Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominantly inherited disease associated with germ-line mutations in mismatch repair genes and microsatellite instability. This article reviews the molecular biology and clinical pathology of HNPCC.
Colorectal Neoplasms, Hereditary Nonpolyposis ; diagnosis ; genetics ; pathology ; DNA Mismatch Repair ; Humans ; Microsatellite Instability

Hereditary syndromes cause approximately 5 to 15% of overall colorectal cancer (CRC) cases. Hereditary CRC is conventionally divided into two major categories: hereditary non-polyposis colorectal cancer (HNPCC) and those related to polyposis syndromes including familial adenomatous polyposis (FAP), Peutz-Jegher syndrome (PJS), and juvenile polyposis (JP). The screening for the cancer and methods of treatment applied to patients with hereditary CRC are quite different from those applied to the general population. The genes responsible for these syndromes has recently identified, as a result, genetic testing has become the most important determining factor in clinical decisions. Germ-line mutation of the APC gene induces FAP, an autosomal dominant disorder, characterized by the development of hundreds to thousands of colonic adenomas. CRC appears in almost all affected individuals by the time they are 50 years of age. An affected individual should undergo colectomy by his/her late teens. Furthermore, according to the findings of genetic testing, at-risk family members also need endoscopic surveillance and surgery. Recently, a mutation on the MYH gene is increasingly being investigated in patients with multiple polyps, and autosomal recessive MYH polyposis is considered to be a new category of polyposis. More common than FAP, HNPCC is caused by germ-line mutations in DNA mismatch repair genes, mainly MLH1 and MSH2. Although there is no polyposis, polyps seem to be more villous and dysplastic and appear to grow rapidly into CRCs. The aggregate lifetime risk of CRC is about 80% for mutation carriers. The risk for other types of cancer, such as endometrial, ovarian, small bowel, and transitional cell cancer, is also increased. The Amsterdam criteria and Bethesda guidelines are the best-known tools for diagnosis and genetic testing, and colectomy followed by endoscopic follow-up is the standard treatment. PJS and JP are reported to be characterized by hamartomatous polyps throughout the GI tract and germ-line mutations in the STK11 gene (PJS) and the DPC4/BMPR1A gene (JP).
Adenomatous Polyposis Coli/*genetics ; Colorectal Neoplasms, Hereditary Nonpolyposis/diagnosis/*genetics ; Genetic Predisposition to Disease ; Germ-Line Mutation ; Humans ; Intestinal Polyposis/diagnosis/*genetics ; Peutz-Jeghers Syndrome/diagnosis/*genetics

Adenomatous Polyposis Coli ; diagnosis ; drug therapy ; genetics ; surgery ; Antineoplastic Agents ; therapeutic use ; Colectomy ; Colorectal Neoplasms, Hereditary Nonpolyposis ; diagnosis ; drug therapy ; genetics ; surgery ; DNA Mismatch Repair ; Humans ; Ileostomy ; Peutz-Jeghers Syndrome ; diagnosis ; drug therapy ; genetics ; surgery

OBJECTIVETo evaluate the application of mismatch repair (MMR) genes proteins expression to screen for Lynch syndrome in colorectal cancer patients.

METHODSOne hundred consecutive colorectal cancers cases collected from 2012 to 2013 were tested immunohistochemically for the protein expression of MLH1, MSH2, MSH6 and PMS2, and also by the ARMS method for the mutation status of BRAF genes in those cases lacking protein expression for MLH1.

RESULTSThe result of MMR immunocytochemistry showed that nine of 100 cases lacked MMR protein expression, including three cases each that were MLH1-/PMS2- and MSH2-/MSH6- respectively, two cases were MLH6- and one case was PMS2-; overall, the majority of these cases lacked protein expression of MLH1 and MSH2. The BRAF genes mutation test showed one case of mutation, indicating that the patient might have MLH1 gene methylation as a result of the mutation of BRAF genes, and that was a sporadic case. The age of onset for patients lacking MMR protein expression was lower than patients with sporadic colorectal cancer (P = 0.011). Colorectal cancers associated with the lack of MMR protein expression mostly occurred in the right colon (P = 0.001), and histomorphologically were often accompanied by mucinous adenocarcinoma (P = 0.010) and tumor lymphocytic infiltration.

CONCLUSIONImmunohistochemical staining for MMR proteins in patients with colorectal cancer, accompanied by testing for BRAF genes mutation, may be an effective approach to screen for Lynch syndrome.

Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Colorectal Neoplasms, Hereditary Nonpolyposis ; diagnosis ; genetics ; DNA Mismatch Repair ; Humans ; Immunohistochemistry ; MutL Protein Homolog 1 ; Mutation ; Nuclear Proteins ; genetics ; metabolism ; Proto-Oncogene Proteins B-raf ; genetics ; metabolism

Objective: To explore the concordance and causes of different mismatch repair (MMR) and microsatellite instability (MSI) detection results in endometrial carcinoma (EC) molecular typing. Methods: A total of 214 EC patients diagnosed from January 2021 to April 2023 were selected at the Department of Pathology, Peking University Third Hospital. The immunohistochemistry (IHC) results of MMR protein were reviewed. Tumor specific somatic mutations, MMR germline mutations, microsatellite scores and tumor mutation burden (TMB) were detected by next-generation sequencing (NGS) with multi-gene panel. Methylation-specific PCR was used to detect the methylation status of MLH1 gene promoter in cases with deficient MLH1 protein expression. In cases with discrepant results between MMR-IHC and MSI-NGS, the MSI status was detected again by PCR (MSI-PCR), and the molecular typing was determined by combining the results of TMB and MLH1 gene promoter methylation. Results: (1) In this study, there were 22 cases of POLE gene mutation subtype, 55 cases of mismatch repair deficient (MMR-d) subtype, 29 cases of p53 abnormal subtype, and 108 cases of no specific molecular profile (NSMP). The median age at diagnosis of MMR-d subtype (54 years old) and the proportion of aggressive histological types (40.0%, 22/55) were higher than those of NSMP subtype [50 years old and 12.0% (13/108) respectively; all P<0.05]. (2) Among 214 patients, MMR-IHC test showed that 153 patients were mismatch repair proficient (MMR-p), 49 patients were MMR-d, and 12 patients were difficult to evaluate directly. MSI-NGS showed that 164 patients were microsatellite stable (MSS; equal to MMR-p), 48 patients were high microsatellite instability (MSI-H; equal to MMR-d), and 2 patients had no MSI-NGS results because the effective sequencing depth did not meet the quality control. The overall concordance between MMR-IHC and MSI-NGS was 94.3% (200/212). All the 12 discrepant cases were MMR-d or subclonal loss of MMR protein by IHC, but MSS by NGS. Among them, 10 cases were loss or subclonal loss of MLH1 and (or) PMS2 protein. Three discrepant cases were classified as POLE gene mutation subtype. In the remaining 9 cases, 5 cases and 3 cases were confirmed as MSI-H and low microsatellite instability (MSI-L) respectively by MSI-PCR, 6 cases were detected as MLH1 gene promoter methylation and 7 cases demonstrated high TMB (>10 mutations/Mb). These 9 cases were classified as MMR-d EC. (3) Lynch syndrome was diagnosed in 27.3% (15/55) of all 55 MMR-d EC cases, and the TMB of EC with MSH2 and (or) MSH6 protein loss or associated with Lynch syndrome [(71.0±26.2) and (71.5±20.1) mutations/Mb respectively] were significantly higher than those of EC with MLH1 and (or) PMS2 loss or sporadic MMR-d EC [(38.2±19.1) and (41.9±24.3) mutations/Mb respectively, all P<0.01]. The top 10 most frequently mutated genes in MMR-d EC were PTEN (85.5%, 47/55), ARID1A (80.0%, 44/55), PIK3CA (69.1%, 38/55), KMT2B (60.0%, 33/55), CTCF (45.5%, 25/55), RNF43 (40.0%, 22/55), KRAS (36.4%, 20/55), CREBBP (34.5%, 19/55), LRP1B (32.7%, 18/55) and BRCA2 (32.7%, 18/55). Concurrent PTEN, ARID1A and PIK3CA gene mutations were found in 50.9% (28/55) of MMR-d EC patients. Conclusions: The concordance of MMR-IHC and MSI-NGS in EC is relatively high.The discordance in a few MMR-d EC are mostly found in cases with MLH1 and (or) PMS2 protein loss or MMR protein subclonal staining caused by MLH1 gene promoter hypermethylation. In order to provide accurate molecular typing for EC patients, MLH1 gene methylation, MSI-PCR, MMR gene germline mutation and TMB should be combined to comprehensively evaluate MMR and MSI status.
Female ; Humans ; Middle Aged ; Class I Phosphatidylinositol 3-Kinases/metabolism* ; Colorectal Neoplasms, Hereditary Nonpolyposis/diagnosis* ; DNA Mismatch Repair/genetics* ; Endometrial Neoplasms/pathology* ; Microsatellite Instability ; Mismatch Repair Endonuclease PMS2/genetics* ; Molecular Typing

OBJECTIVETo investigate the effect of the protocol recommended by NCCN-2007 on the diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC) in China.

METHODSNCCN protocol consists of identifying HNPCC characteristics according to the revised Bethesda Guidelines,genetic counseling with immunohistochemistry and finally genetic testing. Four hundred and nineteen patients diagnosed as colorectal cancer from January 2002 to February 2006 were selected. The hMLH1 and hMSH2 immunostaining were implemented for 90 patients who fulfilled the revised Bethesda Guidelines, in whom 8 patients fulfilling the Amsterdam II (Criteria were classified as group A and the other 82 patients as group B. The frozen tissues were collected from patients who showed loss of hMLH1 or hMSH2 protein expression, then RNA was extracted, and RT-PCR and cDNA sequencing were adopted to detect the germline mutations of hMLH1 and hMSH2.

RESULTSTumor tissues from 18 patients showed loss of hMLH1 or hMSH2 protein expression (5 patients in group A and 13 in group B). Finally, 21 patients(8 in group A and 13 in group B showed loss expression of MMR protein) were diagnosed as HNPCC, including 2 cases of hMLH1 and 1 case of hMSH2 mutations. These 3 cases with cDNA mutations did not fulfill the Amsterdam II( Criteria, and were finally diagnosed as HNPCC.

CONCLUSIONThe protocol recommended by NCCN-2007 offers a useful approach to identify HNPCC patients,and reduces the possibility of missed diagnosis of HNPCC.

Adult ; Aged ; Aged, 80 and over ; Base Pair Mismatch ; China ; Colorectal Neoplasms, Hereditary Nonpolyposis ; diagnosis ; genetics ; Female ; Gene Deletion ; Genetic Testing ; methods ; Guidelines as Topic ; Humans ; Male ; Middle Aged ; Young Adult

OBJECTIVETo compare the clinical and genetic features between Chinese and Korean hereditary nonpolyposis colorectal cancer (HNPCC) families.

METHODSThirty-one Chinese HNPCC families and 63 HNPCC Korean families were involved in this study. The clinical data of the probands and families were collected. Genomic DNAs were prepared from peripheral blood samples of probands for DNA test. PCR and DHPLC were employed to screen the mutations. Sequencing analysis was followed to find out the exact mutation site and feature in samples showing abnormalities in SSCP or DHPLC analysis.

RESULTSIn a total, there were 136 malignant neoplasms diagnosed in the 31 Chinese families, about 77.9% of them were colorectal cancer. The mean age of colorectal cancer at diagnosis was (48.6+/- 29.0) years. Gastric cancer was the second most common cancer in these familiesîSeven pathogenic mutations (3 in hMLH1 gene and 4 in hMSH2 gene) were detected in the 31 probands, including 2 missense mutations, 2 nonsense mutations, 2 frameshift mutations and 1 large-fragment deletion. The total mutation rate was 22.6%. In the 63 Korean families, 293 malignant neoplasms were documented, 82.6% of them were diagnosed as colorectal cancer. The mean age of colorectal cancer at diagnosis was (45.9+/- 11.0) years. Gastric cancer was also the most common extracolonic cancer in these Korean families. Nineteen pathogenic mutations (17 in hMLH1 gene and 2 in hMSH2 genes) were detected in the 63 probands, including 12 frameshift mutations, 5 missense mutations, 1 nonsense mutation and 1 base-change at the splicing site. The total mutation rate was 30.2%.

CONCLUSION(1) Chinese and Korean HNPCC families had many similar clinical features, such as early-onset of colorectal cancer, predominance in distal colon and rectum, lower incidence of synchronous or metachronous colorectal cancers as compared with Western countries, and a frequent occurrence of gastric cancer in the families. (2) The total mutation rate of hMLH1 and hMSH2 gene in Chinese and Korean HNPCC families was similar and lower than that reported in Western countries. But the mutation characteristics, such as predominant gene, mutation type and mutation distribution, were different in the two populations.

Adaptor Proteins, Signal Transducing ; genetics ; Adult ; Aged ; Asian Continental Ancestry Group ; Chromatography, High Pressure Liquid ; Colorectal Neoplasms ; genetics ; Colorectal Neoplasms, Hereditary Nonpolyposis ; diagnosis ; genetics ; Female ; Humans ; Male ; Middle Aged ; MutL Protein Homolog 1 ; MutS Homolog 2 Protein ; genetics ; Nuclear Proteins ; genetics ; Phenotype ; Polymorphism, Single-Stranded Conformational ; Stomach Neoplasms ; genetics ; Young Adult

OBJECTIVE: To explore the clinicopathologic and molecular characteristics of hereditary nonpolyposis colorectal cancer (HNPCC), and to improve the level of diagnosis and treatments of HNPCC. METHODS: Thirty HNPCC patients (HNPCC group) who were treated in Xiangya Hospital were retrospectively analyzed, and 25 patients with sporadic colorectal cancer in the same duration were randomly chosen as a control group. The onset of age, location of tumor, pathological type, treatment method, and prognosis were compared in the 2 groups. The expression loss rate of mismatch repair gene (MMR) MLH1 and MSH2 in the 2 groups was detected by immunohistochemistry. RESULTS: The onset age in the HNPCC group was earlier than that in the control group (P<0.05). The rate of proximal colonic tumor the occurrence of multiple tumors, and the proportion of well differentiated adenocarcinoma in the HNPCC group were all higher than those in the control group (P<0.05). The expression loss rate of MLH1 and MSH2 in the HNPCC group was higher than that in the control group (P<0.05). One third in the HNPCC group received subtotal proctocolectomy. The prognosis of HNPCC patients was comparable with that of patients with sporadic colorectal cancer (P>0.05). CONCLUSION HNPCC patients are characterized with early onset associating with multiple tumors. The accuracy of diagnosis can be improved by combining the detection of MMR gene. Optimal surgical treatment and close follow-up may bring good result to HNPCC patients.
Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Adenocarcinoma ; diagnosis ; genetics ; pathology ; surgery ; Aged ; Case-Control Studies ; Colorectal Neoplasms, Hereditary Nonpolyposis ; diagnosis ; genetics ; pathology ; surgery ; Endometrial Neoplasms ; pathology ; Female ; Humans ; Male ; Middle Aged ; MutL Protein Homolog 1 ; MutS Homolog 2 Protein ; genetics ; metabolism ; Mutation ; Neoplasms, Second Primary ; pathology ; Nuclear Proteins ; genetics ; metabolism ; Retrospective Studies

OBJECTIVETo evaluate the frequency of microsatellite instability (MSI) and absence of hMLH1/hMSH2 expression in young patients with colorectal cancer, and investigate their role in screening hereditary nonpolyposis colorectal cancer (HNPCC).

METHODSeventy-three young patients (below 40 years old) with colorectal cancer were examined for DNA mismatch repair deficiency by microsatellite testing and immunohistochemical detection of hMLH1/hMSH2 gene products.

RESULTSThe frequency of MSI and absence rate of hMLH1/hMSH2 expression are 56.16% and 49.32% in these patients, respectively, which increased significantly with younger age for cancer diagnosis.

CONCLUSIONDefects in the DNA mismatch repair system are frequent in Chinese young patients with colorectal cancer. Microsatellite analysis and immunohistochemical detection are useful for efficient identification of HNPCC in these young patients.

Adaptor Proteins, Signal Transducing ; biosynthesis ; Adolescent ; Adult ; Colorectal Neoplasms ; genetics ; metabolism ; pathology ; Colorectal Neoplasms, Hereditary Nonpolyposis ; diagnosis ; genetics ; metabolism ; Female ; Humans ; Immunohistochemistry ; Male ; Mass Screening ; Microsatellite Instability ; Microsatellite Repeats ; genetics ; MutL Protein Homolog 1 ; MutS Homolog 2 Protein ; biosynthesis ; Nuclear Proteins ; biosynthesis ; Young Adult

Adenomatous Polyposis Coli ; genetics ; pathology ; Colonic Neoplasms ; classification ; genetics ; pathology ; Colorectal Neoplasms, Hereditary Nonpolyposis ; diagnosis ; genetics ; DNA Glycosylases ; metabolism ; Humans ; Intestinal Polyps ; pathology ; Lymphatic Metastasis ; Neoplasm Staging ; Neuroendocrine Tumors ; classification ; pathology ; Precancerous Conditions ; pathology ; Rectal Neoplasms ; classification ; genetics ; pathology ; World Health Organization