MUTYH-associated Polyposis Research Articles

1474 Cowden and MAP Syndrome: The Untold Story of a Screening Colonoscopy—Case Report

INTRODUCTION: Cowden syndrome is a rare autosomal dominant condition associated with PTEN gene mutation. MUTYH-associated polyposis (MAP) is inherited by autosomal recessive fashion. Cowden syndrome presents with multiple hamartomas in a variety of tissues, oral fibromas, and punctate palmoplantar keratoses, and an increased risk of breast, endometrial, thyroid, kidney and colorectal cancers. MAP syndrome is associated with adenomatous polyps and colon cancer predisposition. CASE DESCRIPTION/METHODS: 51-year-old female underwent screening colonoscopy and was found to have multiple polyps throughout the colon. Biopsy showed ganglioneuromas and hamartomous polyps. Medical history was significant for hypothyroidism and hypoparathyroidism secondary to thyroidectomy for a goiter, bilateral mastectomy for a ductal carcinoma in situ, hysterectomy for fibroids, palmar keratosis and oral papillomatosis. Family history was relevant for breast cancer in her mother at age 50. Genetic analysis revealed mosaicism for a loss of function variant in PTEN and autosomal recessive pathogenic single MUTYH variant which confirmed Cowden Syndrome and carrier state for MAP syndrome. Appropriate cancer surveillance was arranged for our patient according to the National Cancer Center Network Guidelines through multidisciplinary approach. DISCUSSION: PTEN gene is a tumor suppressor responsible for regulating the cell cycle. Because of her mutation, our patient is susceptible for an array of different malignancies. Her genetic profile showed mosaicism for PTEN genetic variant. Adequate cancer surveillance for colon cancer, renal cell carcinoma and recurrence of breast cancer were discussed with our patient. MUTYH variant mutation was found in this patient. However, she inherited only one single copy of this recessive gene expecting not to develop clinical MAP syndrome. Risks associated with a single variant in MUTYH are unclear. There are some reports that suggest an inconsistent increased risk of colon, endometrial, and breast cancer. National Cancer Center Network Guidelines has created surveillance guidelines for individuals with a single MUTYH variant but cautioned that these guidelines are likely to change over time. Uniquely, extracolonic neoplastic complications were detected before the diagnosis of Cowden in our patient. High clinical suspicion and early diagnosis of this condition is crucial for effective prevention of colonic and extracolonic malignancies that these individuals are at high risk for.

Declining detection rates for APC and biallelic MUTYH variants in polyposis patients, implications for DNA testing policy.

This study aimed to determine the prevalence of APC-associated familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP) in a large cohort, taking into account factors as adenoma count and year of diagnosis. All application forms used to send patients in for APC and MUTYH variant analysis between 1992 and 2017 were collected (n = 2082). Using the data provided on the application form, the APC and biallelic MUTYH prevalence was determined and possible predictive factors were examined using multivariate multinomial logistic regression analysis in SPSS. The prevalence of disease causing variants in the APC gene significantly increases with adenoma count while MAP shows a peak prevalence in individuals with 50-99 adenomas. Logistic regression analysis shows significant odds ratios for adenoma count, age at diagnosis, and, interestingly, a decline in the chance of finding a variant in either gene over time. Moreover, in 22% (43/200) of patients with FAP-related extracolonic manifestations a variant was identified. The overall detection rates are above 10% for patients with >10 adenomas aged <60 and >20 adenomas aged <70. Patients with variants outside these criteria had FAP-related extracolonic manifestations, colorectal cancer aged <40, somatic KRAS c.34G > T variant in the tumor or a first-degree relative with >10 adenomas. Therefore, APC and MUTYH testing in patients with >10 adenomas aged <60 and with >20 adenomas aged <70 is advised. Almost all FAP and MAP patients not meeting these criteria showed other characteristics that can be used as an indication to prompt genetic testing.

An Update on Inherited Colon Cancer and Gastrointestinal Polyposis.

It is estimated that 5-10% of colorectal cancers arise due to a known genetic syndrome. Individuals with these cancer syndromes are also at risk of extracolonic cancers. Polyposis and nonpolyposis hereditary syndromes are generally recognized. Inclusion of next-generation sequencing technology, especially multiple-gene panel testing, in routine laboratory practice has made identifying the causes of these diseases significantly easier. To summarize current knowledge of the causes, clinical manifestations, diagnostic criteria, and recommendations for presymptomatic screening of individuals at risk of hereditary gastrointestinal polyposis and colorectal cancer syndromes. We dicuss currently defined syndromes detected by multiple-gene panel next-generation sequencing; these include constitutional mismatch repair deficiency (biallelic MLH1, MSH2, MSH6, PMS2 gene mutations), gastric adenocarcinoma and proximal polyposis of the stomach (APC gene), NTHL1-associated polyposis, polymerase proofreading-associated polyposis (POLD1, POLE genes), juvenile polyposis (SMAD4, BMPR1A genes), and serrated polyposis syndromes. Another aim is to summarize recent knowledge about well-known syndromes, including hereditary nonpolyposis colon cancer (Lynch syndrome), familial adenomatous polyposis, MUTYH-associated polyposis, and Peutz-Jeghers and Cowden/PTEN hamartoma tumor syndromes. Awareness of hereditary polyposis/colon cancer syndromes enables early diagnosis and prevention of cancer in affected individuals and their relatives. Genetic counseling, presymptomatic testing of at-risk individuals, and efficient screening may be beneficial for affected families. Thank to Lenka Foretová, M.D., PhD, (Masaryk Memorial Cancer Institute, Brno) for a critical review of the manuscript and valuable advices. The author declares she has no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 1. 3. 2019 Accepted: 6. 6. 2019.

Abstract 4171: Identification of individuals with colonic polyposis in a highly inbred region

Abstract Familial adenomatous polyposis (FAP), also known as colonic polyposis, is a hereditary autosomal dominant disease, responsible for only 1% of colorectal cancer (CRC) in the population. FAP patients with a germline mutation in the APC gene have a 100% risk of developing CRC. MAP (Mutyh associated polyposis) is the polyposis associated with biallelic mutations in the MUTYH gene, and carriers are at risk of developing CRC. Few studies propose heterozygous Mutyh mutation is associated with high risk for breast cancer, but the results are conflicting. In the city Caicó, Brazil, we identified 8 non-related breast cancer patients with the same mutation c.536A&amp;gt;G, p.Tyr179Cys. In this region we find high frequencies of consanguineous marriages, which varied from about 9% to 32%, suggesting a direct association to genetic diseases. We hypothesize the founding mutation MUTYH_c.536A&amp;gt;G was established during Dutch colonization in Brazil between 1620 and 1650. For this, we are developing a population-based, case-control study of all newly diagnosed breast cancer in this city. In our group we have one oncologist, one psychologist and one geneticist. We recruited the patients (index-cases) from the archives in the Laboratory of Pathology at the Hospital Liga contra o Cancer and we invited the individuals to participate in the research. Citation Format: Tirzah Braz Petta Lajus, Ana Rafaela Timoteo. Identification of individuals with colonic polyposis in a highly inbred region [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4171.

Gastric Polyposis Syndromes

Abstract Most gastric polyps are fundic gland polyps and hyperplastic polyps. Adenomas, inflammatory fibroid polyps, and neuroendocrine tumors are other types of gastric polyps that occur less frequently. Rarely, a gastric polyp may be associated with a syndrome, including hereditary cancer syndromes. Some of these syndromes are also associated with an increased risk of gastric cancer. We present a case of a 50-year-old woman with known Cowden syndrome who presents with multiple gastric hamartomatous polyps. We then review the clinical, endoscopic, and pathologic features of various syndromes that are associated with gastric polyps. Fundic gland polyp–predominant syndromes include familial adenomatous polyposis, gastric adenocarcinoma and proximal polyposis of the stomach, and MUTYH-associated polyposis, all of which are hereditary cancer syndromes. Gastric hamartomatous polyps are found in patients with juvenile polyposis syndrome, Peutz-Jeghers syndrome, PTEN hamartoma tumor syndrome including Cowden syndrome, and Cronkhite-Canada syndrome. Syndromic gastric polyps may be biopsied in patients with a previously established diagnosis of the underlying syndrome, such as surveillance endoscopies in familial adenomatous polyposis. On other occasions, the pathologic assessment of gastric polyps may prompt or contribute to a diagnostic workup of an underlying syndrome in conjunction with other clinical and endoscopic findings.

Intussusception reveals MUTYH-associated polyposis syndrome and colorectal cancer: a case report

BackgroundWe are reporting a rare case of MUTYH-associated polyposis, a colorectal cancer hereditary syndrome, diagnosticated after an intussusception. Colorectal cancer is an important cause of cancer related mortality that can be manifested by an intussusception, a rare occurrence in adults and almost always related to tumors. Approximately 5% of colorectal cancers can be attributed to syndromes known to cause hereditary colorectal cancer, such as MUTYH-associated polyposis, autosomal genetic syndrome associated with this disease.Case presentationWe present the case of a 44 years old male, that sought medical consultation with a complaint of abdominal discomfort, that after five days changed its characteristics. The patient was sent to the emergency department were a CT-scan revealed intestinal sub-occlusion by ileocolic invagination. Right colectomy was carried out. The anatomic-pathological examination revealed a moderately differentiated mucinous adenocarcinoma and multiples sessile polyps, which led to the suspicion of a genetic syndrome. In the genetics analysis two mutations were observed in the MUTYH gene, and MUTYH-associated polyposis was diagnosticated.ConclusionThis case demonstrates the importance of meticulous analysis of the patient examinations results to identify possible discrete alterations that can lead to improved understanding of disease.

Endoscopic Papillectomy for Major and Minor Papillary Adenoma in Familial Adenomatous Polyposis.

ABSTRACTAmpullary adenomas can occur sporadically or in the patients with adenomatous polyposis syndrome, including familial adenomatous polyposis (FAP) and MUTYH-associated polyposis. The potential for malignant transformation is high in the setting of FAP. Although endoscopic resection of major papillary adenoma has been well described, minor papilla adenomas are exceptionally rare. This is the second documented case of an endoscopic papillectomy in a patient with FAP with simultaneous ampullary adenoma of the major and minor papilla.

MutYH-associated polyposis.

MutYH-associated polyposis is the only polyposis syndrome with an autosomal recessive type of inheritance, often phenotypically similar to a weakened form of familial adenomatous polyposis. For the development of the disease mutations in both alleles of the gene are required, but an increased risk of developing colorectal cancer in carriers of monoallelic mutations is noted. The diagnosis of MutYH-associated polyposis should be suspected in a patient with colorectal cancer over 45 years old on the background of polyps in the colon. The review presents modern algorithms for diagnostic and treatment of the disease.

Single molecule glycosylase studies with engineered 8-oxoguanine DNA damage sites show functional defects of a MUTYH polyposis variant.

Proper repair of oxidatively damaged DNA bases is essential to maintain genome stability. 8-Oxoguanine (7,8-dihydro-8-oxoguanine, 8-oxoG) is a dangerous DNA lesion because it can mispair with adenine (A) during replication resulting in guanine to thymine transversion mutations. MUTYH DNA glycosylase is responsible for recognizing and removing the adenine from 8-oxoG:adenine (8-oxoG:A) sites. Biallelic mutations in the MUTYH gene predispose individuals to MUTYH-associated polyposis (MAP), and the most commonly observed mutation in some MAP populations is Y165C. Tyr165 is a ‘wedge’ residue that intercalates into the DNA duplex in the lesion bound state. Here, we utilize single molecule fluorescence microscopy to visualize the real-time search behavior of Escherichia coli and Mus musculus MUTYH WT and wedge variant orthologs on DNA tightropes that contain 8-oxoG:A, 8-oxoG:cytosine, or apurinic product analog sites. We observe that MUTYH WT is able to efficiently find 8-oxoG:A damage and form highly stable bound complexes. In contrast, MUTYH Y150C shows decreased binding lifetimes on undamaged DNA and fails to form a stable lesion recognition complex at damage sites. These findings suggest that MUTYH does not rely upon the wedge residue for damage site recognition, but this residue stabilizes the lesion recognition complex.

Differential Diagnosis of MutYH-Associated Polyposis from Sporadic Colon Polyps

Aim. In this research, we aim to develop a criterion for differentiating MutYH-associated polyposis from sporadic colon polyps.Materials and methods. A search for mutations in the MutYH gene was carried out using the PCR, electrophoresis and direct sequencing methods among the following groups of people: 18 patients under 45 years old with more than 100 polyps diagnosed in the large intestine; 86 patients over 45 years old with 4–100 polyps; 150 people of the control group.Results. Mutations in the MutYH gene were detected in 2 out of 18 patients having more than 100 polyps. Among 86 patients with 4–100 polyps, mutations were found in 10 people having more than 20 polyps. Mutations in the MutYH gene were not detected in patients with 4–19 polyps (p &lt;0.05). The pathogenic significance of the disease development was established not only for biallelic, but also for monoallelic mutations.Conclusion. For the first time, the lower limit of the polyp number has been established, allowing the MutYH-associated polyposis to be differentiated from sporadic polyps.

Multi-gene panel testing confirms phenotypic variability in MUTYH-Associated Polyposis.

Biallelic pathogenic variants (PVs) in MUTYH cause MUTYH-Associated Polyposis (MAP), which displays phenotypic overlap with other hereditary colorectal cancer (CRC) syndromes including Familial Adenomatous Polyposis (FAP) and Lynch syndrome. We report the phenotypic spectrum of MAP in the context of multi-gene hereditary cancer panel testing. Genetic testing results and clinical histories were reviewed for individuals with biallelic MUTYH PVs detected by panel testing at a single commercial molecular diagnostic laboratory. Biallelic MUTYH PVs were identified in 82 individuals (representing 0.2% of tested individuals) with most (75/82; 91.5%) reporting a personal history of CRC and/or polyps. Ten percent (6/61) of individuals reporting polyp number reported fewer than 10 polyps and therefore did not meet current MAP testing criteria. Extracolonic cancers (21/82; 25.6%), multiple primaries (19/82; 23.2%), Lynch-like (17/82; 20.7%) and FAP-like phenotypes (16/82; 19.5%) were observed, including individuals with mismatch repair-deficient tumors (3/82; 3.7%), sebaceous neoplasms (2/82; 2.4%), or congenital hypertrophy of the retinal pigment epithelium (CHRPE) (2/82; 2.4%). We report what is to our knowledge the first cohort of individuals with MAP identified by panel testing. The phenotypic spectrum of MAP observed in this cohort aligns with the published literature. In addition to standard indications for MUTYH testing, our data provide evidence to support consideration of MAP in the differential diagnosis for some individuals with fewer than 10 polyps, depending on other personal and/or family history, as well as for individuals suspected to have Lynch syndrome or FAP.

The role of inherited genetic variants in colorectal polyposis syndromes.

Colorectal carcinoma (CRC) is the third most common cancer in men and the second most common cancer in women across the world. Most CRCs occur sporadically, but in 15-35% of cases, hereditary factors are important. Some patients with an inherited predisposition to CRC will be diagnosed with a "genetic polyposis syndrome" such as familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), polymerase proofreading associated polyposis (PPAP), NTHL1-associated polyposis, MSH3-associated polyposis or a hamartomatous polyposis syndrome. Individuals with ≥10 colorectal polyps have traditionally been referred for genetic diagnostic testing to identify APC and MUTYH mutations which cause FAP and MAP respectively. Mutations are found in most patients with >100 adenomas but in only a minority of those with 10-100 adenomas. The reasons that diagnostic laboratories are not identifying pathogenic variants include mutations occurring outside of the open reading frames of genes, individuals exhibiting generalized mosaicism and the involvement of additional genes. It is important to identify patients with an inherited polyposis syndrome, and to define the mutations causing their polyposis, so that the individuals and their relatives can be managed appropriately.

Declining Detection Rates for &lt;i&gt;APC&lt;/i&gt; and Biallelic &lt;i&gt;MUTYH&lt;/i&gt; Pathogenic Variants in Polyposis Patients, Implications for DNA Testing Policy

Background: This study aimed to determine the prevalence of APC-associated familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP) in a large cohort, taking into account several factors including adenoma count and year of diagnosis. Methods: All application forms used to send patients in for APC and MUTYH mutation analysis between 1992 and 2017 were collected (n=2082). Using this data, possible predictive factors were examined using multivariate multinomial logistic regression analysis in SPSS. Findings: The prevalence of APC mutations significantly increases with adenoma count while MAP shows a peak prevalence in individuals with 50-99 adenomas. Logistic regression analysis shows significant odds ratios for adenoma count, age at diagnosis and having a first degree family member with more than 10 polyps. Moreover, the chance of finding an APC or MUTYH mutation steadily declined over the past 23 years. Mutations in APC and MUTYH were found in 22% (43/200) of patients with FAP-related extracolonic manifestations, such as duodenal polyps and desmoid tumors. Mutation detection rate were 40% and 10% for respectively patients with >10 adenomas under age 60 and >20 adenomas under age 70. Mutation carriers not falling into these criteria, had FAP-related extracolonic manifestations, colorectal cancer (CRC) below the age of 40, somatic KRAS c.34G>T variant in the tumor or a first-degree family member with >10 adenomas. Interpretation: Adenoma count, age at diagnosis of the adenomas and year of analysis are important predictive factors for APC and MUTYH mutations. Based on our results, APC and MUTYH testing is advised in patients >10 adenomas under age 60 and >20 adenomas under age 70. Almost all FAP and MAP patients who did not meet these criteria showed other characteristics that can be used as an indication to prompt genetic testing. Funding Statement: The authors declare: N/A. Declaration of Interests: The authors state: No competing interest to declare. Ethics Approval Statement: The study was approved by local ethics review boards (P01.019).

Contribution of MUTYH Variants to Male Breast Cancer Risk: Results From a Multicenter Study in Italy.

Inherited mutations in BRCA1, and, mainly, BRCA2 genes are associated with increased risk of male breast cancer (MBC). Mutations in PALB2 and CHEK2 genes may also increase MBC risk. Overall, these genes are functionally linked to DNA repair pathways, highlighting the central role of genome maintenance in MBC genetic predisposition. MUTYH is a DNA repair gene whose biallelic germline variants cause MUTYH-associated polyposis (MAP) syndrome. Monoallelic MUTYH variants have been reported in families with both colorectal and breast cancer and there is some evidence on increased breast cancer risk in women with monoallelic variants. In this study, we aimed to investigate whether MUTYH germline variants may contribute to MBC susceptibility. To this aim, we screened the entire coding region of MUTYH in 503 BRCA1/2 mutation negative MBC cases by multigene panel analysis. Moreover, we genotyped selected variants, including p.Tyr179Cys, p.Gly396Asp, p.Arg245His, p.Gly264Trpfs*7, and p.Gln338His, in a total of 560 MBC cases and 1,540 male controls. Biallelic MUTYH pathogenic variants (p.Tyr179Cys/p.Arg241Trp) were identified in one MBC patient with phenotypic manifestation of adenomatous polyposis. Monoallelic pathogenic variants were identified in 14 (2.5%) MBC patients, in particular, p.Tyr179Cys was detected in seven cases, p.Gly396Asp in five cases, p.Arg245His and p.Gly264Trpfs*7 in one case each. The majority of MBC cases with MUTYH pathogenic variants had family history of cancer including breast, colorectal, and gastric cancers. In the case-control study, an association between the variant p.Tyr179Cys and increased MBC risk emerged by multivariate analysis [odds ratio (OR) = 4.54; 95% confidence interval (CI): 1.17–17.58; p = 0.028]. Overall, our study suggests that MUTYH pathogenic variants may have a role in MBC and, in particular, the p.Tyr179Cys variant may be a low/moderate penetrance risk allele for MBC. Moreover, our results suggest that MBC may be part of the tumor spectrum associated with MAP syndrome, with implication in the clinical management of patients and their relatives. Large-scale collaborative studies are needed to validate these findings.

Intussusception reveals MUTYH-related polyposis syndrome and colorectal cancer

We are reporting a rare case of MUTYH-associated polyposis, a colorectal cancer hereditary syndrome, diagnosticated after an intussusception. Colorectal cancer is an important cause of cancer related mortality that can be manifested by an intussusception, a rare occurrence in adults and almost always related to tumors. Approximately 5% of colorectal cancers can be attributed to syndromes known to cause hereditary colorectal cancer, such as MUTYHassociated polyposis, autosomal genetic syndrome associated with this disease. We present the case of a 44 years old male, that sought medical consultation with a complaint of abdominal discomfort, that after five days changed its characteristics. The patient was sent to the emergency department were a CT-scan revealed intestinal sub-occlusion by ileocolic invagination. Right colectomy was carried out. The anatomic-pathological examination revealed a moderately differentiated mucinous adenocarcinoma and multiples sessile polyps, which led to the suspicion of a genetic syndrome. In the genetics analysis two mutations were observed in the MUTYH gene, and MUTYH-associated polyposis was diagnosticated. This case demonstrates the importance of meticulous analysis of the patient examinations results to identify possible discrete alterations that can lead to improved understanding of disease.

The Zinc Linchpin Motif in the DNA Repair Glycosylase MUTYH: Identifying the Zn2+ Ligands and Roles in Damage Recognition and Repair.

The DNA base excision repair (BER) glycosylase MUTYH prevents DNA mutations by catalyzing adenine (A) excision from inappropriately formed 8-oxoguanine (8-oxoG):A mismatches. The importance of this mutation suppression activity in tumor suppressor genes is underscored by the association of inherited variants of MUTYH with colorectal polyposis in a hereditary colorectal cancer syndrome known as MUTYH-associated polyposis, or MAP. Many of the MAP variants encompass amino acid changes that occur at positions surrounding the two-metal cofactor-binding sites of MUTYH. One of these cofactors, found in nearly all MUTYH orthologs, is a [4Fe-4S]2+ cluster coordinated by four Cys residues located in the N-terminal catalytic domain. We recently uncovered a second functionally relevant metal cofactor site present only in higher eukaryotic MUTYH orthologs: a Zn2+ ion coordinated by three Cys residues located within the extended interdomain connector (IDC) region of MUTYH that connects the N-terminal adenine excision and C-terminal 8-oxoG recognition domains. In this work, we identified a candidate for the fourth Zn2+ coordinating ligand using a combination of bioinformatics and computational modeling. In addition, using in vitro enzyme activity assays, fluorescence polarization DNA binding assays, circular dichroism spectroscopy, and cell-based rifampicin resistance assays, the functional impact of reduced Zn2+ chelation was evaluated. Taken together, these results illustrate the critical role that the "Zn2+ linchpin motif" plays in MUTYH repair activity by providing for proper engagement of the functional domains on the 8-oxoG:A mismatch required for base excision catalysis. The functional importance of the Zn2+ linchpin also suggests that adjacent MAP variants or exposure to environmental chemicals may compromise Zn2+ coordination, and ability of MUTYH to prevent disease.

Abstract 560: Identification of a novel MUTYH mutation in non-small cell lung cancer

Abstract Introduction: Lung cancer is the leading cause of death from cancer in Hong Kong and worldwide. Nearly 80-85% of lung cancers are diagnosed with non-small cell lung cancer (NSCLC). Treatment strategies can be refined according to the distinct difference of NSCLC molecular profiling among different ethnic populations. Moreover, oncogenic driver mutations are closely linked to NSCLC in non-smokers and young people. Therefore, the urge of finding pathogenic mutations is inevitable. This study aims to discover novel mutations in NSCLC patients in Hong Kong by next-generation sequencing and characterize the clinical significance of these mutations. Methods: In order to identify mutations, DNA was purified from 6 pairs of lung tumor-normal tissues from 2 stage I adenocarcinoma (LUAD), 2 stage III LUAD and 2 stage I squamous cell carcinoma (LUSC) patients. Samples were sequenced by targeted sequencing with the TOMA OS-Seq 130 cancer gene panel. Sequence alignment and variant calling were performed by combining TOMA Stratus and in-house pipelines. Results: The mean aligned reads exceeded 14 million and the mean coverage of target region was over 1000X. MUTYH deletion was found in 66.7% (4/6) of the patients. Data from The Cancer Genome Atlas (TCGA) revealed that MUTYH deletion is significantly associated with poorer disease-free survival (DFS) (p=0.0063) and overall survival (p=0.022) in LUAD patients. TCGA data also showed that MUTYH copy number correlates with gene expression (r=0.473) and LUAD patients with MUTYH mRNA overexpression have better DFS (p=0.0205). However, such correlations were not observed in LUSC patients. MUTYH is a DNA glycosylase which involves in the base excision repair and it repairs oxidative DNA damage by preventing G:C to T:A transversion. Numerous studies indicated that biallelic mutations in MUTYH cause MUTYH-associated polyposis and increase the lifetime risk of colorectal cancer. MUTYH mutations could be associated with increased risk of endometrial and breast cancer. Conclusion: To elucidate the clinical significance of MUTYH in LUAD, an independent cohort will be sequenced to validate the primary result. Immunohistochemistry, RT-qPCR and functional assays will be performed to examine the protein expression, the gene expression and the functional role. All these findings suggested that MUTYH deletion may play a crucial role in LUAD and potentially lead to the development of biomarker and therapeutic target. Citation Format: Alvin Hong-Wai Fong, Eunice Yuen-Ting Lau, William Ka-Chun Cheung, William Chi-Shing Cho. Identification of a novel MUTYH mutation in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 560.

A human MUTYH variant linking colonic polyposis to redox degradation of the [4Fe4S]2+ cluster.

The human DNA repair enzyme MUTYH excises mispaired adenine residues in oxidized DNA. Homozygous MUTYH mutations underlie the autosomal, recessive cancer syndrome MUTYH-associated polyposis. We report a MUTYH variant, p.C306W (c.918C>G), with a tryptophan residue in place of native cysteine, that ligates the [4Fe4S] cluster in a patient with colonic polyposis and family history of early age colon cancer. In bacterial MutY, the [4Fe4S] cluster is redox active, allowing rapid localization to target lesions by long-range, DNA-mediated signalling. In the current study, using DNA electrochemistry, we determine that wild-type MUTYH is similarly redox-active, but MUTYH C306W undergoes rapid oxidative degradation of its cluster to [3Fe4S]+, with loss of redox signalling. In MUTYH C306W, oxidative cluster degradation leads to decreased DNA binding and enzyme function. This study confirms redox activity in eukaryotic DNA repair proteins and establishes MUTYH C306W as a pathogenic variant, highlighting the essential role of redox signalling by the [4Fe4S] cluster.

Наследственный колоректальный рак: генетика и скрининг

Aim of review. To present the data on main forms of hereditary colorectal cancer (CRC) and to discuss issues of its diagnostics, genetic testing and patient management. Summary. CRC is one of the most widespread oncologic diseases and takes the leading positions for morbidity and mortality in the pattern of neoplastic diseases in Russia. In 30% of cases disease development is associated to genetic predisposition, however only 5% of all CRC cases are linked to established hereditary syndromes, such as Lynch syndrome (hereditary non-polyposis colorectal cancer), family adenomatous polyposis, MUTYH-associated polyposis, juvenile polyposis, hereditary mixed polyposis syndrome, Peutz-Jeghers syndrome and serrated polyposis syndrome. The current review presents clinical and genetic features of two basic colorectal hereditary syndromes - Lynch syndrome and family adenomatous polyposis. Conclusion. Both clinical and molecular genetic investigations of hereditary CRC forms make possible individual comprehensive approach for diagnosis verification, evaluation of cancer risk, early diagnostics, treatment and prevention for decrease of morbidity and mortality.

The impact of chromoendoscopy for surveillance of the duodenum in patients with MUTYH-associated polyposis and familial adenomatous polyposis

Duodenal polyposis and cancer have become a key issue for patients with familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP). Almost all patients with FAP will develop duodenal adenomas, and 5% will develop cancer. The incidence of duodenal adenomas in MAP appears to be lower than in FAP, but the limited available data suggest a comparable increase in the relative risk and lifetime risk of duodenal cancer. Current surveillance recommendations, however, are the same for FAP and MAP, using the Spigelman score (incorporating polyp number, size, dysplasia, and histology) for risk stratification and determination of surveillance intervals. Previous studies have demonstrated a benefit of enhanced detection rates of adenomas by use of chromoendoscopy both in sporadic colorectal disease and in groups at high risk of colorectal cancer. We aimed to assess the effect of chromoendoscopy on duodenal adenoma detection, to determine the impact on Spigelman stage and to compare this in individuals with known pathogenic mutations in order to determine the difference in duodenal involvement between MAP and FAP. A prospective study examined the impact of chromoendoscopy on the assessment of the duodenum in 51 consecutive patients with MAP and FAP in 2 academic centers in the United Kingdom (University Hospital Llandough, Cardiff, and St Mark's Hospital, London) from 2011 to2014. Enhanced adenoma detection of 3 times the number of adenomas after chromoendoscopy was demonstrated in both MAP (P= .013) and FAP (P= .002), but did not affect adenoma size. In both conditions, there was a significant increase in Spigelman stage after chromoendoscopy compared with endoscopy without dye spray. Spigelman scores and overall adenoma detection was significantly lower in MAP compared with FAP. Chromoendoscopy improved the diagnostic yield of anomas in MAP and FAP 3-fold, and in both MAP and FAP this resulted in a clinically significant upstaging in Spigelman score. Further studies are required to determine the impact of improved adenoma detection on the management and outcome of duodenal polyposis.