CTTGATTATCTCAGAGGGATCGTCA5406835
M13R-TCTCACTGTGTTGCCCAGTCCTAAT
6M13F-TGCTTCCCTTGATTTGTGCGATGAT5046732
M13R-TGAGGCAGGAGAATTGCTTGAATCT
7M13F-ACCCACGAGTTTGACATTGCAGTGA4986035
M13R-GTAGAGGTTGCAGTGAGCCAAGATA
8M13F-AGATTTGGAGCACAGATACCCGTGA4146132
M13R-TGCGGTAGACTTCTGTAAATGCACA
9M13F-CCTTCTAAGAACATGCTGGTTGGTT2796445
M13R-ATCTCATTCCAGTCATAGCAGAGCT
10M13F-AGCCCTTCCGTATTTTGTCTATTCA7196132
M13R-GCTTTAGAAGCTGTTTGTACACTGT
11M13F-TCACATAAGCACGTCCTCTCACCAT10216445
M13R-GCAACAGAGCAAGACTCTGTCTCAA
12M13F-GCCAAGATTGTGCCATTGCACTGTA4936425
M13R-AGTAGATACAAGGTCTTGCTGTGTT
13M13F-GTGACACTTAGCTGAGTAGTGTTGT3726435
M13R-ATGTTAGCCAGGCTGGTCTCAAACT
14M13F-GGTCTGTATCTCCTGACCTCATGAT4736435
M13R-GCACGTAGCTCTCTGTGTAAAATGA
15M13F-GCTGAGATCTAGAACCTAGGCTTCT5226435
M13R-ACACACGAGCGCATGCAAACATAGA

PCR (exon 6, 7, 8 and 10): Conventional PCR was performed to detect the four exons (exon 6, 7, 8 and 10) which were seldom influenced by pseudogenes. Four sets of primers and PCR amplification profile are listed in Table 2.

DNA sequencing: The conventional PCR products were subjected to 2% agarose gel electrophoresis, while for LR-PCR products, 1% agarose was used with 9Kb as marker. After observation of clear and expected size bands, the products were purified and used as a template for sequencing reactions with BigDye terminator cycle sequencing kit (Applied Biosystems, Foster City, CA, USA). The sequencing primers were M13F or M13R. Automated fluorescence analysis was performed on a 3700 DNA sequence system (ABI, USA).

Bioinformatics analysis

Each result of sequencing was analyzed by DNAStar 5.08 bioanalysis software. The type of mutations and potential significance were determined by comparing the corresponding amino acids and proteins in the following databases (http://www.ncbi.nlm.nih.gov/; http://www.ensemble.org/homosapies; and http://www.insight-group. org).

RESULTS
Germline mutation of hPMS2 gene in HNPCC probands

Among the 26 unrelated HNPCC probands, only one (H13) was found to carry the germline mutation of hPMS2 gene. She was a 30-year-old female BG patient. The mutation was a missense mutation at codon 511 (ACG>ATG, Thr>Met) (Figure 1). To further investigate the pathological effects of the missense mutation, we analyzed the related exon 11 in 130 controls by PCR-based sequencing. The results showed that the mutation of codon 511, consistent with the HNPCC case at c.1532C>T of exon 11 of hPSM2 gene, was also found in three healthy controls. The occurrence rate was approximately 2.3% (3/130). It could not be found in the PMS2-SNP database (http://www.nfdht.nl; http://www.insight-group.org; and http://www.ensembl.org). Thus, the mutation at c.1532C>T of hPSM2 gene which we detected in the HNPCC patient is an unreported new single nucleotide polymorphism (SNP).

Figure 1
Figure 1 Missense germline mutation of exon 11 of hPMS2 gene in the proband of H13 hereditary nonpolyposis colorectal cancer kindreds. A: The forward sequence; B: The reverse sequence. Arrow indicates the mutation site, the single basyl substitution was transversed from C to T (C>T) at the codon 511, the codon from ACG to ATG, causing the amiod acid changes from Thr>Met, the change was identified as a new single nucleotide polymorphism.
SNP detection and analysis of hPMS2 gene

By DNA sequencing, 27 loci on the exons of hPMS2 gene including 260 reported SNP (http://www.ensembl.org/homo_sapies) were detected in the 26 HNPCC probands. Among them, 30% (78/260) were located in the 2nd exon, 23.1% (60/260) in the 5th exon, 13.8% (36/260) in the 15th exon, 10% (26/260) in the 7th exon, and 9.2% (24/260) in the 11th exon. However, none variant was detected in the remaining exons of the 1st, 3rd, 6th, 8th, 9th and 10th. The 2nd and 5th exons were probably the hot SNP regions of hPMS2 gene because 53.1% of the reported SNP were located in them. Distribution of the SNP of hPMS2 gene is shown in Table 3.

Table 3 Distribution of single nucleotide polymorphism of hPMS2 gene in 26 probands.
ExonNucleotide changeAmino acid changenSNP (%)
2c.24-4C>T-1478 (30)
c.89A>CGln30Pro15
c.117A>GVal39Val15
c.120G>ALys40Ly4
c.121G>AGlu41Lys15
c.124T>ALeu42Ile8
4c.288C>TAla96Ala818 (6.9)
c.295A>CThr99Pro10
5c.406A>GMet136Val1060 (23.1)
c.418A>GAsn140Asp10
c.429T>CIle143Ile10
c.452G>AArg151His10
c.478C>AGln160Lys10
c.492C>TSer164Ser10
11c.1408C>TPro470Ser724 (9.2)
c.1454C>AThr485Lys11
c.2006+6G>A-7
12c.2007-4G>A-1112 (4.6)
c.2007-7C>T-1
13c.2253T>CPhe751Phe11 (0.4)
14c.2324A>GAsn775Ser35 (1.9)
c.2340C>TPro780Pro2
15c.2466T>CLeu822Leu1236 (13.8)
c.2570G>CGly857Ala2
c.92dupA-17
c.17G>C-5
DISCUSSION

HNPCC, also called Lynch syndrome, is one of the most common autosomal dominantly inherited cancer syndromes with a high risk of colorectal cancer as well as other tumors occurring in endometrium, stomach, ovary, urinary tract, pancreas, small intestine, brain and skin. People with HNPCC take about 80% risk to develop colorectal cancer in their lifetime. It accounts for 2%-15% of all colorectal cancers. Compared to sporadic colorectal cancer, HNPCC possesses its own characteristics in clinical presentations, treatment, genetic features and management of kindred[17,18]. Many countries have established the clinical diagnostic criteria for HNPCC, such as AC, JC and BG. Defects in MMR genes, mainly in hMLH1, hMSH2 and hMSH6 were considered to be closely related to the genetic mechanism of HNPCC. The defection would consequently lead to the dysfunction of MMR system, ultimately resulting in the development of neoplasm. So, detection of MMR gene mutation is the only gold criteria to make a diagnosis of HNPCC.

Within the family of MMR genes, germline mutations in the coding region of hMSH2 and hMLH1 could be detected in up to 45%-64% of all HNPCC families, while hMSH6 about 10%. Previously we analyzed germline mutations and large genomic variations of the entire coding regions of hMSH2/hMLH1/hMSH6 genes and the methylation of hMLH1 promoter in 58 Chinese HNPCC probands, resulting in 29 germline mutations and 2 exhaustive inherited methylations of hMLH1 promoter (excluding 3 part-methylations of hMLH1 promoter). The total gene abnormality rate was only 53.4% (31/58). We suspected that the other MMR gene mutations might be associated with the remaining probands without hMSH2, hMLH1 or hMSH6 gene abnormalities.

The hPMS2 gene is a member of a set of human mismatch repair genes, located on chromosome 7. It encodes the protein that plays an essential role in repairing DNA by forming an active protein complex with the MLH1 protein which interacts with MSH2 bound to mismatched bases. In 1994, Nicolaides et al[19] firstly found the germline mutation of hPMS2 gene in a HNPCC patient. Since then, more and more data have proved that hPMS2 germline mutation is involved in the development of HNPCC. In some reports, it could be detected in as high as 62% of HNPCC probands[20]. The hPMS2 gene was suggested as the first candidate gene for testing germline mutations in HNPCC families in which hMSH2, hMLH1and hMSH6 aberrant was excluded. However, genetic testing for germline mutation of hPMS2 gene was technically challenging because they were severely hampered by a large family of highly homologous pseudogenes located on the same chromosome as the true hPMS2, such as PMS2CL. They shared similar sequences to hPMS2 but had no functions. Data from literature indicated that the exon 6 to 8 and exon 10 of hPMS2 could be easily screened by direct sequencing of genomic DNA without interference of pseudogenes. But detection of exon 1-5, 9 and exon 11-15 was complicated due to the interference of PMS2CL. LR-PCR was recommended as a useful method to preferentially identify hPMS2 but not the pseudogenes. In this study, we used LR-PCR to investigate the germline mutation of hPMS2 gene in those HNPCC probands who did not carry hMLH1/hMSH2/hMSH6 germline mutations investigated by the previous studies. Four overlapping sets of primers were designed to amplify the complete coding region of hPMS2 gene by LR-PCR firstly. Then, exon-specific amplifications from the LR-PCR products were performed to obtain a clear sequence with no evidence of pseudogene contamination. We only found one missense mutation in 26 probands, which has not been reported in Chinese HNPCC families. This mutation could also be detected in the 130 control persons with an occurrence rate of about 2.3%. Since it could not be found in the PMS2-SNP database (http://www.nfdht.nl; http://www.insight-group.org; and http://www.ensembl.org), the mutation at c.1532C>T of hPMS2 gene in our HNPCC case was an unreported new single nucleotide polymorphism (SNP). Our results showed that the germline mutation of hPMS2 gene was probably a rare event in Chinese HNPCC, even in those probands without hMLH1/hMSH2/hMSH6 mutations. It was consistent with the results of some other studies[21]. Interestingly, another mutation was found in the same nucleotide, c1532_1533 delCGinsAC, causing the amiod changes from Thr to Asn (http://www.insight-group.org). So, the exon 11 may be a hot SNP or mutation region of hPMS2 gene.

The frequency of germline mutation in hPMS2 gene was reported to be up to 62% if patients whose tumor tissues lacked protein expression of hPMS2 or had MSI-H features, were selected[22]. Among the HNPCC families with monoallelic mutation in hPMS2, 65.5% were complied with BG. Recently, Niessen et al[23] identified 4 patients with pathogenic mutation of hPMS2 among 97 patients with suspected Lynch syndrome who carried no germline mutation in hMLH1, hMSH2 or hMSH6. All these 4 patients fulfilled BG and their corresponding tumor cells showed MSI-H and loss of expression of hPMS2. Clendenning et al[24] reported that a kind of frame-shift mutation of hPMS2 occurred in 12 ostensibly unrelated Lynch syndrome patients with 20% being the deleterious mutation. However, those families with pathogenic mutation did not have significantly high incidence of Lynch syndrome associated malignant tumors, indicating that the germline mutation of hPMS2 and occurrence of HNPCC were not concurrent sometimes. The patient with hPMS2 gene mutation in our group also met the requirements of BG. By reviewing the family history of our mutation positive patient, we found that in her first-degree relatives, three suffered from colorectal cancer but diagnosed at age over 60 years, not in accordance with the typical feature of HNPCC. Although we are not so certain about this, the non-classical presentation of her family history, to some extent, represents the phenomenon of separation of HNPCC occurrence and hPMS2 gene mutation.

At the same time, we detected the reported SNP in these 26 probands and found some interesting results. Most of the SNP (21/27) were in the exons and 12 were non-synonymous coding SNP(cSNP). Since these non-synonymous cSNP can induce the change of amino acid and the relationship between cSNP and pathogenesis of HNPCC still remains unclear, whether they are involved in the development of HNPCC and HNPCC related tumors needs to be further investigated.

In conclusion, the germline mutation of hPMS2 gene is rare in the probands of Chinese HNPCC families. Since the testing of hPMS2 gene mutation is costly and complicated, it may be not reasonable to be included in the screening strategy of Chinese HNPCC. However, the frequency of SNP of hPMS2 gene is high and further studies are needed to identify its relationship with HNPCC.

COMMENTS
Background

Germline mutations in mismatched repair genes can lead to hereditary nonpolyposis colorectal cancer (HNPCC). Previously, the authors had analyzed the abnormalities of hMSH2/hMLH1/hMSH6 genes in a serious of Chinese HNPCC families and the total abnormality rate was only 53.4% (31/58). So the aberrant MMR genes such as hPMS2 were suspected to be involved in Chinese HNPCC.

Research frontiers

HNPCC or Lynch syndrome, is an autosomal dominantly inherited disease with cancer-susceptibility. The testing of hPMS2 gene mutation is costly and complicated, it may be not reasonable to be included in the screening strategy of Chinese HNPCC. However, the frequency of single nucleotide polymorphism (SNP) of hPMS2 gene is high and further studies are needed to identify its relationship with HNPCC.

Innovations and breakthroughs

One HNPCC proband was found to carry the germline mutation of hPMS2 gene. It was a new unreported coding SNP, which could also be detected in the control with an occurrence rate of 2.3% (3/130).

Applications

Germline mutations in genes can be used to diagnose early HNPCC and enrich the databases about HNPCC and SNP.

Peer review

This is an interesting article which deals with a remarkably rare germline mutation, namely PMS2, which is important in the etiology of Lynch syndrome (HNPCC). Their science appears to be sound.

Footnotes

Peer reviewers: Henry Thomson Lynch, MD, Department of Preventive Medicine, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE 68178, United States; Minna Nyström, PhD, Department of Biological and Environmental Sciences, PO Box 56 (Viikinkaari 5 D), University of Helsinki, FI-00014 Helsinki, Finland

S- Editor Wang YR L- Editor Ma JY E- Editor Lin YP

References
1.  Stephenson BM, Finan PJ, Gascoyne J, Garbett F, Murday VA, Bishop DT. Frequency of familial colorectal cancer. Br J Surg. 1991;78:1162-1166.  [PubMed]  [DOI]  [Cited in This Article: ]
2.  Lagerstedt Robinson K, Liu T, Vandrovcova J, Halvarsson B, Clendenning M, Frebourg T, Papadopoulos N, Kinzler KW, Vogelstein B, Peltomäki P. Lynch syndrome (hereditary nonpolyposis colorectal cancer) diagnostics. J Natl Cancer Inst. 2007;99:291-299.  [PubMed]  [DOI]  [Cited in This Article: ]
3.  Wagner A, Tops C, Wijnen JT, Zwinderman K, van der Meer C, Kets M, Niermeijer MF, Klijn JG, Tibben A, Vasen HF. Genetic testing in hereditary non-polyposis colorectal cancer families with a MSH2, MLH1, or MSH6 mutation. J Med Genet. 2002;39:833-837.  [PubMed]  [DOI]  [Cited in This Article: ]
4.  Liu SR, Zhao B, Wang ZJ, Wan YL, Huang YT. Clinical features and mismatch repair gene mutation screening in Chinese patients with hereditary nonpolyposis colorectal carcinoma. World J Gastroenterol. 2004;10:2647-2651.  [PubMed]  [DOI]  [Cited in This Article: ]
5.  Park JG, Kim DW, Hong CW, Nam BH, Shin YK, Hong SH, Kim IJ, Lim SB, Aronson M, Bisgaard ML. Germ line mutations of mismatch repair genes in hereditary nonpolyposis colorectal cancer patients with small bowel cancer: International Society for Gastrointestinal Hereditary Tumours Collaborative Study. Clin Cancer Res. 2006;12:3389-3393.  [PubMed]  [DOI]  [Cited in This Article: ]
6.  Peltomäki P, Vasen HF. Mutations predisposing to hereditary nonpolyposis colorectal cancer: database and results of a collaborative study. The International Collaborative Group on Hereditary Nonpolyposis Colorectal Cancer. Gastroenterology. 1997;113:1146-1158.  [PubMed]  [DOI]  [Cited in This Article: ]
7.  Lipton LR, Johnson V, Cummings C, Fisher S, Risby P, Eftekhar Sadat AT, Cranston T, Izatt L, Sasieni P, Hodgson SV. Refining the Amsterdam Criteria and Bethesda Guidelines: testing algorithms for the prediction of mismatch repair mutation status in the familial cancer clinic. J Clin Oncol. 2004;22:4934-4943.  [PubMed]  [DOI]  [Cited in This Article: ]
8.  Fujita S, Moriya Y, Sugihara K, Akasu T, Ushio K. Prognosis of hereditary nonpolyposis colorectal cancer (HNPCC) and the role of Japanese criteria for HNPCC. Jpn J Clin Oncol. 1996;26:351-355.  [PubMed]  [DOI]  [Cited in This Article: ]
9.  Yan SY, Zhou XY, Du X, Zhang TM, Lu YM, Cai SJ, Xu XL, Yu BH, Zhou HH, Shi DR. Three novel missense germline mutations in different exons of MSH6 gene in Chinese hereditary non-polyposis colorectal cancer families. World J Gastroenterol. 2007;13:5021-5024.  [PubMed]  [DOI]  [Cited in This Article: ]
10.  Zhou HH, Yan SY, Zhou XY, Du X, Zhang TM, Cai X, Lu YM, Cai SJ, Shi DR. MLH1 promoter germline-methylation in selected probands of Chinese hereditary non-polyposis colorectal cancer families. World J Gastroenterol. 2008;14:7329-7334.  [PubMed]  [DOI]  [Cited in This Article: ]
11.  Cai Q, Sun MH, Fu G, Ding CW, Mo SJ, Cai SJ, Ren SX, Min DL, Xu XL, Zhu WP. [Mutation analysis of hMSH2 and hMLH1 genes in Chinese hereditary nonpolyposis colorectal cancer families]. Zhonghua Binglixue Zazhi. 2003;32:323-328.  [PubMed]  [DOI]  [Cited in This Article: ]
12.  Wang CF, Zhou XY, Zhang TM, Sun MH, Xu Y, Shi DR. [The analysis for mRNA mutation of MLH1, MSH2 genes and the gene diagnosis for hereditary nonpolyposis colorectal cancer]. Zhonghua Yixue Yichuanxue Zazhi. 2006;23:32-36.  [PubMed]  [DOI]  [Cited in This Article: ]
13.  Wang CF, Zhou XY, Zhang TM, Xu Y, Cai SJ, Shi DR. Two novel germline mutations of MLH1 and investigation of their pathobiology in hereditary non-polyposis colorectal cancer families in China. World J Gastroenterol. 2007;13:6254-6258.  [PubMed]  [DOI]  [Cited in This Article: ]
14.  Wang CF, Zhou XY, Zhang TM, Sun MH, Shi DR. Detection of germline mutations of hMLH1 and hMSH2 based on cDNA sequencing in China. World J Gastroenterol. 2005;11:6620-6623.  [PubMed]  [DOI]  [Cited in This Article: ]
15.  Etzler J, Peyrl A, Zatkova A, Schildhaus HU, Ficek A, Merkelbach-Bruse S, Kratz CP, Attarbaschi A, Hainfellner JA, Yao S. RNA-based mutation analysis identifies an unusual MSH6 splicing defect and circumvents PMS2 pseudogene interference. Hum Mutat. 2008;29:299-305.  [PubMed]  [DOI]  [Cited in This Article: ]
16.  Clendenning M, Hampel H, LaJeunesse J, Lindblom A, Lockman J, Nilbert M, Senter L, Sotamaa K, de la Chapelle A. Long-range PCR facilitates the identification of PMS2-specific mutations. Hum Mutat. 2006;27:490-495.  [PubMed]  [DOI]  [Cited in This Article: ]
17.  Luo DC, Cai Q, Sun MH, Ni YZ, Ni SC, Chen ZJ, Li XY, Tao CW, Zhang XM, Shi DR. Clinicopathological and molecular genetic analysis of HNPCC in China. World J Gastroenterol. 2005;11:1673-1679.  [PubMed]  [DOI]  [Cited in This Article: ]
18.  Cai Q, Sun MH, Lu HF, Zhang TM, Mo SJ, Xu Y, Cai SJ, Zhu XZ, Shi DR. Clinicopathological and molecular genetic analysis of 4 typical Chinese HNPCC families. World J Gastroenterol. 2001;7:805-810.  [PubMed]  [DOI]  [Cited in This Article: ]
19.  Nicolaides NC, Papadopoulos N, Liu B, Wei YF, Carter KC, Ruben SM, Rosen CA, Haseltine WA, Fleischmann RD, Fraser CM. Mutations of two PMS homologues in hereditary nonpolyposis colon cancer. Nature. 1994;371:75-80.  [PubMed]  [DOI]  [Cited in This Article: ]
20.  Senter L, Clendenning M, Sotamaa K, Hampel H, Green J, Potter JD, Lindblom A, Lagerstedt K, Thibodeau SN, Lindor NM. The clinical phenotype of Lynch syndrome due to germ-line PMS2 mutations. Gastroenterology. 2008;135:419-428.  [PubMed]  [DOI]  [Cited in This Article: ]
21.  Thompson E, Meldrum CJ, Crooks R, McPhillips M, Thomas L, Spigelman AD, Scott RJ. Hereditary non-polyposis colorectal cancer and the role of hPMS2 and hEXO1 mutations. Clin Genet. 2004;65:215-225.  [PubMed]  [DOI]  [Cited in This Article: ]
22.  Nakagawa H, Lockman JC, Frankel WL, Hampel H, Steenblock K, Burgart LJ, Thibodeau SN, de la Chapelle A. Mismatch repair gene PMS2: disease-causing germline mutations are frequent in patients whose tumors stain negative for PMS2 protein, but paralogous genes obscure mutation detection and interpretation. Cancer Res. 2004;64:4721-4727.  [PubMed]  [DOI]  [Cited in This Article: ]
23.  Niessen RC, Kleibeuker JH, Westers H, Jager PO, Rozeveld D, Bos KK, Boersma-van Ek W, Hollema H, Sijmons RH, Hofstra RM. PMS2 involvement in patients suspected of Lynch syndrome. Genes Chromosomes Cancer. 2009;48:322-329.  [PubMed]  [DOI]  [Cited in This Article: ]
24.  Clendenning M, Senter L, Hampel H, Robinson KL, Sun S, Buchanan D, Walsh MD, Nilbert M, Green J, Potter J. A frame-shift mutation of PMS2 is a widespread cause of Lynch syndrome. J Med Genet. 2008;45:340-345.  [PubMed]  [DOI]  [Cited in This Article: ]