Association of polymorphisms in microRNA-binding sites and colorectal cancer in an Iranian population.

MicroRNAs (miRNAs) are agents of post-transcriptional gene expression, and they can affect many functions of an individual cell or tissue from extracellular matrix production to inflammatory processes and tumor development. We aimed to determine the possible role of miRNA-binding site polymorphisms located in five cancer-related genes: IL-16, CDKN2A (p16), RAF1, PTGER4, and ITGB4 in colorectal cancer (CRC) risk modification in an Iranian population. This study was performed on 643 individuals (249 CRC cases and 394 healthy controls). We selected five cancer-related genes (IL-16, CDKN2A (p16), RAF1, PTGER4, and ITGB4) and investigated the genotypes of the 3' untranslated region miRNA-binding site polymorphisms in these genes in our study population. The restriction fragment length polymorphism results were confirmed by a direct sequencing method. We found a statistically significant difference between the rs1131445 polymorphism of the IL-16 gene and CRC. The frequencies of the genotypes TT, CT, and CC in controls were 51%, 40.4%, and 8.6%, respectively, and in cases were 41.4%, 44.1%, and 14.5%, respectively, which shows a significant association between the CC genotype of the rs1131445 polymorphism and CRC (P = 0.004). The frequency of the C allele in the CRC group was higher than in the controls, and the C allele of the rs1131445 polymorphism was found to be in association with CRC (P = 0.009). These associations remained significant after Bonferroni's correction for multiple testing. We found that the AA genotype of the rs743554 polymorphism in the ITGB4 gene and the T allele of the rs1051208 polymorphism of the RAF1 gene were associated with the risk of CRC in females; however, after Bonferroni's correction we found that they were non-significant. Finally, we can conclude that a significant relationship exists between the miRNA-binding site polymorphism of the IL-16 gene and CRC risk in the Iranian population.

Characterization of hepatitis B virus genome variability in Iranian patients with chronic infection, a nationwide study.

Hepatitis B virus (HBV) isolates from Iranian patients around the country were characterized. Eighty-one complete genomes from HBV isolates were sequenced and analyzed. The studied population was grouped into three categories including inactive carriers, patients with chronic hepatitis, and patients with liver cirrhosis. Molecular and phylogenetic analyses revealed that Iranian patients were infected with HBV genotype D and subgenotype D1. The most common subtype was ayw2, followed by ayw3 and ayw4. Several deletions and insertions that had no correlation with disease outcome were observed in the HBV genomes. The most frequent mutation in the major hydrophilic region (MHR) of HBV surface antigen (HBsAg) was sP120S. Almost half of the patients studied carried precore (PC) mutant variants and one-third of the studied population was infected with variants carrying basal core promoter (BCP) mutations. PC and BCP mutations were observed in older patients, especially in those with chronic liver disease. Sixty-seven patients (82.7%) were HBeAg negative, and the prevalence of precore mutant isolates (G1896A) was higher in this group than in HBeAg-positive patients. Lamivudine drug resistance mutations were detected after 1 year of treatment in about 30% of lamivudine-treated patients. In conclusion, these results demonstrate that HBV subgenotype D1 is the only subgenotype circulating in Iran, and there is no evidence of any exotic genotype in the region. The HBV PC (G1896A) mutation may play an important role in the clinical outcome of the disease by increasing the risk of progressive liver disease among Iranian patients infected with HBV.

Prevalence of sapovirus infection among infant and adult patients with acute gastroenteritis in Tehran, Iran.

AIM: This study investigated the prevalence of sapovirus infections in patient with acute gastroenteritis in Tehran, Iran. BACKGROUND: Sapovirus, a member of the family Caliciviridae is one of the major causative agents of viral gastroenteritis affecting both children and adult individuals. There isn't enough data about prevalence and genotypes of sapovirus infection in Tehran, the capital city of Iran. PATIENTS AND METHODS: A total of 42 fecal samples were collected from patients with acute gastroenteritis from May to July 2009. RT nested- PCR was performed for screening. To genotype the sapovirus isolates, some positive samples were subjected to phylogenetic analysis by sequencing of fragments of viral capsid gene region. RESULTS: Sapovirus was detected in 5 of 42 stool specimens from patients with acute gastroenteritis. Sapovirus detected in this study was clustered into only one distinct genogroup I/2. Sapovirus GI/2 was predominant. CONCLUSION: Our results show that among the studied viruses responsible for this disease, sapovirus was a major viral isolate virus.

Simplified MSI marker panel for diagnosis of colorectal cancer.

BACKGROUND: Colorectal cancers (CRCs) tumors are diagnosed by microsatellite instability (MSI) due to accumulation of insertion/deletion mutations in tandem repeats of short DNA motifs (1-6 bp) called microsatellites. Microsatellite instability (MSI) is not only a hallmark marker for screening of hereditary nonpolyposis colorectal cancer (HNPCC), but also a prognostic and predictive marker for sporadic colorectal cancer. Our objective was to determine and study of five mononucleotide microsatellite markers status among Iranian patients with HNPCC and sporadic colorectal cancer. MATERIALS AND METHODS: In the current investigation 80 sporadic CRC and 80 HNPCC patients were evaluated for MSI. The pentaplex panel including 5 quasimonomorphic mononucleotide repeats (NR-21, BAT-26, BAT-25, NR-27 and NR-24) was used. RESULTS: Our findings showed that the NR-21 was the most frequent instable marker among the other markers. 53% and 25.6% specimens had instability in sporadic CRC and HNPCC, respectively. Furthermore, the frequencies of instability BAT-25 was determined in 20% sporadic CRC and 23% HNPCC samples. Interestingly our results demonstrated that the frequency of instability NR-24 was similar 20% sporadic CRC and 20.5% HNPCC. Moreover, percentage of NR-27 in HNPCC was 19.2 and 0% in sporadic CRC. Finally, BAT-26 was instable in 21.8% HNPCC patients while we could find 6.6% instability for BAT-26 in sporadic cases. CONCLUSION: It seems that among 5 mononucleotides markers NR-21 was the most useful marker for diagnosis HNPCC and sporadic cancer. Following NR-21, BAT-25 and NR-24 are the most reliable markers. Therefore using a triplex panel including 3 aforementioned MSI markers should be more promising markers for identifying MSI status in both patients with HNPCC and/or sporadic colorectal cancer.

Prevalence of ATP7B Gene Mutations in Iranian Patients With Wilson Disease.

BACKGROUND: Wilson disease (WD) is an autosomal recessive disorder. The WD gene, ATP7B, encodes a copper-transporting ATPase involved in the transport of copper into the plasma protein ceruloplasmin and in excretion of copper from the liver. ATP7B mutations cause copper to accumulate in the liver and brain. OBJECTIVES: We examined the ATP7B mutation spectrum in Wilson disease patients in Iran. PATIENTS AND METHODS: Genomic DNA was extracted from patients with Wilson disease. The entire coding region of the ATP7B gene was amplified using PCR and analyzed using direct sequencing. RESULTS: We identified five novel mutations in 5 Iranian patients with Wilson disease. The first was a transversion, c.2363C > T, which led to an amino acid change from threonine to isoleucine. The second mutation was a deletion, c.2532delA (Val845Ser), which occurred in exon 10. The third mutation was a transition mutation, c.2311C > G (Leu770Leu), which occurred in the TM4 domain of the ATP7B protein. The fourth mutation was a transversion, (c.3061G > A) (Lys1020Lys), in exon 14. Lastly, we identified a transversion, c.3206C > A (His1069Asn) in exon 14 which led to a change in function of the ATP loop domain of the ATP7B protein. The H1069Q mutation was identified as the most common mutation in our study population. CONCLUSIONS: Based on our findings, the H1069Q may be a biomarker that can be used in a rapid detection assay for diagnosing WD patients.

Frequent MSI mononucleotide markers for diagnosis of hereditary nonpolyposis colorectal cancer.

BACKGROUND: Failure in the DNA mismatch repair system is commonly accompanied by microsatellite instability and leads to colorectal cancer. The aim of this study was to find the most frequent of five mononucleotide markers in order to devise the simplest diagnostic strategy for identification of patients with hereditary nonpolyposis colorectal cancer (HNPCC) who were defined by defects in mismatch repair system. MATERIALS AND METHODS: 78 patients with colorectal cancer were recruited for this investigation. Five mononucleotide markers, NR-27, NR-21, NR-24, BAT-25 and BAT-26, were used as a pentaplex panel to determine MSI status. RESULTS: Two out of five mononucleotide markers, NR-21 (25.6%) and BAT-25 (23.1%) showed more instability than the others. CONCLUSION: In defining individuals with colorectal cancer, BAT25 and NR-21 may provide diagnostic assistance.

Impact of EXO1 polymorphism in susceptibility to colorectal cancer.

BACKGROUND AND AIM: One candidate gene for colorectal cancer (CRC) susceptibility is exonuclease 1 (EXO1). It is a member of RAD2 nuclease family, which plays a major role in mismatch repair, DNA replication, and recombination. Single-nucleotide polymorphisms are shown to be related with cancer incidence. The aim of the present study was to examine the association between the L757P polymorphism at exon 13 of the EXO1 gene and the risk of CRC in Iranian patients. METHODS: In this case-control study, 90 cases and 98 healthy control samples were analyzed genetically. The EXO1 polymorphism, P757L, was analyzed by polymerase chain reaction-restriction fragment length polymorphism. The obtained polymorphisms were examined for the relationship with CRC risk and also clinicopathological characteristics. RESULTS: Our findings showed that patients with the Leu/Leu genotype have a reduced risk of CRC (adjusted odds ratio [OR] = 0.192, 95% confidence interval [CI]: 0.040-0.921) when the Pro/Leu and Pro/Pro genotypes were blended and they were considered as the reference. The Leu/Leu genotype also showed a reduced risk (adjusted OR = 0.168, 95% CI: 0.034-0.816) when the Pro/Pro genotype was a reference; nevertheless, the Pro/Leu genotype did not reveal a significant association with CRC at the same status (adjusted OR = 0.686, 95% CI: 0.367-1.284). CONCLUSIONS: Our results provide evidence diagnosing that the Leu/Leu genotype of EXO1 showed an inverse association with CRC. In addition, despite other investigations, we could define a significant association between the Leu allele and CRC (p = 0.001).

Four novel germline mutations in the MLH1 and PMS2 mismatch repair genes in patients with hereditary nonpolyposis colorectal cancer.

BACKGROUND: Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common cause of early onset hereditary colorectal cancer. In the majority of HNPCC families, microsatellite instability (MSI) and germline mutation in one of the DNA mismatch repair (MMR) genes are found. MATERIALS AND METHODS: The entire coding sequence of MMR genes (MLH1, MLH2, MLH6, and PMS2) was analyzed using direct sequencing. Also, tumor tests were done as MSI and immunohistochemistry testing. RESULTS: We were able to find three novel MLH1 and one novel PMS2 germline mutations in three Iranian HNPCC patients. The first was a transversion mutation c.346A>C (T116P) and happened in the highly conserved HATPase-c region of MLH1 protein. The second was a transversion mutation c.736A>T (I246L), which caused an amino acid change of isoleucine to leucine. The third mutation (c.2145,6 delTG) was frameshift and resulted in an immature stop codon in five codons downstream. All of these three mutations were detected in the MLH1 gene. The other mutation was a transition mutation, c.676G>A (G207E), which has been found in exon six of the PMS2 gene and caused an amino acid change of glycine to glutamic acid. MSI assay revealed high instability in microsatellite for two patients and microsatellite stable for one patient. CONCLUSION: In all patients, an abnormal expression of the MMR proteins in HNPCC was related to the above novel mutations.

Molecular epidemiology of hepatitis delta virus (HDV) in Iran: a preliminary report.

To identify hepatitis delta virus (HDV) genetic variability and its circulating genotypes amongst infected Iranian patients, 25 patients with positive anti-HDV status from different parts of Iran were enrolled in this cross-sectional study. A portion of the HDV delta antigen was amplified, sequenced, and subjected to molecular and phylogenetic analysis. Clinical features and virological markers were evaluated. HDV RNA could be detected in 88% of anti-HDV positive cases (22 patients) with chronic hepatitis B virus (HBV) infection and liver cirrhosis. Phylogenetic analysis revealed that all Iranian patients were infected by genotype I (clade 1) of HDV, supported by a high bootstrap value (100%, 1,000 replicates). All HDV-positive patients were coinfected with genotype D1 of HBV. No significant association was determined between demographic, clinical, and virological variables in the population studied. In conclusion, the present molecular epidemiology survey reveals that clade 1 of HDV is predominant among coinfected HBV patients in Iran.