Deletion of PTEN and BMPR1A on chromosome 10q23 is not always associated with juvenile polyposis of infancy

SHH medulloblastoma and very early onset of bowel polyps in a child with PTEN hamartoma tumor syndrome

Phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome (PHTS) is a cancer predisposition syndrome characterized by an increased risk of developing benign and malignant tumors, caused by germline pathogenic variants of the PTEN tumour suppressor gene. PTEN gene variants often present in childhood with macrocephaly, developmental delay, and/or autism spectrum disorder while tumors and intestinal polyps are commonly detected in adults. PHTS is rarely associated with childhood brain tumors with only two reported cases of medulloblastoma (MB). We report the exceptional case of an infant carrying a germline and somatic pathogenic variant of PTEN and a germline and somatic pathogenic variant of CHEK2 who developed a MB SHH in addition to intestinal polyposis.

Genotype-phenotype correlation of BMPR1a disease causing variants in juvenile polyposis syndrome

BACKGROUND

Juvenile Polyposis Syndrome (JPS) is an autosomal dominant condition with hamartomatous polyps in the gastrointestinal tract, associated with an increased risk of gastrointestinal malignancy. Disease causing variants (DCVs) in BMPR1a or SMAD4 account for 45-60% of JPS cases, with BMPR1a DCVs accounting for 17-38% of JPS cases. Within those with either a BMPR1a or SMAD4 DCV, there is phenotypic variability in location of polyps, risk of malignancy and extra-intestinal manifestations with limited published reports of gene-phenotype association or genotype-phenotype correlation. We aimed to identify any gene-phenotype association or genotype-phenotype correlation in BMPR1a to inform surveillance recommendations, and gene-specific modification to the ACMG classification of pathogenicity of DCVs.

METHODS

A literature search was performed through EMBASE, MEDLINE and PubMed. Studies that were included explored BMPR1a DCV-related JPS or contiguous deletion of PTEN and BMPR1a. Data was also drawn from the BMPR1a specific databases on LOVD and ClinVar.

RESULTS

There were 211 DCVs in BMPR1a identified, 82 from patients with JPS in the literature, and 17 from LOVD and 112 from ClinVar classified as pathogenic or likely pathogenic. These included missense, nonsense and frameshift variants and large deletions, occurring across all functional domains of the gene. Unlike in SMAD4 carriers, gastric polyposis and malignancy were not identified in our review in BMPR1a carriers, but colonic polyposis and malignancy occurred in carriers of either BMPR1a or SMAD4 DCVs. Those with contiguous deletion of PTEN and BMPR1a can present with JPS of infancy, with a severe phenotype of GI bleeding, diarrhoea, exudative enteropathy and rectal prolapse. No specific BMPR1a genotype-phenotype correlation could be ascertained including by variant type or functional domain.

CONCLUSION

Phenotypic characteristics cannot be used to inform variant location in BMPR1a. However, the phenotypic characteristics of BMPR1a DCV carriers, being almost exclusively related to the colon and rectum, can assist in pathogenicity assessment of BMPR1a variants. Given these findings, we propose that carriers of BMPR1a DCVs should only require surveillance for colorectal polyps and malignancy, and that surveillance for gastric polyps and malignancy may be unnecessary. However variant location within BMPR1a does not support differential surveillance recommendations.

PTEN Hamartoma tumor syndrome in childhood: A review of the clinical literature

PTEN hamartoma tumor syndrome (PHTS) is a highly variable autosomal dominant condition associated with intellectual disability, overgrowth, and tumor predisposition phenotypes, which often overlap. PHTS incorporates a number of historical clinical presentations including Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome, and a macrocephaly-autism/developmental delay syndrome. Many reviews in the literature focus on PHTS as an adult hamartoma and malignancy predisposition condition. Here, we review the current literature with a focus on pediatric presentations. The review starts with a summary of the main conditions encompassed within PHTS. We then discuss PHTS diagnostic criteria, and clinical features. We briefly address rarer PTEN associations, and the possible role of mTOR inhibitors in treatment. We acknowledge the limited understanding of the natural history of childhood-onset PHTS as a cancer predisposition syndrome and present a summary of important management considerations.

Variable Features of Juvenile Polyposis Syndrome With Gastric Involvement Among Patients With a Large Genomic Deletion of BMPR1A

Loss-of-function mutations of BMPR1A cause juvenile polyposis syndrome (JPS), but large genomic deletions in BMPR1A are rare, reported in few families only, and data regarding the associated phenotype are limited.

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.

Pathology and Genetics of Syndromic Gastric Polyps

Gastric polyps are found in 1% to 4% of patients undergoing gastroscopy. The vast majority are sporadic, but some gastric polyps indicate an underlying syndrome. Gastric polyps can manifest in each of the gastrointestinal polyposis syndromes, including the recently described gastric adenocarcinoma and proximal polyposis of the stomach syndrome. In addition, gastric polyps occur in Lynch syndrome and in a few rare conditions that are not primarily gastrointestinal. While some of these syndromes are clearly associated with an increased risk of gastric cancer, others are not. Interestingly, even in disorders with a well-established risk of gastric cancer, the neoplastic potential and the precursor status of these gastric polyps are not always clear. Although rare, recognition of syndromic gastric polyps is important for individual patient management. These conditions also serve as important models to study gastric homeostasis and gastric tumorigenesis.

A mild phenotype associated with a de novo microdeletion 10q23.1-q23.2: a new patient with a novel feature

Chromosome 10q23 contains several genes, includingPTENandBMPR1A, the mutations or microdeletion of which are associated with aggressive polyposis and malignancies in children. Deletions in this chromosomal region have also been associated with heart anomalies, developmental delay and macrocephaly. Most of the cases reported involve thePTENandBMPR1Agenes, usually associated with complex and severe anomalies. We report a case of a boy with a de novo interstitial microdeletion in 10q23.1-q23.2 spanning 6.7 Mb with boundaries from 82 087 077 to 88 847 906, not includingPTENandBMPR1A Clinical features consisted of mildly dysmorphic facies, frontal telangiectasias, poor scholastic performance and hyperactivity. Furthermore, the boy presented toe anomalies, which appeared to be novel features associated with 10q23 deletion. Further observations of 10q23.1-q23.2 deletions are necessary to confirm the clinical features observed in the proband, and to show that deletion or mutations not involvingPTENandBMPR1Amay not be associated with severe neurological impairment and malformation anomalies.

Syndromic Gastric Polyps: At the Crossroads of Genetic and Environmental Cancer Predisposition

Gastric polyps occur in 1-4 % of patients undergoing gastroscopy. Although most are sporadic, some gastric polyps are part of an underlying hereditary syndrome. Gastric polyps can be seen in each of the well-known gastrointestinal polyposis syndromes, but also in Lynch syndrome and in several rare not primarily gastrointestinal syndromes. In addition, Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS) is a recently described heritable syndrome characterized by isolated gastric polyposis and risk of gastric cancer.Some of these syndromes are associated with an increased risk of gastric cancer, whereas others are not. However, the neoplastic potential and the precursor status of these gastric polyps are not always clear, even in syndromes with a well-established risk of gastric cancer. For instance, the neoplastic potential of Peutz-Jeghers polyps is debatable, despite the well-established risk of gastric cancer in this syndrome. Also fundic gland polyps and gastric foveolar-type adenomas in FAP carry a low risk of malignant transformation. In contrast, gastric juvenile polyps are precursor lesions of gastric cancer in juvenile polyposis syndrome through neoplastic progression of juvenile polyps in these patients.Although these hereditary syndromes with gastric polyps are rare, recognition is important for individual patient management. Furthermore, the initiation and progression of these lesions can be influenced by environmental factors such as Helicobacter Pylori infection. This makes these rare lesions an appropriate model for understanding the clonal evolution of early gastric cancer in the wider population.

Overlap of Juvenile polyposis syndrome and Cowden syndrome due to de novo chromosome 10 deletion involving BMPR1A and PTEN: implications for treatment and surveillance

We describe a patient with a severe juvenile polyposis phenotype, due to a de novo deletion of chromosome 10q22.3-q24.1. He was initially diagnosed with Juvenile polyposis syndrome (JPS) at age four after presenting with hematochezia due to multiple colonic juvenile polyps. He then re-presented at 23 years with recurrent hematochezia from juvenile polyps in his ileoanal pouch. He is one of the earliest reported cases of JPS associated with a large deletion of chromosome 10. Since his initial diagnosis of JPS further studies have confirmed an association between JPS and mutations in BMPR1A in chromosome band 10q23.2, which is in close proximity to PTEN. Mutations in PTEN cause Cowden syndrome (CS) and other PTEN hamartoma tumor syndromes. Due to the chromosome 10 deletion involving contiguous portions of BMPR1A and PTEN in our patient, he may be at risk for CS associated cancers and features, in addition to the polyps associated with JPS. This case presents new challenges in developing appropriate surveillance algorithms to account for the risks associated with each syndrome and highlights the importance of longitudinal follow-up and transitional care between pediatric and adult gastroenterology for patients with hereditary polyposis syndromes.

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.

Aggressive juvenile polyposis in children with chromosome 10q23 deletion

Juvenile polyps are relatively common findings in children, while juvenile polyposis syndrome (JPS) is a rare hereditary syndrome entailing an increased risk of colorectal cancer. Mutations in BMPR1A or SMAD4 are found in roughly half of patients diagnosed with JPS. Mutations in PTEN gene are also found in patients with juvenile polyps and in Bannayan-Riley-Ruvalcaba syndrome and Cowden syndrome. Several previous reports have described microdeletions in chromosome 10q23 encompassing both PTEN and BMPR1A causing aggressive polyposis and malignancy in childhood. These reports have also described extra-intestinal findings in most cases including cardiac anomalies, developmental delay and macrocephaly. In this report we describe a boy with a 5.75 Mb deletion of chromosome 10q23 and a 1.03 Mb deletion within chromosome band 1p31.3 who displayed aggressive juvenile polyposis and multiple extra-intestinal anomalies including macrocephaly, developmental delay, short stature, hypothyroidism, atrial septal defect, ventricular septal defect and hypospadias. He required colectomy at six years of age, and early colectomy was a common outcome in other children with similar deletions. Due to the aggressive polyposis and reports of dysplasia and even malignancy at a young age, we propose aggressive gastrointestinal surveillance in children with 10q23 microdeletions encompassing the BMPR1A and PTEN genes to include both the upper and lower gastrointestinal tracts, and also include a flowchart for an effective genetic testing strategy in children with juvenile polyposis.

Juvenile polyposis of infancy in a child with deletion of BMPR1A and PTEN genes: surgical approach

Juvenile polyposis of infancy is the most severe and life-threatening form of juvenile polyposis. This disease typically presents in the first two years of life with gastrointestinal bleeding, diarrhea, inanition, and exudative enteropathy. In very few reports concerning this entity, a large deletion in the long arm of chromosome 10 (10q23), encompassing the PTEN and BMPR1A genes, was found. The authors report a case of delayed diagnosis of juvenile polyposis of infancy at 6 years of age. A 3.34 Mb long de novo deletion was identified at 10q23.1q23.31, encompassing the PTEN and BMPR1A genes. The disease course was severe with diarrhea, abdominal pain, inanition, refractory anemia, rectal bleeding, hypoalbuminemia, and exudative enteropathy. A sub-total colectomy, combined with intraoperative endoscopic removal of ileal and rectal stump polyps, was required for palliative disease control.

A new case with 10q23 interstitial deletion encompassing both PTEN and BMPR1A narrows the genetic region deleted in juvenile polyposis syndrome

We report on a patient with a contiguous interstitial germline deletion of chromosome 10q23, encompassing BMPR1A and PTEN, with clinical manifestations of juvenile polyposis and minor symptoms of Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba syndrome (BRRS). The patient presented dysmorphic features as well as developmental delay at the age of 5 months. Multiple polyps along all parts of the colon were diagnosed at the age of 3 years, following an episode of a severe abdominal pain and intestinal bleeding. The high-resolution comparative genomic hybridisation revealed a 3.7-Mb deletion within the 10q23 chromosomal region: 86,329,859-90,035,024. The genotyping with four polymorphic microsatellite markers confirmed a de novo 10q deletion on the allele with a paternal origin, encompassing both PTEN and BMPR1A genes. The karyotype analysis additionally identified a balanced translocation involving chromosomes 5q and 7q, and an inversion at chromosome 2, i.e. 46,XY,t(5;7)(q13.3-q36), inv(2)(p25q34). Although many genetic defects were detected, it is most likely that the 10q23 deletion is primarily the cause for the serious phenotypic manifestations. The current clinical findings and deletion of BMPR1A indicate a diagnosis of severe juvenile polyposis, but the existing macrocephaly and PTEN deletion also point to either CS or BRRS, which cannot be ruled out at the moment because of their clinical manifestation later in life and the de novo character of the deletion. The deletion detected in our patient narrows the genetic region deleted in all reported cases with juvenile polyposis by 0.04 Mb from the telomeric side, mapping it to the region chr10:88.5-90.03Mb (GRCh37/hg19), with an overall length of 1.53 Mb.

A new case with 10q23 interstitial deletion encompassing both PTEN and BMPR1A narrows the genetic region deleted in juvenile polyposis syndrome

We report on a patient with a contiguous interstitial germline deletion of chromosome 10q23, encompassing BMPR1A and PTEN, with clinical manifestations of juvenile polyposis and minor symptoms of Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba syndrome (BRRS). The patient presented dysmorphic features as well as developmental delay at the age of 5 months. Multiple polyps along all parts of the colon were diagnosed at the age of 3 years, following an episode of a severe abdominal pain and intestinal bleeding. The high-resolution comparative genomic hybridisation revealed a 3.7-Mb deletion within the 10q23 chromosomal region: 86,329,859-90,035,024. The genotyping with four polymorphic microsatellite markers confirmed a de novo 10q deletion on the allele with a paternal origin, encompassing both PTEN and BMPR1A genes. The karyotype analysis additionally identified a balanced translocation involving chromosomes 5q and 7q, and an inversion at chromosome 2, i.e. 46,XY,t(5;7)(q13.3-q36), inv(2)(p25q34). Although many genetic defects were detected, it is most likely that the 10q23 deletion is primarily the cause for the serious phenotypic manifestations. The current clinical findings and deletion of BMPR1A indicate a diagnosis of severe juvenile polyposis, but the existing macrocephaly and PTEN deletion also point to either CS or BRRS, which cannot be ruled out at the moment because of their clinical manifestation later in life and the de novo character of the deletion. The deletion detected in our patient narrows the genetic region deleted in all reported cases with juvenile polyposis by 0.04 Mb from the telomeric side, mapping it to the region chr10:88.5-90.03Mb (GRCh37/hg19), with an overall length of 1.53 Mb.

Juvenile polyposis and other intestinal polyposis syndromes with microdeletions of chromosome 10q22-23

Juvenile polyposis (JP) is an autosomal dominant hamartomatous polyposis syndrome that carries a significant risk for the development of colorectal cancer. Microdeletions of one of the two predisposing genes to JP, BMPR1A, have been associated with a severe form of JP called juvenile polyposis of infancy. Many of these deletions have also been found to contiguously include PTEN, which is the gene responsible for the development of Cowden syndrome. The advent of molecular techniques that localize genomic copy number variations and others that target specific genes such as multiplex-ligation probe analysis has allowed researchers to explore this area further for deletions. Here, we review the literature for microdeletions described on chromosome 10q22-23 in patients with JP and other intestinal polyposis syndromes.

The phenotype of recurrent 10q22q23 deletions and duplications

The genomic architecture of the 10q22q23 region is characterised by two low-copy repeats (LCRs3 and 4), and deletions in this region appear to be rare. We report the clinical and molecular characterisation of eight novel deletions and six duplications within the 10q22.3q23.3 region. Five deletions and three duplications occur between LCRs3 and 4, whereas three deletions and three duplications have unique breakpoints. Most of the individuals with the LCR3-4 deletion had developmental delay, mainly affecting speech. In addition, macrocephaly, mild facial dysmorphisms, cerebellar anomalies, cardiac defects and congenital breast aplasia were observed. For congenital breast aplasia, the NRG3 gene, known to be involved in early mammary gland development in mice, is a putative candidate gene. For cardiac defects, BMPR1A and GRID1 are putative candidate genes because of their association with cardiac structure and function. Duplications between LCRs3 and 4 are associated with variable phenotypic penetrance. Probands had speech and/or motor delays and dysmorphisms including a broad forehead, deep-set eyes, upslanting palpebral fissures, a smooth philtrum and a thin upper lip. In conclusion, duplications between LCRs3 and 4 on 10q22.3q23.2 may lead to a distinct facial appearance and delays in speech and motor development. However, the phenotypic spectrum is broad, and duplications have also been found in healthy family members of a proband. Reciprocal deletions lead to speech and language delay, mild facial dysmorphisms and, in some individuals, to cerebellar, breast developmental and cardiac defects.

Mucinous cystadenoma of ovary in a patient with juvenile polyposis due to 10q23 microdeletion: expansion of phenotype

Juvenile polyposis syndrome (JPS) is a hereditary condition characterized by development of gastrointestinal polyps, and caused by mutations in SMAD4 or BMPR1A genes. Juvenile polyps can also be found in a related group of syndromes with multisystemic involvement including Cowden disease, Lhermitte-Duclos disease, Bannayan-Riley-Ruvalcaba syndrome, and Proteus-like syndrome, all grouped as PTEN hamartoma tumor syndromes (PHTS). In all these conditions including JPS, polyps manifest in older childhood or early adulthood. Infantile juvenile polyposis (JPI) is a rare entity, presenting in the first year of life with severe gastrointestinal symptoms. Many of these patients have associated macrocephaly, hypotonia, and congenital anomalies. It was recently recognized that patients with infantile polyposis have a 10q23 microdeletion, involving both BMPR1A and PTEN genes. There is a major risk for gastrointestinal malignancies in these patients, but the risk for development of other tumors is not known. We describe a patient with a history of infantile polyposis, macrocephaly, developmental delay, hypotonia, and a 10q23 microdeletion. At age 14 she presented with bilateral mucinous cystadenoma of the ovary. This type of tumor was not previously reported in association with JPS, 10q23 microdeletion syndrome, or infantile polyposis. We believe that ovarian cystadenomas may be another neoplastic complication of infantile polyposis, and that our report widens the spectrum of the 10q23 microdeletion phenotype.

Juvenile polyposis of infancy associated with paracentric inversion and deletion of chromosome 10 in a Hispanic patient: a case report

Juvenile polyposis of infancy is a rare genetic disorder, involving multiple hamartomatous polyps of the gastrointestinal tract, which usually has a very aggressive clinical course and is often fatal. It is characterized by early onset (during the 1st months of life) and by diffuse juvenile polyposis with anemia, recurrent gastrointestinal bleeding, diarrhea, rectal prolapse, intussusception, protein-losing enteropathy, starvation, and malnutrition. There is a hypothesis that mutation of the tumor-suppressor genes BMPR1A and PTEN, located on the long arm of chromosome 10, is associated with the development of this disease. Medical treatment for this disorder is challenging and should be conservative whenever possible. We present the case of a 3-year-old girl with juvenile polyposis of infancy who eventually died from mesenteric artery thrombosis during surgical colectomy. Karyotype of the patient showed a paracentric inversion in 10q and a deletion in 10p. We will briefly comment on some genetic considerations of this disease.

Discovery of the BMPR1A promoter and germline mutations that cause juvenile polyposis

Juvenile polyposis (JP) is an autosomal dominant hamartomatous polyposis syndrome where affected individuals are predisposed to colorectal and upper gastrointestinal cancer. Forty-five percent of JP patients have mutations or deletions involving the coding regions of SMAD4 and BMPR1A, but the genetic basis of other cases is unknown. We set out to identify the JP gene in a large kindred having 10 affected members without SMAD4 or BMPR1A coding sequence mutations or deletions. We found a germline deletion segregating in all affected members, mapping 119 kb upstream of the coding region of BMPR1A by multiplex ligation-dependent probe amplification and comparative genomic hybridization. To further understand the genomic structure of BMPR1A, we performed 5' RACE from lymphoblastoid cell lines and normal colon tissue, which revealed four non-coding (NC) exons and two putative promoters. Further analysis of this deletion showed that it encompassed 12 433 bp, including one promoter and NC exon. The activities of each promoter and deletion constructs were evaluated by luciferase assays, and the stronger promoter sequence analyzed for changes in JP patients without SMAD4 or BMPR1A alterations. A total of 6 of 65 JP probands were found to have mutations affecting this promoter. All probands examined had diminished BMPR1A protein by ELISA, and all promoter mutations but one led to significantly reduced luciferase activity relative to the wild-type promoter reporter. We conclude that we have identified the promoter for BMPR1A, in which mutations may be responsible for as many as 10% of JP cases with unknown mutations.

Prevalence of AIP mutations in a large series of sporadic Italian acromegalic patients and evaluation of CDKN1B status in acromegalic patients with multiple endocrine neoplasia

BACKGROUND

Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene and the p27(KIP1) encoding gene CDKN1B have been associated with two well-defined hereditary conditions, familial isolated pituitary adenoma (FIPA) and multiple endocrine neoplasia type 4 (MEN4). Somatotropinomas are present in most AIP mutated FIPA kindreds, as well as in two-thirds of MEN4 patients who carry pituitary tumors.

METHODS

Germline DNA samples of 131 Italian sporadic acromegalic patients including 38 individuals with multiple tumors, and of six FIPA families (four homogeneous for prolactinomas and two heterogeneous with prolactin/nonfunctioning pituitary adenomas) were collected in a multicentric collaborative study. The prevalence of AIP and CDKN1B gene point mutations and copy number variations were evaluated.

RESULTS

Two novel (IVS3+1G>A and c.871G>A) and one previously described (c.911G>A) AIP mutations were detected in four apparently sporadic cases (3.1%) with relatively high age at diagnosis (49+/-18, range 30-67). No mutations/rearrangements were detected in FIPA families. The highly conserved c.871G>A substitution was detected in a patient who also carried a MEN1 mutation suggesting that she is a double heterozygote. The possible pathogenic effect on AIP splicing of the silent substitution c.144G>A found in another patient was ruled out using a minigene-based approach. CDKN1B mutations/rearrangements were neither identified in patients with multiple neoplasia nor in FIPA families.

CONCLUSION

AIP is mutated in about 3% of apparently sporadic acromegalic patients. The relatively high age at diagnosis, as well as its sporadic presentation, suggests that these patients are carriers of mutations with reduced pathogenicity. p27(KIP1) is unlikely to represent the common unifying nonendocrine etiology for acromegaly and cancer.

Clinical and molecular characterization of individuals with recurrent genomic disorder at 10q22.3q23.2

The identification of genomic imbalances in young patients can affect medical management by allowing early intervention for developmental delay and by identifying patients at risk for unexpected medical complications. Using a 105K-feature oligonucleotide array, we identified a 7.25 Mb deletion at 10q22.3q23.2 in six unrelated patients. Deletions of this region have been described in individuals with cognitive and behavioral abnormalities, including autistic features, and may represent a recurring genetic syndrome. All four patients in this study for whom clinical information was available had mild dysmorphic features and three had developmental delay. Of note is the emerging clinical phenotype in these individuals with similar dysmorphic features such as macrocephaly, hypertelorism, and arachnodactyly, and neurodevelopmental delay that includes failure to thrive, hypotonia, and feeding difficulties in the neonatal period, and receptive and expressive language delay with global neurodevelopmental delay after the neonatal period. However, there is no pattern of abnormalities, craniofacial, behavioral, or otherwise, that would have aroused clinical suspicion of a specific syndrome. Finally, the patients' deletions encompass BMPR1A but not PTEN, and these patients may be at risk for colon cancer and should be referred for appropriate prophylactic care and surveillance. Of the two patients in this study who had colonoscopy following the array results, neither had polyps. Therefore, the magnitude of the increased risk for colon cancer is currently unknown.

Less common colorectal cancer predisposition syndromes

A variety of syndromes confer increased risk for intestinal polyp development, outside the more commonly occurring syndromes. Each of these uncommon syndromes predispose to pathognomonic histologies that are uncommonly observed. Accurate diagnosis of these syndromes is contingent on higher-level pathology review, evaluation of signs and symptoms beyond sole consideration of the polyps, and collection of a detailed family history. When a genetic mutation can be identified in the proband, the management of intestinal and extra-intestinal cancer screening can be more appropriately tailored.

Pediatric juvenile polyposis syndromes: an update

Colon polyps are a common finding in pediatrics and can present with rectal bleeding, abdominal pain, or polyp prolapse from the rectum. Histologically classified as hamartomas, these isolated pediatric polyps lack epithelial dysplasia and have no cancer risk. However, when polyps are present in greater numbers, or are associated with a family history of polyps or colon or other cancers, a polyposis or hereditary colorectal cancer syndrome should be considered. Using a case-based format, this article reviews the clinical features and provides updates on the three most common hamartomatous polyp syndromes of childhood: juvenile polyposis syndrome, Peutz-Jeghers syndrome, and the PTEN hamartoma tumor syndrome. Each syndrome has distinctive intestinal and extra-intestinal findings that, when present, can guide genetic counseling and testing. Lifelong cancer surveillance is crucial to disease prevention and the long-term health of these patients and their families.

Hamartomatous polyposis syndromes

Hamartomatous polyposis syndromes are a diverse group of inherited conditions grouped together because they exhibit hamartomatous rather than epithelial polyp histology. Each syndrome exhibits characteristic polyp histology, gastrointestinal polyp distribution, gastrointestinal cancer risks, extra-intestinal benign findings and often extra-intestinal cancer risks. Identifying individuals at risk for these syndromes and accurately defining the precise diagnosis are necessary for planning surveillance and management in order to prevent the benign and malignant complications. Characteristic syndrome features including gastrointestinal findings, pathology, genetics, and management options for the three most common hamartomatous polyposis syndromes, Peutz-Jeghers syndrome, PTEN hamartoma tumour syndrome, and juvenile polyposis will be presented in this review.

The rate of germline mutations and large deletions of SMAD4 and BMPR1A in juvenile polyposis

Juvenile polyposis (JPS) is an autosomal dominant syndrome that predisposes individuals to develop gastrointestinal polyps and cancer. Germline point mutations in SMAD4 and BMPR1A have been identified as causing JPS in approximately 40-60% of patients, but few studies have looked at the rate of large deletions. In this study, we determined the overall prevalence of genetic changes of SMAD4 and BMPR1A by sequencing and by screening for larger deletions. DNA was extracted from 102 JPS probands, and each exon and intron-exon boundary of SMAD4 and BMPR1A were sequenced. Coding and non-coding exons of SMAD4 and BMPR1A were screened for deletions with multiplex ligation-dependent probe amplification (MLPA). By sequencing, 20 probands had point mutations of SMAD4 and 22 of BMPR1A. By MLPA, one proband had deletion of most of SMAD4, one of both BMPR1A and PTEN, one of the 5' end of BMPR1A, and another of the 5' end of SMAD4. The overall prevalence of SMAD4 and BMPR1A point mutations and deletions in JPS was 45% in the largest series of patients to date. Large deletions are less frequent in JPS patients, but represent other heritable causes of JPS, which should be screened for in pre-symptomatic genetic testing.

Variable phenotypes associated with 10q23 microdeletions involving the PTEN and BMPR1A genes

Infantile juvenile polyposis is a rare disease with severe gastrointestinal symptoms and a grave clinical course. Recently, 10q23 microdeletions involving the PTEN and BMPR1A genes were found in four patients with infantile juvenile polyposis. It was hypothesized that a combined and synergistic effect of the deletion of both genes would explain the condition. Subsequently, however, a patient with a larger 10q23 deletion including the same genes but with a mild clinical phenotype was identified. Here, we present four additional patients with 10q23 microdeletions involving the PTEN and BMPR1A genes. The sizes of the deletions were analyzed using single nucleotide polymorphism array analysis. All patients had macrocephaly, dysmorphic features, retardation and congenital abnormalities. One patient developed colorectal cancer. However, only one case had disease onset before 2 years of age and severe symptoms requiring colectomy. No clear correlation was found between ages at onset or severity of gastrointestinal symptoms and the sizes of the deletions. We conclude that patients with 10q23 microdeletions involving the PTEN and BMPR1A genes have variable clinical phenotypes, which cannot be explained merely by the deletion sizes. The phenotypes are not restricted to severe infantile juvenile polyposis but include childhood-onset cases with macrocephaly, retardation, mild gastrointestinal symptoms and possibly early-onset colorectal cancer.

Cancer phenomics: RET and PTEN as illustrative models

Cancer phenomics, the systematic acquisition and objective documentation of host and/or somatic cancer phenotypic data at many levels, is a young field compared with other molecular-based 'omics'. Two relatively advanced phenomic paradigms are associated with phosphatase and tensin homologue (PTEN) and rearranged during transfection (RET), genes that are associated with cancer predisposition syndromes in addition to developmental disorders. The phenomic characterization of PTEN and RET underscores the importance of incorporating robust phenomics into the host 'omic' profile, and shows that the evolution of phenomics will be crucial to the advancement of personalized medicine.