A comparison of the phenotype and genotype in adenomatous polyposis patients with and without a family history

An update of the variant spectrum of the APC gene in Iranian familial adenomatous polyposis patients

Familial adenomatous polyposis (FAP) is an autosomal dominant colorectal cancer syndrome that is characterized by the development of multiple adenomas in the colon and rectum with high penetrance rates. This disease has specific features like the occurrence of pathogenic variations in the APC gene and diverse FAP phenotypes due to the occurrence region. In this study we aimed to evaluate pathogenic variants in exons of the APC gene in Iranian patients with FAP. A total of 35 FAP individuals were referred to the gastroenterology ward of Taleghani Hospital. As the aim of the study was to study the germline variations in the participants, the peripheral blood was collected and after the DNA extraction, PCR, and Sanger sequencing processes for the APC gene, the results were evaluated by the ACMG classification guidelines to report their pathogenicity. Accordingly, out of eight specific detected variants, three of them were novel, and the rest were reported previously. These eight variants were all truncating protein and pathogenic, and they were limited to 849-1378 codons. Overall, detected variants revealed discrepancies and parallels with previous reported cases in terms of quantity, occurrence region, and association with demographic and clinicopathological characteristics of patients. The spectrum of detected variants and the patient's phenotype showed distinct characteristics, such as occurrence in specific regions and the absence of extracolonic symptoms like Congenital hypertrophy of the retinal pigment epithelium (CHRPE). These findings open the path to comprehending the typical symptoms, their rarity, and their occurrence in the Iranian population and also due to the facts, we found that the studying of the APC gene alone for diagnosing FAP disease is not sufficient, and considering other genes are completely rational in the case of sequencing and studying the variants.

Strong Hereditary Predispositions to Colorectal Cancer

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

APC Splicing Mutations Leading to In-Frame Exon 12 or Exon 13 Skipping Are Rare Events in FAP Pathogenesis and Define the Clinical Outcome

Familial adenomatous polyposis (FAP) is caused by germline mutations in the tumor suppressor gene APC. To date, nearly 2000 APC mutations have been described in FAP, most of which are predicted to result in truncated protein products. Mutations leading to aberrant APC splicing have rarely been reported. Here, we characterized a novel germline heterozygous splice donor site mutation in APC exon 12 (NM_000038.5: c.1621_1626+7del) leading to exon 12 skipping in an Italian family with the attenuated FAP (AFAP) phenotype. Moreover, we performed a literature meta-analysis of APC splicing mutations. We found that 119 unique APC splicing mutations, including the one described here, have been reported in FAP patients, 69 of which have been characterized at the mRNA level. Among these, only a small proportion (9/69) results in an in-frame protein, with four mutations causing skipping of exon 12 or 13 with loss of armadillo repeat 2 (ARM2) and 3 (ARM3), and five mutations leading to skipping of exon 5, 7, 8, or (partially) 9 with loss of regions not encompassing known functional domains. The APC splicing mutations causing skipping of exon 12 or 13 considered in this study cluster with the AFAP phenotype and reveal a potential molecular mechanism of pathogenesis in FAP disease.

Clinico-pathological Features of Colon Cancer Patients Undergoing Emergency Surgery: A Comparison Between Elderly and Non-elderly Patients

BACKGROUND

Colorectal cancer (CRC) is one of the most common cancers in patients older than 65 years. Emergency presentation represents about 30% of cases, with increased morbidity and mortality rates. The aim of this study is to compare the perioperative outcome between elderly and non-elderly patients undergoing emergency surgery.

METHOD

We retrospectively analysed CRC patients that underwent emergency surgery at the Departments of Surgery of the Sapienza University Sant'Andrea Hospital in Rome, and at San Donato Hospital in Arezzo, between June 2012 and June 2017. Patients were divided into two groups: non-elderly (< 65 years) and elderly (≥ 65 years). Variables analysed were sex, onset symptoms, associated disease, ASA score, tumor site and TNM stage, surgical procedures and approach, and morbidity and mortality.

RESULTS

Of a total of 123 patients, 29 patients were non-elderly and 94 patients were elderly. No significant differences were observed in sex, onset symptoms and tumor site between the two groups. Comorbidities were significantly higher in elderly patients (73.4% vs 41.4%, p<0.001). No significant differences were observed between the two groups in surgical approach and the rate of one-stage procedures. Elderly patients were more frequently treated by Hartmann's procedure compared to non-elderly patients (20.2% vs 6.9%). Left colorectal resection with protective ileostomy was most frequent in the non-elderly group (27.6% vs 11.7%). No significant differences were found in the pT and pN categories of the TNM system between the two groups. However, a higher number of T3 in non-elderly patients was observed. A consistent number of non-oncologically adequate resections were observed in the elderly (21.3% vs 3.5%; p<0.03). The morbidity rate was significantly higher in the elderly group (31.9 % vs 3.4%, p<0.001). No significant difference was found in the mortality rate between the two groups, being 13.8% in the elderly and 6.9% in the non-elderly.

CONCLUSIONS

Emergency colorectal surgery for cancer still presents significant morbidity and mortality rates, especially in elderly patients. More aggressive tumors and advanced stages were more frequent in the non-elderly group and as a matter it should be taken into account when treating such patients in the emergency setting in order to perform a radical procedure as much as possible.

Familial Polyposis Coli: The Management of Desmoid Tumor Bleeding

Background

There is currently no standard treatment for desmoid tumors (DTs) associated with familial polyposis coli (FAP). Familial adenomatous polyposis in DT patients is sometimes a life-threatening condition.

Methods

We enrolled all consecutive patients with FAP treated at Unit of General Surgery and Transplant, University of Naples Federico II and evaluated the incidence of DTs on FAP between 1996 and 2016.

Results

We observed 45 consecutive patients with FAP; of these 5 were DT-FAP-associated. All 5 cases with FAP were young women, age 25 to 65 years, previously treated by colectomy. Of these, 4 patients presented a parietal localization and had been treated with a wide surgical exeresis; one patient had an intra-abdominal, mesenteric tumor that was unresectable at laparotomy. We performed CT-guided drainage, ureteral stenting, medical therapy (sulindac+tamoxifene), and chemotherapy (dacarba-zine+doxorubicine).All patients were alive and underwent follow-ups for 5 years post-surgery; only 1 patient with parietal localization showed a local relapse after 2 years.

Conclusions

We propose a modulated approach to the single patient with FAP, with surgery as treatment of choice for parietal localization disease and integrating different kinds of therapies (surgery alone or associated with RT, CT) for the intra-abdominal tumor.

Whole-Genome Sequencing Identifies a Novel Variation of WAS Gene Coordinating With Heterozygous Germline Mutation of APC to Enhance Hepatoblastoma Oncogenesis

Hepatoblastoma (HB), a leading primary hepatic malignancy in children, originates from primitive hepatic stem cells. This study aimed to uncover the genetic variants that are responsible for HB oncogenesis. One family, which includes the healthy parents, and two brothers affected by HB, was recruited. Whole-genome sequencing (WGS) of germline DNA from all the family members identified two maternal variants, located within APC gene and X-linked WAS gene, which were harbored by the two brothers. The mutation of APC (rs137854573, c.C1606T, p.R536X) could result in HB carcinogenesis by activating Wnt signaling. The WAS variant (c.G3T, p.M1-P5del) could promote HB cell proliferation and inhibit T-cell-based immunity by activating PLK1 signaling and inactivating TCR signaling. Further analysis reflected that WAS deficiency might affect the antitumor activity of natural killer and dendritic cells. In summary, the obtained results imply that an APC mutant together with an X-linked WAS mutant, could lead to HB tumorigenesis by activating Wnt and PLK1 signaling, inhibiting TCR signaling, and reducing the antitumor activity of natural killer and dendritic cells.

Colon adenocarcinoma after jejunoileal bypass for morbid obesity

Jejunoileal bypass (JIB) was developed as a surgical treatment for morbid obesity in the early 1950s. However, this procedure is now known to be associated with multiple metabolic complications and has subsequently been abandoned as a viable bariatric procedure. Some of these known complications include renal stone formation, liver failure, migratory arthritis, fat-soluble deficiencies, blind-loop syndrome and severe diarrhea. Additionally, there have been animal models suggesting colon dysplasia after JIB. To our knowledge however, in humans, no colon cancers have been attributed to JIB in the literature. Here we report a 63-year-old morbidly obese female who had a JIB surgery in 1973 and subsequently was found to have numerous sessile colonic polyps throughout her colon and adenocarcinoma of the ascending colon without any family history of colonic polyposis syndromes or colon cancer.

Laparoscopic distal pancreatectomy in elderly patients: is it safe?

BACKGROUND

Laparoscopic distal pancreatectomy (LDP) appears to be safe and effective as open distal pancreatectomy (ODP) for benign or borderline malignant lesion. However, studies comparing LDP with ODP in elderly patients are limited. The purpose of this study is to compare the clinical outcomes of these two several approaches in elderly patients.

METHODS

A retrospective analysis was carried out by comparing laparoscopic (n = 7) and open (n = 15) distal pancreatectomy in elderly patients performed at the University of Naples "Federico II" and University of Perugia between January 2012 and December 2015. Demographic data, operative and postoperative outcomes were analyzed.

RESULTS

Demographic and tumor characteristics of laparoscopic and ODP were similar. There were also no significant differences in operating room time. Patients undergoing LDP had lower blood loss, first flatus time, diet start time and postoperative hospital stay. There were no significant differences in complication rates or 90-day mortality.

DISCUSSION

LDP is safe and feasible as ODP in selected elderly patients.

Robot-assisted surgery in elderly and very elderly population: our experience in oncologic and general surgery with literature review

BACKGROUND

Although there is no agreement on a definition of elderly, commonly an age cutoff of ≥65 or 75 years is used. Nowadays most of malignancies requiring surgical treatment are diagnosed in old population. Comorbidities and frailty represent well-known problems during and after surgery in elderly patients. Minimally invasive surgery offers earlier postoperative mobilization, less blood loss, lower morbidity as well as reduction in hospital stay and as such represents an interesting and validated option for elderly population. Robot-assisted surgery is a recent improvement of conventional minimally invasive surgery.

AIMS

We provided a complete review of old and very old patients undergoing robot-assisted surgery for oncologic and general surgery interventions.

PATIENTS AND METHODS

A retrospective review of all patients undergoing robot-assisted surgery in our General Surgery Unit from September 2012 to June 2016 was conducted. Analysis was performed for the entire cohort and in particular for three of the most performed surgeries (gastric resections, right colectomy, and liver resections) classifying patients into three age groups: ≤64, 65-79, and ≥80. Data from these three different age groups were compared and examined in respect of different outcomes: ASA score, comorbidities, oncologic outcomes, conversion rate, estimated blood loss, hospital stay, geriatric events, mortality, etc.

RESULTS

Using our in-patient robotic surgery database, we retrospectively examined 363 patients, who underwent robot-assisted surgery for different diseases (402 different robotic procedures): colorectal surgery, upper GI, HPB, etc.; the oncologic procedures were 81%. Male were 56%. The mean age was 65.63 years (18-89). Patients aged ≥65 years represented 61% and ≥80 years 13%. Overall conversion rate was of 6%, most in the group 65-79 years (59% of all conversions). The more frequent diseases treated were colorectal surgery 43%, followed by hepatobilopancreatic surgery 23.4%, upper gastro-intestinal 23.2%, and others 10.4%.

DISCUSSION

Robot-assisted surgery is a safe and effective technique in aging patient population too. There was no increased risk of death or morbidity compared to younger patients in the three groups examined. A higher conversion rate was observed in our experience for patients aged 65-79. Prolonged operative time and in any cases steep positions (Trendelenburg) have not represented a problem for the majority of patients.

CONCLUSIONS

In any case, considering the high direct costs, minimally invasive robot-assisted surgery should be performed on a case-by-case basis, tailored to each patient with their specific histories and comorbidities.

Our experience in the treatment of Malignant Fibrous Hystiocytoma of the larynx: clinical diagnosis, therapeutic approach and review of literature

Hereditary spherocytosis (HS) and Chronic myelocytic leukemia (CML) are both life threatening hemotologic diseases. They are rarely seen to occur simultaneously in one individual patient. Here we demonstrate a case of HS associated with CML in this study. The patient is a young female, diagnosed with HS in 2005, and was given partial embolization of the splenic artery. She got significant remission after the procedure. In 2008, she was found abnormal in blood routine test, after bone marrow routine, chromosome and fusion gene tests, she was diagnosed with CML (chronic phase). She did not receive regular treatment until 3 months prior, and is currently being treated with Dasatimib. She achieved hematological remission, but had no significant improvement in chromosome and fusion gene figures. Due to her severe condition of hemolysis, a splenectomy or an allogeneic hematopoietic stem cell transplantation is considered.

Bowel Angiodysplasia and Myocardial Infarction secondary to an ischaemic imbalance: a case report

Angiodysplasia, defined as a vascular ectasia or arteriovenous malformation, is the most frequent cause of occult bleeding in patients older than 60 years and a significant association with several cardiac condition is described. Patients with anemia and negative findings on upper endoscopy and colonoscopy should be referred for further investigation of the small bowel. The investigation of choice, when available, is wireless capsule endoscopy. Several therapeutic options are available in this cases, as we reviewed in this report. We report a case of 78-year old man admitted to our Intensive Coronary Unit for dyspnea and chest pain. A diagnosis of non-ST-segment elevation acute coronary syndrome was made and a concomintant, significant anemia was found (hemoglobin 8.2 g/dl).

No cororary disease was found by an angiography though the past medical history revealed systemic hypertension, chronic kidney disease (KDOQY stage III), and diabetes mellitus type II on insuline therapy. A Wireless Video capsule examination was positive for jejunum angiodysplasia and an argon plasma coagulation was chosen as terapeutic option. No subsequent supportive therapy and interventions were required in subsequent one year of follow-up.

Clinical characterization and mutation spectrum in Hispanic families with adenomatous polyposis syndromes

Several genetically defined hereditary colorectal cancer (CRC) syndromes are associated with colonic polyposis including familial adenomatous polyposis (FAP) and MUTYH adenomatous polyposis (MAP). Limited data exists on the clinical characterization and genotypic spectrum of polyposis syndromes among Hispanics. To describe the phenotype and genotype of Puerto Rican Hispanic patients with FAP and MUTYH and compare with other ethnic and racial groups. Probands were identified from the Puerto Rico Familial Colorectal Cancer Registry (PURIFICAR). Recruited individuals completed risk factors, medical, and family history questionnaires and underwent genetic testing for genotype analysis. Frequency analysis, Chi square, Fisher's exact and Wilcoxon rank-sum tests were used for statistical analysis methods. A total of 31 FAP (from 19 families) and 13 MAP (from 13 families) Hispanic patients recruited from the PURIFICAR were evaluated. Among the FAP cases, mean age at diagnosis was 27.6 (range 9-71 years); 67.7 % cases had more than 100 polyps and 41.9 % had upper gastrointestinal polyps. Among the 19 FAP families, there were 77 affected FAP individuals and 26 colorectal cancer cases. Genetic mutations were available for 42.2 % of FAP families; all mutations identified were unique. Surgeries were reported in 31 cases; 14 (45.2 %) prophylactic surgeries and 6 (19.4 %) therapeutic surgeries for management of CRC. Among MAP cases, mean age at diagnosis was 53 (range 34-76 years). Genetic analysis revealed homozygous biallelic mutations (G382D) in 53.8 %, compound heterozygous mutations (G382/Y165C) in 23 %, and non-G382/Y165C monoallelic mutations in 23 %. Familial cancer registries should be promoted as vehicles for detection, education and follow up of families at-risk of acquiring familial cancers. PURIFICAR is the first and only familial cancer registry in Puerto Rico providing these services to families affected with familial cancer syndromes promoting education, testing and surveillance of at-risk family members, and focusing on cancer prevention efforts. The fact that only 40 % of FAP patients had access to genetic testing stresses the need to promote the establishment of policies supporting genetic testing coverage by medical insurance companies in order to provide patients with the highest standard of care to prevent cancer. Furthermore, our results suggest that Hispanics may have uncommon mutations in adenomatous polyposis related genes, which emphasize the need for full gene sequencing to establish genetic diagnosis.

Minimal invasive surgery in treatment of liver metastases from colorectal carcinomas: case studies and survival rates

BACKGROUND

Liver represents the main organ subject to metastases from colorectal tumors. Resections of liver metastases from colorectal cancer have a well-considered therapeutic role underlined by survival of 5 years by approximately 50-60% of surgical cases as is deduced from an analysis of the most recent literature. The objective of surgery is to eradicate the metastases present and obtain a margin free from neoplastic impact of amplitude of approximately 1 cm with residual liver quantity at the end of the intervention that allows the patient to survive. Currently the dimensions and the number of colorectal liver metastases (CRLM) do not limit the hepatectomy. Purpose of this work is to evaluate the survival, according to our case studies of patients treated only with the wedge resection (atypical resection) approximately 1 cm from the margins of metastases.

METHODS

In "A. Rizzoli" Lacco Ameno Hospital (Ischia), from 2005 to 2010, 12 liver resections were performed for metastases from colorectal carcinoma with atypical resection. Synchronous surgical treatment with resection of the colorectal carcinoma and metastases was performed in 6 patients, 2 female and 4 male (Group 1). Surgical liver metastasectomy post-colectomy was performed on 6 patients, 3 female and 3 male (Group 2).

RESULTS

No patient was treated with chemotherapy. The mortality rate of intraoperative and perioperative infection was in both cases of 0%. Survival:11 patients treated surgically from 2005-2010 with synchronous surgery resection (Group 1) and liver metastasectomy (Group 2) are currently living. One 77-years-old patient died three years after surgery for BPCO.

CONCLUSIONS

This result was able to be obtained due to the wedge resection technique routinely used in our Hospital, associated with the indispensable use of intraoperatory ultrasound (IOUS). Significant differences between the synchronous and non-synchronous intervention emerged only regarding the number of days of hospital stay, higher in the first case.

Role of conventional radiology and MRi defecography of pelvic floor hernias

Background

Purpose of the study is to define the role of conventional radiology and MRI in the evaluation of pelvic floor hernias in female pelvic floor disorders.

Methods

A MEDLINE and PubMed search was performed for journals before March 2013 with MeSH major terms 'MR Defecography' and 'pelvic floor hernias'.

Results

The prevalence of pelvic floor hernias at conventional radiology was higher if compared with that at MRI. Concerning the hernia content, there were significantly more enteroceles and sigmoidoceles on conventional radiology than on MRI, whereas, in relation to the hernia development modalities, the prevalence of elytroceles, edroceles, and Douglas' hernias at conventional radiology was significantly higher than that at MRI.

Conclusions

MRI shows lower sensitivity than conventional radiology in the detection of pelvic floor hernias development. The less-invasive MRI may have a role in a better evaluation of the entire pelvic anatomy and pelvic organ interaction especially in patients with multicompartmental defects, planned for surgery.

Minimal invasive surgery in treatment of liver metastases from colorectal carcinomas: case studies and survival rates

BACKGROUND

Liver represents the main organ subject to metastases from colorectal tumors. Resections of liver metastases from colorectal cancer have a well-considered therapeutic role underlined by survival of 5 years by approximately 50-60% of surgical cases as is deduced from an analysis of the most recent literature. The objective of surgery is to eradicate the metastases present and obtain a margin free from neoplastic impact of amplitude of approximately 1 cm with residual liver quantity at the end of the intervention that allows the patient to survive. Currently the dimensions and the number of colorectal liver metastases (CRLM) do not limit the hepatectomy. Purpose of this work is to evaluate the survival, according to our case studies of patients treated only with the wedge resection (atypical resection) approximately 1 cm from the margins of metastases.

METHODS

In "A. Rizzoli" Lacco Ameno Hospital (Ischia), from 2005 to 2010, 12 liver resections were performed for metastases from colorectal carcinoma with atypical resection. Synchronous surgical treatment with resection of the colorectal carcinoma and metastases was performed in 6 patients, 2 female and 4 male (Group 1). Surgical liver metastasectomy post-colectomy was performed on 6 patients, 3 female and 3 male (Group 2).

RESULTS

No patient was treated with chemotherapy. The mortality rate of intraoperative and perioperative infection was in both cases of 0%. Survival:11 patients treated surgically from 2005-2010 with synchronous surgery resection (Group 1) and liver metastasectomy (Group 2) are currently living. One 77-years-old patient died three years after surgery for BPCO.

CONCLUSIONS

This result was able to be obtained due to the wedge resection technique routinely used in our Hospital, associated with the indispensable use of intraoperatory ultrasound (IOUS). Significant differences between the synchronous and non-synchronous intervention emerged only regarding the number of days of hospital stay, higher in the first case.

Clinical and genetic characterization of classical forms of familial adenomatous polyposis: a Spanish population study

BACKGROUND

Classical familial adenomatous polyposis (FAP) is characterized by the appearance of >100 colorectal adenomas.

PATIENTS AND METHODS

We screened the APC and MUTYH genes for mutations and evaluated the genotype-phenotype correlation in 136 Spanish classical FAP families.

RESULTS

APC/MUTYH mutations were detected in 107 families. Sixty-four distinct APC point mutations were detected in 95 families of which all were truncating mutations. A significant proportion (39.6%) had not been previously reported. Mutations were spread over the entire coding region and great rearrangements were identified in six families. Another six families exhibited biallelic MUTYH mutations. No APC or MUTYH mutations were detected in 29 families. These APC/MUTYH-negative families showed clinical differences with the APC-positive families. A poor correlation between phenotype and mutation site was observed.

CONCLUSIONS

Our results highlight that a broad approach in the genetic study must be considered for classical FAP due to involvement of both APC and MUTYH and the heterogeneous spectrum of APC mutations observed in this Spanish population. The scarcely consistent genotype-phenotype correlation does not allow making specific recommendations regarding screening and management. Differences observed in APC/MUTYH-negative families may reflect a genetic basis other than mutations in APC and MUTYH genes for FAP predisposition.

APC gene mutations causing familial adenomatous polyposis in Polish patients

Familial adenomatous polyposis (FAP) is a well-known hereditary condition characterised by alimentary system tumours. Tens to thousands of polyps occur in the colon and rectum of the patients. There is a high heterogeneity with regard to the number and time of the occurrence of polyps. The occurrence of FAP is associated with mutations in the APC tumour suppressor gene, which was described in 1991. Since then, many studies have been done to analyse the distribution of mutations in individual populations and to determine the function of the gene and a diagnostic approach to FAP. Here the APC gene was studied with respect to the occurrence of small mutations and large rearrangements in 300 unrelated Polish FAP families. Ninety-seven mutations were identified in 164 families. Out of these mutations, 80 were small mutations, including 58 small mutations that were first identified in the Polish population (42 novel and 16 described previously). An increased frequency of mutation c.3927_3931delAAAGA was observed in 10% of the Polish group. Seventeen large rearrangements were found in 29 families. Out of those rearrangements, 8 repeat rearrangements occurred in 20 families. A problem in fast molecular diagnostics of FAP is a high heterogeneity of mutations in the APC gene. It seems that a multiplex ligation-dependent probe amplification test and searching for small mutations by the use of screening methods at the 5' end of exon 15 and exons 14, 9, 11, 13, 5, and 3, help to improve the molecular diagnostics of FAP in Polish patients.

Clinical characterization and the mutation spectrum in Swedish adenomatous polyposis families

BACKGROUND

The dominantly inherited condition familial adenomatous polyposis (FAP) is caused by germline mutations in the APC gene. Finding the causative mutations has great implications for the families. Correlating the genotypes to the phenotypes could help to improve the diagnosis and follow-up of patients.

METHODS

Mutation screening of APC and the clinical characterization of 96 unrelated FAP patients from the Swedish Polyposis Registry was performed. In addition to generally used mutation screening methods, analyses of splicing-affecting mutations and investigations of the presence of low-frequency mutation alleles, indicating mosaics, have been performed, as well as quantitative real-time polymerase chain reaction to detect lowered expression of APC.

RESULTS

Sixty-one different APC mutations in 81 of the 96 families were identified and 27 of those are novel. We have previously shown that 6 of the 96 patients carried biallelic MUTYH mutations. The 9 mutation-negative cases all display an attenuated or atypical phenotype. Probands with a genotype (codon 1250-1464) predicting a severe phenotype had a median age at diagnosis of 21.8 (range, 11-49) years compared with 34.4 (range, 14-57) years among those with mutations outside this region (P < 0.017). Dense polyposis (> 1000) occurred in 75% of the probands with a severe phenotype compared with 30% in those with mutations outside this region. The morbidity in colorectal cancer among probands was 25% at a mean age of 37.5 years and 29% at a mean age of 46.6 years.

CONCLUSION

Using a variety of mutation-detection techniques, we have achieved a 100% detection frequency in classical FAP. Probands with APC mutations outside codon 1250-1464, although exhibiting a less-severe phenotype, are at high risk of having a colorectal cancer at diagnosis indicating that age at diagnosis is as important as the severity of the disease for colorectal cancer morbidity.

Colorectal adenomatous polyposis Associated with MYH mutations: genotype and phenotype characteristics

PURPOSE

Recent literature reports that several digestive diseases are associated with mutations in the base excision repair gene MYH. This study was designed to establish the prevalence of germ-line MYH mutations in a series of 56 consecutive patients with no detectable APC mutation and describe the phenotype of those with MYH mutations.

METHODS

MYH mutations were screened by DNA sequencing after polymerase chain reaction amplification of each exon. Clinical, endoscopic, and surgical data were collected for the tested patients.

RESULTS

MYH mutations were identified only in the group of patients with attenuated adenomatous polyposis with ten or more adenomatous polyps. The prevalence of MYH mutations was 34.4 percent (11 cases) in this subgroup of 30 patients. There were two homozygotes and eight compound heterozygotes. Only one patient had a monoallelic mutation. At least one of two mutational hot spots was identified in ten patients. Three patients presented with a family history of adenomatous polyposis in siblings, without vertical transmission. The median number of colorectal adenomatous polyps was 53 without preferential localization. Colorectal cancer was associated with polyposis in seven patients. Gastric and duodenal adenomas were diagnosed in one case. Ten of 11 patients underwent colectomy.

CONCLUSIONS

MYH mutations have been observed in one-third of patients with attenuated polyposis. The phenotype of the disease is similar to attenuated familial adenomatous polyposis. Upper gastrointestinal endoscopy also should be recommended. However, its transmission shows evidence of a recessive pattern.