MUTYH-associated Polyposis Research Articles

Carrier Frequency and Incidence of MUTYH-Associated Polyposis Based on Database Analysis in East Asians and Koreans.

MUTYH-associated polyposis is an autosomal recessive disorder associated with an increased lifetime risk of colorectal cancer and a moderately increased risk of ovarian, bladder, breast, and endometrial cancers. We analyzed the carrier frequency and estimated the incidence of MUTYH-associated polyposis in East Asian and Korean populations, for which limited data were previously available. We examined 125,748 exomes from the gnomAD database, including 9,197 East Asians, and additional data from 5,305 individuals in the Korean Variant Archive and 1,722 in the Korean Reference Genome Database. All MUTYH variants were interpreted according to the American College of Medical Genetics and Genomics and Association for Molecular Pathology guidelines and the Sequence Variant Interpretation guidelines from ClinGen. The global carrier frequency of MUTYH-associated polyposis was 1.29%, with Europeans (non-Finnish) having the highest frequency of 1.86% and Ashkenazi Jews the lowest at 0.06%. East Asians and Koreans had a carrier frequency of 0.35% and 0.37% and an estimated incidence of 1 in 330,409 and 1 in 293,304 in Koreans, respectively, which were substantially lower than the global average of 1 in 24,160 and the European (non-Finnish) incidence of 1 in 11,520. This was the first study to investigate the frequency of carriers of MUTYH-associated polyposis in East Asians, including specific subgroups, utilizing gnomAD and a Korean genome database. Our data provide valuable reference information for future investigations of MUTYH-associated polyposis to understand the genetic diversity and specific variants associated with this condition in East Asian populations.

Familial adenomatous polyposis gene MUTYH mutations are identified in anaplastic thyroid carcinoma

Abstract Introduction/Objective Anaplastic thyroid carcinoma (ATC) is a rare aggressive disease unresponsive to treatment. Next-Generation Sequencing (NGS) allows identification of targets for precision therapies, such as BRAF, with implications in treating ATC. Our prior work identified ATC clusters with characteristic gene mutations and multiple previously unreported mutations. One of these is MUTYH, which is associated with colon (CRC), ovarian, breast, bladder, and duodenal carcinomas in MUTYH-associated polyposis (MAP). Its association with ATC is not defined. Methods/Case Report Exploratory analysis of pathogenic mutations in 727 ATC cases using a 324-gene panel (FoundationOneCDx) and an interactive visualization of association rules was conducted for informative maximal frequent patterns among mutated gene combinations to identify gene clusters including genes not commonly associated with ATC. TCGA database was reviewed for frequency of MUTYH mutations. My Cancer Genome and the Drug-Gene Interaction Database were used to identify potential targeted drugs for MUTYH gene-mutated cancers. Results (if a Case Study enter NA) NGS showed MUTYH short-variant mutations in 17 cases (2.34%). Germline MUTYH variants incidence is 1.43% in normal samples. 5 cases harbored only Y165C and 7 had only G382D, with 1 case having both Y165C and G382D. The other 4 cases contained sporadic truncating events in MUTYH. All instances of Y165C and G382D were predicted to be germline. 6 patients (35%) had BRAF co-mutations, correlating with expected frequency of ATC thought to transform from papillary carcinoma (PC). One case had only MUTYH mutation while a second had MUTYH with TERT and TP53. TCGA database contained 6(0.2%) cases of PC with MUTYH mutations (total 2871 MUTYH-mutated carcinomas), but no cases of ATC or other thyroid tumors were described. Conclusion MUTYH is a DNA repair enzyme linked to CRC and other cancers. MUTYH mutations occur in 6.7% of MAP patients and 1–2.2% of sporadic CRC cases that are mutually exclusive of BRAF mutations. While MAP increases the lifetime risk of CRC by over 60%, the link of MUTYH mutations to PC has only been observed in MAP and not been described outside of it. To our knowledge this is the first description of MUTYH mutations in ATC, especially without concurrent BRAF mutation (11 cases), suggesting MUTYH may independently contribute to pathogenesis of ATC. PARP inhibitors, PD-1/PD-L1 inhibitors, and ATR inhibitors demonstrate promising results in clinical trials of MUTYH-mutated cancers, warranting further research.

Additional 30-second observation of the right-sided colon for missed polyp detection with linked color imaging compared with narrow band imaging

Abstract Background and study aims We previously demonstrated the efficacy of an additional-30-seconds (Add-30s) observation with linked color imaging (LCI) or narrow band imaging (NBI) of the cecum and ascending colon (right-sided colon) after white light imaging (WLI) observation for improving adenoma detection rate (ADR) by 3% to 10%. We herein compared Add-30s LCI with Add-30s NBI in a large number of cases. Patients and methods We retrospectively collected 1023 and 1011 cases with Add-30s LCI and NBI observation for right-sided colon in 11 affiliated institutions from 2018 to 2022 and propensity score matching was performed. Add-30s observation was as follows. First observation: WLI observation of the right-sided colon as first observation. Second observation: Reobservation of right-sided colon by Add-30s LCI or NBI. The comparison of the mean numbers of adenoma+sessile serrated lesions (SSLs) and adenomas per patient (MASP and MUTYH-associated polyposis) were analyzed in the Add-30s LCI/NBI groups. The increase in right-sided ADR was also analyzed in the groups. Results Among 748 matched cases in the Add-30s LCI/NBI groups, the MASP and MAP were 0.18/0.19 (P = 0.54) and 0.14/0.15 (P = 0.70). Among experts, they were 0.17/0.22 (P = 0.16) and 0.15/0.21 (P = 0.08). Among non-experts, they were 0.13/0.12 (P = 0.71) and 0.12/0.07 (P = 0.04). The right-sided ADRs of the first+second observations in the LCI and NBI groups were 32.2% and 28.9% (P = 0.16) and the increase of ADRs were 7.5% and 7.2% (P = 0.84). Conclusions In right-sided colon, the detection of adenoma/SSL did not differ between Add-30s LCI and NBI. Both of them significantly increased ADR.

Germline and somatic MUTYH mutations: Clinicopathologic and mutational analysis in a pan-cancer cohort.

10590 Background: MUTYH is a tumor suppressor gene involved in the base-excision DNA repair pathway. Biallelic pathogenic or likely pathogenic germline variants (gPV) in MUTYH are associated with MUTYH-associated polyposis (MAP), inclusive of colorectal carcinoma (CRC) and additional cancer risks. While monoallelic MUTYH gPV carriers do not have the same cancer risk as those with biallelic MAP, further work is needed to fully characterize secondary somatic events, including allelic imbalances. Methods: Using the MSK-IMPACT targeted NGS to detect both MUTYH gPVs and MUTYH somatic variants in patients (pts) with a solid tumor diagnosis, we analyzed clinicopathologic characteristics at cancer diagnosis, ancestry label as defined per cBioPortal, genomic biomarkers, as well as allele-specific copy number estimates using FACETS annotation. Results: Out of 38,907 samples with germline testing available, 587 pts with a solid tumor and presence of MUTYH gPV were identified. Of these, 15 pts had ≥2 MUTYH gPVs, including 4 pts with homozygous MUTYHgPVs (G396D, T179C, p.G480* and c.389-1G>C) and 11 pts with compound heterozygous MUTYHgPVs. In pts of European ancestry (n=403), the MUTYH G396D and T179C variants were predominant, present in 56% and 19% of cases, respectively. All patients with the R241W variant were listed as being of South Asian ancestry (n=6). Concurrent gPV in other genes were observed in 12% (n=69), with high/moderate-penetrance gPVs in 4% (n=24) including BRCA2 (n=6), BRCA1 (n=5), ATM (n=4) and PALB2 (n=3). Among all pts with MUTYH gPVs, 254/587 pts had concurrent tumor samples with FACETS results. Among pts with monoallelic MUTYH gPVs and FACETS annotation available, 24% of evaluable tumors exhibited biallelic MUTYH inactivation due to loss of heterozygosity (LOH). CRC (29% vs 13%; p=0.004) and cholangiocarcinoma (11% vs. 2%; p=0.04) were enriched in the biallelic MUTYH inactivation cohort vs. the cohort of pts with monoallelic MUTYH gPVs. Co-alterations in KRAS G12C and APC were enriched in the biallelic as compared to the monoallelic cohort (9% vs. 3%, p=0.04 and 27% vs. 12%, p=0.005, respectively). In addition, we identified 244 pts for whom FACETS annotation was available without MUTYH gPVs, but with somatic variants at MUTYH. Of these 244 pts, 117 pts had biallelic MUTYH inactivation either from homozygous deletions (n=87), somatic hit + LOH (n=27) or ≥2 somatic hits (n=3). The predominant cancer types with biallelic somatic MUTYH inactivation were breast cancer (16%), non-small cell lung cancer (14%) and CRC (11%). Conclusions: This study represents the largest cohort of pts with MUTYH gPVs and FACETS analysis on concurrent tumor samples, confirming a high prevalence of LOH in pts with monoallelic MUTYH gPVs and enrichment in KRAS G12Cin pts with MUTYH gPVs and biallelic MUTYH inactivation.

Updated European guidelines for clinical management of familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), gastric adenocarcinoma, proximal polyposis of the stomach (GAPPS) and other rare adenomatous polyposis syndromes: a joint EHTG-ESCP revision.

Hereditary adenomatous polyposis syndromes, including familial adenomatous polyposis and other rare adenomatous polyposis syndromes, increase the lifetime risk of colorectal and other cancers. A team of 38 experts convened to update the 2008 European recommendations for the clinical management of patients with adenomatous polyposis syndromes. Additionally, other rare monogenic adenomatous polyposis syndromes were reviewed and added. Eighty-nine clinically relevant questions were answered after a systematic review of the existing literature with grading of the evidence according to Grading of Recommendations, Assessment, Development, and Evaluation methodology. Two levels of consensus were identified: consensus threshold (≥67% of voting guideline committee members voting either 'Strongly agree' or 'Agree' during the Delphi rounds) and high threshold (consensus ≥ 80%). One hundred and forty statements reached a high level of consensus concerning the management of hereditary adenomatous polyposis syndromes. These updated guidelines provide current, comprehensive, and evidence-based practical recommendations for the management of surveillance and treatment of familial adenomatous polyposis patients, encompassing additionally MUTYH-associated polyposis, gastric adenocarcinoma and proximal polyposis of the stomach and other recently identified polyposis syndromes based on pathogenic variants in other genes than APC or MUTYH. Due to the rarity of these diseases, patients should be managed at specialized centres.

Carrier frequency and incidence of MUTYH-associated polyposis in an East Asian and Korean population by population database-based analysis

Carrier frequency and incidence of MUTYH-associated polyposis in an East Asian and Korean population by population database-based analysis

A comprehensive characterization of the spectrum of MUTYH germline pathogenic variants in Latin America.

MUTYH-Associated Polyposis (MAP) is caused by biallelic pathogenic germline variants in the MUTYH gene. However, individuals harboring monoallelic MUTYH pathogenic variants in the presence of a positive family history have been reported to have a twofold increased risk of colorectal cancer (CRC) and extra colonic cancers. Our aim was to characterize the spectrum of monoallelic and biallelic germline MUTYH pathogenic variants in Latin American patients and to describe their clinical and genetic characteristics. Patients were identified from eight high-risk genetic cancer centers of five Latin American countries. Statistical analysis was performed using the two-sided P test using the Vassarstats statistical tools. Statistical significance was set at a p value ≤ 0.05. Of the 105 unrelated patients with cancer or colorectal polyposis, 84.8% and 15.2% carried pathogenic monoallelic and biallelic MUTYH variants, respectively. The most common pathogenic variants were p.Gly396Asp and p.Tyr179Cys (55% and 23%, respectively). The mean age at first diagnosis was 48.29years (range 31-71) and 49.90years (range 27-87) in biallelic and monoallelic MUTYH patients, respectively. CRC was the only cancer diagnosed in patients with biallelic MUTYH pathogenic variants (75%), while breast cancer (46.1%) was more common than CRC (24.7%) in individuals with monoallelic MUTYH pathogenic variants. We reported a high frequency of European founder variants in our diverse population. Some phenotypic differences from current studies were identified, such as a higher breast cancer burden in monoallelic carriers and a complete absence of extra-colon tumors in biallelic patients.

Cellular Repair of Synthetic Analogs of Oxidative DNA Damage Reveals a Key Structure-Activity Relationship of the Cancer-Associated MUTYH DNA Repair Glycosylase.

The base excision repair glycosylase MUTYH prevents mutations associated with the oxidatively damaged base, 8-oxo-7,8-dihydroguanine (OG), by removing undamaged misincorporated adenines from OG:A mispairs. Defects in OG:A repair in individuals with inherited MUTYH variants are correlated with the colorectal cancer predisposition syndrome known as MUTYH-associated polyposis (MAP). Herein, we reveal key structural features of OG required for efficient repair by human MUTYH using structure-activity relationships (SAR). We developed a GFP-based plasmid reporter assay to define SAR with synthetically generated OG analogs in human cell lines. Cellular repair results were compared with kinetic parameters measured by adenine glycosylase assays in vitro. Our results show substrates lacking the 2-amino group of OG, such as 8OI:A (8OI = 8-oxoinosine), are not repaired in cells, despite being excellent substrates in in vitro adenine glycosylase assays, new evidence that the search and detection steps are critical factors in cellular MUTYH repair functionality. Surprisingly, modification of the O8/N7H of OG, which is the distinguishing feature of OG relative to G, was tolerated in both MUTYH-mediated cellular repair and in vitro adenine glycosylase activity. The lack of sensitivity to alterations at the O8/N7H in the SAR of MUTYH substrates is distinct from previous work with bacterial MutY, indicating that the human enzyme is much less stringent in its lesion verification. Our results imply that the human protein relies almost exclusively on detection of the unique major groove position of the 2-amino group of OG within OGsyn:Aanti mispairs to select contextually incorrect adenines for excision and thereby thwart mutagenesis. These results predict that MUTYH variants that exhibit deficiencies in OG:A detection will be severely compromised in a cellular setting. Moreover, the reliance of MUTYH on the interaction with the OG 2-amino group suggests that disrupting this interaction with small molecules may provide a strategy to develop potent and selective MUTYH inhibitors.

Apparition of germline mutation c.1395-1397del of MUTYH in Algerian consanguineous family with colorectal cancer

MUTYH is a glycosylase that removes adenine opposite 8-oxoguanine (OG) during base-excision repair of DNA. Variants of MUTYH defective in functional activity lead to MUTYH-associated polyposis (MAP), autosomal recessive predisposition to colorectal cancer (CRC). MAP combines clinical features with other hereditary CRC syndromes, and exhibits phenotypic overlap, particularly with Lynch syndrome (LS). To determine the impact of MUTYH mutations in colorectal adenomas and cancer susceptibility, this prospective objective screens the MUTYH gene in seventeen Eastern Algerian families with clinically suspected LS but without mismatch repair (MMR) mutations. Methods: We examined the presence of the mutations in the probands and their relatives using direct sequencing of the entire coding region of the MUTYH gene. Results: The biallelic and monoallelic pathogenic MUTYH mutations, c.1395_1397del, were discovered in a consanguineous family with CRC and gastric cancer as a novel finding in our Eastern Algerian population. Conclusion: High rates of consanguinity in Algerian population increase the risk of CRC caused by biallelic mutations in the MUTYH gene. In our families, the LS and MAP phenotypes might coexist.

MUTYH-associated polyposis: Is it time to change upper gastrointestinal surveillance? A single-center case series and a literature overview

BACKGROUND The presence of Spigelman stage (SS) IV duodenal polyposis is considered the most significant risk factor for duodenal cancer in patients with MUTYH -associated polyposis (MAP). However, advanced SS disease is rarely reported in MAP patients, and no clear recommendations on small bowel (SB) surveillance have been proposed in this patient setting. AIM To research more because that case reports of duodenal cancers in MAP suggest that they may develop in the absence of advanced benign SS disease and often involve the distal portion of the duodenum. METHODS We describe a series of MAP patients followed up at the Regina Elena National Cancer Institute of Rome (Italy). A literature overview on previously reported SB cancers in MAP is also provided. RESULTS We identified two (6%) SB adenocarcinomas with no previous history of duodenal polyposis. Our observations, supported by literature evidence, suggest that the formula for staging duodenal polyposis and predicting risk factors for distal duodenum and jejunal cancer may need to be adjusted to take this into account rather than focusing solely on the presence or absence of SS IV disease. CONCLUSION Our study emphasizes the need for further studies to define appropriate upper gastrointestinal surveillance programs in MAP patients.

Distinctive Formation of a DNA-Protein Cross-Link during the Repair of DNA Oxidative Damage: Insights into Human Disease from MD Simulations and QM/MM Calculations.

Reactive oxygen species damage DNA and result in health issues. The major damage product, 8-oxo-7,8-dihydroguanine (8oG), is repaired by human adenine DNA glycosylase homologue (MUTYH). Although MUTYH misfunction is associated with a genetic disorder called MUTYH-associated polyposis (MAP) and MUTYH is a potential target for cancer drugs, the catalytic mechanism required to develop disease treatments is debated in the literature. This study uses molecular dynamics simulations and quantum mechanics/molecular mechanics techniques initiated from DNA-protein complexes that represent different stages of the repair pathway to map the catalytic mechanism of the wild-type MUTYH bacterial homologue (MutY). This multipronged computational approach characterizes a DNA-protein cross-linking mechanism that is consistent with all previous experimental data and is a distinct pathway across the broad class of monofunctional glycosylase repair enzymes. In addition to clarifying how the cross-link is formed, accommodated by the enzyme, and hydrolyzed for product release, our calculations rationalize why cross-link formation is favored over immediate glycosidic bond hydrolysis, the accepted mechanism for all other monofunctional DNA glycosylases to date. Calculations on the Y126F mutant MutY highlight critical roles for active site residues throughout the reaction, while investigation of the N146S mutant rationalizes the connection between the analogous N224S MUTYH mutation and MAP. In addition to furthering our knowledge of the chemistry associated with a devastating disorder, the structural information gained about the distinctive MutY mechanism compared to other repair enzymes represents an important step for the development of specific and potent small-molecule inhibitors as cancer therapeutics.

Large Rearrangements in Genes Responsible for Familial Adenomatous Polyposis, <i>MUTYH</i>-Associated Polyposis and Peutz–Jeghers Syndrome in Russian Patients

Аim: to reveal the rate of large rearrangements in the genes responsible for familial adenomatous polyposis, MUTYH-associated polyposis and Peutz–Jeghers syndrome.Materials and methods. The MLPA method was used for identification of large rearrangements. A total number of 135 patients was included in the study: 83 patients with a clinical diagnosis of “familial adenomatous polyposis”, 18 — with suspected MUTYH-associated polyposis, and 34 — with a clinical diagnosis of “Peutz–Jeghers syndrome”.Results. Seven large deletions and one large duplication in the APC gene were identified in 83 patients with classic familial adenomatous polyposis, with rate of large rearrangements 9.6 % (8/83). In 18 patients with suspected MUTYH-associated polyposis, no large rearrangements were found in the MUTYH gene. Four large deletions in the STK11 gene (12 %, 4/34) were detected in 34 patients with Peutz–Jeghers syndrome.Conclusion. For the first time, the expediency of including the method of detecting large rearrangements in routine DNA test list for Russian patients with various hereditary polyposis syndromes is demonstrated. Routine use of MLPA method makes it possible to increase the total frequency of detection of pathogenic variants in the APC and STK11 genes above 90 %. At the same time, the need for searching of large rearrangements in the MUTYH gene were not justified.

The Unique Spectrum of MUTYH Germline Mutations in Colombian Patients with Extracolonic Carcinomas.

Protein MUTYH, encoded by the gene MUTYH, is an important mismatch repair enzyme in the base-excision repair pathway of DNA repair. When genetically altered, different neoplastic conditions can arise. One of the widely known syndromes associated with MUTYH mutations is MUTYH-associated polyposis, a form of familial colorectal cancer syndrome. MUTYH may also be a driver in other familial cancer syndromes, as well as breast cancer and spontaneous cancer cases. However, some controversies about the role of these alterations in oncogenesis remain, especially when affected in a heterozygous way. Most available data on MUTYH mutations are on Caucasian patients. We analyzed a small cohort of non-Caucasian, Colombian cancer patients with MUTYH germline heterozygous mutations, clinical features suggestive of familial cancer, and extensive genetic studies with no other mutations and without MUTYH-associated polyposis. With this case series, we intended to provide important data for the understanding of MUTYH as a possible driver of familial cancer, even when only heterozygous mutations are found.

Surgical strategies for hereditary colorectal cancer

Hereditary colorectal cancer (hCRC) represents amajor diagnostic and therapeutic challenge. In addition to the usual diagnostic methods, the family history, histological confirmation and mutation analysis play an important role in identifying the type of hereditary CRC. The diagnosis and classification of hCRC are carried out based on the anamnesis, clinical presentation and histology and the further treatment is determined depending on the underlying type of hCRC. For familial adenomatous polyposis (FAP) coloproctomucosectomy after the end of puberty is always recommended, whereas the treatment recommendations for other forms, such as attenuated FAP (aFAP), MUTYH-associated polyposis (MAP) and hereditary nonpolyposis colon cancer (HNPCC, Lynch syndrome), range from close surveillance and endoscopic control, through segmental resection up to colectomy. Irrespective of the type of hCRC, the treatment regimens necessitate an individualized approach and require close interdisciplinary cooperation. When colorectal resection is performed, minimally invasive procedures should principally be prioritized and some studies could demonstrate apotential benefit of robotic surgery compared to laparoscopy.

Genetic Predisposition to Colorectal Cancer: How Many and Which Genes to Test?

Colorectal cancer is one of the most common tumors, and genetic predisposition is one of the key risk factors in the development of this malignancy. Lynch syndrome and familial adenomatous polyposis are the best-known genetic diseases associated with hereditary colorectal cancer. However, some other genetic disorders confer an increased risk of colorectal cancer, such as Li-Fraumeni syndrome (TP53 gene), MUTYH-associated polyposis (MUTYH gene), Peutz-Jeghers syndrome (STK11 gene), Cowden syndrome (PTEN gene), and juvenile polyposis syndrome (BMPR1A and SMAD4 genes). Moreover, the recent advances in molecular techniques, in particular Next-Generation Sequencing, have led to the identification of many new genes involved in the predisposition to colorectal cancers, such as RPS20, POLE, POLD1, AXIN2, NTHL1, MSH3, RNF43 and GREM1. In this review, we summarized the past and more recent findings in the field of cancer predisposition genes, with insights into the role of the encoded proteins and into the associated genetic disorders. Furthermore, we discussed the possible clinical utility of genetic testing in terms of prevention protocols and therapeutic approaches.

Surgery for MutYH-associated polyposis (systematic review, meta-analysis)

BACKGROUND: to date, there are no clear guidelines for MutYH-associated polyposis (MAP) surgery.AIM: to study the world literature on MutYH-associated polyposis surgery using a meta-analysis.MATERIALS AND METHODS: the systematic review was carried out in accordance with the practice and guidelines of PRISMA. The meta-analysis included the results of 14 case studies, 4 cohort studies, as well as own data on patients with MAP. A total of 474 patients with MAP were analyzed.RESULTS: when analyzing the number of colorectal polyps, the total occurrence value (95% CI: 0-14) of less than 10 polyps was 10%, in 52% cases (95% CI: 0-100) from 10 to 100 polyps were detected, in the remaining cases there were more than 100 polyps. Colorectal cancer was diagnosed in 56% of patients (95% CI: 45–66) of patients, while tumors with the T1-T3 were found in 38% of cases, tumors with the T4 were found in 7% of cases, lesions of the regional lymph nodes N + were found in 8%. The synchronous tumors were detected in 12%, and metachronous — in 5%. In 87%, some parts of the large intestine were preserved, in 38% [95% CI: 0-100] — colectomy with ileorectal anastomosis, in 27% [95% CI: 23-31] — colorectal resection, in 22% [95% CI: 16-27] — polypectomy), in other cases total removal of all parts of the large bowel was performed.CONCLUSION: patients with MAP who have been diagnosed with less than 100 colorectal polyps may undergo endoscopic polypectomy, if technically possible. Despite the risk of developing CRC, which in most cases has a nonaggressive course, the clinical course of MutYH-associated polyposis is relatively favorable. For this category of patients, it is possible to limit colorectal resection with annual endoscopic control and removal of detectable polyps in the remaining parts of the large bowel

Strong Hereditary Predispositions to Colorectal Cancer

Cancer is one of the most common causes of death worldwide. A strong predisposition to cancer is generally only observed in colorectal cancer (5% of cases) and breast cancer (2% of cases). Colorectal cancer is the most common cancer with a strong genetic predisposition, but it includes dozens of various syndromes. This group includes familial adenomatous polyposis, attenuated familial adenomatous polyposis, MUTYH-associated polyposis, NTHL1-associated polyposis, Peutz-Jeghers syndrome, juvenile polyposis syndrome, Cowden syndrome, Lynch syndrome, and Muir-Torre syndrome. The common symptom of all these diseases is a very high risk of colorectal cancer, but depending on the condition, their course is different in terms of age and range of cancer occurrence. The rate of cancer development is determined by its conditioning genes, too. Hereditary predispositions to cancer of the intestine are a group of symptoms of heterogeneous diseases, and their proper diagnosis is crucial for the appropriate management of patients and their successful treatment. Mutations of specific genes cause strong colorectal cancer predispositions. Identifying mutations of predisposing genes will support proper diagnosis and application of appropriate screening programs to avoid malignant neoplasm.

Squamous Morules in a Fundic Gland Polyp: A Rare Benign Mimic of Well-Differentiated Neuroendocrine Tumor

Abstract Introduction/Objective Fundic gland polyp is a benign polypoid lesion consisting of cystically dilated oxyntic glands; it can be either sporadic or associated with familial adenomatous polyposis or MUTYH-associated polyposis. Squamous morules are well-described in association with numerous epithelial lesions including tubular adenomas, cribriform- morular variant of papillary thyroid carcinoma, and endometrial neoplasia. However, to date only 2 cases have been reported in the stomach. Methods/Case Report We describe a third case, in a 53-year-old female who presented to endoscopy for hematemesis. Thirty-five sessile polyps ranging from 10-18 mm were identified and resected. On histologic sections, all were fundic gland polyps. Of these, one showed scattered small nests of epithelial cells with monomorphic round nuclei, inconspicuous nucleoli, and moderate eosinophilic cytoplasm, situated just below the luminal surface in continuity with adjacent glands. The nests showed focal expression of synaptophysin and cytokeratin 5/6, striking nuclear expression of β-catenin, and no expression of p63. Ki67 proliferative index was <1%. Interestingly, all 3 cases of gastric squamous morules have arisen in adults with symptoms of reflux, including our patient who was on a proton pump inhibitor. All were identified in a gastric polyp (either hyperplastic or fundic gland) within a background of numerous large fundic gland polyps (up to 2 cm), and none were associated with lower gastrointestinal polyposis. Nuclear accumulation of β-catenin, a common feature of squamous morules, was demonstrated in the one prior case that was tested. Results (if a Case Study enter NA) NA. Conclusion Gastric squamous morules are a rare finding. Given the nested arrangement of cells and bland cytology, well-differentiated neuroendocrine tumor may enter the differential diagnosis. Features that can help distinguish squamous morules from neuroendocrine tumor are: (1) focal expression of synaptophysin, (2) superficial location and continuity with adjacent glandular epithelium, and (3) nuclear accumulation of β-catenin.

ODP488 Incidental papillary thyroid cancer found after hemi-thyroidectomy in man with MUTYH-associated polyposis

Abstract MUTYH-associated polyposis (MAP) is an autosomal recessive syndrome caused by a mutation to the MUTYH gene, a base excision repair gene that repairs oxidative damage to DNA. Mutations to both allelic copies of this gene typically manifest as multiple colonic polyps, which develop by middle age. Individuals with MAP are also at higher risk for developing non-gastrointestinal (GI) cancers including those affecting the ovary, bladder, breast, endometrium, and possibly thyroid. A 66-year-old man with a history of MAP complicated by colonic polyposis requiring subtotal colectomy, an esophageal adenocarcinoma resected by esophagectomy, and a gastrointestinal stromal tumor also resected was referred to endocrinology clinic for an incidental thyroid nodule found on routine surveillance. The patient denied prior neck radiation but reported having a daughter and cousin with thyroid cancer. Ultrasound showed a left 3.3 by 2.8 by 1.6 cm thyroid nodule with multiple lobulations. Although a fine needle aspiration (FNA) of the nodule was benign, a repeat ultrasound several months later noted an increase in size to 3.5 by 3.5 by 2. 0 cm. Given the nodule's significant growth, the patient's history of MAP, and family history of thyroid cancer, the patient underwent a left hemi-thyroidectomy. Pathology revealed that the nodule was a follicular adenoma, however also identified two papillary microcarcinomas, measuring 1 and 2 mm. The patient was started on levothyroxine 50 mcg with a goal TSH below 0.5 mU/L and was monitored with ultrasounds which were unremarkable. In 2021, the national cancer institute estimated approximately 150,000 cases of colorectal cancer (CRC) with a 65% 5-year survival, compared to 44,000 cases of thyroid cancer with a 98% 5-year survival. Although the incidence of CRC in patients with MAP is high, approximately 43-63% by age 60, the risks of several associated non-GI malignancies are not as well defined. The national comprehensive cancer network (NCCN) and the American College of Gastroenterology (ACG) both published guidelines regarding appropriate screening for both GI and associated non-GI malignancies. In regards to thyroid cancer, both advise screening in patients with familiar adenomatous polyposis (FAP), another familial condition, due to the increased risk of papillary thyroid cancer (PTC) of approximately 1-2%. The evidence concerning MUTYH is not as strong, with the ACG recommending annual thyroid cancer screening, although the quality of evidence is low. Since a thyroid ultrasound is both low-cost and non-invasive and the overall survival of patients with PTC is high, we agree that patients with MAP be screened with thyroid ultrasounds. This case highlights the possibility that thyroid cancer is a manifestation of MAP, and a lower threshold to send for surgery may be warranted for those with other risk factors such as a family history or prior neck radiation. Presentation: No date and time listed

356P Biallelic MUTYH germline inactivation in patients with colon polyposis and subjects with sporadic colorectal cancer

MUTYH-associated polyposis (MAP) is a rare recessive condition typically characterized by the presence of 10-100 colorectal polyps and the elevated risk of colorectal cancer (CRC). CRCs arising in biallelic carriers of MUTYH mutation often contain KRAS G12C substitution and frequently arise without concomitant polyposis. This study included 74 consecutive patients with colon polyposis and 3486 consecutive patients with CRC referred to the N.N. Petrov Institute of Oncology (St. Petersburg, Russia) for molecular testing. Normal DNA obtained from subjects with polyposis was analyzed by NGS using custom panel for hereditary cancer genes. CRC patients were screened for recurrent MUTYH pathogenic alleles p.Y179C, p.R245H and p.G396D. The status of the remaining allele in MUTYH-heterozygous CRC cases was analyzed by Sanger sequencing. Biallelic MUTYH mutations were identified in 8/74 (11%) patients with polyposis. MAP was the second most common hereditary polyposis syndrome after familial adenomatous polyposis (47/74, 64%), with Peutz-Jeghers syndrome being in the third place (3/74, 5%). MUTYH biallelic alterations were detected in 9/3486 (0.3%) consecutive CRC patients. Somatic KRAS G12C substitution was observed in 223/3486 (6%) CRCs. Germ-line MUTYH inactivation was identified in 7/223 (3%) KRAS G12C-positive CRCs vs. 2/3253 (0.06%) patients without this mutation (p < 0.00001). Germ-line MUTYH biallelic mutations are significant contributors to the incidence of polyposis, while their impact in CRC morbidity is moderate. However, MUTYH gene analysis is highly feasible in CRC patients whose tumor harbors KRAS G12C substitution.