ABSTRACT
Background: In patients with colorectal carcinoma, insertions or deletions of short sequences of DNA, a phenomenon called microsatellite instability, are observed. Aim: To look for microsatellite instability and mutations of MLH1 and MSH2 gene mutations in patients with colorectal carcinoma. Material and Methods: Ten patients with sporadic colorectal carcinoma and 31 patients fulfilling criteria for hereditary nonpolyposis colon cancer (HNPCC), aged 9 to 70 years, were studied. Microsatellite instability was studied in samples of tumor and peripheral blood mononuclear cell DNA. Six markers were amplified by polymerase chain reaction and capillary electrophoresis. In samples with microsatellite instability, mutations of MLH1 and MSH2 genes were studied by direct sequencing. Results: Thirty four percent of patients had microsatellite instability and among these, 76 percent had a high degree of instability. BAT40 marker had the higher frequency of instability. No mutations for MLH1 and MSH2 genes were observed. However a new polymorphism, C399T, was identified in exon 3 of MSH2 gene. This polymorphism was observed both in patients with sporadic colorectal carcinoma and patients with HNPCC. Conclusions: There is a high frequency of microsatellite instability among patients with colorectal cancer. A new polymorphism, not previously reported, was identified in MSH2 gene.
Subject(s)
Adolescent , Adult , Aged , Child , Humans , Middle Aged , Adaptor Proteins, Signal Transducing/genetics , Carcinoma/genetics , Colorectal Neoplasms/genetics , Microsatellite Instability , /genetics , Nuclear Proteins/genetics , Polymorphism, Genetic/genetics , Genetic Testing , Colorectal Neoplasms, Hereditary Nonpolyposis/diagnosis , Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , DNA Mutational Analysis , Polymerase Chain ReactionABSTRACT
The Nramp1 gene has been associated with natural resistance to intracellular microorganisms in several species including bovine. Recent evidence suggests an association between polymorphism in the 3. untranslated region (3. UTR) of this gene with resistance/susceptibility (R/S) to Brucella abortus as determined in vivo and in vitro. In this study we tested for the variability of the short tandem repeat (STR) within the 3. UTR of Nramp1 in six breeds of Colombian creole cattle (CCC) and compared the genotypes with those of Holstein and Brahman, which were recently introduced into this country. In CCC as well as in Holstein we found the allele 175 fixed in all populations. In Brahman, 175 allele was also present with a frequency of 0.467 but additionally, in this breed there appeared five other alleles and among them two previously unreported: 183 y 185; also was found the allele 189 in the Colombian creole Harton del Valle cattle, which is not previously reported. Together these results suggest that the 175 allele in the 3. UTR Nramp1 may be an ancestral allele in cattle and if this is true the association previously reported with the R/S trait requires further evaluation.