Genetic testing and phenotype in a large kindred with attenuated familial adenomatous polyposis

BACKGROUND & AIMS: An attenuated form of familial adenomatous polyposis has been described, but the phenotype remains poorly understood. METHODS: We performed genetic testing on 810 individuals from 2 attenuated familial adenomatous polyposis kindreds harboring an identical germline adenomatous polyposis coli gene mutation. Colonoscopy was performed on mutation-positive persons. RESULTS: The disease-causing mutation was present in 184 individuals. Adenomatous polyps were present in 111 of 120 gene carriers who had colonoscopy at an average age of 41 years. The median number of adenomas was 25 (range, 0-470), with striking variability of polyp numbers and a proximal colonic predominance of polyps. Colorectal cancer occurred in 27 mutation carriers (average age, 58 years; range, 29-81 years), with 75% in the proximal colon. The cumulative risk of colorectal cancer by age 80 was estimated to be 69%. An average of 3.4 recurrent polyps (range, 0-29) were found in the postcolectomy rectal remnant over a mean of 7.8 years (range, 1-34 years), with 1 rectal cancer. CONCLUSIONS: This investigation shows that attenuated familial adenomatous polyposis in the kindreds examined shows a much smaller median number of polyps than typical familial adenomatous polyposis, a wide variability in polyp number even at older ages, and a more proximal colonic location of polyps and cancer, yet it is associated with an extremely high risk of colon cancer. The phenotype of attenuated familial adenomatous polyposis mimics typical familial adenomatous polyposis in some cases but in others is difficult to distinguish from sporadic adenomas and colorectal cancer, thus making genetic testing particularly important.     

MYH mutations in patients with attenuated and classic polyposis and with young-onset colorectal cancer without polyps

BACKGROUND & AIMS: MYH-associated polyposis is a recently described disease that is characterized by multiple colorectal adenomas and a recessive pattern of inheritance. Individuals with MYH-associated polyposis have biallelic mutations in MYH, a base excision repair gene, and are negative for germline mutations in the APC gene. In this study, the 2 most prevalent MYH mutations in white persons, Y165C and G382D, were analyzed for their presence in 984 subjects selected from 3 groups: 400 undergoing screening colonoscopy and found to have 0-3 polyps, 444 with colorectal cancer (CRC), and 140 referred for APC mutation analysis in which a germline mutation was not identified. METHODS: Genotyping for Y165C and G382D was performed by Pyrosequencing. RESULTS: Biallelic mutations for Y165C and/or G382D were not found in any of those undergoing screening colonoscopy with 0-3 polyps (n = 400), in those APC-negative patients with <20 adenomatous polyps (n = 26), or in those with CRC who were older than 50 years (n = 328). Furthermore, these 2 MYH mutations were not found among patients whose tumors showed the presence of defective DNA mismatch repair (n = 62). However, the presence of biallelic germline MYH mutations correlated with the presence of >or=20 adenomatous polyps. Interestingly, 2 of the 116 individuals with CRC diagnosed at 50 years of age or younger also presented with biallelic germline mutations in MYH. CONCLUSIONS: These data suggest that screening of MYH should be considered not only in patients with multiple polyps but also in patients with early-onset CRC.     

Nine-year follow-up of a patient with attenuated familial adenomatous polyposis treated with cyclo-oxygenase-2 inhibitors

Familial adenomatous polyposis (FAP) is caused by germline mutations in the adenomatous polyposis coli (APC) gene with onset of florid polyposis in childhood and development of colorectal cancer by age 30. Colectomy is advised because of the high risk of developing colorectal cancer. Attenuated FAP (AFAP) is a variant of this condition with a later age of onset and milder clinical phenotype; however, colectomy is advised once polyposis develops and polyps cannot be managed endoscopically. We report a case of a patient with AFAP and previously resected colonic carcinoma that was treated with chemoprophylaxis with long-term cyclooxygenase-2 (COX-2) inhibitors after declining colectomy. Colonoscopic examination demonstrated regression of polyps by 18 months. After 9 years of follow-up, there was no evidence of colorectal cancer development or progression of polyposis. This is the first case report on long-term treatment with COX-2 inhibition in a patient with AFAP and previous colonic carcinoma.     

Long-term treatment with sulindac in familial adenomatous polyposis: a prospective cohort study

BACKGROUND & AIMS: Management of patients with familial adenomatous polyposis (FAP) can consist of colectomy with ileorectal anastomosis (IRA). Sulindac, a nonsteroidal anti-inflammatory drug, causes regression of colorectal adenomas in the retained rectal segment of FAP patients, although long-term use of this therapy has not been studied. We evaluated the long-term effectiveness and toxicity of sulindac in attempting to maintain retained rectal segments free of adenomas. METHODS: Twelve FAP patients (5 women), mean age 37.1 years, with IRA received sulindac (mean dosage, 158 mg/day) for a mean period of 63.4 +/- 31.3 months (range, 14-98 months). Number, size, and histologic grade of polyps, side effects, and medication compliance were assessed every 4 months. RESULTS: Seven of 12 patients (58%) remained in the study (6 of these polyp-free) for a mean of 76.9 +/- 27.5 months. Five of 12 patients (42%) withdrew from the trial after a mean follow-up period of 44 +/- 28 months (range, 14-89 months). A significant regression of polyp number was observed in all patients at 12 months (P = 0.039) and at a mean of 63.4 +/- 31.3 months (P = 0.006). Prevention of recurrence of higher-grade adenomas (tubulovillous, villous adenomas) was also observed (P = 0.004). At 35 months of follow-up, 1 patient developed stage III cancer in the rectal stump. The most common side effect was rectal mucosal erosions in 6 patients. CONCLUSIONS: Long-term use of sulindac seems to be effective in reducing polyp number and preventing recurrence of higher-grade adenomas in the retained rectal segment of most FAP patients. Erosions at the IRA site can preclude adequate dose maintenance.     

Prostanoids, ornithine decarboxylase, and polyamines in primary chemoprevention of familial adenomatous polyposis

BACKGROUND & AIMS: Familial adenomatous polyposis because of germline mutation of the adenomatous polyposis coli gene is characterized by development of colorectal adenomas and, ultimately, colorectal cancer. The usefulness of colorectal mucosal compounds to predict the effect on adenoma development of primary chemoprevention with the nonsteroidal anti-inflammatory drug sulindac was evaluated. METHODS: A randomized, double-blind, placebo-controlled study of 41 subjects genotypically affected with familial adenomatous polyposis but phenotypically unaffected was conducted. Patients received either sulindac or placebo for 48 months, and development of new adenomas was evaluated. The levels of 5 prostanoids, ornithine decarboxylase, and polyamines were measured serially in normal-appearing rectal mucosa. RESULTS: There were no statistically significant differences between treatment groups in baseline levels of prostanoids, ornithine decarboxylase, or polyamines. At conclusion of the study, 4 of 5 prostaglandin levels were statistically significantly lower in the sulindac group than in the placebo group. Among the subset of patients taking sulindac, 3 of 5 prostaglandin levels were statistically significantly lower in patients who were polyp free than in those who developed polyps. By contrast, there were no statistically significant differences in ornithine decarboxylase or polyamines between treatment groups or in those on sulindac who were polyp free compared with those who developed polyps. CONCLUSIONS: Colorectal mucosal prostaglandin levels, but not ornithine decarboxylase or polyamines, may be valuable biomarkers to assess appropriate drug dosage and medication compliance in patients undergoing primary chemoprevention therapy with sulindac. Reduction of mucosal prostaglandin levels may be necessary to achieve chemopreventive benefit from this agent.     

APC gene mutations in Chinese familial adenomatous polyposis patients

AIM:To study the characteristics of APC(adenomatous polyposis coli)gene germline mutation in Chinese patients with familial adenomatous polyposis(FAP).METHODS:APC gene from 14 FAP families was amplified by polymerase chain reaction(PCR)and underwent direct sequencing to determine the micromutation type.For the samples without micromutation,the large fragment deletion of APC gene was examined by multiplex ligation-dependent probe amplification(MLPA).RESULTS:There were gene micromutations in 9 families with a...     

APC gene mutations in a jejunal adenoma causing intussusception in a patient with familial adenomatous polyposis

Adenomatous polyps of the jejunum/ileum in patients with familial adenomatous polyposis (FAP) are usually small (<5 mm) and are considered to be of little clinical importance. Genetic alterations in these polyps have not previously been analyzed. We herein report an extremely rare case of FAP presenting with intussusception caused by jejunal adenomas. Both somatic and germline mutations of the APC gene were detected in one of the polyps. A 40-year-old man with FAP was admitted for closure of an ileostomy that had been created because of an anastomotic leak after subtotal proctocolectomy with ileo-anal-canal anastomosis. During the follow-up after that surgery, he had occasionally complained of colicky abdominal pain, but it had quickly subsided. At the second laparotomy, for closure of the ileostomy, jejuno-jejunal intussusception was incidentally found, and segmental resection of the jejunum, including the leading point of the intussusception, was performed. There were five polyps clustered in the resected jejunum. Histologically, the polyps, ranging from 5 to 26 mm in diameter, were adenomas with moderate to severe atypia. Genetic examinations of one of the largest polyps, using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) and direct sequencing methods, revealed somatic (T insertion at codon 1557) and germline mutations (4 base-pair deletion at codons 181–182) of the APC gene. This is the first evidence that the coexistence of somatic and germline alterations in the APC gene is involved in the development of a jejunal adenoma causing small-bowel intussusception. Received: April 3, 2001 / Accepted: July 20, 2001     

Hepatocellular adenoma in a male with familial adenomatous polyposis coli

Hepatocellular adenoma (HA) is a benign liver tumor most frequently occurring in young women using oral contraceptives. We report a rare case of HA in a 27-year-old male patient with familial adenomatous polyposis (FAP). The patient underwent a total colectomy and ileo-rectal anastomosis for FAP in 2003. A preoperative computed tomography scan of the abdomen disclosed a tumor in the left-lobe of the liver, 5.8 cm in diameter. Pathologic examination of a needle biopsy disclosed HA, but he had never used anabolic steroids or other known inducers of HA. The size of the liver mass gradually increased to 8.5 cm during a follow-up period of 38 months, and a left hepatectomy was performed in 2006. Pathology of the resected specimen confirmed the diagnosis of HA. Although FAP is known to be complicated with neoplasia in various extracolonic organs, only five reported cases of HA have developed in patients with FAP, including this case. This is the first report of HA to develop in a male FAP patient.     

Phenotypic differences in familial adenomatous polyposis based on APC gene mutation status

Background—Familial adenomatous polyposis(FAP) is a clinically well defined hereditary disease caused bygermline mutations within the adenomatous polyposis coli (APC) gene.Although several techniques are applied in the mutation analysis of FAPkindreds about 20-50% of cases remain unclear, with no APC mutationidentified (APC negative).
Aims—To delineate phenotypic differences betweenAPC positive and APC negative patients with respect to colonic andextracolonic disease in order to determine whether additionalmechanisms are involved in the pathogenesis of FAP.
Methods—The entire coding region of the APC genewas analysed using single stranded conformation polymorphism andprotein truncation tests in 50 Swiss FAP families with a total of 161affected individuals. Differences in phenotypic manifestation werestatistically evaluated by Student's t test, Fisher'sexact test, and χ² test.
Results—Thirty six families (72%) were APCpositive. Statistically significant differences between APC positiveand APC negative groups were found for the mean age at diagnosis ofcolonic polyposis (35.2 versus 45.3 years, respectively) and for theoccurrence of stomach polyps (14 patients, all APC positive).Additionally, APC negative patients displayed lower polyp numbers atdiagnosis and less extracolonic manifestations.
Conclusions—FAP kindreds without detected APCgene mutations present with a notably milder disease phenotype comparedwith APC positive families, suggesting that different genetic factors might be involved.

Keywords:familial adenomatous polyposis; adenomatouspolyposis coli gene; mutation; colorectal cancer; extracolonicmanifestations

     

Development of duodenal cancer in a patient with familial adenomatous polyposis

A Japanese woman with familial adenomatous polyposis in whom a duodenal ampullary adenoma underwent malignant change during a 10-year follow-up period is reported. After restorative proctocolectomy in 1989, and extensive small bowel resection for desmoid disease in 1991, regular surveillance duodenoscopies, including three to nine biopsies (mean, 4.8) were performed annually or biannually. Until 1995, the endoscopic findings of duodenal polyposis (including an ampullary polyp) did not progress and the histopathology did not worsen. In 1996, there was an increase in the number and size of the duodenal polyps, and the ampulla of Vater looked enlarged. Open surgery was discussed but not proceeded with because of the risk for short bowel syndrome. In January 1998, she was admitted with a diagnosis of acute pancreatitis. Duodenoscopy and radiological examination revealed that an advanced ampullary cancer had developed, and histopathology revealed a well-differentiated adenocarcinoma. Multiple hepatic metastases and ascites led to her death, in June, 1998. This in-vivo demonstration of the adenoma-carcinoma sequence highlights current limitations in the surveillance and treatment of duodenal lesions. Received: June 28, 1999/Accepted March 24, 2000     

Capsule endoscopy is useful and safe for small-bowel surveillance in familial adenomatous polyposis

BACKGROUND: Duodenal cancer and ampullary cancer are major causes of death after a prophylactic colectomy in patients with familial adenomatous polyposis (FAP). Forward-viewing endoscopy and side-viewing endoscopy are recommended in patients with FAP for surveillance of periampullary and duodenal polyposis. The study of polyps distal to the duodenum in FAP is limited. A capsule endoscopy (CE) allows visualization of the mucosa of the entire small bowel. OBJECTIVE: The objective was to detect whether CE has clinical value or any utility for the surveillance of small-bowel polyps in patients with FAP and to evaluate whether there are genotypic factors that predict which patients are at a lower risk of small-bowel polyps. SETTING: Two Italian tertiary-referral centers. PATIENTS: Twenty-three patients with FAP who presented for a CE. MAIN OUTCOME MEASUREMENTS: Patients with FAP were examined by CE to assess the location, size, and number of small-bowel polyps. Patient age at CE, sex, years of observation after surgery, type of surgery, duodenal adenomas, and colorectal cancer at surgery were analyzed. All patients were selected for mutation analysis, and the germline adenomatous polyposis coli (APC) gene mutation was detected. RESULTS: Eleven of 23 patients with FAP had duodenal polyps. During CE, jejunal-ileal polyps were detected in 7 of 23 FAPs, with a total number of 15 polyps in the ileum. The presence of duodenal adenomas was the only clinical feature predictive of small-bowel polyps. Identification of the ampulla of Vater was not achieved with CE; duodenal polyps were only seen in 4 of 11 patients identified endoscopically, with an underestimation of polyp numbers. APC mutations between codons 499 and 805 were associated with the absence of small-bowel polyps. CONCLUSIONS: CE is useful and safe for the surveillance of jejunal-ileal polyps in selected patients with FAP. CE is not useful in the surveillance of the duodenum where the majority of small-bowel cancers occur.     

Rectal epithelial apoptosis in familial adenomatous polyposis patients treated with sulindac

BACKGROUND: Sulindac regresses colorectal adenomas in patients with familial adenomatous polyposis (FAP), although the mechanism of polyp regression is unclear. AIMS: To determine whether differences occur in alteration of rectal epithelial apoptotic index and expression of apoptosis related proteins in FAP patients treated with sulindac compared with placebo. PATIENTS: Twenty one FAP patients; 12 had not undergone colectomy. METHODS: Patients with FAP were treated with sulindac 150 mg orally twice a day for three months (n=10) or placebo (n=11). Colorectal polyp number was determined and biopsies of the normal rectal mucosa were performed before and after three months of treatment. Response to treatment and alteration of the apoptotic ratio (index in base of crypt divided by index in surface epithelium) were evaluated. Bcl-2, bax, p21/WAF-1, and p53 proteins were assessed semiquantitatively by immunohistochemistry. RESULTS: Significant decreases in polyp number and in the apoptotic ratio were seen in patients treated with sulindac compared with controls. The mean percentage change in polyp number from baseline was -46% in the sulindac group and +13% in the placebo group (p=0.005). Mean percentage change in the apoptotic ratio was -8% and +25% in the sulindac and placebo treated patients, respectively (p=0.004). No differences in expression or compartmentalisation of apoptosis related proteins were noted between treatment groups. CONCLUSIONS: Sulindac regression of colorectal adenomas is accompanied by alteration of the rectal epithelial apoptotic ratio with relative increase in apoptosis in surface cells compared with the deeper crypt. The utility of the apoptotic ratio as an intermediate biomarker for colorectal tumorigenesis deserves further study.     

Hyperplastic polyposis syndrome: phenotypic presentations and the role of MBD4 and MYH

BACKGROUND & AIMS: Hyperplastic polyposis syndrome (HPS) is defined phenotypically with multiple, large and/or proximal hyperplastic polyps. There is no known germ-line predisposition. We aimed to characterize the clinicopathologic features of 38 patients with HPS and explore the role of germ-line mutations in the base excision repair genes MBD4 and MYH. METHODS: Utilizing clinical databases of The Royal Melbourne Hospital Bowel Cancer Surveillance Service and the Familial Cancer Clinic, 38 patients with HPS were recruited. The patients were analyzed for age at first diagnosis, features of hyperplastic polyposis, family histories of polyposis and colorectal cancer (CRC), coexisting adenomas, serrated adenomas, incidence of CRC, and microsatellite instability in the tumours. Mutation analysis of MBD4 and MYH were performed. RESULTS: Serrated adenomas were common (26%), and 19 (50%) of the 38 patients had a first-degree relative with CRC. Family history of HPS was uncommon, with only 2 cases found. Ten patients developed CRC, and 3 required surgery for polyposis. No pathogenic mutations in MBD4 were detected in the 27 patients tested, but 6 single nucleotide polymorphisms of uncertain functional significance were identified. Pathogenic biallelic MYH mutations were detected in 1 patient. CONCLUSIONS: Mutations in MBD4 are unlikely to be implicated in HPS; MYH mutations should be studied, especially when adenomas occur in the same patient. The clinical, histopathologic, and molecular findings of this study should contribute to our understanding of HPS and its relationship to the serrated neoplasia pathway.