A survey of phenotypic features in juvenile polyposis

Gastrointestinal Malignancy: Genetic Implications to Clinical Applications

Advances in molecular genetics have revolutionized our understanding of the pathogenesis, progression, and therapeutic options for treating gastrointestinal (GI) cancers. This chapter provides a comprehensive overview of the molecular landscape of GI cancers, focusing on key genetic alterations implicated in tumorigenesis across various anatomical sites including GIST, colon and rectum, and pancreas. Emphasis is placed on critical oncogenic pathways, such as mutations in tumor suppressor genes, oncogenes, chromosomal instability, microsatellite instability, and epigenetic modifications. The role of molecular biomarkers in predicting prognosis, guiding treatment decisions, and monitoring therapeutic response is discussed, highlighting the integration of genomic profiling into clinical practice. Finally, we address the evolving landscape of precision oncology in GI cancers, considering targeted therapies and immunotherapies.

Hamartomatous polyps: Diagnosis, surveillance, and management

Hereditary polyposis syndrome can be divided into three categories: Ade-nomatous, serrated, and hamartomatous polyps. Hamartomatous polyps, malformations of normal tissue presenting in a disorganized manner, are characterized by an autosomal dominant inheritance pattern. These syndromes exhibit hamartomatous gastrointestinal polyps in conjunction to extra-intestinal manifestations, which require conscientious and diligent monitoring. Peutz-Jeghers syndrome, Cowden syndrome, and juvenile polyposis syndrome are the most common displays of hamartomatous polyposis syndrome (HPS). Diagnosis can be pursued with molecular testing and endoscopic sampling. Early identification of these autosomal dominant pathologies allows to optimize malignancy sur-veillance, which helps reduce morbidity and mortality in both the affected patient population as well as at-risk family members. Endoscopic surveillance is an important pillar of prognosis and monitoring, with many patients eventually requiring surgical intervention. In this review, we discuss the diagnosis, surveillance, and management of HPS.

An Unexpected Anemia Hiding a Rare Syndrome With Overlapping Phenotypes

Gastric polyposis is a rare endoscopic finding that can imply genetic syndromes predisposing to cancer development. Among the possible conditions associated with gastric polyposis and early onset gastric cancer (younger than 45 years) is juvenile polyposis syndrome. We present a clinical case of early onset gastric cancer associated with a frameshift mutation in the gene SMAD4. Individuals carrying a pathogenic variant of this gene have a high risk of malignant transformation, especially of gastric cancer. Moreover, most of these patients present also with extraintestinal features of the hereditary hemorrhagic telangiectasia, and the first symptom prompting medical evaluation is anemia.

PTEN Hamartoma Syndrome in a Child Presenting With Malrotation, Panintestinal Polyps, Severe Anemia, and Protein-Losing Enteropathy

PTEN hamartoma syndrome (PTEN-HS) is a rare syndrome including neurologic, neurodevelopmental, integumentary, endocrine, and gastrointestinal manifestations. Eosinophilic disorders of the gastrointestinal system are diverse group of disorders reported to be more common in PTEN-HS. Our patient had malrotation and obstruction in infancy and subsequently developed macrocephaly and a lipoma. She presented at 4 years of age with both iron deficiency anemia and hypoalbuminemia from protein-losing enteropathy. She went on to endoscopy, colonoscopy, and video capsule endoscopy showing gastric, small intestinal, and colonic polyps but with histology including both a mixed histologic characterization of the polyps as expected with PTEN-HS, along with eosinophilic esophagitis, gastric, duodenal, colonic and polyp eosinophilia. She improved with enteral nutritional support and budesonide. Intestinal malrotation is a previously unrecognized feature of PTEN-HS, in our patient protein-losing enteropathy may have resulted from polyposis or eosinophilic gastrointestinal disorder. Albeit rare, PTEN-HS represents an elusive differential diagnosis with a broad spectrum including gastrointestinal symptomatology. Our case report illustrates the overlap of clinical, endoscopic, and histologic findings that can complicate PTEN-HS.

Management of Juvenile Polyposis Syndrome in Children and Adolescents: A Position Paper From the ESPGHAN Polyposis Working Group

The European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Polyposis Working Group developed recommendations to assist clinicians and health care providers with appropriate management of patients with juvenile polyposis. This is the first juvenile polyposis Position Paper published by ESPGHAN with invited experts. Many of the published studies were descriptive and/or retrospective in nature, consequently after incorporating a modified version of the GRADE system many of the recommendations are based on expert opinion. This ESPGHAN Position Paper provides a guide for diagnosis, assessment, and management of juvenile polyposis syndrome in children and adolescents, and will be helpful in the appropriate management and timing of procedures in children and adolescents. The formation of international collaboration and consortia is proposed to monitor patients prospectively to advance our understanding of juvenile polyposis conditions.

Malformations, choristomas, and hamartomas of the gastrointestinal tract and pancreas

Congenital and hamartomatous lesions of the gastrointestinal tract cause diagnostic challenges for surgical pathologists. Many of these are merely histologic curiosities, whereas others have substantial clinical implications because they herald cancer syndromes or associated anomalies. Although a comprehensive discussion of all developmental abnormalities that can occur in the gastrointestinal tract is beyond the scope of a single manuscript, some entities are more likely to be encountered by surgical pathologists, have important clinical consequences, or pose diagnostic difficulties. The purpose of this review is to discuss the more common malformations and choristomas, as well as hamartomatous lesions that may be clinically important due to their risk for cancer development, frequent associations with heritable cancer syndromes and other anomalies, or potential to simulate other entities.

Massive juvenile polyposis of the stomach in a family with SMAD4 gene mutation

Relatively little is known on the genotype-phenotype correlations between SMAD4 gene mutations, juvenile polyposis of the intestine and Hereditary Hemorrhagic Teleangectasia. We describe a family in which the proband (a 46-year old woman) had massive polyposis of the stomach-leading to surgery-with high-grade dysplasia at histology. Molecular analysis was carried out using Next Generation sequencing techniques with Miseq Illumina Platforms and a minimal coverage of 40 reads. In the proband, the analysis showed the presence of a truncating mutation in the SMAD4 gene (c.1213dupC, a variant previously associated with juvenile polyposis and Hereditary Hemorrhagic Teleangectasia). The same mutation was detected in two other members of the family (father and brother of the proband), who showed massive polypoid involvement of the stomach at gastroscopy. By taking the family history, subtle evidence of Hereditary Teleangectasia was found (nasal bleeding and arterovenous malformations) in the three gene carriers. Colonoscopy showed polyp occurrence in all three affected members with SMAD4 mutation, with prevalence of adenomatous lesions in one (father), of hamartomas in the brother, and of a mix of histological types in the proband. The main features of the family can be summarized as follows: (A) In hereditary juvenile polyposis, lesions of different histology can be detected at colonoscopy; (B) In the gene carriers of SMAD4 mutations, lesions of the stomach require careful surveillance and, when necessary, surgical interventions; (C) Signs and symptoms of Hereditary Hemorrhagic Teleangectasia should be suspected (and searched) in individuals with SMAD4 constitutional mutations.

Update on Hereditary Colorectal Cancer: Improving the Clinical Utility of Multigene Panel Testing

Colorectal cancer (CRC), one of the most common cancers, is a major public health issue globally, especially in Westernized countries. Up to 35% of CRCs are thought to be due to heritable factors, but currently only 5% to 10% of CRCs are attributable to high-risk mutations in known CRC susceptibility genes, predominantly the mismatch repair genes (Lynch syndrome) and adenomatous polyposis coli gene (APC; familial adenomatous polyposis). In this era of precision medicine, high-risk mutation carriers, when identified, can be offered various risk management options that prevent cancers and improve survival, including risk-reducing medication, screening for early detection, and surgery. The practice of clinical genetics is currently transitioning from phenotype-directed single gene testing to multigene panels, now offered by numerous providers. For CRC, the genes included across these panels vary, ranging from well established, clinically actionable susceptibility genes with quantified magnitude of risk, to genes that lack extensive validation or have less evidence of association with CRC and, therefore, have minimal clinical utility. The current lack of consensus regarding inclusion of genes in CRC panels presents challenges in patient counseling and management, particularly when a variant in a less validated gene is identified. Furthermore, there remain considerable challenges regarding variant interpretation even for the well established CRC susceptibility genes. Ironically though, only through more widespread testing and the accumulation of large international data sets will sufficient information be generated to (i) enable well powered studies to determine if a gene is associated with CRC susceptibility, (ii) to develop better models for variant interpretation and (iii) to facilitate clinical translation.

Malignant tumors associated with juvenile polyposis syndrome in Japan

PURPOSE

The risk of malignant tumors developing in association with juvenile polyposis syndrome (JPS) was evaluated to explore the optimal treatment for this rare disease.

METHODS

We reviewed the data on JPS cases reported in Japan between January, 1971 and March, 2016.

RESULTS

A total of 171 cases were evaluable. Of these 171 patients, 83 (48.5%) were female and the median age at diagnosis was 28 years (range 1-80 years). The polyps were located in the stomach alone (n = 62; 36.3%), in the stomach and intestine (n = 47; 27.4%), or in the colorectum alone (n = 62; 36.3%). The sites of malignant tumors were the stomach (n = 31), colorectum (n = 29), small intestine (n = 2), breast (n = 1), and thyroid (n = 1). The lifetime risk (at 70 years) of any malignant tumor was 86.2%. The lifetime risk of gastric cancer was 73.0% and that of colorectal cancer was 51.1%. The risk of these cancers developing was dependent on the type of polyp distribution.

CONCLUSIONS

Long-term surveillance of the stomach and colorectum based on the phenotype of JPS seems a reasonable approach to monitor these patients for the development of malignant tumors.

Somatic mosaicism containing double mutations in PTCH1 revealed by generation of induced pluripotent stem cells from nevoid basal cell carcinoma syndrome

BACKGROUND

Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterised by developmental defects and tumorigenesis, such as medulloblastomas and basal cell carcinomas, caused by mutations of the patched-1 (PTCH1) gene. In this article, we seek to demonstrate a mosaicism containing double mutations in PTCH1 in an individual with NBCCS.

METHODS AND RESULTS

A de novo germline mutation of PTCH1 (c.272delG) was detected in a 31-year-old woman with NBCCS. Gene analysis of two out of four induced pluripotent stem cell (iPSC) clones established from the patient unexpectedly revealed an additional mutation, c.274delT. Deep sequencing confirmed a low-prevalence somatic mutation (5.5%-15.6% depending on the tissue) identical to the one found in iPSC clones.

CONCLUSIONS

This is the first case of mosaicism unequivocally demonstrated in NBCCS. Furthermore, the mosaicism is unique in that the patient carries one normal and two mutant alleles. Because these mutations are located in close proximity, reversion error is likely to be involved in this event rather than a spontaneous mutation. In addition, this study indicates that gene analysis of iPSC clones can contribute to the detection of mosaicism containing a minor population carrying a second mutation.

De novo inbred heterozygous Zeb2/Sip1 mutant mice uniquely generated by germ-line conditional knockout exhibit craniofacial, callosal and behavioral defects associated with Mowat-Wilson syndrome

Mowat-Wilson syndrome (MOWS) is caused by de novo heterozygous mutation at ZEB2 (SIP1, ZFHX1B) gene, and exhibit moderate to severe intellectual disability (ID), a characteristic facial appearance, epilepsy and other congenital anomalies. Establishing a murine MOWS model is important, not only for investigating the pathogenesis of this disease, but also for identifying compounds that may improve the symptoms. However, because the heterozygous Zeb2 knockout mouse could not be maintained as a mouse line with the inbred C57BL/6 background, it was difficult to use those mice for the study of MOWS. Here, we systematically generated de novo Zeb2 Δex7/+ mice by inducing the Zeb2 mutation in the germ cells using conditional recombination system. The de novo Zeb2 Δex7/+ mice with C57BL/6 background developed multiple defects relevant to MOWS, including craniofacial abnormalities, defective corpus callosum formation and the decreased number of parvalbumin interneurons in the cortex. In behavioral analyses, these mice showed reduced motor activity, increased anxiety and impaired sociability. Notably, during the Barnes maze test, immobile Zeb2 mutant mice were observed over repeated trials. In contrast, neither the mouse line nor the de novo Zeb2 Δex7/+ mice with the closed colony ICR background showed cranial abnormalities or reduced motor activities. These results demonstrate the advantages of using de novo Zeb2 Δex7/+ mice with the C57BL/6 background as the MOWS model. To our knowledge, this is the first time an inducible de novo mutation system has been applied to murine germline cells to produce an animal model of a human congenital disease.

Genotype-defined cancer risk in juvenile polyposis syndrome

Background

Germline mutations in SMAD4 and BMPR1A disrupt the transforming growth factor β signal transduction pathway, and are associated with juvenile polyposis syndrome. The effect of genotype on the pattern of disease in this syndrome is unknown. This study evaluated the differential impact of SMAD4 and BMPR1A gene mutations on cancer risk and oncological phenotype in patients with juvenile polyposis syndrome.

Methods

Patients with juvenile polyposis syndrome and germline SMAD4 or BMPR1A mutations were identified from a prospectively maintained institutional registry. Medical records were reviewed and the clinical patterns of disease were analysed.

Results

Thirty-five patients had germline mutations in either BMPR1A (8 patients) or SMAD4 (27). Median follow-up was 11 years. Colonic phenotype was similar between patients with SMAD4 and BMPR1A mutations, whereas SMAD4 mutations were associated with larger polyp numbers (number of patients with 50 or more gastric polyps: 14 versus 0 respectively). The numbers of patients with rectal polyps was comparable between BMPR1A and SMAD4 mutation carriers (5 versus 17). No patient was diagnosed with cancer in the BMPR1A group, whereas four men with a SMAD4 mutation developed gastrointestinal (3) or extraintestinal (1) cancer. The gastrointestinal cancer risk in patients with juvenile polyposis syndrome and a SMAD4 mutation was 11 per cent (3 of 27).

Conclusion

The SMAD4 genotype is associated with a more aggressive upper gastrointestinal malignancy risk in juvenile polyposis syndrome.

Juvenile polyposis syndrome

Juvenile polyposis syndrome (JPS) is an autosomal dominant predisposition to the occurrence of hamartomatous polyps in the gastrointestinal tract. Diagnosis of JPS is based on the occurrence of numerous colon and rectum polyps or any number of polyps with family history and, in the case of juvenile polyps, their occurrence also outside the large intestine. The JPS is caused by mutations in SMAD4 and BMPR1A. Products of the SMAD4 gene are involved in signal transduction in the transforming growth factor β pathway and BMPR1A protein is a receptor belonging to the family of transmembrane serine/threonine kinases. Both proteins are responsible for processes determining appropriate development of colonic mucosa. The JPS belongs to the group of hamartomatous polyposes. The hamartomatous polyposis syndromes constitute a group of diseases in which manifestations differ slightly and only molecular diagnostics gives the possibility of verifying the clinical diagnosis.

The growing complexity of the intestinal polyposis syndromes

Familial adenomatous polyposis has been the first form of inherited intestinal polyposis to be recognized. For a long time it has been considered the main polyposis syndrome, associated with an easily recognizable phenotype, with a marginal role attributed to a few very rare hamartomatous conditions. More recently, it has been gradually demonstrated that the intestinal polyposes encompass a range of conditions within a wide spectrum of disease severity, polyp histology, and extraintestinal manifestations. A growing number of genes and phenotypes has been identified, and heterogeneity of somatic molecular pathways underlying epithelial transformation in different syndromes and associated tumors has been documented. Increasing knowledge on the molecular bases and more widespread use of genetic tests has shown phenotypic overlaps between conditions that were previously considered distinct, highlighting diagnostic difficulties. With the advent of next generation sequencing, the diagnosis and the classification of these syndromes will be progressively based more on genetic testing results. However, the phenotypic variability documented among patients with mutations in the same genes cannot be fully explained by different expressivity, indicating a role for as yet unknown modifying factors. Until the latter will be identified, the management of patients with polyposis syndromes should be guided by both clinical and genetic findings.

Juvenile polyposis syndrome: a study of genotype, phenotype, and long-term outcome

BACKGROUND

Juvenile polyposis syndrome is phentoypically and genotypically heterogeneous. It is associated with an increased risk of GI cancers, and surveillance is recommended. Few data exist that detail the outcomes of surveillance in juvenile polyposis syndrome.

OBJECTIVE

The aim of this study was to review clinical features, genetic mutations, and long-term outcome data in patients with juvenile polyposis syndrome.

DESIGN

This study is a retrospective review.

SETTING

The Polyposis Registry, St Mark's Hospital, was used in the performance of this study.

PATIENTS

Patients with juvenile polyposis syndrome who were followed up at our institution were included.

RESULTS

Forty-four patients (27 male) from 30 kindreds were included. Fifteen were diagnosed by screening, and 29 presented symptomatically. Nineteen patients had SMAD4 mutation and 9 had BMPR1A mutation. Five patients (11%) had valvular heart disease. Telangiectasia/vascular abnormalities were observed in 4 (9%) patients, and macrocephaly was observed in 5 (11%). Six patients (14%) developed cancer; 4 had cancer at the time of diagnosis of juvenile polyposis syndrome, 3 developed cancer while on surveillance (1 patient had a second primary). All patients with advanced upper GI disease had SMAD4 mutations. Where germline mutation was known, all patients with telangiectasia had SMAD4 mutation. Seven patients required GI surgery at our institution: colectomy and ileorectal anastomosis (1), restorative proctocolecotomy (1), anteroposterior excision for rectal cancer (1), gastrectomy (2), and laparotomy and intraoperative enteroscopy (1). There were no complications of endoscopic surveillance. Colonic polyps predominated; 535 of 767 (69.8%) of colonic polyps were right sided. One patient had a solitary significant small-bowel polyp. Sixty-five juvenile polyps contained dysplasia (mild to moderate). Two patients had severe dysplasia or cancer found in carpeting polyps.

LIMITATIONS

This is a retrospective review. The cohort size, although modest, is good for such a rare condition.

CONCLUSION

Extraintestinal features are common. Gastrointestinal surveillance is safe. Most colonic polyps are right sided, and detecting dysplasia is uncommon. Carpeting polyps are of particular concern.

Hereditary colon cancer syndromes

Colon cancer is associated with a family history in up to 25% of cases. As many as 5% are associated with an established hereditary syndrome, demonstrating the profound influence of inheritable genetic mechanisms in the development of this disease. These syndromes confer a diverse spectrum of risk, age of presentation, endoscopic and histological findings, extracolonic manifestations, and modes of inheritance. As the molecular characteristics of these disorders become better described, enhanced genotype-phenotype correlations may offer a more targeted approach to diagnosis, screening, and surveillance. While the strategies for diagnosis and management of familial adenomatous polyposis (FAP) and Lynch syndrome are more established, the approach to newly recognized syndromes such as MUTYH-associated polyposis (MAP) and hyperplastic polyposis syndromes continues to evolve. Effective cancer prevention in affected individuals and at-risk family members first requires timely recognition of these hereditary colon cancer syndromes followed by integration of genetic testing and clinical examinations.

[Colorectal polyposis syndrome: a guide to diagnosis]

Biopsies and resection specimens of the gastrointestinal tract are a major part of the routine workload in many histopathology departments, whereby polypoid lesions are generally the main focus. In addition to distinguishing non-neoplastic from neoplastic polyps and evaluating the grade of dysplasia of the latter, the pathologist should always consider the possibility of an underlying polyposis syndrome. Not only have additional hereditary polyposis syndromes been identified in recent years due to a better understanding of their genetic and epigenetic alterations but also knowledge on well known polyposes has improved, leading to subtyping of various forms according to their different genotype. It is essential for the histopathologist to understand that the conventional histomorphology of individual polyps combined with information on the number and distribution of these lesions and clinical data can provide clues regarding a possible hereditary background. Therefore, the correct histological assessment of polyps is not just about getting the diagnosis right, it might also lead to genetic screening of family members and spouses.

Overlapping spectra of SMAD4 mutations in juvenile polyposis (JP) and JP-HHT syndrome

Juvenile polyposis (JP) and hereditary hemorrhagic telangiectasia (HHT) are clinically distinct diseases caused by mutations in SMAD4 and BMPR1A (for JP) and endoglin and ALK1 (for HHT). Recently, a combined syndrome of JP-HHT was described that is also caused by mutations in SMAD4. Although both JP and JP-HHT are caused by SMAD4 mutations, a possible genotype:phenotype correlation was noted as all of the SMAD4 mutations in the JP-HHT patients were clustered in the COOH-terminal MH2 domain of the protein. If valid, this correlation would provide a molecular explanation for the phenotypic differences, as well as a pre-symptomatic diagnostic test to distinguish patients at risk for the overlapping but different clinical features of the disorders. In this study, we collected 19 new JP-HHT patients from which we identified 15 additional SMAD4 mutations. We also reviewed the literature for other reports of JP patients with HHT symptoms with confirmed SMAD4 mutations. Our combined results show that although the SMAD4 mutations in JP-HHT patients do show a tendency to cluster in the MH2 domain, mutations in other parts of the gene also cause the combined syndrome. Thus, any mutation in SMAD4 can cause JP-HHT. Any JP patient with a SMAD4 mutation is, therefore, at risk for the visceral manifestations of HHT and any HHT patient with SMAD4 mutation is at risk for early onset gastrointestinal cancer. In conclusion, a patient who tests positive for any SMAD4 mutation must be considered at risk for the combined syndrome of JP-HHT and monitored accordingly.

Inherited cancer syndromes in children and young adults

Geneticists estimate that 5% to 10% of all cancers diagnosed in the pediatric age range occur in children born with a genetic mutation that directly increases their lifetime risk for neoplasia. However, despite the fact that only a fraction of cancers in children occur as a result of an identified inherited predisposition, characterizing genetic mutations responsible for increased cancer risk in such syndromes has resulted in a profound understanding of relevant molecular pathways involved in carcinogenesis and/or resistance to neoplasia. Importantly, because most cancer predisposition syndromes result in an increased risk of a small number of defined malignancies, personalized prophylactic surveillance and preventive measures can be implemented in affected patients. Lastly, many of the same genetic targets identified from cancer-prone families are mechanistically involved in the majority of sporadic cancers in adults and children, thereby underscoring the clinical relevance of knowledge gained from these defined syndromes and introducing novel therapeutic opportunities to the broader oncologic community. This review highlights the clinical and genetic features of many of the known constitutional genetic syndromes that predispose to malignancy in children and young adults.

Hereditary hamartomatous polyposis syndromes: understanding the disease risks as children reach adulthood

Hamartomatous polyposis syndromes are a rare group of hereditary autosomal dominant disorders that comprise less than 1% of all hereditary colorectal cancers. Hamartomatous polyps, in and of themselves, are benign entities; however, these hamartomatous polyposis syndromes have a malignant potential for the development of colorectal cancer as well as extracolonic cancers. Early detection and proper surveillance are vital to minimizing the risk of carcinoma. This article provides a critical review of the clinical presentation, pathology, genetics, and screening and surveillance guidelines of juvenile polyposis syndrome, PTEN hamartoma tumor syndrome, and Peutz-Jeghers syndrome.

Matrix metalloproteinases in the urine and tissue of patients with juvenile polyps: potential biomarkers for the presence of polyps

BACKGROUND AND AIMS

Juvenile polyps are the most common type of pediatric gastrointestinal polyp and are typically characterized as hamartomatous overgrowths. Juvenile polyps are highly vascularized tissues and display a markedly increased mucosal microcirculation. Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes that play an essential role in the physiological degradation of the extracellular matrix in normal development, tumor invasion, and metastasis, as well as angiogenesis. We hypothesized that the presence of these enzymes in urine may serve as clinical biomarkers of juvenile polyps.

PATIENTS AND METHODS

In this preliminary study, we analyzed 32 urine samples collected prospectively from 16 subjects with known or suspected juvenile polyps who presented to the endoscopy unit for colonoscopic evaluation and 16 age- and sex-matched controls. Urinary MMPs were analyzed by zymography and their localized tissue expression was assayed via immunohistochemistry of tissue sections.

RESULTS

MMPs were detected in the urine of patients with juvenile polyps with significantly higher frequency when compared with urine of control subjects. In addition, immunohistochemistry demonstrated that high levels of MMPs were localized in the epithelium and lamina propria of polyp tissue when compared with colonic tissue collected from healthy control subjects.

CONCLUSIONS

These data are the first to demonstrate that MMPs are present in the urine and tissue of patients with juvenile polyps, and these enzymes have the potential to serve as surrogate markers for the presence of polyps.

[Sporadic colonic juvenile polyps in adults]

Sporadic colonic juvenile polyps are uncommon in adults. We report three cases for which clinical manifestations were presence of occult blood in the stool, rectal bleeding or chronic diarrhea. Two of these polyps occurred in the caecum which is an uncommon localisation. Endoscopic characteristics of these polyps were indistinguishable from adenomas. Endoscopic resection was complicated in one case by bleeding.

High proportion of large genomic deletions and a genotype phenotype update in 80 unrelated families with juvenile polyposis syndrome

BACKGROUND

In patients with juvenile polyposis syndrome (JPS) the frequency of large genomic deletions in the SMAD4 and BMPR1A genes was unknown.

METHODS

Mutation and phenotype analysis was used in 80 unrelated patients of whom 65 met the clinical criteria for JPS (typical JPS) and 15 were suspected to have JPS.

RESULTS

By direct sequencing of the two genes, point mutations were identified in 30 patients (46% of typical JPS). Using MLPA, large genomic deletions were found in 14% of all patients with typical JPS (six deletions in SMAD4 and three deletions in BMPR1A). Mutation analysis of the PTEN gene in the remaining 41 mutation negative cases uncovered a point mutation in two patients (5%). SMAD4 mutation carriers had a significantly higher frequency of gastric polyposis (73%) than did patients with BMPR1A mutations (8%) (p<0.001); all seven cases of gastric cancer occurred in families with SMAD4 mutations. SMAD4 mutation carriers with gastric polyps were significantly older at gastroscopy than those without (p<0.001). In 22% of the 23 unrelated SMAD4 mutation carriers, hereditary hemorrhagic telangiectasia (HHT) was also diagnosed clinically. The documented histologic findings encompassed a wide distribution of different polyp types, comparable with that described in hereditary mixed polyposis syndromes (HMPS).

CONCLUSIONS

Screening for large deletions raised the mutation detection rate to 60% in the 65 patients with typical JPS. A strong genotype-phenotype correlation for gastric polyposis, gastric cancer, and HHT was identified, which should have implications for counselling and surveillance. Histopathological results in hamartomatous polyposis syndromes must be critically interpreted.

Café au lait macules and juvénile polyps

Several hereditary and nonhereditary gastrointestinal tract polyposis syndromes exhibit extra-intestinal manifestations, including cutaneous findings. However, a lack of information exists regarding cutaneous features of juvenile polyposis. Our objective was to document the prevalence of cutaneous hyperpigmented lesions in children with juvenile polyposis coli or juvenile polyposis coli and their first degree relatives.Children seen in the gastroenterology practice at The Children's Hospital in Denver, Colorado with polyps (juvenile polyposis coli, sporadic juvenile polyps, and familial adenomatous polyposis coli) and their first degree relatives were invited to participate in the study. A comprehensive skin examination was performed on those who consented to participate. We found that 8 of 14 patients (eight with juvenile polyposis coli, four with juvenile polyposis, and two with familial adenomatous polyposis coli) had at least one café-au-lait macule, compared with three of 27 relatives (p=0.003).The prevalence of at least one café-au-lait macule in our patients (8/14 or 57.1%, CI: 28.9–82.3%) was significantly higher than the general population prevalence of 28.5% (p=0.023). However, if the two patients with familial adenomatous polyposis coli were excluded, the comparison with the general population prevalence did not reach statistical significance (p=0.095). The prevalence of multiple cafe´-au-lait macules in our patients (4/14 or 28.6%; CI:8.4–58.1%) was significantly higher than the general population prevalence of 5.2% (p ¼ 0.005). A notable finding was the presence of multiple café -au-lait macules in 4 of 12 juvenile polyposis coli/juvenile polyposis patients.Two patients with juvenile polyposis coli also had lentigines. In this selected case series, we observed single or multiple café-au-lait macules in a high proportion of children with the three types of polyps. Further studies are needed to assess a possible common pathway for hamartomatous polypsand café-au-lait macules.

Mutation screening in juvenile polyposis syndrome

Juvenile polyposis syndrome (JPS) is an autosomal dominant cancer predisposition syndrome characterized by congenital anomalies, hamartomatous polyps in the gastrointestinal tract, and the development of tumors in these tissues. The diagnosis of JPS is often difficult because of the phenotypic overlap with other hamartomatous polyposis syndromes. Germline mutations have been identified in MADH4 and BMPR1A, aiding in presymptomatic genetic testing. In this study, we describe the results from 3 years of molecular diagnostic screening in JPS. Seventy unrelated individuals referred to our lab for JPS testing were examined through the sequence analysis of coding regions and exon-intron boundaries in both genes. Germline mutations were identified in 30% of cases, with 11.4% in BMPR1A and 18.6% in MADH4. All mutation-positive individuals were negative for cancer at testing, and a single pulmonary valve stenosis was the only congenital anomaly reported. A majority of mutations identified were novel including the first splice site alteration in MADH4. Based on the limited number of exons in each gene, low polymorphism frequency, and high frequency of frameshift or nonsense mutations identified, direct sequence analysis is a suitable methodology for mutation screening if all coding regions and exon-intron boundaries are examined in both genes.

Inherited polyposis syndromes: molecular mechanisms, clinicopathology, and genetic testing

The inherited polyposis syndromes are a group of conditions in which multiple gastrointestinal polyps occur in the lumen of the gastrointestinal tract, most exhibit an increased risk of colon cancer. Benign and malignant extraintestinal tumors might also be observed. Recent elucidation of the underlying gene mutations has contributed to our understanding of the cell biology and molecular mechanisms associated with gastrointestinal tumorigenesis. Developments have also allowed genetic testing to become an integral component in accurate diagnosis, categorization, and management of inherited polyposis syndromes. In this review, we will focus on familial adenomatous polyposis, mutY human homologue-associated polyposis, Peutz-Jeghers syndrome, juvenile polyposis, and Cowden syndrome. It is essential that both physician and patient understand the benefits and limitations of genetic testing before submission of samples to the laboratory. There are many issues accompanying molecular diagnosis of cancer syndromes, and genetic counseling is an essential prelude to genetic testing.

Genetic testing for inherited colon cancer

The genes associated with each of the inherited syndromes of colon cancer have now been identified, and genetic testing is available for diagnosis. These syndromes include familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer, Peutz-Jeghers syndrome, juvenile polyposis syndrome, and, possibly, Cowden's syndrome. Clinical genetic testing approaches have been developed for each of these syndromes and are now a part of accepted clinical care. Disease-causing mutations can be found in the majority of families affected with one of the inherited syndromes, and, most importantly, once a mutation is found in an index case of the family, relatives can be tested for the presence or absence of that mutation with near 100% accuracy. Cancer screening and management in syndrome families is then based on the results of genetic testing. For the physician to order and properly interpret genetic tests, a basic understanding of the types of mutations that lead to inherited disease and the methods for detecting them is vital. These issues will be presented. Additional clinical issues somewhat unique to genetic testing include genetic counseling and informed consent for genetic testing, both of which will also be reviewed. Often the most difficult aspect of genetic testing is deciding which patients and families should undergo the testing. Furthermore, this issue is quite specific for each of the syndromes. Thus, following presentation of general principles of selection for genetic testing, a detailed approach for identifying persons who should undergo testing for each of the individual syndromes will be given, together with relevant descriptions of the syndromes. Finally, the ongoing work to discover new and possibly more common but less penetrant colon cancer susceptibility genes that cause common familial colon cancer will be presented.

Genetics of hereditary colorectal cancer

Genetic factors can dramatically influence the risk of colorectal cancer, and the molecular bases of many hereditary colorectal cancer syndromes, including familial adenomatous polyposis (FAP), attenuated FAP (AFAP), and hereditary nonpolyposis colorectal cancer (HNPCC) have been elucidated. Additional syndromes continue to be defined as new genes, including MYH , are linked to the development of colonic polyps and cancer. The risks of colorectal cancer are variable and depend on the specific germline alterations. Some mutations are associated with a 100% lifetime risk of developing cancer, while others are associated with only a mild increase in risk. Although there are overlapping clinical features in many of these syndromes, they can be distinguished by the age at cancer diagnosis, inheritance pattern, number and distribution of polyps, specific histologic features of the cancers, and the presence of distinctive extracolonic features. The introduction and refinement of genetic testing has provided a new and invaluable tool for the diagnosis and assessment of cancer risk for suspected cases of hereditary colon cancer.

The hamartomatous polyposis syndromes: a clinical and molecular review

Inherited forms of gastrointestinal cancer have been a major focus of study and advancement over the past decade. Familial adenomatous polyposis and hereditary nonpolyposis colon cancer are the two most common heritable colon cancer syndromes. Inherited polyposis syndromes are characterized by the dominant type of polyp (whether adenomatous or hamartomatous) present and by the polyp's location within the gastrointestinal tract. The hamartomatous polyposis syndromes are characterized by an overgrowth of cells native to the area in which they normally occur. They represent a small but appreciable number of the gastrointestinal inherited cancer predisposition syndromes; it is now known that many of these syndromes carry a substantial risk for developing colon cancer as well as other gastrointestinal and pancreatic cancers. Patients afflicted with these syndromes are also at significant risk for extraintestinal malignancies. Seven inherited hamartomatous polyposis syndromes have been described: familial juvenile polyposis syndrome, Cowden's syndrome, Bannayan-Ruvalcaba-Riley syndrome, Peutz-Jeghers syndrome, basal cell nevus syndrome, neurofibromatosis 1, and multiple endocrine neoplasia syndrome 2B. Hereditary mixed polyposis syndrome is a variant of juvenile polyposis characterized by both hamartomatous and adenomatous polyps. The hamartomatous syndromes occur at approximately 1/10th the frequency of the adenomatous syndromes and account for <1% of colorectal cancer in Northern America. While the diagnosis of these inherited syndromes is primarily clinical, genetic testing is now available for all six syndromes. However, there are a significant number of spontaneous mutations seen in each of the syndromes. The management of these patients necessitates a coordinated multidisciplinary approach. The purpose of this review is to characterize the clinical and pathological features of these syndromes and to review the targets of cancer surveillance. The molecular alterations responsible for the inherited hamartomatous polyposis syndromes will also be discussed.

Characteristics of familial juvenile polyps expressing cyclooxygenase-2

OBJECTIVES

Familial juvenile polyposis (FJP) is a dominant genetic disorder characterized by colorectal, gastric, and small bowel juvenile polyps, and high risk for gastrointestinal cancer. Patients are treated by repeated endoscopic polypectomies and elective surgery. We determined the characteristics of FJP polyps expressing cyclooxygenase-2 (COX-2).

METHODS

A total of 115 colorectal and 6 gastric polyps were available from 17 FJP patients. Comparison tissues were 18 sporadic juvenile colorectal polyps, 6 gastric hyperplastic polyps, 9 normal colons, and 3 colorectal cancers (CRCs). Histology sections were classified and stained for COX-2. The polyps' epithelium and stroma and comparison tissues were quantified for COX-2 by: area of staining (0-3) x intensity (0-3). Epithelial and stromal scores (0-9) and total scores (0-18) were evaluated in relationship to patient's age, polyp site, size, dysplasia, and stromal cellularity.

RESULTS

Colonic FJP polyps mean total COX-2 score was 10.3 +/- 6.0, and that of sporadic juvenile polyps 3.6 +/- 2.2 (p < 0.01), and in contrast to the latter, FJP COX-2 scores increased significantly (p < 0.01) with polyp size. Linear regression analysis showed significant associations of COX-2 in FJP polyps with dysplasia (p < 0.01), stromal cellularity (p < 0.01), size (> or =1.5 cm) (p= 0.02), and site (right colon) (p= 0.01), and not with age. COX-2 total scores of gastric FJP polyps and hyperplastic polyps were similar.

CONCLUSIONS

Expression of COX-2 in FJP polyps and its association with size and dysplasia suggest that, in these patients, chemoprevention with selective COX-2 inhibitors might be a useful adjunct therapy to colonoscopic polypectomy.

Highly penetrant hereditary cancer syndromes

The past two decades have brought many important advances in our understanding of the hereditary susceptibility to cancer. Approximately 5-10% of all cancers are inherited, the majority in an autosomal dominant manner with incomplete penetrance. While this is a small fraction of the overall cancer burden worldwide, the molecular genetic discoveries that have resulted from the study of families with heritable cancer have not only changed the way these families are counselled and managed, but have shed light on molecular regulatory pathways important in sporadic tumour development as well. In this review, we consider 10 of the more highly penetrant cancer syndromes, with emphasis on those predisposing to breast, colon, and/or endocrine neoplasia. We discuss the prevalence, penetrance, and tumour spectrum associated with these syndromes, as well as their underlying genetic defects.

A combined syndrome of juvenile polyposis and hereditary haemorrhagic telangiectasia associated with mutations in MADH4 (SMAD4)

BACKGROUND

Juvenile polyposis and hereditary haemorrhagic telangiectasia are autosomal dominant disorders with distinct and non-overlapping clinical features. The former, an inherited gastrointestinal malignancy predisposition, is caused by mutations in MADH4 (encoding SMAD4) or BMPR1A, and the latter is a vascular malformation disorder caused by mutations in ENG (endoglin) or ACVRL1 (ALK1). All four genes encode proteins involved in the transforming-growth-factor-beta signalling pathway. Although there are reports of patients and families with phenotypes of both disorders combined, the genetic aetiology of this association is unknown.

METHODS

Blood samples were collected from seven unrelated families segregating both phenotypes. DNA from the proband of each family was sequenced for the ACVRL1, ENG, and MADH4 genes. Mutations were examined for familial cosegregation with phenotype and presence or absence in population controls. Findings No patient had mutations in the ENG or ACVRL1 genes; all had MADH4 mutations. Three cases of de-novo MADH4 mutations were found. In one, the mutation was passed on to a similarly affected child. Each mutation cosegregated with the syndromic phenotype in other affected family members.

INTERPRETATION

Mutations in MADH4 can cause a syndrome consisting of both juvenile polyposis and hereditary haemorrhagic telangiectasia phenotypes. Since patients with these disorders are generally ascertained through distinct medical specialties, genetic testing is recommended for patients presenting with either phenotype to identify those at risk of this syndrome. Patients with juvenile polyposis who have an MADH4 mutation should be screened for the vascular lesions associated with hereditary haemorrhagic telangiectasia, especially occult arteriovenous malformations in visceral organs that may otherwise present suddenly with serious medical consequences.

Genetic conditions associated with intestinal juvenile polyps

Juvenile polyps are hamartomatous polyps found primarily in infants and children, and in association with juvenile polyposis (JP; OMIM #174900), Cowden syndrome (CS; OMIM #158350), and Bannayan-Riley-Ruvalcaba syndrome (BRRS; OMIM# 153480). Although solitary juvenile polyps are benign lesions, when present in JP patients they may lead to gastrointestinal cancers. Germline mutations in MADH4 and BMPR1A predispose to JP, and both genes are involved in TGF-beta superfamily signaling pathways. In CS and BRRS, juvenile polyps are a less consistent feature, and CS patients are at risk for breast and thyroid cancers. Mutations of the tumor suppressor gene PTEN have been found in the germline of both CS and BRRS patients. Despite different underlying genetic mechanisms, these and other syndromes share the same phenotypic feature of juvenile polyps.

Clinical management of hereditary colorectal cancer syndromes

PURPOSE OF REVIEW

Colorectal cancer is the second leading cause of cancer-related death in the United States. Although most colorectal cancers are sporadic, approximately 25% have a familial predisposition, and 5 to 7% are hereditary and occur in genetically distinct high-risk families. This review focuses on four hereditary colon cancer syndromes: familial adenomatosus polyposis, hereditary nonpolyposis colorectal cancer, juvenile polyposis syndrome, and Peutz-Jeghers syndrome.

RECENT FINDINGS

The management of the inherited colorectal cancer syndromes has progressed substantially over the past years because of advancement of genetic understanding and testing options, which have led to the possibility of preclinical diagnosis and early surveillance and treatment. Genetic testing is based on identification of specific abnormalities and should be combined with counseling of affected families.

SUMMARY

Recent advances have contributed to the understanding of the molecular basis of various types of colorectal cancer, and among these, the inherited colorectal cancer syndromes have attracted much attention. Expanding recognition of clinical characteristics, targeted surveillance strategies and new methods of treatment have led to improved clinical management of these syndromes.

Genetic predisposition as a basis for chemoprevention, surgical and other interventions in colorectal cancer

Strategies of cancer prevention are generally developed with the population at large in mind. However, special attention is warranted for those persons with rare genetic traits associated with a greatly elevated risk of developing colorectal cancer (CRC) and some other malignancies: Orphan diseases demand Orphan preventive measures! Recent advances in modern genetics have enhanced our understanding of several genes and the specific germ-line mutations responsible for colorectal carcinogenesis. A number of features provide evidence for a genetic predisposition to CRC. These include typical clinical and histological features of a particular syndrome, a familial aggregation of CRC and associated malignancies, young age at onset of CRC, occurrence of multiple neoplasias and/or unusual localisation of the tumour (e.g., right side of the colon). In hereditary colorectal cancer, genetic testing can easily be demonstrated as cost-effective.

An audit of familial juvenile polyposis at the Tel Aviv Medical Center: demographic, genetic and clinical features

Familial juvenile polyposis (JP) is an uncommon genetic disorder that, if untreated, can lead to gastrointestinal cancer. To evaluate familial JP prevalence, phenotypic manifestations, causative mutations, treatment and compliance for diagnosis and follow-up in our registry. Since 1993 our familial JP patients were registered, followed-up before and/or after surgery and their families encouraged to have mutation analysis, endoscopic screening and treatment. Ten pedigrees were identified, all Jewish, but only one was Ashkenazi, six were Sepharadi and three were Oriental; the only mutation found was BMPR1A in two of six pedigrees examined. Of 139 first-degree relatives at risk for JP, 62 (45%) had JP or cancer; 56 (40.3%) were available for follow-up and 35 entered the registry. Of these, 71% reported rectal bleeding, 40% had <20 colonic polyps, 31% had 20-100 polyps; 2 had >100 gastric polyps. Cancer occurred in 22.9% (6 colonic, 2 gastric) before familial JP diagnosis or during follow-up elsewhere or non-compliance for follow-up; however, 1 gastric cancer developed during our treatment. In 46% the initial clinical-pathological diagnosis was incorrect. Compliance for evaluation and follow-up of pedigree members and individual familial JP patients was inadequate in 20% and 26%, respectively. Familial JP does not occur in the Israeli Ashkenazi Jewish population at the expected proportion; it is often misdiagnosed and is inadequately recognized in Israeli non-Jews. Mutations were identified in only a minority of pedigrees despite comprehensive screening. The inadequate compliance for screening and follow-up needs to be addressed by educating the public, health care workers and health insurances.

Gastrointestinal polyposis in childhood: clinicopathologic and genetic features

Gastrointestinal polyps and certain extraintestinal lesions in children may herald a hereditary polyposis syndrome, with an increased risk of neoplasia and other health problems for both children and their relatives. The availability of molecular/genetic screening tests has increased early diagnosis of younger members of known polyposis families. This article reviews the gross and microscopic features of polyposis syndromes of childhood and summarizes the molecular/genetic advances in this field. Clinical management is also briefly discussed.

Genetic testing for high-risk colon cancer patients

Colorectal cancer is the third leading cause of cancer-related deaths in both men and women in the United States and is estimated to have affected 148,000 people in 2002. The cumulative lifetime risk for colon cancer is approximately 5%-6%, and this risk is influenced by hereditary and lifestyle factors. In fact, 20%-30% of all colon cancer cases have a potentially definable inherited cause, and 3%-5% of colon cancers occur in genetically defined high-risk colon cancer family syndromes. Although the genes responsible for the cases of moderate-risk colon cancer remain to be characterized, many of the genes responsible for the high-risk colon cancer cases have already been determined. These genetic discoveries have been translated into clinical practice and have led to improved risk assessment through the use of genetic testing. The introduction into clinical practice of genetic testing for the assessment of colon cancer risk has led to more effective management strategies for patients with potentially high-risk colon cancer and has presented new challenges to the clinician because of the unique issues involved with genetic testing. In this review, an overview of the colon cancer high-risk syndromes, with a focus on the availability and indications for genetic testing, is presented.

Molecular etiology of gut malformations and diseases

This review describes recent advances using animal models in the analysis of the molecular controls of gastrointestinal development, with specific attention to mutations causing maldevelopment similar to those seen in human gut malformations. By focusing on specific human gut pathologic conditions and maldevelopment, we describe the probable roles of signaling pathways, including the hedgehog pathway, the bone morphogenic protein pathway, and the role of the homeotic genes.

Gastrointestinal polyps and polyposis syndromes in children

Gastrointestinal polyps are common during childhood and most often present with painless rectal bleeding. Most polyps occur as isolated colonic lesions and are not harbingers of an underlying genetic disorder, nor do they bestow a risk of gastrointestinal cancer. The astute pediatrician must be aware, however, that occasionally polyps may occur in the context of a genetic polyposis disorder characterized by an increase in the life-time risk of cancer in the gastrointestinal tract and other organ systems. This review outlines the major polyposis syndromes affecting children and highlights associated findings that might clue the alert physician to an underlying diagnosis. Recent developments in the understanding of the genetics of each disorder are emphasized.

Colorectal cancer screening

During the past decade we have seen dramatic advances in colon cancer screening. Reduction in mortality in average risk screening for colorectal cancer has now been shown in multiple trials. Efforts to increase public awareness and compliance with evidence-based screening guidelines are underway. Recent guidelines have incorporated family history, as it has been identified as a common risk factor. The genes responsible for the inherited syndromes of colon cancer have been identified and genetic testing is available. Currently, screening the average risk population over the age of 50 would reduce mortality from colon cancer by 50%. Future advances will likely include improved screening tests, and the development of familial genetic testing.

Secondary prevention: screening and surveillance of persons at average and high risk for colorectal cancer

Secondary prevention of colorectal cancer with FOBT and endoscopy with polypectomy decreases cancer deaths. Other available modalities include genetic tests and imaging studies, but outcomes data are not yet available. Issues remain concerning the most appropriate test, the optimal intervals, and cost-efficacy. Patients may be stratified by personal and family risk, and specific strategies may be used. Newer developments in genetic tests and imaging, including virtual colonoscopy, hold promise for the future. The most important issue at present is to have people screened or surveilled by any of the recommended modalities.

Hereditary hemorrhagic telangiectasia in association with generalised juvenile polyposis

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Genetic predisposition and somatic diversification in tumor development and progression

Studies on human cancer predisposition syndromes have contributed significantly to our understanding on tumor initiation and progression. Work performed on hereditary colon cancer has been particularly fruitful. Much of the molecular background of the various intestinal polyposis syndromes, such as familial adenomatous polyposis (FAP), juvenile polyposis, and Peutz-Jeghers syndrome, has been revealed, pinpointing several key cancer-associated genes. Studies on hereditary nonpolyposis colorectal cancer (HNPCC) have revealed a novel mechanism of tumorigenesis; genomic instability caused by defective DNA mismatch repair (MMR). Understanding the molecular background of these diseases helps us to understand tumor initiation in the affected individuals. Relatively little is known about the details of tumor progression in hereditary and sporadic neoplasia. Certain additional gene mutations can be associated with advancing stages of the disease, but the pace and tempo of the process have remained obscure. A high mutation rate in MMR-deficient tumors has provided a new approach in the analysis of human tumor dynamics. Microsatellite (MS) sequences are frequently mutated in MMR deficient tumors. The high mutation rate allows the use of microsatellite mutations as a tool for analyzing the past patterns of tumor progression. This approach is similar to the use of MS mutations in studying human evolution and migrations. Such tumor studies have revealed progression pathways that differ from the classic adenoma-cancer sequence. The reasons why and how molecular clocks may reveal something new about a well-studied problem are discussed.