Cases reported "Colonic Polyps"

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1/3. Evidence for a recessive inheritance of Turcot's syndrome caused by compound heterozygous mutations within the PMS2 gene.

    Turcot's syndrome is a genetic disease characterized by the concurrence of primary brain tumors and colon cancers and/or multiple colorectal adenomas. We report a Turcot family with no parental consanguinity, in which two affected sisters, with no history of tumors in their parents, died of a brain tumor and of a colorectal tumor, respectively, at a very early age. The proband had a severe microsatellite instability (MIN) phenotype in both tumor and normal colon mucosa, and mutations in the TGFbeta-RII and APC genes in the colorectal tumor. We identified two germline mutations within the PMS2 gene: a G deletion (1221delG) in exon 11 and a four-base-pair deletion (2361delCTTC) in exon 14, both of which were inherited from the patient's unaffected parents. These results represent the first evidence that two germline frameshift mutations in PMS2, an MMR gene which is only rarely involved in HNPCC, are not pathogenic per se, but become so when occurring together in a compound heterozygote. The compound heterozygosity for two mutations in the PMS2 gene has implications for the role of protein PMS2 in the mismatch repair mechanism, as well as for the presymptomatic molecular diagnosis of at-risk family members. Furthermore, our data support and enlarge the notion that high dna instability in normal tissues might trigger the development of cancer in this syndrome.
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ranking = 1
keywords = microsatellite instability, microsatellite, instability
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2/3. Multiple synchronous primaries of the gastrointestinal tract: a molecular case report.

    Six synchronous gastrointestinal primaries were identified in a 70 year old male with no known cancer predisposition syndrome or recognized risk factors except alcohol abuse. These specimens appeared to be independent and unrelated by gross and histopathological examination. In order to further evaluate the six tumors, we analyzed selected dna sequences for alterations in the K-ras oncogene and p53 tumor suppressor gene. In addition, three loci were analyzed to determine microsatellite instability. Using the polymerase chain reaction, single stranded conformational polymorphism, and dna sequencing, we demonstrated that each primary manifests genetic characteristics typical of the tissue of origin. In addition, one primary, a moderately differentiated colon adenocarcinoma, exhibited mutations not detected in the other specimens. This study suggests that these synchronous primaries arose independently and progressed along different carcinogenic pathways.
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ranking = 0.99924906515555
keywords = microsatellite instability, microsatellite, instability
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3/3. Mixed epithelial polyps in association with hereditary non-polyposis colorectal cancer providing an alternative pathway of cancer histogenesis.

    A member of a hereditary non-polyposis colorectal cancer (HNPCC) family developed two colorectal cancers and multiple polyps within four years of a negative colonoscopic examination. One of the cancers was only 4 mm in diameter and showed the gross and endoscopic appearances of a de novo carcinoma. Microscopic examination of multiple levels revealed a mixed hyperplastic polyp/adenoma (mixed polyp) in contiguity with the cancer. The colon harboured additional polyps of which five were tubular adenomas, seven were hyperplastic polyps and seven were mixed polyps (architecturally compatible with hyperplastic polyps but with atypical cytology). Atypical features of the mixed polyps included tripolar mitoses, bizarre chromatin aggregations and multinucleation. One mixed polyp showed dna microsatellite instability. Under the influence of the mutator defect, hyperplastic polyps may develop atypical or adenomatous features and show progression to carcinoma. Such an alternative morphogenetic pathway could explain the differing molecular and pathological profiles of cancers showing dna microsatellite instability.
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ranking = 1.9984981303111
keywords = microsatellite instability, microsatellite, instability
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