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Lynch syndrome is a hereditary disease characterized by an increased risk of colorectal and other cancers. Germline variants in the mismatch repair (MMR) genes are responsible for this disease. Previously, we screened the MMR genes in colorectal cancer patients who fulfilled modified Amsterdam II criteria, and multiplex ligation-dependent probe amplification (MPLA) identified 11 structural variants (SVs) of MLH1 and MSH2 in 17 patients. In this study, we have tested the efficacy of long read-sequencing coupled with target enrichment for the determination of SVs and their breakpoints. DNA was captured by array probes designed to hybridize with target regions including four MMR genes and then sequenced using MinION, a nanopore sequencing platform. Approximately, 1000-fold coverage was obtained in the target regions compared with other regions. Application of this system to four test cases among the 17 patients correctly mapped the breakpoints. In addition, we newly found a deletion across an 84 kb region of MSH2 in a case without the pathogenic single nucleotide variants. These data suggest that long read-sequencing combined with hybridization-based enrichment is an efficient method to identify both SVs and their breakpoints. This strategy might replace MLPA for the screening of SVs in hereditary diseases., (© 2021. The Author(s), under exclusive licence to The Japan Society of Human Genetics.)

Background: Patients with Lynch syndrome are at an increased risk of developing colorectal cancer, and the adenoma-carcinoma sequence is accelerated in these patients. However, the clinicopathological characteristics of colorectal neoplasms in Lynch syndrome patients are not well-known., Methods: A total of 325 consecutive colorectal neoplasms were endoscopically removed from 68 patients with Lynch syndrome between June 2005 and May 2018 and retrospectively reviewed., Results: Of the 325 lesions, 94 (29%), 220 (68%) and 11 (3%) were from patients with MLH1, MSH2 and MSH6 mutations, respectively. The median lesion size was 5 mm (range 2-40 mm), with 229 (71%) lesions having a non-polypoid morphology. The frequencies of advanced neoplasms, including high-grade adenomas, intramucosal carcinomas and submucosal invasive carcinomas were 14, 34, 97 and 93% for lesions with diameters of <5, ≥5 and <10, ≥10 and <20, and ≥20 mm, respectively. The frequencies of advanced neoplasms in the proximal colon, distal colon and rectum did not significantly differ (36, 35 and 41%, respectively)., Conclusions: Our results suggest that the malignant transformation interval from low-grade adenomas to advanced neoplasms is similar in all parts of the colon. Furthermore, since one-third of neoplastic lesions with diameters of ≥5 and <10 mm and most of those ≥10 mm were advanced neoplasms, we recommend that in Lynch syndrome patients, careful colonoscopic surveillance should be performed throughout the colon, and all neoplastic lesions, regardless of the size, should be subjected to detailed endoscopic examination, complete resection and detailed pathological examination., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.)

Lynch syndrome (LS) is an autosomal dominantly inherited disease predisposed to not only colorectal cancer but also other LS-related tumors. Although the clinical and genetic characteristics of LS in Western countries have been well characterized, the information of Japanese LS is limited. As a collaborative study of Japanese Society for Cancer of the Colon and Rectum (JSCCR), we registered colorectal cancer (CRC) patients who fulfilled the modified Amsterdam II criteria including gastric cancer as an LS-related tumor. Among 4030 CRC patients initially registered in this project, 85 patients (2.1%) fulfilled the modified criteria. An additional 26 patients who met the same criteria were enrolled in the analysis. We analyzed three major responsible genes, MLH1, MSH2, and MSH6 by direct sequencing, and further performed multiplex ligation-dependent probe amplification for MLH1 and MSH2. Consequently, we identified pathogenic variants in 64 of the 111 patients comprising of 34 patients in MLH1, 28 in MSH2, and 2 in MSH6. It is of note that large structural alterations were found in 17 patients. Among the 64 patients, 11 patients would not have been enrolled in the analysis if gastric cancer were not included in the modified criteria. In addition, 10 of the 64 variant carriers (15.6%) had medical history of gastric cancer. Furthermore, the standardized incidence ratio of gastric cancer in the LS patients to the Japanese population is estimated to be as high as 20.2. These data underscore the importance of gastric cancer in the diagnosis and healthcare of Japanese LS patients.

We conducted this study to establish whether drinking alcohol alters the risk of early-onset colorectal cancer (CRC) in Japanese patients with Lynch syndrome (LS). The subjects were 66 LS patients with pathogenic mutation of mismatch repair genes (MLH1, MSH2, and MSH6) from the nationwide Japanese retrospective multicenter study. Cox proportional hazards modeling was used to investigate the factors correlating with early-onset CRC diagnosis, using clinical data such as gender, tobacco use, alcohol consumption, body mass index, gene mutation (MLH1, MSH2 vs MSH6), and family cancer history. Alcohol was significantly correlated with an increased risk of early-onset CRC [HR 2.44, 95% CI 1.13-5.16 (p = 0.02)], but tobacco use was not [HR 0.8, 95%CI 0.38-1.62 (p = 0.53)]. These findings suggest that alcohol consumption is correlated with an earlier onset of CRC in Japanese patients with LS.

Objectives: To assess the detection rate of putative Lynch syndrome-associated upper urinary tract urothelial cancer among all upper urinary tract urothelial cancers and to examine its clinicopathological characteristics., Methods: A total of 143 patients with upper urinary tract urothelial cancer who had received total nephroureterectomy were immunohistochemically stained for the expression of mismatch repair proteins MLH1, PMS2, MSH2 and MSH6. For all suspected mismatch repair-deficient cases, MMR genetic testing was recommended and clinicopathological features were examined., Results: Loss of mismatch repair proteins was found in seven patients (5%) who were thus categorized as putative Lynch syndrome-associated upper urinary tract urothelial cancer. Five of these patients showed dual loss of MSH2/MSH6. Two patients were confirmed to be MSH2 germline mutation carriers. Histologically, all seven tumors were low-grade atypical urothelial carcinoma and showed its unique histological features, such as an inverted papilloma-like growth pattern and a villous to papillary structure with mild stratification of tumor cells. Six tumors had no invasion of the muscularis propria. No recurrence or cancer-related deaths were reported in these seven patients. Just three patients met the revised Amsterdam criteria., Conclusions: This is the first report that universally examined mismatch repair immunohistochemical screening for upper urinary tract urothelial cancers. The prevalence (5%) of putative Lynch syndrome-associated upper urinary tract urothelial cancers is much higher than we had expected. We ascertained that putative Lynch syndrome-associated upper urinary tract urothelial cancers were clinically in the early stage and histologically classified into low-grade malignancy with its characteristic pathological features. The clinicopathological characteristics that we found in the present study could become additional possible markers in the diagnosis of Lynch syndrome-associated upper urinary tract urothelial cancers., (© 2017 The Japanese Urological Association.)

Background: Initial surgical procedures for colorectal cancer (CRC) patients with Lynch syndrome remain controversial. This study assessed the validity of segmental colectomy (SGC) followed by endoscopic surveillance as a treatment strategy for CRC patients with Lynch syndrome., Methods: Among consecutive patients who underwent surgery for primary CRC between April 1985 and December 2014, 49 patients were observed to have germline mutations in a mismatch repair gene, and 38 patients who underwent SGC followed by periodic endoscopic surveillance at our institution were evaluated for metachronous CRC, need for secondary surgery, and the details of endoscopic surveillance., Results: Of the 38 patients who underwent SGC followed by periodic endoscopic surveillance at our institution, 6 (15.8%) patients showed metachronous CRC, 3 (7.9%) patients underwent endoscopic resection, and the other 3 patients (7.9%) underwent secondary surgery. The dispersion of the endoscopic surveillance interval was significantly greater in patients with metachronous CRC (364 ± 332.9 days) than in those without metachronous CRC (370 ± 129.7 days; p < 0.001)., Conclusions: SGC followed by annual endoscopic surveillance was feasible as a treatment strategy for CRC patients with Lynch syndrome, because the incidence of metachronous CRC and the need for secondary surgery were low. Annual and periodic endoscopic surveillance might be essential for early detection of metachronous CRC and prevention of secondary surgery because of metachronous CRC in CRC patients with Lynch syndrome after SGC., (© 2017 S. Karger AG, Basel.)

Aim: To elucidate the causes of cancer death in Japanese families with Lynch syndrome (LS)., Methods: The distributions of cancer deaths in 485 individuals from 67 families with LS (35, 30, and two families with MutL homologue 1 (MLH1), MSH2, and MSH6 gene mutations, respectively), obtained from the Registry of the Japanese Society for Cancer of the Colon and Rectum were analyzed., Results: Among 98 cancer deaths of first-degree relatives of unknown mutation status, 53%, 19%, 13% (among females), 7% (among females) and 5% were due to colorectal, gastric, uterine, ovarian, and hepatobiliary cancer, respectively. The proportion of deaths from extra-colonic cancer was significantly higher in families with MSH2 mutation than in those with MLH1 mutation (p=0.003)., Conclusion: In addition to colonic and uterine cancer, management and surveillance targeting gastric, ovarian and hepatobiliary cancer are considered important for Japanese families with LS. Extra-colonic cancer in families with MSH2 mutation might require for more intensive surveillance., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

Heterozygous deleterious mutation of the PMS2 gene is a cause of Lynch syndrome, an autosomal dominant cancer disease. However, the frequency of PMS2 mutation is rare compared with that of the other causative genes; MSH2, MLH1 and MSH6. PMS2 mutation has so far only been reported once from a Japanese facility. Detection of PMS2 mutation is relatively complicated due to the existence of 15 highly homologous pseudogenes, and its gene conversion event with the pseudogene PMS2CL. Therefore, for PMS2 mutation analysis, it is crucial to clearly distinguish PMS2 from its pseudogenes. We report here a novel deleterious 11 bp deletion mutation of exon 11 of PMS2 distinguished from PMS2CL in a 34-year-old Japanese female with rectal cancer. PMS2 mutated at c.1492del11 results in a truncated 500 amino acid protein rather than the wild-type protein of 862 amino acids. This is supported by the fact that, although there is usually concordance between MLH1 and PMS2 expression, cells were immunohistochemically positive for MLH1, whereas PMS2 could not be immunohistochemically stained using an anti-C-terminal PMS2 antibody, or effective PMS2 mRNA degradation with NMD caused by the frameshift mutation., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Lynch syndrome is an autosomal dominantly inherited disease that is characterized by a predisposition to cancers, mainly colorectal cancer. Germline mutations of DNA mismatch repair genes such as MLH1, MSH2, MSH6 and PMS2 have been described in patients with Lynch syndrome. Here, we report deletion of 2 bp in the splice donor site of the MLH1 exon 6 (c.545+4&#95;545+5delCA) in a 48-year-old Japanese woman with Lynch syndrome. RT-PCR direct sequencing analysis revealed that this mutation led to an increase in the level of an MLH1 transcript in which exon 6 was skipped, and may cause a frameshift (p.E153FfsX8). Therefore, this mutation appears to be pathogenic and is responsible for Lynch syndrome. Additionally, analysis of the patient's tumor cells indicated microsatellite instability high phenotype and loss of the MLH1 and PMS2 proteins. To our knowledge, this is a germline splice site mutation of MLH1 that has not been reported previously., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The positive correlation between smoking and cancer risk is well estimated in sporadic colorectal cancer, whereas little is known with regard to Lynch syndrome-associated colorectal cancer. A total of 118 familial colorectal cancer patients from the Hereditary Nonpolyposis Colorectal Cancer Registry and Genetic Testing Project of the Japanese Society for Cancer of the Colon and Rectum, were assessed to determine whether smoking alters the incidence of multiple colorectal cancers. In male patients with Lynch syndrome (n = 29), the incidence of multiple colorectal cancers in patients who had ever smoked (smoking duration: median of 19 years) was higher than that in those who never smoked (58.8% vs. 10.0%, P = 0.02). The cumulative risk for metachronous colorectal cancer was significantly higher in male Lynch syndrome patients who had previously smoked than in those who had never smoked (P = 0.03). Our data suggest that long-term cigarette smoking might be a strong risk factor for the development of multiple colorectal cancers in male Lynch syndrome patients., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objective: The characteristics of familial colorectal cancer type X are poorly defined. Here we aimed to clarify the differences in clinical features between suspected familial colorectal cancer type X and Lynch syndrome in Japanese patients., Methods: We performed germline mutation analyses of mismatch repair genes in 125 patients. Patients who met the Amsterdam Criteria I but lacked mismatch repair gene mutations were diagnosed with suspected familial colorectal cancer type X., Results: We identified 69 patients with Lynch syndrome and 25 with suspected familial colorectal cancer type X. The frequencies of gastric and extracolonic Lynch syndrome-associated cancers were lower with suspected familial colorectal cancer type X than with Lynch syndrome. The number of organs with Lynch syndrome-associated cancer was significantly lower with suspected familial colorectal cancer type X than with Lynch syndrome. The cumulative incidence of extracolonic Lynch syndrome-associated cancer was significantly lower with suspected familial colorectal cancer type X than with Lynch syndrome. We estimated that the median cancer risk in 60-year-old patients with Lynch syndrome was 89, 36 and 24% for colorectal, endometrial and gastric cancers, respectively. Analyses of family members, including probands, revealed that the median age at diagnosis of extracolonic Lynch syndrome-associated cancer was significantly older with suspected familial colorectal cancer type X than with Lynch syndrome. The frequency of extracolonic Lynch syndrome-associated cancer was significantly lower with suspected familial colorectal cancer type X than with Lynch syndrome., Conclusion: A significant difference in extracolonic Lynch syndrome-associated cancer was evident between suspected familial colorectal cancer type X and Lynch syndrome., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

A woman in her 80s had two episodes of ileus, which led to the diagnosis of advanced jejunal cancer. She was diagnosed with Lynch syndrome when she was in her 60s, for which she underwent annual follow-up with computed tomography for 8 years. Unfortunately, she died from the recurrence of jejunal cancer and liver metastases. Jejunal cancer is relatively rare in Lynch syndrome, and no surveillance strategy has been established for small bowel cancer. In patients with unexplained abdominal complaints, small bowel cancer should be considered.

Lynch syndrome (HNPCC) is an autosomal dominant hereditary cancer syndrome, and members of affected families are at-risk for developing colorectal and other associated tumors. Such individuals should disseminate familial genetic information, so they can seek specific medical assessment or genetic testing to reduce mortality and morbidity rates by early detection. Since published results have been encouraging, we explored which factors influence the likelihood of good communication within families regarding medical assessment. We studied 40 individuals from 33 families who satisfied the Japanese clinical criteria for Lynch syndrome and their relatives at our hospital. We determined the status of relatives of the 40 individuals after genetic counseling and testing using questionnaires and semi-structured interviews based on pedigree charts. We also examined their knowledge or perception of colorectal cancer syndrome, levels of intimacy and whether or not they encouraged their relatives to have specific medical assessments. We found that 75% of the individuals advised their relatives to seek medical assessment, and any significant background factors that promoted such encouragement were observed. They tended to encourage first degree relatives and discuss the issue with other family members such as spouses before undertaking such attempts at encouragement. The reasons and methods of imparting encouragement were essentially identical. We also found that genetic testing for at-risk or more distant relatives was not encouraged so often. Therefore, providing individuals who have been tested for Lynch syndrome with opportunities for disseminating familial genetic information through appropriate genetic counseling is important.

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.

Purpose: Colorectal cancer and gastric cancer are the two most commonly associated malignancies in Japan. We examined mismatch repair deficiency in the tumors of patients with primary colorectal and gastric cancers retrospectively., Methods: In 103 cases and 102 healthy control subjects, surgical specimens of colorectal and gastric cancer underwent immunohistochemical analysis of mismatch repair proteins (hMLH1 and hMSH2) and microsatellite instability testing., Results: Immunohistochemical and microsatellite instability testing produced similar results. High microsatellite instability in colorectal cancer was found in 23 of 103 cases (23 percent) with colorectal and gastric cancers, and in 8 of 102 healthy control subjects (8 percent). Twelve (12 percent) had mismatch repair deficiency in both colorectal and gastric cancers, and both tumors had loss of the same mismatch repair protein (hMLH1, n = 5; hMSH2, n = 7). They had the first cancer at a younger age, with a higher frequency of familial colorectal cancer than the others. Seventeen had mismatch repair deficiency in either tumor, which showed loss of expression of hMLH1. Multiple cancers and right-sided colon cancers developed more frequently in patients with mismatch repair deficiency., Conclusions: Patients with both colorectal and gastric cancers are more likely to have phenotypic evidence of hereditary nonpolyposis colorectal cancer than patients with colorectal cancer only. Among patients with double tumors, 12 percent showed a common deficiency in the same mismatch repair protein in both tumors by immunohistochemistry, and they should undergo genetic counseling for germline mutational analysis. Immunohistochemistry was effective in detecting mismatch repair deficiency of colorectal and gastric cancer as well as microsatellite instability testing, and may be more practical to perform phenotypic analysis of tumors because of its cost-effectiveness.