RESUMO
Germ-line mutations in the adenomatous polyposis coli (APC) gene are responsible for familial adenomatous polyposis (FAP). In the present study, we have used the protein truncation test to screen for mutations in exon 15 and exons 1-14 of the APC gene and denaturing gradient gel electrophoresis to analyze exons 1-14. We have studied nine unrelated FAP kindreds, eight with the classical phenotype and one with an atypical phenotype, with several family members exhibiting fewer than 50 colonic polyps. The combined use of these two methodologies allowed the identification of seven novel mutations, with two unrelated families sharing the same mutation. All mutations were chain terminating: six resulted from small deletions, one from a small insertion, and one was a point mutation, resulting in a premature stop codon. Seven mutations were located in exon 15 of the APC gene, one was in exon 10, and the remaining one, which corresponded to the kindred with an atypical phenotype, was located in exon 4.
Assuntos
Polipose Adenomatosa do Colo/genética , Proteínas do Citoesqueleto/genética , Genes APC , Mutação , Proteína da Polipose Adenomatosa do Colo , Proteínas do Citoesqueleto/metabolismo , Análise Mutacional de DNA , Eletroforese/métodos , Feminino , Humanos , Masculino , Linhagem , Fenótipo , PortugalRESUMO
BACKGROUND: Colorectal tumors with microsatellite instability (MSI) that do not comply with previously defined clinical criteria may be found in recently diagnosed hereditary nonpolyposis colorectal carcinoma families. Until recently, the indications for MSI testing were not clearly established. The objective of the current study was to validate the recently published Bethesda guidelines for MSI testing in a series of patients with apparently sporadic forms of colorectal carcinoma (CRC). METHODS: Sixty-two patients with so-called sporadic CRC were included in the current study. MSI was analyzed at seven poly(CA) repeat sequences and at one poly(A) locus. RESULTS: Nine of 62 patients (14.5%) had tumors exhibiting MSI at > or = 2 loci and 7 patients (11%) had MSI at > or = 3 loci. Patients with MSI positive tumors were younger (P < 0.05), and their tumors more frequently were right-sided (P < 0.02) and more often exhibited a mucinous component (P < 0.05). The Bethesda guidelines were positive in 18% (11 of 62) of patients. The sensitivity of these guidelines in identifying tumors with MSI at > or = 3 loci was 43% and the positive predictive value (PPV) was 27% (3 of 11 cases). Other variables were considered as alternative criteria to identify CRCs with MSI: age < 45 years and/or a right-sided tumor with a mucinous component. Using these 2 criteria alone, sensitivity increased to 85% and PPV to 46%. CONCLUSIONS: In this study group, the use of three clinical criteria as sole indicators for MSI testing in patients with apparently sporadic forms of CRC were significantly more discriminating compared with the Bethesda guidelines, in addition to being substantially easier.
Assuntos
Neoplasias do Colo/genética , Guias como Assunto , Repetições de Microssatélites/genética , Neoplasias Retais/genética , Adenocarcinoma Mucinoso/genética , Adenocarcinoma Mucinoso/patologia , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Neoplasias do Colo/patologia , Feminino , Marcadores Genéticos , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Retais/patologia , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeAssuntos
Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Neoplasias Colorretais Hereditárias sem Polipose/genética , Repetições de Microssatélites , Adulto , Fatores Etários , Diagnóstico Diferencial , Humanos , Pessoa de Meia-Idade , National Institutes of Health (U.S.) , Guias de Prática Clínica como Assunto , Estados UnidosRESUMO
BACKGROUND: Studies using DNA technology have reported the presence of human papillomavirus (HPV) DNA in esophageal carcinomas, suggesting that it could play a role in the pathogenesis of this tumor. In the present study, in addition to DNA from neoplasms, normal mucosa was screened for viral DNA, assuming that this would increase HPV detection substantially. METHODS: Seventeen patients with esophageal carcinoma and 10 control subjects were studied. In 8 of the patients, normal mucosa was also available. Polymerase chain reaction (PCR) was performed using primers for the E6 region of HPV-16 and HPV-18. Koilocytosis, a commonly accepted histopathologic marker of viral infection, was studied, and results were correlated with PCR findings. RESULTS: DNA from neoplastic lesions was positive for HPV-16 and HPV-18 in 8 of 16 (50%) and in 3 of 16 (18.8%), respectively. When tumor tissue and normal mucosa were available, PCR results were 3 of 8 (37.5%), 5 of 8 (62.5%), and 8 of 8 (100%) for HPV-16, in tumor, normal mucosa, and both. For HPV-18, results were 0 of 8 (0%), 5 of 8 (62.5%), and 5 of 8 (62.5%), respectively. In comparison with tumor samples, positivity in normal mucosa was increased for HPV-18 and for both viral genotypes (P = 0.01). No amplification was obtained in the control group. Koilocytosis was present in 33% of the cases. CONCLUSIONS: These results suggested a high prevalence of HPV in esophageal carcinoma. The detection rate is significantly higher in normal mucosa specimens, suggesting that infection probably antedates tumor development. Koilocytosis was substantially less sensitive than PCR.
