[Familial colorectal cancer type X: clinical, pathological and molecular characterization]. / Carcinoma colorectal familiar de tipo X: caracterização clínica, patológica e molecular.

BACKGROUND: Some families fulfilling the Amsterdam Criteria (AC) differ from the Lynch syndrome (LS) in that colorectal cancers (CRC) do not present microsatellite instability (MSI) and DNA mismatch repair gene mutations are not found. These families have been designated as Familial Colorectal Cancer type X (XS) and their genetic basis remains unknown. AIMS: In families fulfilling AC for LS: 1) To perform MSI testing in CRC and to correlate it with clinical and pathological characteristics and with the mutational analysis in the DNA mismatch repair genes; 2) In cases suggestive of XS, to study the suppressor pathway (SP) of carcinogenesis. PATIENTS AND METHODS: 45 patients with CRC, from 41 families fulfilling AC, were included. Clinical and pathological data were recorded. MSI testing was performed with the Bethesda marker panel and mutational analysis in MLH1, MSH2 and MSH6 genes was undertaken by DGGE, MLPA and direct sequencing. To study the SP, loss of heterozigoty was evaluated at the following loci: APC, p53, DCC and SMAD4 genes. RESULTS: 33/41 (80%) and 8/41 (20%) families presented high-grade microsatellite instability (MSI-H) and microsatellite stable (MSS) CRC, respectively. In families suggestive of XS, a smaller number of CRC and less frequent spectrum associated tumors were detected. In comparison with MSI-H CRC, MSS CRC were preferentially located at the distal colon/rectum and less often presented mucous production or lymphocytic infiltrate. In 70% of families with MSI-H CRC, a pathogenic mutation in one of the DNA mismatch repair genes was identified, as opposed to none in the group with MSS CRC. The SP was followed in 2 cases and an alternative one in other two. The remaining 4 cases were noninformative; however, 5/8 (63%) presented allelic losses in the APC gene. CONCLUSIONS: 1) Families fulfilling AC and harbouring MSS CRC presented particular characteristics, which reinforce the existence of a new entity, different from LS; 2) The designation of Familial Colorectal Cancer type X seems appropriate to classify an entity whose CRC follow an unclear carcinogenesis pathway and that presents an unknown genetic basis; 3) The designation of LS should be restricted to families with an identified pathogenic DNA mismatch repair gene mutation.

Aggressive phenotype of MYH-associated polyposis with jejunal cancer and intra-abdominal desmoid tumor: report of a case.

MYH-associated polyposis is an inherited autosomal recessive disease, linked to biallelic germline MYH mutations, which predisposes to the development of multiple colorectal adenomas and cancer. The colonic and extracolonic phenotype of this syndrome is very heterogeneous. We report the case of a young male patient with an aggressive MYH-associated polyposis phenotype. He presented at aged 30 years with more than 100 colonic polyps and 4 colonic adenocarcinomas. At aged 35 years, Spigelman Stage IV duodenal adenomatosis was detected. When he was 39 years old, he developed three synchronous jejunal adenocarcinomas and a mesenteric desmoid tumor. Based on this report, we believe that screening of the entire small bowel should be recommended in MYH-associated polyposis patients, especially in those with duodenal adenomas. Similar to patients with familial adenomatous polyposis, desmoid tumors also may be part of the clinical spectrum of MYH-associated polyposis and may prove to be a significant clinical problem in patients submitted to prophylactic colectomy.

Cancer risk in Barrett's oesophagus.

(Table is included in full-text article.)Barrett's oesophagus results from the replacement of the normal squamous lining of the oesophagus by a columnar epithelium. It is the sole known premalignant condition for oesophageal adenocarcinoma. The annual cancer incidence of 1% in Barrett's oesophagus, calculated from published series, has been recently considered an overestimation owing to publication bias, and a 0.5% risk was proposed. The prerequisite of the presence of intestinal metaplasia for the diagnosis of Barrett's oesophagus, although widely accepted, is questioned by some authors. How adenocarcinoma incidence is influenced by requiring or not intestinal metaplasia for Barrett's oesophagus diagnosis is unknown. Most of the published studies included only (or preferentially) patients with long segments. Data on adenocarcinoma incidence in short segments (<3 cm) are very scarce, but it is believed to be lower than in long segments. The magnitude of cancer risk influences cost effectiveness of surveillance of Barrett's oesophagus. Frequently, therapeutic intervention is performed when high-grade dysplasia is diagnosed, preventing progression to adenocarcinoma. This could lead to an underestimation of cancer risk in Barrett's surveillance studies.

[MYH associated polyposis: severe phenotype in the homozygosity for the 1103delC mutation]. / Polipose associada ao MYH: fenótipo grave na homozigotia para a mutação 1103delC.

MYH-associated polyposis (MAP) is an autosomal recessive disease associated with multiple colonic adenomas and colorectal cancer. Y165C and G382D MYH missense mutations are involved in more than 80% of cases in Caucasians and the large series published do not include patients homozygous for other mutations. We present the report of two siblings homozygous for the nonsense frameshift mutation 1103delC. The proband aged 28 presented with four colonic adenocarcinomas and 20-30 synchronous adenomas. Her sister aged 24 had 20 colonic adenomas and a severe Spigelman's III duodenal adenomatosis. Their parents, aged 60 and 51, heterozygous for the 1103delC MYH mutation, presented 5 and 2 low risk colorectal adenomas, respectively.

Chromosomal analysis of Barrett's cells: demonstration of instability and detection of the metaplastic lineage involved.

UNLABELLED: Barrett's esophagus is lined by columnar and goblets cells with gastric and intestinal characteristics. Despite the association between goblet elements and malignancy, it was not demonstrated that other columnar cells lineages are not related to neoplasia. Chromosomal abnormalities were described in metaplasia adjacent to Barrett's neoplasia, but it is unknown which metaplastic lineages are involved. This work assessed the frequency and the type of chromosomal abnormalities in Barrett's esophagus without neoplasia and performed the identification of the metaplastic cells carrying chromosomal gains. Barrett's esophagus biopsies were collected and processed for short-term cell culture and cytogenetic analysis. Combined immunofluorescence/fluorescence in situ hybridization was performed in cases exhibiting chromosomal gains by using antisera against intestinal (MUC2) and gastric (MUC5AC and MUC6) apomucins and chromosome pericentromeric alpha satellite DNA probes for the chromosomes involved. Each case was scored for the number of spots (0, 1, 2, >2) in 200 nonoverlapping nuclei. Columnar and goblet cells were separately assessed. Short-term cell cultures were achieved in 40/60 cases (67%). There were clonal abnormalities in 27/40 cases (68%) and tetraploid (4n) clones in 10/40 (25%). Structural alterations were detected in 14/40 (35%) with recurrent breakpoints at 1q21, 15q15 and 15q22. Numerical changes (trisomies 7 and 18 and loss of Y) occurred in 16/40 (40%). Gains of chromosomes 7 and 18 were more frequent in columnar than in goblet cells (9.8% vs 0.7% (P<0.05)) and (7.9 vs 1.9% (P<0.05)) respectively. These alterations were detected in cells exhibiting gastric as well as intestinal features and were more frequent in cells without apomucin production. CONCLUSIONS: (1) chromosomal instability is a common finding in Barrett's esophagus without neoplasia. (2) The two metaplastic populations are committed, chromosomal gains being more frequent in columnar nongoblet than in goblet cells. (3) The two metaplastic phenotypes, gastric and intestinal, are equally involved.

[Need of new clinical criteria for the identification of genetic Lynch syndrome]. / Necessidade de novos critérios clínicos para a identificação de famílias com síndroma de Lynch em base genética.

BACKGROUND: Surveillance programs in families with Hereditary Non-Polyposis Colorectal Cancer (HNPCC), which is an autossomal dominant disease, decrease colorectal carcinoma mortality. There are multiple clinical criteria for the identification of these families, mainly: the Amsterdam Criteria (ACI), the modified Amsterdam Criteria (ACII) and the Bethesda Guidelines (BG). AIMS: To correlate, in families with HNPCC, the clinical criteria with the probability of detecting a germ-line mutation in MLH1, MSH2 and MSH6 mismatch repair genes. METHODS: We included 92 affected patients belonging to different families. Clinical criteria leading to HNPCC diagnosis were evaluated. Germ-line mutations in MLH1, MSH2 and MSH6 genes were performed by DGGE/MLPA and direct sequencing. RESULTS: Germ-line mutations were detected in 54/92 (59%) families, 30 in MLH1, 23 in MSH2 and 1 in MSH6. Germ-line mutation detection was significantly lower in ACI without age criteria (0%), when compared to: ACI (60%), ACII (62%), ACII without age criteria (67%) and BG (61%). CONCLUSIONS: The classic, modified AC and BG allowed the detection of an identical percentage of families with mutation positive HNPCC. The absence of the age criteria in the ACI makes the HNPCC diagnosis highly unlikely. Simpler and uniform criteria should be elaborated, to allow a homogeneous identification of families with HNPCC.

Association of colonic and endometrial carcinomas in Portuguese families with hereditary nonpolyposis colorectal carcinoma significantly increases the probability of detecting a pathogenic mutation in mismatch repair genes, primarily the MSH2 gene.

BACKGROUND: Hereditary nonpolyposis colorectal carcinoma (HNPCC) significantly raises the risk of developing colorectal carcinoma (CRC) and other extracolonic tumors. It is defined by the Amsterdam Criteria and is associated with germline mutations in mismatch repair genes, primarily MLH1 and MSH2. The objectives of the current study were to evaluate the presence of CRC (Type I) and other extracolonic tumors (Type II) in families with HNPCC and to analyze the findings for correlations with germline mutations in the MLH1 and MSH2 genes. METHODS: Seventy families with an HNPCC diagnosis were analyzed. Denaturing gradient gel electrophoresis and direct sequencing were used for germline mutation analysis in the MLH1 and MSH2 genes. RESULTS: Forty-three of 70 families (61%) presented with HNPCC Type II. In 21 of 30 families that had a complete genetic diagnosis, 16 pathogenic germline mutations (7 MLH1 mutations and 9 MSH2 mutations) and 5 mutations of unknown pathogenecity (all MLH1 mutations) were found. In the remaining nine families, no mutations were detected. Unequivocally pathogenic mutations were far more common in families with HNPCC Type II compared with families that had CRC only (P = 0.01). Families with endometrial carcinoma presented with the greatest probability of mutational detection (P = 0.005). MLH1 was only gene affected in families with HNPCC Type I, whereas mutations in both MLH1 and MSH2 were found in families with HNPCC Type II (P = 0.04). However, the MSH2 gene was more frequently involved in families with HNPCC in which endometrial carcinoma was present (P = 0.005). CONCLUSIONS: CRC and endometrial carcinoma were associated with a greater probability of detecting pathogenic mutations in mismatch repair genes, with MSH2 involvement predominating. The results support specific mutational screening strategies, based on observed phenotypes, for families with HNPCC.

Losses of heterozygosity on chromosomes 9p and 17p are frequent events in Barrett's metaplasia not associated with dysplasia or adenocarcinoma.

OBJECTIVE: Losses of heterozygosity (LOH) on chromosomes 9p and 17p frequently accompany malignant transformation of Barrett's esophagus (BE). They have been reported in adenocarcinoma, dysplasia, and adjacent metaplasia of patients with long-segment BE (LSBE). This study aimed to evaluate and compare the frequency of LOH on 9p and 17p in patients with long- and short-segment BE (SSBE) without dysplasia or adenocarcinoma. METHODS: Matched metaplasia and blood DNA were evaluated for LOH on chromosomes 9p and 17p in patients with a previous diagnosis of BE and no dysplasia or cancer. RESULTS: We included 18 patients (12 long-segment BE and six short-segment BE). The overall prevalence of LOH was 61% (10 of 18), with no significant difference between LSBE (58%) and SSBE (50%). The frequencies of LOH on 9p and 17p were similar (35% and 39%, respectively), with 18% of the patients showing losses at both chromosomes. CONCLUSIONS: LOH on 9p and 17p are highly frequent events in BE, even in the absence of dysplasia and adenocarcinoma. The presence of these abnormalities in non-neoplastic epithelium suggests they might be useful markers for risk stratification within endoscopic surveillance programs.