Frequency of hereditary non-polyposis colorectal cancer among unselected patients with colorectal cancer in Germany

INTRODUCTION: Hereditary non-polyposis colorectal cancer (HNPCC) is a major form of familial colorectal cancer (CRC). It is diagnosed when either the Amsterdam criteria (AC) are fulfilled or mutations in one of the mismatch repair (MMR) genes have been identified. This project aims at estimating the proportion of HNPCC among unselected patients with CRC. PATIENTS AND METHODS: During a period of 2 years, a total of 351 non-selected patients with CRC were registered prospectively. 92 patients met the Bethesda criteria (9 of them fulfilled the AC) and 259 did not. 348 tumours were examined for microsatellite instability (MSI) and expression of MMR proteins. RESULTS: MSI-H and MSI-L were identified in 17 and 6%, respectively. Loss of MSH2 or MLH1 was found in 1.5 and 8.8%, respectively. Based on the results of tumour tissue analyses, 80 patients with MSI and/or loss of MSH2 or MLH1 expression were identified as candidates for germline mutation screening. DNA of 40/80 patients was available. These patients were screened for MSH2 and MLH1 mutations; 19/40 patients with MSI and normal MSH2 or MLH1 expression were screened for mutations in MSH6. Three patients had relevant MMR gene mutations and six variants of unknown functional relevance were detected. CONCLUSIONS: After adjusting for the cases not evaluable for germline mutations, 1.7% of the CRC patients had HNPCC proven by molecular genetics.     

Evolution of hereditary non-polyposis colorectal cancer.

The prevalence of colorectal adenoma in 23 affected patients with hereditary non-polyposis colorectal cancer (HNPCC) was compared with that in an age matched forensic autopsy population. The mean ages at diagnosis of colorectal cancer in men (13) and women (10) were 39 and 37 years respectively. In HNPCC patients who presented below the age of 50 years, at least one adenoma was found in 3 of 10 (30%) men and in 4 of 9 (44%) women. In the age matched autopsy specimens of large bowel, a solitary adenoma was found in 2/42 (5%) men (p = 0.015) and 1/21 (5%) women (p = 0.0075). Of the 11 adenomas from HNPCC patients, nine were greater than 1 cm and six showed a pure villous architecture. Contiguous adenocarcinoma was observed with six adenomas. Adenomas do not occur in large numbers in HNPCC, but develop at a young age, attain a large size, often show a villous configuration, and are more prone to malignant conversion than sporadic adenomas.     

Clinical and molecular analysis of hereditary non-polyposis colorectal cancer in Chinese colorectal cancer patients

AIM:To analyze the frequency of hereditary non-polyposis colorectal cancer(HNPCC)in Chinese colorectal cancer(CRC)patients,and to discuss the value of microsatellite instability(MSI)and/or immunohistochemistry(IHC)for MSH2/MLH1 protein analysis as pre-screening tests in China.METHODS:The Amsterdam criteriaⅠandⅡ(clinical diagnosis)and/or germline hMLH1/hMSH2 mutations(genetic diagnosis)were used to classify HNPCC families.Genetic tests,including microsatellite instability,immunohistochemistry for MSH2/MLH1 proteins and hMSH2/hMLH1 genes,were performed in each proband.RESULTS:From July 2000 to June 2004,1988 patients with colorectal cancer were analysed and 114 CRC patients(5.7%)from 48 families were categorized as having HNPCC,including 76 from 26 families diagnosed clinically and 38 from the other 22 families diagnosed genetically.The sensitivity and specificity of high MSI and IHC for predicting mutations were 100% and 54%,and 79% and 77%,respectively.CONCLUSION:The frequency of HNPCC is approximately 10% among all Chinese CRC cases.The MSI and IHC detections for hMSH2/hMLH1 proteins are reliable pre-screening tests for hMLH1/hMSH2 germline mutations in families suspected of having HNPCC.     

Genetic diagnosis strategy of hereditary non-polyposis colorectal cancer

AIM： To study the characteristics of mismatch repair gene mutation of Chinese hereditary non-polyposis colorectal cancer （HNPCC） and hMLH1 gene promoter methylation, and to improve the screening strategy and explore the pertinent test methods. METHODS： A systematic analysis of 30 probands from HNPCC families in the north of China was performed by immunohistochemistry, microsatellite instability （MSI）, gene mutation and methylation detection. RESULTS： High frequency microsatellite instability occurred in 25 probands （83.3%） of HNPCC family. Loss of hMLH1 and hMSH2 protein expression accounted for 88% of all microsatellite instability. Pathogenic mutation occurred in 14 samples and 3 novel mutational sites were discovered. Deletion of exons 1-6, 1-7 and 8 of hMSH2 was detected in 3 samples and no large fragment deletion was found in hMLH1. Of the 30 probands, hMLH1 gene promoter methylation occurred in 3 probands. The rate of gene micromutation detection combined with large fragment deletion detection was 46.7%-56.7%. The rate of the two methods in combination with methylation detection was 63.3%. CONCLUSION： Scientific and rational detection strategy can improve the detection rate of HNPCC. Based on traditional molecular genetics and combined with epigenetics, multiple detection methods can accurately diagnose HNPCC.     

Hereditary polyposis syndromes and hereditary non-polyposis colorectal cancer

Colorectal cancer due to hereditary syndromes comprises approximately 5% of the overall colorectal cancer burden. Conditions fall into two distinct categories, the polyposis syndromes and hereditary non-polyposis colorectal cancer. It is important for the clinician to have a working knowledge of both as screening and surveillance recommendations differ significantly from those applicable to the general population. The polyposis syndromes include familial adenomatous polyposis, Peutz-Jeghers syndrome, juvenile polyposis, and Cowden syndrome. For each condition, a review of both the intestinal and extra-intestinal clinical findings is presented as well as the genetic basis, genetic testing, screening, surveillance and treatment options. As genetic testing for several of these conditions has recently become both commercially available and standard practice, special attention is given to indications and strategies for genetic testing in hereditary colorectal cancer syndromes.     

Fordyce granules and hereditary non-polyposis colorectal cancer syndrome

BACKGROUND: Germline mutations in mismatch repair (MMR) genes are found in only about half of clinically diagnosed families with hereditary non-polyposis colorectal cancer syndrome (HNPCC) (or Lynch syndrome). Early identification of gene carriers is essential to reduce cancer incidence and overall mortality. AIMS: Recent evidence indicates an increase in size and number of sebaceous glands following activation of the hedgehog pathway, a crucial signalling pathway for animal development that is aberrantly activated in several types of cancer. Here we sought to assess a possible association between Fordyce granules (FGs-that is, ectopic sebaceous glands on the oral mucosa) and HNPCC. METHODS: A total of 15 members of five different genetically unrelated HNPCC kindreds (MLH1 gene mutation n = 8; undetectable MLH1 protein at immunochemistry n = 4; clinical diagnosis n = 3) and 630 genetically unrelated age and sex matched healthy controls were examined. Following examination of the oral mucosa surface, subjects were categorised as either FGs positive or FGs negative. RESULTS: Evidence of FGs was significantly associated with HNPCC (13/15 (86.7%) affected patients v 6/630 (0.95%) controls; p<0.0001), with a relative risk of 91.0 (95% confidence interval 40.05-206.76). The observed difference remained significant when carriers of germline mutations in MMR genes were considered (8/15 v 6/630; p<0.0001). The most common site for the FGs in HNPCC patients was the lower gingival and vestibular oral mucosa. CONCLUSIONS: Our findings suggest that a previously unrecognised activation of the sebaceous glands system occurs in HNPCC. The observation could be of value for attending physicians in identifying affected families and/or increase the accuracy of the currently available molecular genetics screenings.     

Colonic epithelial cell proliferation in hereditary non-polyposis colorectal cancer

Background—Despite the recentdiscovery of four genes responsible for up to 90% of all cases ofhereditary non-polyposis colorectal cancer (HNPCC), there will still befamilies in whom predictive testing is not possible. A phenotypicbiomarker would therefore be useful. An upwards shift of theproliferative compartment in colonic crypts is reported to be one ofthe earliest changes in premalignant mucosa.
Aims—To assess the role of cryptcell proliferation as a phenotypic biomarker in HNPCC.
Patients—Thirty five patients at50% risk of carrying the HNPCC gene (21 of whom subsequently underwentpredictive testing and hence gene carrier status was known) and 18controls.
Methods—Crypt cell proliferationwas measured at five sites in the colon using two different techniques.Labelling index was determined using the monoclonal antibody MIB1 andwhole crypt mitotic index was measured using the microdissection andcrypt squash technique. The distribution of proliferating cells within the crypts was also assessed.
Results—There were no significantdifferences in the total labelling index or mean number of mitoses percrypt, nor in the distribution of proliferating cells within the crypt,between the study and control groups at any site. When the 21 patients in whom gene carrier status was known were analysed separately therewere no significant differences in the measured indices ofproliferation between the HNPCC gene carriers and non-gene carriers.
Conclusion—Crypt cell proliferationis not a discriminative marker of gene carriage in HNPCC.

Keywords:cell proliferation; hereditary non-polyposiscolorectal cancer

     

Somatic mutations of APC gene in carcinomas from hereditary non-polyposis colorectal cancer patients

AIM: To investigate the mutational features of adenomatous polyposis coli (APC) gene and its possible arising mechanism in hereditary non-polyposis colorectal cancers (HNPCC). METHODS: PCR-based In Vitro Synthesized Protein Test (IVSP) assay and sequencing analysis were used to confirm somatic mutations of whole APC gene in 19 HNPCC cases. RESULTS: Eleven cases with 13 mutations were determined to harbor APC mutations. The prevalence of APC mutation was 58%(11/19). The mutations consisted of 9 frameshift and 4 nonsense ones, indicating that there were more frameshift mutations (69%). The frameshift mutations all exhibited deletion or insertion of 1-2 bp and most of them (7/9) happened at simple nucleotide repeat sequences, particularly within (A)n tracts (5/9). All point mutations presented C-to-T transitions at CpG sites. CONCLUSION: Mutations of APC gene were detected in more than half of HNPCC, indicating that its mutation was a common molecular event and might play an important role in the tumorigenesis of HNPCC. Locations of frameshift mutations at simple nucleotide repeat sequences and point mutations at CpG sites suggested that many mutations probably derived from endogenous processes including mismatch repair (MMR) deficiency. Defective MMR might affect the nature of APC mutations in HNPCC and likely occur earlier than APC mutational inactivation in some patients.     

Analysis of Ha-ras 1 allele frequencies in hereditary non-polyposis colorectal cancer.

Restriction enzyme digests of genomic DNA show multiple alleles of common, intermediate, and rare frequencies at the minisatellite locus of Ha-ras. It has been suggested that a higher frequency of rare alleles is associated with the presence of colorectal and other types of cancer. This study investigated the distribution of Ha-ras alleles in 40 members of hereditary non-polyposis colorectal carcinoma (HNPCC) families and in 34 cancer free subjects (spouses). There was no difference in rare allele frequency between the cancer group and cancer free group (chi2 = 0.25, not significant).     

Molecular signaling mechanisms of apoptosis in hereditary non-polyposis colorectal cancer

Colorectal cancer is the second most leading cause of cancer related deaths in the western countries. One of the forms of colorectal cancer is hereditary non-polyposis colorectal cancer (HNPCC), also known as "Lynch syndrome". It is the most common hereditary form of cancer accounting for 5%-10% of all colon cancers. HNPCC is a dominant autosomal genetic disorder caused by germ line mutations in mismatch repair genes. Human mismatch repair genes play a crucial role in genetic stability of DNA, the inactivation of which results in an increased rate of mutation and often a loss of mismatch repair function. Recent studies have shown that certain mismatch repair genes are involved in the regulation of key cellular processes including apoptosis. Thus, differential expression of mismatch repair genes particularly the contributions of MLH1 and MSH2 play important roles in therapeutic resistance to certain cytotoxic drugs such as cisplatin that is used normally as chemoprevention. An understanding of the role of mismatch repair genes in molecular signaling mechanism of apoptosis and its involvement in HNPCC needs attention for further work into this important area of cancer research, and this review article is intended to accomplish that goal of linkage of apoptosis with HNPCC. The current review was not intended to provide a comprehensive enumeration of the entire body of literature in the area of HNPCC or mismatch repair system or apoptosis; it is rather intended to focus primarily on the current state of knowledge of the role of mismatch repair proteins in molecular signaling mechanism of apoptosis as it relates to understanding of HNPCC.     

遗传性非息肉病性大肠癌的研究进展

遗传性非息肉病性大肠癌(HNPCC)是一种由错配修复基因(MMR)突变造成的常染色体显性遗传病,又称Lynch综合征,是遗传性大肠癌的代表.HNPCC约占全部大肠癌的5%-15%.错配修复基因(MMR)的种系突变和微卫星不稳定(MSI)是其分子遗传学基础.HNPCC的临床病理特点突出,具有右半结肠多见、发病早、病理分化差、多原发癌多见的特点.目前其治疗方法以手术为主,COX-2阻滞剂可能成为HNPCC治疗的一个新的途径.近年来分子生物学的进展也为人们对HNPCC生物学行为和治疗的认识提供了有益的参考.     

Critical issues in the identification and management of patients with hereditary non-polyposis colorectal cancer

Inherited defects of the DNA mismatch repair system are the underlying cause of the hereditary non-polyposis colorectal cancer (HNPCC) syndrome and are responsible for 3-4% of all cases of colorectal cancer. The HNPCC syndrome also carries the risk of development of additional malignancies such as endometrial, stomach, small bowel, ovarian, pancreas, ureter, renal pelvis, biliary tract and brain tumours. Amsterdam I and II criteria have been developed to clinically identify affected families. The revised Bethesda criteria function to select patients whose tumours should be investigated for microsatellite instability, the molecular hallmark of defects of the DNA mismatch repair proteins such as hMLH1 and hMSH2. Microsatellite instability-positive cases should be investigated for germline defects in the respective genes. This facilitates identification of affected family members that have to be included in special surveillance programmes, while unaffected family members are spared the physical discomfort and psychological burden of cancer surveillance. In this article, strategies for effective clinical as well as genetic detection of affected individuals, surveillance and appropriate preventive measures are discussed. Open questions include the role of chemoprevention, preventive surgical procedures, new endoscopic procedures as well as non-invasive 'virtual colonoscopy' and the exact implications of some mutations of the DNA mismatch repair genes. Perhaps most importantly, efforts should be made to more efficiently transfer information about the HNPCC syndrome and the cancer risk associated with it from the specialists to primary health care providers and the general public.     

Frequency of hereditary non-polyposis colorectal cancer and other colorectal cancer familial forms in Spain: a multicentre, prospective, nationwide study

BACKGROUND: Colorectal cancer is the third leading cause of cancer mortality in Western countries. Hereditary nonpolyposis colorectal cancer is the most common type of hereditary colorectal cancer, but its incidence remains controversial, ranging from 1 to 5%. OBJECTIVE: This present prospective, multicentre, nationwide study was aimed at compiling prominent epidemiological and clinical data with respect to hereditary non-polyposis colorectal cancer and other familial colorectal cancer forms in Spain, where information is lacking. METHODS: All patients with a de-novo diagnosis of colorectal cancer and who attended between November 2000 and October 2001 in 25 hospitals all over Spain were registered. Demographic, clinical and tumour-related characteristics of probands, and detailed family history, were obtained. RESULTS: A total of 1872 colorectal cancer patients were included. Clinical diagnosis of hereditary non-polyposis colorectal cancer was established in 46 (2.5%) patients according to the Amsterdam II criteria. Comparison between patients fulfilling either the Amsterdam I or the Amsterdam II criteria revealed no differences with respect to demographic, clinical and tumour-related characteristics. A total of 504 (27.0%) patients had a family history of hereditary non-polyposis colorectal cancer-related neoplasm not fulfilling the Amsterdam criteria (familial colorectal cancer), while 360 (19.2%) patients fulfilled at least one of the Bethesda's criteria. CONCLUSION: These clinicoepidemiological data provide a more accurate characterization of hereditary non-polyposis colorectal cancer and other familial colorectal cancer forms in Spain, with potential implications in preventive strategies.     

MS-HRM在遗传性非息肉性大肠癌筛查中的应用

目的探讨甲基化敏感性高分辨率熔解曲线分析(MS-HRM)在遗传性非息肉性大肠癌(HNPCC)筛查中的应用价值。方法采用实时荧光定量PCR技术检测miR-195在41例散发性大肠癌(SCRC)和9例HNPCC患者癌组织及对应癌旁正常组织(距离癌组织5 cm)中的表达水平,随后使用MS-HRM检测miR-195启动子区域CpG岛甲基化情况。结果 miR-195在HNPCC癌组织中的表达量为1.20±1.48,甲基化比例为55.56%(5/9);miR-195在SCRC组织中的表达量为0.76±1.06,甲基化比例为58.54%(24/41),差异无统计学意义(P0.05);miR-195在肠癌组织及癌旁正常组织中的平均表达水平分别为0.837±1.145和2.236±2.468,差异具有统计学意义(P0.05)。结论 miR-195在SCRC和HNPCC癌组织中的表达有无差异尚待进一步研究。miR-195可能有助于抑制肠癌发展,并且因其甲基化而参于大肠癌的发病机制。     

Direct mutational analysis in a family with hereditary non-polyposis colorectal cancer

Background: It is now known that a proportion of cases of hereditary non-polyposis colorectal cancer (HNPCC) is caused by mutations in the human homologue of the yeast DNA mismatch repair gene MSH2. A proline to leucine change due to a C to T transition in codon 622 of hMSH2 has been identified in a large HNPCC family of over 240 individuals.
Aim: To develop an assay to detect the family-specific mutation and apply the findings to genetic screening.
Methods: The C to T change in codon 622 creates a new Mae I site (CTAG) allowing a simple, non-radioactive assay to be developed in order to detect this mutation. The assay was applied to affected members of the family and their first degree relatives (siblings and offspring) between the ages of 17 and 77 years, a total of 75 subjects within two generations (IV and V).
Results: 13/13 (100%) subjects with cancer were mutation positive, 7/7 (100%) elderly subjects from generation IV and with no evidence of cancer were mutation negative, 23/57 (40%) subjects from generation V were mutation positive and 0/50 (100%) unrelated subjects were mutation negative. Following the demonstration of perfect segregation of the disease with the mutation, family members were invited to receive the results of the test. Sixty-three (84%) responded within six weeks of receiving the invitation. Genetic screening and counselling members of HNPCC families was perceived as beneficial overall, allowing non-carriers of the mutant gene (as well as their descendants) to be removed from a programme of colonoscopic surveillance. (Aust NZ J Med 1994; 24: 682–686.)     

Frequency of hereditary nonpolyposis colorectal cancer

PURPOSE: Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant cancer syndrome characterized by early onset of colorectal carcinomas (CRC). Recently, two HNPCC genes have been mapped and cloned, one in the short arm of chromosome 2 and another in the short arm of chromosome 3. There has been a major controversy about the frequency of HNPCC. The few estimates available have been based on series selected by age or series representing local area. The purpose of the present study was to design a nonselected, prospective, multicenter study, taking into account the family background and other risk factors of CRC. METHODS: The proportion of HNPCC of all (N=406) CRC cases was evaluated in a prospective multicenter study. Family history and other risk factors were investigated over a 12-month period for all new CRC patients in ten hospitals. These cases constituted 23 percent of all CRCs diagnosed in Finland during the study period. RESULTS: Three (0.7 percent) cases of verified and seven (1.7 percent) cases of suspected HNPCC were identified, following the evaluation of all families with features indicative of susceptibility to cancer. The proportion of identifiable risk factors of CRC was 5.8–7.5 percent (HNPCC, 0.7-2.4 percent; previous CRC, 3.4 percent; ulcerative colitis, 1.0 percent; familial adenomatous polyposis coli, 0.7 percent). CONCLUSION. This prospective multicenter study revealed that the frequency of hereditary colorectal cancer is lower than in some previous studies, when diagnosis is based on extensive pedigree analysis. This result with recent findings of common ancestral founding mutation in Finnish HNPCC families indicates that there may be geographic differences in the occurrence of HNPCC. However, this does not change the fact that identification of HNPCC—perhaps one of the most common inherited diseases identified in humans—has become a question of vital importance now when diagnosis of the syndrome and largescale screening of gene carriers using specific tests are on the horizon.Supported by grants from the Finnish Cancer Society, the Finnish Foundation for Gastroenterological Research, the Sigrid Juselius Foundation, and the Academy of Finland, Helsinki, Finland.