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Introduction Most cases of colorectal cancer (CRC) occur sporadically; however, ∼ 3% to 6% of all CRCs are related to inherited syndromes, such as Lynch syndrome and familial adenomatous polyposis (FAP). The adenomatous polyposis coli (APC) and mutY DNA glycosylase (MUTYH) germline mutations are the main genetic causes related to colorectal polyposis. Nevertheless, in many cases mutations in these genes have not been identified. The aim of the present case report is to describe a rare case of genetic colorectal polyposis associated with the axis inhibition protein 2 (AXIN2) gene. Case Report The first colonoscopy screening of a 61-year-old male patient with no known family history of CRC revealed ∼ 50 colorectal polyps. A histological evaluation of the resected polyps showed low-grade tubular adenomas. Germline genetic testing through a multigene panel for cancer predisposition syndromes revealed a pathogenic variant in the AXIN2 gene. In addition to colorectal polyposis, the patient had mild features of ectodermal dysplasia: hypodontia, scant body hair, and onychodystrophy. Discussion The AXIN2 gene acts as a negative regulator of the Wnt/β -catenin signaling pathway, which participates in development processes and cellular homeostasis. Further studies are needed to support the surveillance recommendations for carriers of the AXIN2 pathogenic variant.

In addition to classic germline APC gene variants, APC mosaicism and deep intronic germline APC variants have also been reported to be causes of adenomatous polyposis. In this study, we investigated 80 unexplained colorectal polyposis patients without germline pathogenic variants in known polyposis predisposing genes to detect mosaic and deep intronic APC variants. All patients developed more than 50 colorectal polyps, with adenomas being predominantly observed. To detect APC mosaicism, we performed next-generation sequencing (NGS) in leukocyte DNA. Furthermore, using Sanger sequencing, the cohort was screened for the following previously reported deep intronic pathogenic germline APC variants: c.1408 + 731C > T, p.(Gly471Serfs*55), c.1408 + 735A > T, p.(Gly471Serfs*55), c.1408 + 729A > G, p.(Gly471Serfs*55) and c.532-941G > A, p.(Phe178Argfs*22). We did not detect mosaic or intronic APC variants in the screened unexplained colorectal polyposis patients. The results of this study indicate that the deep intronic APC variants investigated in this study are not a cause of colorectal polyposis in this Dutch population. In addition, NGS did not detect any further mosaic variants in our cohort.

Background. Colorectal obturation is a fairly rare complication in patients with colorectal polyposis. Case descriptions of colonic obturation with underlying familial adenomatous colorectal polyposis have not been reported to date in national and foreign literature.Clinical Case Description. Patient G., female, 31 yo, was emergently admitted to a surgical unit with a preliminary diagnosis: acute intestinal obstruction, complaints of abdominal pain, nausea, vomiting, stool and gas outlet blockage, marked general weakness. Clinical and biochemical blood tests without peculiarities. Signs of intestinal obstruction in abdominal ultrasonic and X-ray examination. Obstructive right hemicolectomy performed as emergent surgery. Diagnosis: transverse colonic C-r T3NoMo, stage II, clinical group 2. Patient had routine fibrocolonoscopy in six months; polyps were revealed in all operated colon portions. APC genetic test was positive, total colectomy was decided with single-barrel ileostomy excretion on anterior abdominal wall. Definitive diagnosis: transverse colonic C-r T3NoMo, stage II, developed with underlying familial adenomatous colorectal polyposis, clinical group 2.Conclusion. Diagnosis of familial adenomatous colorectal polyposis with acute intestinal obturation is challenging due to forced urgent surgical intervention and lack of time for a detailed deeper examination in avoidance of baleful consequences. The case reported demonstrates that clinical manifestations of familial adenomatous colorectal polyposis extend beyond the routine complaints of abdominal bloating, stool blockage and rectal bleeding towards a formidable complication of acute colonic obturation of polypoid genesis.

Background Constitutional mismatch repair deficiency (CMMRD) is an extremely rare autosomal recessive hereditary disease characterized by the absence of mismatch repair gene activity from birth, which results in brain tumors, colonic polyposis, gastrointestinal cancers, and lymphomas later in life. An aggressive approach, including colectomy or proctocolectomy, is recommended for the treatment of colorectal cancer. Additionally, partial colectomy with subsequent endoscopic surveillance may be an alternative strategy due to poor patient’s condition, although there is no evidence of surveillance endoscopy after partial colectomy for CMMRD. Case presentation A 13-year-old male patient with a history of T-lymphoblastic lymphoma underwent total gastrointestinal endoscopy, which revealed rectal cancer, colorectal polyposis, and duodenal adenoma. Differential diagnosis included constitutional mismatch repair deficiency according to its scoring system and microsatellite instability, and subsequent germline mutation testing for mismatch repair genes confirmed the diagnosis of constitutional mismatch repair deficiency based on a homozygous mutation in mutS homolog 6 (MSH6). The patient and his family refused colectomy due to the high risk of malignancies other than colorectal cancer, which could require radical surgery. Therefore, the patient underwent low anterior resection of the rectosigmoid colon for rectal cancer and intensive surveillance endoscopy for the remaining colon polyposis. During the 3-year period after initial surgery, 130 polyps were removed and the number of polyps gradually decreased during 6-months interval surveillance endoscopies, although only one polyp was diagnosed as invasive adenocarcinoma (pT1). Conclusions Our experience of short surveillance endoscopy illustrates that this strategy might be one of options according to patient’s condition.

Background Constitutional mismatch repair deficiency (CMMRD) is a rare autosomal recessive condition, which is caused by biallelic mutations in mismatch repair genes: MSH2, MLH1, MSH6, and PMS2. Case presentation We reported a unique case of an 11-year-old Chinese girl with colorectal polyposis and café-au-lait macules who had no obvious family history of Lynch syndrome-associated tumors, followed by brain gliomas and colorectal carcinoma five years later. The diagnosis of CMMRD was based on gene sequencing analysis showing a homozygous deletion NM_00535.5:c.1577delA (p.Asp526fs) in exon 11 of the PMS2 gene. Although the patient underwent surgery and radiation therapy, and close surveillances including radiological, endoscopic and hematological screening have been recommended, she died of the exacerbation of neurological symptoms at the age of 18. Conclusions We identified a novel homozygous deletion in the PMS2 gene in a CMMRD patient with complex clinical features.

Inherited defects in base-excision repair (BER) predispose to adenomatous polyposis and colorectal cancer (CRC), yet our understanding of this important DNA repair pathway remains incomplete. By combining detailed clinical, histological and molecular profiling, we reveal biallelic germline loss-of-function (LOF) variants in the BER gene MBD4 to predispose to adenomatous polyposis and –uniquely amongst CRC predisposition syndromes– to myeloid neoplasms. Neoplasms from MBD4-deficient patients almost exclusively accumulate somatic CpG>TpG mutations, resembling mutational signature SBS1. MBD4-deficient adenomas harbour mutations in known CRC driver genes, although AMER1 mutations were more common and KRAS mutations less frequent. We did not find an increased risk for colorectal tumours in individuals with a monoallelic MBD4 LOF variant. We suggest that this condition should be termed MBD4-associated neoplasia syndrome (MANS) and that MBD4 is included in testing for the genetic diagnosis of polyposis and/or early-onset AML.

An expert consensus panel convened by the Italian Association for Inherited and Familial Gastrointestinal Tumors (Associazione Italiana per lo Studio della Familiarita ed Ereditarieta dei Tumori Gastrointestinali, AIFEG) reviewed the literature and agreed on a number of position statements regarding the definition and management of polyposis coli without an identified pathogenic mutation on the APC or MUTYH genes, defined in the document as NAMP (non-APC/MUTYH polyposis).

Simple Summary Cancer is the second leading cause of death worldwide. Serrated polyposis syndrome (SPS) is characterized by the presence of serrated lesions in the colon and a higher colorectal cancer (CRC) risk. An important part of risk is due to the alteration of certain genes, which will be transmitted from one generation to another in the same family. Our main objective was to identify alterations of the human genome relevant to the hereditary predisposition to SPS, by focusing on families with several cases of this disease (familial SPS) and by using massive sequencing techniques to decode the genome. Our strategy allowed us to suggest the implication of 14 new genes in SPS predisposition. Identifying the inherited genetic factors involved in SPS can be useful to identify those families with medium-high CRC risk and, therefore, implement more targeted, intensive preventive measures for this group of patients. Abstract The serrated polyposis syndrome (SPS) is the most common and yet underdiagnosed colorectal polyposis syndrome. It is characterized by multiple and/or large colonic serrated polyps and a higher associated risk for colorectal cancer (CRC). The main objective of this study was to identify new candidate genes involved in the germline predisposition to SPS/CRC. Thirty-nine SPS patients from 16 families (≥2 patients per family) were recruited without alterations in well-known hereditary CRC genes, and germline and somatic whole-exome sequencing were performed. Germline rare variants with plausible pathogenicity, located in genes involved in cancer development, senescence and epigenetic regulation were selected. Somatic mutational profiling and signature analysis was pursued in one sample per family, when possible. After data filtering, ANXA10, ASXL1, CFTR, DOT1L, HIC1, INO80, KLF3, MCM3AP, MCM8, PDLIM2, POLD1, TP53BP1, WNK2 and WRN were highlighted as the more promising candidate genes for SPS germline predisposition with potentially pathogenic variants shared within families. Somatic analysis characterized mutational profiles in advanced serrated polyps/tumors, revealing a high proportion of hypermutated samples, with a prevalence of clock-like mutational signatures in most samples and the presence of DNA mismatch repair-defective signatures in some cases. In conclusion, we identified new candidate genes to be involved in familial SPS. Further functional studies and replication in additional cohorts are required to confirm the selected candidates.

Background Familial adenomatous polyposis (FAP) is characterized by colorectal polyposis and adenocarcinoma that is frequently accompanied by extracolonic neoplasm. The risk of gastric carcinoma is increasing in Western FAP patients as well as Asian patients. Methods We report the case of an FAP patient with fundic gland polyposis who developed gastric adenocarcinoma and metachronous pyloric gland adenomas. These tumors were endoscopically resected, and immunohistochemistry with gastric mucin (i.e., MUC6, MUC5AC) showed that the tumors belonged to the gastric subtype. Somatic mutation profiles were determined by target amplicon sequencing using a next‐generation sequencer. Results Germline APC variant c.5782delC was found by direct sequencing and somatic KRAS mutations in these tumors were identified by next‐generation sequencing. Different KRAS mutation alleles (KRAS p.Gly12Ala, p.Gly12Arg, and p.Gly12Asp) indicated these dysplastic lesions developed from a distinct origin in fundic gland polyposis. Sequential mutations of the APC and KRAS were judged—based on a database search—to be characteristic of the adenoma‐carcinoma sequence in colorectal carcinogenesis. Conclusion The colonic adenoma‐carcinoma sequence among gastric adenocarcinoma and dysplastic lesions was indicated in FAP‐associated gastric carcinogenesis., Germline APC variant c.5782delC was found by direct sequencing and somatic KRAS mutations in these tumors were identified by next‐generation sequencing. The colonic adenoma‐carcinoma sequence among gastric carcinoma and dysplastic lesions was indicated in Familial adenomatous polyposis‐associated gastric carcinogenesis.

Background Tuberous Sclerosis Complex (TSC) is a complex and heterogeneous genetic disease that has well-established clinical diagnostic criteria. These criteria do not include gastrointestinal tumors. Case presentation We report a 45-year-old patient with a clinical and molecular diagnosis of TSC and a family history of cancer, presenting two rare associated findings: gastrointestinal polyposis and pancreatic neuroendocrine tumor. This patient was subjected to a genetic test with 80 cancer predisposing genes. The genetic panel revealed the presence of a large pathogenic deletion in the TSC2 gene, covering exons 2 to 16 and including the initiation codon. No changes were identified in the colorectal cancer and colorectal polyposis genes. Discussion and conclusions We describe a case of TSC that presented tumors of the gastro intestinal tract that are commonly unrelated to the disease. The patient described here emphasizes the importance of considering polyposis of the gastrointestinal tract and low grade neuroendocrine tumor as part of the TSC syndromic phenotype.

Familial adenomatous polyposis is a hereditary polyposis syndrome characterized by colorectal polyposis and eventually cancer if untreated, as well as a variety of benign and malignant extra-colonic features. Genetic testing and counselling is crucial for patients. A surveillance program for at-risk organs is essential to mitigate the risk of developing cancer. Risk reducing colectomy or proctocolectomy is a key component of management. The choice of which procedure to perform and the optimal timing depends on patient phenotype and preferences.

Turcot syndrome is a rare hereditary syndrome characterized with the clinical association of colorectal polyposis and brain tumors. Usually the time interval between either the colorectal polyposis or brain tumors presentation is about 5 years in most situation. Colorectal cancer is one of the most common cancer in adult, however it is rare to be seen before the age of 20 years, with annual incidence of 1–2 per million in the US, colorectal cancer associated with a predisposing syndrome account for about 3–4%. We report a rare case of Turcot Syndrome presenting with acute abdomen due to complicated adenocarcinomas involving the transverse colon, sigmoid and rectum in 17-year-old patient who had Glioblastoma 13 years prior to it suggesting Turcot Syndrome. Keywords: Turcot syndrome, Polyposis, Adenocarcinoma, Glioma, Pilomatrixoma

Odontomas are the most prevalent benign tumors in the mouth, they are normally diagnosed after routine X-ray examinations. Between 2010-2015, a total of 1,261 oral surgical interventions were practiced at the School of Dentistry, University of Cartagena. In them, 12 cases of odontoma were identifi ed after reviewing respective clinical histories. In some cases, when odontomas are accompanied by other characteristics, they can be associated to syndromes, such as Gardner’s syndrome. The present report informs of a case with certain characteristics such as possible presence of colorectal polyposis, supernumerary teeth and bone excrescences present in a 12 year old male, therefore, studies were undertaken to determine association to the aforementioned syndrome. Location of odontomas was an inherent characteristic and found to be altered in the previously mentioned case.

Background and objectives: Familial adenomatous polyposis is one of the APC-associated polyposis conditions described as genetically predetermined colorectal polyposis syndrome with a variety of symptoms. The purpose of this study was to determine sequence variants of the APC gene in patients with familial adenomatous polyposis (FAP) phenotype and positive or negative family history. Materials and Methods: Eight families with defined criteria of adenomatous polyposis underwent molecular genetic testing. Coding regions and flanking intron regions of the APC gene were analyzed by Sanger sequencing. Results: Eight allelic variants of the APC gene coding sequence were detected. All allelic variants of the APC gene were predicted to be pathogenic based on criteria according to the &ldquo, Joint Consensus Recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology&rdquo, (2015), four of them c.1586_1587insAT, c.2336delT, c.3066_3067insGA, and c.4303_4304insC, were considered novel. Conclusions: The timely molecular genetic analysis of APC germline variants and standardized interpretation of the pathogenicity of novel allelic variants has a high impact on choice for treatment, cancer prevention, and family genetic counseling.

Background Germline mutations affecting the exonuclease domains of POLE and POLD1 predispose to colorectal adenomas and carcinoma. Here, we aimed to screen the exonuclease domains to find the genetic causes of multiple colorectal polyps in unexplained cases. Methods Using a custom next‐generation sequencing panel, we sequenced the exonuclease domains of POLE and POLD1 in 332 index patients diagnosed with multiple colorectal polyps without germline alteration in colorectal polyposis predisposing genes. Results We identified two variants of unknown significance. One germline POLD1 c.961G>A, p.(Gly321Ser) variant was found in two cases. The first patient was diagnosed with multiple polyps at age 35 and colorectal cancer (CRC) at age 37, with no known family history of CRC. The second patient was diagnosed with CRC at age 44 and cumulatively developed multiple polyps; this patient had two sisters with endometrial cancer who did not carry the variant. Furthermore, we identified a novel POLD1 c.955 T>G, p.(Cys319Gly) variant in a patient diagnosed with multiple colorectal adenomas at age 40. Co‐segregation analysis showed that one sister who cumulatively developed multiple adenomas from age 34, and another sister who developed CRC at age 38 did not carry the variant. We did not identify pathogenic variants in POLE and POLD1. Conclusion This study confirms the low frequency of causal variants in these genes in the predisposition for multiple colorectal polyps, and also establishes that these genes are a rare cause of the disease.

BACKGROUND Almost no prospective data on endoscopy in MUTYH monoallelic carriers are available. OBJECTIVE This study aimed to define the prevalence of colorectal and duodenal adenomas in a population of people presenting with a single mutation of the MUTYH gene and being first-degree relatives of biallelic MUTYH mutation carriers. DESIGN This study is a prospective cohort evaluation. PATIENTS Patients were first-degree relatives of a patient who had polyposis with biallelic MUTYH mutation and carrying a single gene mutation of the gene from 12 French centers. SETTINGS This is a multicenter study. INTERVENTION Detailed data on life habits (tobacco, alcohol, and nonsteroidal anti-inflammatory drugs), extraintestinal manifestations, and germline analysis were recorded. Complete endoscopic evaluation (colonoscopy and upper endoscopy) with chromoendoscopy was performed. RESULTS Sixty-two patients were prospectively included (34 women (55%), mean age of 54, range 30-70 years). Thirty-two patients (52%) presented with colorectal polyps at colonoscopy. Of these patients with polyps, 15 (25%) had only adenomas, 8 (13%) had only hyperplastic polyps, 1 (1%) had sessile serrated adenomas, and 8 (13%) had adenomas and/or sessile serrated adenomas. We detected, in total, 29 adenomas with low-grade dysplasia, 5 adenomas with high-grade dysplasia, and 6 sessile serrated adenomas. Fourteen patients (23%) presented with a single adenoma, and 10 (16%) had 1 to 5 adenomas. No patient had more than 5 adenomas. At upper endoscopy, 3 had a limited number of fundic gland polyps; none had duodenal adenomas. The 2 main missense mutations c.1145G>A, p.Gly382Asp and c.494A>G, p.Tyr165Cys were associated with the development of colorectal adenomas/serrated polyps in these monoallelic carriers. LIMITATIONS This study was limited by the small number of patients. CONCLUSIONS This prospective study provides unique prospective data suggesting that monoallelic mutation carriers related to patients with polyposis show no colorectal polyposis and have very limited upper GI manifestations justifying an endoscopic follow-up. See Video Abstract at http://links.lww.com/DCR/A862.

We observed inconsistent conclusions regarding the genetic role of glutathione S-transferase gene polymorphisms, including glutathione S-transferase M1 (GSTM1), glutathione S-transferase T1 (GSTT1) present/null, and glutathione S-transferase pi (GSTP1) Ile105Val polymorphisms, in the susceptibility to nasal or colorectal polyposis (NP or CP). Thus, we aimed to perform a meta-analysis to comprehensively evaluate this association by applying Stata/SE software. After the heterogeneity assumption, Mantel–Haenszel statistics were used to obtain the odds ratio (OR), 95% confidence interval (95% CI) and P-value of the association test (PA). We obtained a total of 235 articles by searching online databases. After screening, ten eligible case–control studies were finally enrolled in our meta-analysis. For the meta-analysis of the GSTT1 gene under present versus null, we observed a decreased risk of NP [OR = 0.65; PA=0.018], but not CP. In addition, we did not detect any evident association between the GSTM1 present/null polymorphism and NP or CP risk. For the meta-analysis of the GSTP1 Ile105Val polymorphism, compared with controls, an increased risk of NP cases was detected under the models of Val versus Ile (OR = 1.36; PA=0.027), Ile/Val versus Ile/Ile (OR = 1.70; PA=0.011) and Ile/Val+Val/Val versus Ile/Ile (OR = 1.65; PA=0.010). In conclusion, the null genotype of the GSTT1 polymorphism may be linked to an increased susceptibility to NP, whereas the Ile/Val genotype of the GSTP1 Ile105Val polymorphism may be associated with a decreased risk of NP.

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.

47 Background: National Comprehensive Cancer Network (NCCN) guidelines recommend that individuals with >10 adenomatous polyps, ≥2 hamartomatous polyps, or ≥5 serrated polyps proximal to the sigmoid colon have detailed risk assessment and potential genetic testing to rule out polyposis syndrome. Here, we describe germline testing of patients with a personal history of colorectal polyposis by Cancer Genetics Counseling Services. Methods: This is an IRB-approved retrospective chart-review study. Between 2016 and 2020, 1011 unique genetic counseling visits were conducted. Germline testing was recommended by a certified genetic counselor if medically necessary. All patients with a personal history of colorectal polyposis were identified (N=20) and their germline testing results were summarized. Results: The reasons for referral to the Cancer Genetics Counseling Services were personal history of >10 adenomatous polyps (N=13), personal and family history of colorectal polyposis (N=3), personal history of juvenile colorectal polyps (N=3) or personal history of ≥2 hamartomatous polyps (N=1). The median age is 58 years-old (1-84). Ten (50%) patients were females. Caucasians, African Americans and other ethnic backgrounds represented 80%, 10% and 10% respectively. In our cohort, 6 out of 20 (30%) patients had a pathogenic germline mutation, 5 (25%) patients had variant of unknown significance (VUS) and 9 (45%) patients had negative testing. Among patients with pathogenic germline mutations, 3 patients had a pathogenic APC mutation (APC c.1659G>A, APC c.2802C>A and APC c.1643dupT) and were diagnosed with Familial Adenomatous Polyposis (FAP). One patient had 2 pathogenic MUTYH mutations (MUTYH c.536A>G and MUTYH c.1187G>A) and was diagnosed with One patient had a pathogenic PTEN c.634+5G>A mutation and was diagnosed with PTEN Hamartoma Tumor Syndrome. Among the 3 patients with a personal history of juvenile colorectal polyps, one patient had a CHEK2 c.190G>A mutation while the other two had negative genetic test results. The VUS mutations in our cohort were MRE11A c.826C>T, BLM c.3478T>C, BRCA2 c.2519T>C, CHEK2 p.V395L and CTNNA1 c.392dupT. Conclusions: In our cohort of patients with personal history of colorectal polyposis, the majority of patients (45%) had negative germline testing. An underlying pathogenic germline mutation and VUS were identified in 30% and 25% of the patients, respectively. FAP Syndrome was the most commonly diagnosed hereditary polyposis syndrome with 3 patients found to have APC germline mutations. Other pathogenic mutations were identified in the MUTYH, PTEN and CHEK2 genes. Patients with MUTYH and PTEN mutations were diagnosed with MAP and PTEN Hamartoma Tumor Syndromes respectively.

Desmoid tumor (DT) is a rare myofibroblastic proliferative neoplasm, but can occur in up to 26% of patients with familial adenomatous polyposis (FAP). Therefore, DT may be an extraintestinal manifestation of FAP that precedes the development of advanced malignancies. The aim of this study was to identify the incidence of polyps in DT patients and investigate value of colonoscopy for diagnosis of FAP in DT patients without gastrointestinal symptoms. The records of patients diagnosed with DT were retrospectively reviewed using the clinical data warehouse (CDW) system. Clinical data, including location of tumor, type(s) of treatment, and colonoscopic findings, were collected. Sixty-five patients were diagnosed with DT during the study period; 10 patients received colonoscopies before diagnosis of DT, and 20 patients received colonoscopies after diagnosis of DT. The mean age at diagnosis of DT was 41.9 ± 16.7 years old (range 17–74). Most tumors were extra-abdominal (n = 24, 80.0%), and fewer were intra-abdominal (n = 4, 13.3%) or in an abdominal wall (n = 2, 6.7%). The colonoscopy results revealed one or two tubular adenomas in 11 patients (36.6%), although none of the patients had colorectal polyposis or colorectal cancer. None of the patients in our study population had colorectal polyposis. Routine colonoscopy of DT patients without gastrointestinal symptoms seems to have low diagnostic yield for detection of FAP.

Purpose: Germ-line mutations in the exonuclease domains of POLE and POLD1 have been recently associated with polyposis and colorectal cancer (CRC) predisposition. Here, we aimed to gain a better understanding of the phenotypic characteristics of this syndrome to establish specific criteria for POLE and POLD1 mutation screening and to help define the clinical management of mutation carriers. Genet Med 18 4, 325–332. Methods: The exonuclease domains of POLE and POLD1 were studied in 529 kindred, 441 with familial nonpolyposis CRC and 88 with polyposis, by using pooled DNA amplification and massively parallel sequencing. Genet Med 18 4, 325–332. Results: Seven novel or rare genetic variants were identified. In addition to the POLE p.L424V recurrent mutation in a patient with polyposis, CRC and oligodendroglioma, six novel or rare POLD1 variants (four of them, p.D316H, p.D316G, p.R409W, and p.L474P, with strong evidence for pathogenicity) were identified in nonpolyposis CRC families. Phenotypic data from these and previously reported POLE/POLD1 carriers point to an associated phenotype characterized by attenuated or oligo-adenomatous colorectal polyposis, CRC, and probably brain tumors. In addition, POLD1 mutations predispose to endometrial and breast tumors. Genet Med 18 4, 325–332. Conclusion: Our results widen the phenotypic spectrum of the POLE/POLD1-associated syndrome and identify novel pathogenic variants. We propose guidelines for genetic testing and surveillance recommendations. Genet Med 18 4, 325–332.

Constitutional mismatch repair deficiency syndrome (CMMRD) is a rare autosomal recessive predisposition to colorectal polyposis and other malignancies, often childhood-onset, that is caused by biallelic inheritance of mutations in the same mismatch repair gene. Here, we describe a patient with a clinical diagnosis of CMMRD based on colorectal polyposis and young-onset endometrial cancer who was identified to have two alterations in trans in PMS2: one known pathogenic mutation (c.1831insA; p.Ile611Asnfs*2) and one novel variant of uncertain significance (c.505C>G; p.Arg169Glu), a missense alteration. We describe the clinical and molecular features in the patient harboring this novel alteration c.505C>G, who meets clinical criteria for CMMRD and exhibits molecular evidence supporting a diagnosis of CMMRD. Although experimental validation is needed to confirm its pathogenicity, PMS2 c.505C>G likely has functional consequences that contributes to our patient's phenotype based on the patient's clinical presentation, tumor studies, and bioinformatics analysis.

Genetic testing for hereditary colorectal polyposis/cancers has become increasingly important. Therefore, the development of a timesaving diagnostic platform is indispensable for clinical practice. We designed and validated target enrichment sequencing for 20 genes implicated in familial gastrointestinal polyposis/cancers in 32 cases with previously confirmed mutations using the HaloPlex enrichment system and MiSeq. We demonstrated that HaloPlex captured the targeted regions with a high efficiency (99.66 % for covered target regions, and 99.998 % for breadth of coverage), and MiSeq achieved a high sequencing accuracy (98.6 % for the concordant rate with SNP arrays). Using this approach, we correctly identified 33/33 (100 %) confirmed alterations including SNV, small INDELs and large deletions, and insertions in APC, BMPR1A, EPCAM, MLH1, MSH2, MSH6, PMS2, and SKT11. Our approach yielded the sequences of 20 target genes in a single experiment, and correctly identified all previously known mutations. Our results indicate that our approach successfully detected a wide range of genetic variations in a short turnaround time and with a small sample size for the rapid screening of known causative gene mutations of inherited colon cancer, such as familial adenomatous polyposis, Lynch syndrome, Peutz-Jeghers syndrome, and Juvenile polyposis syndrome.

Background and study aims To determine the clinical features associated with advanced duodenal and ampullary adenomas in familial adenomatous polyposis. Secondarily, we describe the prevalence and clinical significance of jejunal polyposis. Patients and methods This is a single center, prospective study of 62 patients with familial adenomatous polyposis. Duodenal polyposis was classified according to Spigelman and ampullary adenomas were identified. Patients with Spigelman III and IV duodenal polyposis underwent balloon assisted enteroscopy. Predefined groups according to Spigelman and presence or not of ampullary adenomas were related to the clinical variables: gender, age, family history of familial adenomatous polyposis, type of colorectal surgery, and type of colorectal polyposis. Results Advanced duodenal polyposis was present in 13 patients (21 %; 9 male) at a mean age of 37.61 ± 13.9 years. There was a statistically significant association between family history of the disease and groups according to Spigelman (P = 0.03). Seven unrelated patients (6 male) presented ampullary adenomas at a mean age of 36.14 ± 14.2 years. The association between ampullary adenomas and extraintestinal manifestations was statistically significant in multivariate analysis (P = 0.009). Five endoscopic types of non-ampullary adenoma were identified, showing that lesions larger than 10 mm or with a central depression presented foci of high grade dysplasia. Among 28 patients in 12 different families, a similar Spigelman score was identified; 10/12 patients (83.3 %) who underwent enteroscopy presented small tubular adenomas with low grade dysplasia in the proximal jejunum. Conclusions Advanced duodenal polyposis phenotype may be predictable from disease severity in a first-degree relative. Ampullary adenomas were independently associated with the presence of extraintestinal manifestations.Study registration: NCT02656134

Proctocolectomy prevents colorectal cancer in familial adenomatous polyposis (FAP). Colorectal polyp progression is one of the indications for surgery. No data exist regarding the natural history of colorectal polyposis in young patients with FAP. This study examined the rate of polyposis progression and factors associated with it.Patients with FAP 30 years old who had undergone ≥2 colonoscopies since 2000 were identified. Rate of polyposis progression was calculated by review of polyp counts obtained from baseline and last colonoscopy, accounting for any polyps removed during the observation period. Endoscopic and non-endoscopic factors affecting the rate of polyposis progression were evaluated. Multivariate analysis was performed to identify factors associated with rate of polyposis progression.One hundred sixty-eight patients (52% female; median age, 13.5 years) were included. Median rate of polyposis progression was 25.4 polyps/year (interquartile range, 9.5-69.8). Highest median rate of polyposis progression (89 polyps/year) was associated with mutation in codon 1309. The rate of polyposis progression was independently associated with the location of mutation in the adenomatous polyposis coli gene, the number of polyps at the initial colonoscopy, and exposure to chemoprevention. Of the 39.9% of patients who underwent surgery, an increase in polyp number was the most common indication (53.7%).The rate of polyposis progression in young patients with FAP varies with a median of about 25 new polyps per year. Progression is associated with distinct factors, which can be used in discussion with patients regarding the need for and timing of prophylactic colorectal surgery.

Germline MUTYH mutations were investigated in 14 Japanese colorectal polyposis patients without germ line adenomatous polyposis coli (APC) gene mutations. Three patients had a heterozygous IVS10-2A>G MUTYH mutation. The onset of MUTYH-associated polyposis (MAP) occurs later than that of familial adenomatous polyposis with germline APC mutation. Thus, we compared the carrier frequency of MUTYH IVS10-2A>G heterozygote in the APC mutation negative cases with that in 115 controls over 70 years of age who showed no apparent clinical manifestations of cancer and claimed that they had no history of cancer at the time of enrollment. The frequency of IVS10-2A>G heterozygote in APC germline mutation negative polyposis patients was significantly higher than control subject (p = 0.012, Chi square test). Although the sample size is still too small to conclude, the IVS10-2A>G MUTYH heterozygote might add to the risk of developing germline APC mutation negative polyposis.

Familial Adenomatous Polyposis (FAP) is the second most common inherited predisposition to colorectal cancer (CRC) associated with the development of hundreds to thousands of adenomas in the colon and rectum. Mutations in APC are found in ~ 80% polyposis patients with FAP. In the remaining 20% no genetic diagnosis can be provided suggesting other genes or mechanisms that render APC inactive may be responsible. Copy number variants (CNVs) remain to be investigated in FAP and may account for disease in a proportion of polyposis patients. A cohort of 56 polyposis patients and 40 controls were screened for CNVs using the 2.7M microarray (Affymetrix) with data analysed using ChAS (Affymetrix). A total of 142 CNVs were identified unique to the polyposis cohort suggesting their involvement in CRC risk. We specifically identified CNVs in four unrelated polyposis patients among CRC susceptibility genes APC, DCC, MLH1 and CTNNB1 which are likely to have contributed to disease development in these patients. A recurrent deletion was observed at position 18p11.32 in 9% of the patients screened that was of particular interest. Further investigation is necessary to fully understand the role of these variants in CRC risk given the high prevalence among the patients screened., Highlights • Catalogue of 139 CNVs unique to the polyposis patients which represent candidates for involvement in their disease • Identification of CNVs in four unrelated polyposis patients in APC, DCC, MLH1 and CTNNB1 which are likely to be associated with disease in affected individuals • A recurrent deletion at 18p11.32 was identified that affected 9% of the polyposis patients which harbours a lncRNA