No association between <Emphasis Type="Italic">MDR1</Emphasis> (<Emphasis Type="Italic">ABCB1</Emphasis>) 2677G>T and 3435C>T polymorphism and sporadic colorectal cancer among Bulgarian patients

Purpose Variation in genetic factors together with xenobiotic exposure may result in increased risk of colorectal cancer. The P-glycoprotein (P-gp) is highly expressed in the apical membrane of enterocytes, where it pumps xenobiotics from the enterocytes back into the intestinal lumen. Thus, polymorphisms that reduce the activity of the MDR1 (ABCB1) efflux pump are potential risk factors for colorectal carcinogenesis. The aim of the present study is to genotype the MDR1 2677G>T (rs2032582) and 3435C>T (rs1045642) polymorphism in patients with colorectal cancer and controls and to identify a possible association between individual genetic variation and susceptibility to colorectal cancer. Methods In the present study, 146 Bulgarian patients with sporadic colorectal cancer and 160 healthy Bulgarian volunteers were evaluated for the two polymorphisms in MDR1. Polymorphisms were identified using rapid-cycle real-time amplification with allele-specific probes and subsequent melting curve analyses on a LightCycler™ (Roche Diagnostics, Mannheim, Germany). Results No differences were found between the frequencies of the two mutant alleles in the tumor tissue from the cases and lymphocytes from the controls [frequencies of 2677T: 43.5% in patients and 44.1% in controls; frequencies of 3435T: 48.3% in patients and 50.9% in controls (both P > 0.05)]. The MDR1 polymorphic sequence of the tumor tissue always matched that of normal intestinal tissue from the same patient. Consequently, genotyping of DNA from archived tumor tissues is a valid alternative to the use of leukocyte DNA. Conclusions The present study suggests that MDR1 2677G>T and 3435C>T polymorphism is not a risk factor for sporadic colon cancer among Bulgarians and that somatic mutation at these sites is not involved in the genesis of colon tumors. Further examination using larger number of samples must be necessary to reach to more reliable conclusions.     

Ile<Superscript>105</Superscript>Val <Emphasis Type="Italic">GSTP1</Emphasis> polymorphism and susceptibility to colorectal carcinoma in Bulgarian population

Background and aims Etiologically, the sporadic colorectal cancer (CRC) is a complex and multifactorial disease that is linked to both exogenic and endogenic factors. Accumulating evidence indicates that susceptibility to cancers, including CRC, is mediated by genetically determined differences in the effectiveness of detoxification of potential carcinogens. A member of the glutathione-S-transferase (GST) family, GSTP1, is an important candidate for involvement in susceptibility to carcinogen-associated CRC. An A→G transition in exon 5 of the GSTP1 gene resulting in Ile¹⁰⁵Val amino acid substitution has been identified. This change leads to alteration in catalytic efficiency of variant enzyme. The aim of the current study was to evaluate the influence of Ile¹⁰⁵Val GSTP1 polymorphism on susceptibility to CRC. Materials and methods The GSTP1 genotyping was conducted in a case-control study of 80 ethnic Bulgarian CRC patients and 126 unaffected controls using polymerase chain reaction restriction fragment length polymorphism method. Results A statistically significant case-control difference in genotype frequencies was observed: 0.69 vs 0.54 for Ile/Ile, 0.22 vs 0.39 for Ile/Val, and 0.09 vs 0.07 for Val/Val (p = 0.049). The odds ratio (OR) for Val/Val was close to 1 (0.96, 95%CI: 0.35–2.66, p = 0.942), whereas the OR for Ile/Val was significantly lower, 0.45 (95%CI: 0.24–0.86, p = 0.016), compared to the referent Ile/Ile genotype. Although a prevalence of the GSTP1 variant allele-containing genotypes (Ile/Val or Val/Val) was found in controls than in patients (OR = 0.53, 95%CI: 0.30–0.96, p = 0.035), the allele frequencies did not show significant difference between cases and controls (p = 0.127). Conclusions Based on the obtained protective effect of Ile/Val GSTP1 genotype, we could suggest that Ile¹⁰⁵Val GSTP1 polymorphism may play some role in susceptibility to CRC.     

Joint effects of HLA, <Emphasis Type="Italic">INS</Emphasis>, <Emphasis Type="Italic">PTPN22</Emphasis> and <Emphasis Type="Italic">CTLA4</Emphasis> genes on the risk of type 1 diabetes

Background/hypothesis HLA, INS, PTPN22 and CTLA4 are considered to be confirmed type 1 diabetes susceptibility genes. HLA, PTPN22 and CTLA4 are known to be involved in immune regulation. Few studies have systematically investigated the joint effect of multiple genetic variants. We evaluated joint effects of the four established genes on the risk of childhood-onset type 1 diabetes. Methods We genotyped 421 nuclear families, 1,331 patients and 1,625 controls for polymorphisms of HLA-DRB1, −DQA1 and −DQB1, the insulin gene (INS, −23 HphI), CTLA4 (JO27_1) and PTPN22 (Arg620Trp). Results The joint effect of HLA and PTPN22 on type 1 diabetes risk was significantly less than multiplicative in the case-control data, but a multiplicative model could not be rejected in the trio data. All other two-way gene–gene interactions fitted multiplicative models. The high-risk HLA genotype conferred a very high risk of type 1 diabetes (OR 20.6, using the neutral-risk HLA genotype as reference). When including also intermediate-risk HLA genotypes together with risk genotypes at the three non-HLA loci, the joint odds ratio was 61 (using non-risk genotypes at all loci as reference). Conclusion Most established susceptibility genes seem to act approximately multiplicatively with other loci on the risk of disease except for the joint effect of HLA and PTPN22. The joint effect of multiple susceptibility loci conferred a very high risk of type 1 diabetes, but applies to a very small proportion of the general population. Using multiple susceptibility genotypes compared with HLA genotype alone seemed to influence the prediction of disease only marginally. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Novel <Emphasis Type="Italic">hMSH</Emphasis>2, <Emphasis Type="Italic">hMSH</Emphasis>6 and <Emphasis Type="Italic">hMLH</Emphasis>1 gene mutations and microsatellite instability in sporadic colorectal cancer

Purpose To detect the hMSH2, hMSH6 and hMLH1 DNA mismatch repair gene mutations and microsatellite instability in somatic colorectal cancer.Patients and methods The mutations of hMSH2, hMSH6, and hMLH1 genes, including microsatellite instability of BAT-26, BAT-40, D2S123, D5S346 and D17S250 were analyzed in 31 patients with colorectal.Results The results revealed that eight cases (25.8%) harbored mutations in DNA mismatch repair genes. Of these, five novel mutations including I237V in exon 4 of hMSH2, ins T at codon 1196 in exon 7 of hMSH6, and ins G at codon 154 in exon 6, N158H in exon 6, and del A at codon 257 in exon 9 of hMLH1 were identified. Moreover, several intronic polymorphisms, including c–g transversion at IVS-1 nt211 + 9 of hMSH2, del T in poly T track at IVS-6 nt3559-5, ATCT duplicate in IVS-7 nt 3642 + 35 and t–g transversion at IVS-10 nt4080 + 185 of hMSH6 were demonstrated in these patients. In addition, seven cases (22.5%) exhibited microsatellite instability (MSI).Conclusion These results suggested that the inactivation of DNA mismatch repair genes and microsatellite instability may play a minor role in somatic colorectal cancer development.     

Mutation Analysis of <Emphasis Type="Italic">SPINK1</Emphasis> and <Emphasis Type="Italic">CFTR</Emphasis> Gene in Korean Patients with Alcoholic Chronic Pancreatitis

Several genetic mutations have been reported to increase susceptibility to chronic pancreatitis. However, their roles in alcoholic chronic pancreatitis are controversial. We investigated the prevalence of SPINK1 N34S and new CFTR Q1352H mutations in alcoholic chronic pancreatitis in Korea. Forty-three patients with alcoholic chronic pancreatitis were enrolled and 35 healthy individuals served as controls. The SPINK1 N34S mutation was detected by the PCR-RFLP technique. The CFTR Q1352H mutation was examined with PCR direct sequencing. Mean age of chronic pancreatitis and control groups was 53.2 and 51.3 years, respectively. A SPINK1 N34S was detected as a heterozygote in one (2.4%) patient with alcoholic chronic pancreatitis and a heterozygote CFTR Q1352H was detected in one other patient. In the control population, neither SPINK1 nor CFTR mutation was detected. This study shows that SPINK1 N34S and CFTR Q1352H mutations are uncommon and do not play an important role in chronic alcoholic pancreatitis in Korea.     

Molecular insights into Peutz-Jeghers syndrome: two probands with a germline mutation of <Emphasis Type="Italic">LKB1</Emphasis>

LKB1 encodes a serine/threonine protein kinase that is defective in patients with Peutz-Jeghers syndrome (PJS), a hereditary disorder characterized by gastrointestinal hamartomatous polyposis and an increased risk of cancer development. Although a tentative molecular classification of PJS patients was recently made according to their LKB1 mutation status, it is difficult to clarify the genotype-phenotype relationship because of the rarity and genetic heterogeneity of this disease. Here we report on two probands with PJS whose intestinal hamartomatous polyposis was treated by laparoscopyassisted polypectomy. Direct sequencing analyses revealed a nonsense mutation at codon 240 in exon 5 in one patient, and a mutation at a splicing donor site in intron 5 in the other patient. No additional somatic mutations were detected in the resected hamartomas in either case. Immunohistochemical analysis revealed an elevated expression of cyclooxygenase-2, and almost complete loss of LKB1 expression in the polyps, suggesting that a biallelic inactivation of the LKB1 gene was responsible for the hamartoma formation. Methylation-specific polymerase chain reaction analysis revealed no hypermethylation of the LKB1 promoter. Mutation analysis is useful in making a precise diagnosis of PJS in candidate probands, and may in the near future provide valuable information for predicting cancer risk based on genotype-phenotype correlations.     

<Emphasis Type="Italic">cagA</Emphasis> Gene and Protein Status Among Iranian <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Strains

The wide geographic genetic diversity of Helicobacter pylori (Hp) and, in particular, the varying prevalence of cagA in different countries has been documented repeatedly. This study was designed to determine the frequency of cagA in Iranian Hp strains by means of genotyping and assessment of host antibodies. Helicobacter pylori strains from 235 patients, including 174 non-ulcer dyspepsia, 25 peptic ulcer and 36 gastric cancer patients, were studied. The frequencies of the 5′, middle and 3′ terminal regions of the cagA gene were 90.6, 57.6, 89%, respectively, with no correlation to the clinical outcomes. Antibodies against the CagA protein were present in 90.7% of patients. Multiple biopsy sampling in 97 cases revealed multiple infection in 16.5% of the patients. Sequencing of the seven variants of the 3′ end of the cagA gene revealed no clustering and the distribution of the Iranian strains among those of other countries. Our results from the genotyping and serology analyses confirm that the majority of Iranian Hp strains are cagA-positive.     

Human genetics of <Emphasis Type="Italic">GPR54</Emphasis>

Idiopathic hypogonadotropic hypogonadism (IHH) is a condition characterized by absence of sexual maturation in the setting of low sex steroids and low/normal gonadotropins. Despite its rarity, considerable genetic heterogeneity and phenotypic variability exists in this disorder. Loss of function mutations in a G protein coupled receptor, GPR54, have been shown to cause IHH. Although mutations in GPR54 are not a common cause of this condition, patients bearing mutations are critical to explore genotype-phenotype correlations and gene function. In this review, we will examine the human genetics studies of GPR54, the phenotypic implications of mutations in this gene, and the emerging roles of the kisspeptin/GPR54 pathway.     

<Emphasis Type="Italic">PADI4</Emphasis> polymorphisms and rheumatoid arthritis susceptibility: a meta-analysis

We conducted a comprehensive meta-analysis with all available data on the association of allele and genotype of peptidylarginine deiminases 4 (PADI4) polymorphisms with RA overall and in each ethnic population to explore whether the PADI4 polymorphisms confer susceptibility to RA. Nine comparisons, three Asians and six Europeans, from eight studies were included in this meta-analysis. Overall meta-analysis shows a significant association of PADI4_94, 104 and 90 with RA (OR = 1.20, 1.17, 1.35, P = 0.001, <0.0001, 0.006, respectively). There was a significant association with all of the PADI4 polymorphisms with RA in people of Asian descent. However, there was no significant association of PADI4 polymorphisms with RA in people of European descent, except for PADI_94. The presence of 2/2 genotype of the PADI4 significantly increased the risk for RA in European populations (OR = 2.10, 95% CI, 1.66–2.66, P < 0.0001) without between-study heterogeneity (I ² = 44.3, P = 0.15). In conclusion, this meta-analysis demonstrates that the PADI4 polymorphisms may represent a significant risk factor for RA in Asians and Europeans and may play a larger role in susceptibility to RA in Asian than in European populations. Further studies are needed to see if the PADI4 gene confers a risk of RA in other ethnic groups.     

Glutathione<Emphasis Type="Italic"> S</Emphasis>-transferase M1, T1, and P1 gene polymorphisms and carotid atherosclerosis in Korean patients with rheumatoid arthritis

We assessed the contribution of genetic polymorphisms of glutathione S-transferase M1 (GSTM1), T1 (GSTT1), and P1 (GSTP1, Ile105Val) to carotid atherosclerosis in 40 postmenopausal rheumatoid arthritic (RA) women without histories of smoking. We measured mean intima-media thickness (IMT) and plaque of the common carotid arteries by ultrasonography and evaluated relationships among the known risk factors for atherosclerosis, genetic polymorphisms, RA outcomes, and markers of inflammation. Subjects with the GSTT1–0 genotype had greater IMT (P<0.05). On univariate analysis, carotid IMT was positively associated with age, systolic BP, antihypertensive drug use, and the GSTT1–0 genotype (P<0.05). When compared to subjects with a double-positive GSTM1/T1 genotype, IMT in those with concurrent lack of the GSTM1 and GSTT1 genes was significantly increased (P=0.008). This study suggests that the GSTT1–0 genotype might have an interaction with carotid atherosclerosis related to RA in Korean postmenopausal RA women without histories of smoking.     

Association of <Emphasis Type="Italic">Lewis</Emphasis> and <Emphasis Type="Italic">Secretor</Emphasis> gene polymorphisms and <Emphasis Type="Italic">Helicobacter pylori</Emphasis> seropositivity among Japanese-Brazilians

Background Secretor (Se) and Lewis (Le) genes are involved in the synthesis of Lewis b (Le^b) and type I antigens throughout the body, especially in the epithelial cells of gastric mucosa. Helicobacter pylori can attach to the gastric epithelial cells with the blood group antigen-binding adhesin, which binds to Le^b or H type I carbohydrate structures. In a previous study, a marked association between H. pylori seropositivity and polymorphism of the Se and Le genes was observed among Japanese outpatients of a gastroenterology clinic. The present work aims to investigate the associations between Se and Le gene polymorphisms and H. pylori infection among Japanese-Brazilians.Methods The subjects consisted of 942 healthy volunteer Japanese-Brazilians, who were tested for the presence of anti-H. pylori IgG antibodies and genotyped for Se and Le polymorphisms.Results The sex-age-adjusted odds ratios (aORs) for H. pylori seropositivity were 0.99 for the Sese genotype relative to the SeSe genotype (95% confidence interval [CI], 0.73–1.33), and 1.03 for sese relative to SeSe (95% CI, 0.71–1.48). On the other hand, the aOR for the subjects with the le allele (Lele or lele) relative to the LeLe genotype was 1.48 (95% CI, 1.07–1.79). When the Se and Le genotypes were analyzed in combination according to risk group, no statistically significant association was observed.Conclusions These results are inconsistent with previous work and may have been modulated by an external factor or some other unidentified factor. Japanese-Brazilians are genotypically the same as Japanese, but their lifestyle is adapted to that of Brazil. Further investigations are necessary to clarify this influence on susceptibility to H. pylori infection.     

Establishment of thymoma-prone congenic rat strain,ACI.BUF/Mna-<Emphasis Type="Italic">Tsr1</Emphasis>/<Emphasis Type="Italic">Tsr1</Emphasis>

Purpose To confirm the presence of the susceptible gene for the thymoma development in the region that was assumed by the previous linkage study by Oyabu et al. (J Natl Cancer Inst 91:279–282, 1999), we tried to establish a congenic strain of rats. Methods Backcrossings between the BUF/Mna strain as a donor strain and the ACI/NMna strain as an inbred partner were repeated for 12 generations, examining whether rats had the thymoma development region, and then homozygous rats were yielded by mating among the heterozygotes. To detect the phenotypic expression, heterozygous ACI.BUF/Mna-Tsr1/+ (ACI-Tsr1/+) rats were generated by crossing female ACI.BUF/Mna-Tsr1/Tsr1 (ACI-Tsr1/Tsr1) rats with male ACI/NMna rats and were maintained for 24 months. Results These ACI-Tsr1/+ rats produced thymoma in 71%, showing a dominant trait. The thymomas were of the lymphocyte predominant type, as those developed in rats of the original BUF/Mna strain. Conclusions Thus, a new rat congenic strain, ACI-Tsr1/Tsr1, was established, revealing that thymoma develops in the dominant trait in ACI-Tsr1/+ rats.     

The association between the <Emphasis Type="Italic">IFIH1</Emphasis> locus and type 1 diabetes

Aims/hypothesis We set out to validate a recently reported type 1 diabetes association from the IFIH1 gene variation in an independent cohort from a population of mixed European descent. Methods We genotyped five single-nucleotide polymorphisms in the IFIH1 locus, i.e. rs2111485, rs1990760, rs3747517, rs17783344 and rs984971589, in 589 type 1 diabetes nuclear family trios (1,767 individuals). Results This study independently replicated the reported genetic association using a family-based approach. Conclusions/interpretation The reported type 1 diabetes association is from a linkage disequilibrium region including three candidate genes, i.e. FAP, IFIH1 and GCA. Further variant discovery and fine mapping could help clarify a novel type 1 diabetes mechanism. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Molecular genetic defects in endometrial carcinomas: microsatellite instability, <Emphasis Type="Italic">PTEN</Emphasis> and beta-catenin (<Emphasis Type="Italic">CTNNB1</Emphasis>) genes mutations

Purpose The present study aims to assess the incidence of microsatellite instability (MSI) and mutations in the PTEN and beta-catenin (CTNNB1) genes in endometrial carcinomas and to analyze the detected defects in these factors in relation to each other and to the clinico-pathological features of tumors. Materials and methods In a series of 56 endometrioid endometrial carcinomas, the status of MSI was determined using nine polymorphic markers, and mutations in all exons of the PTEN gene and in exon 3 of the CTNNB1 gene were evaluated by SSCP and sequencing methods. Results Microsatellite instability was found in 18 carcinomas (32.1%, MSI+); the remaining 38 tumors were microsatellite stable (MSI−). In 15 cases (26.8%), a loss of heterozygosity (LOH) at the studied microsatellite markers also occurred. In 29 carcinomas (51.8%), mutations were found in the PTEN gene and in nine tumors (16.1%) in the CTNNB1 gene. PTEN mutations occurred significantly more frequently in MSI+ than in MSI− tumors (77.8 vs. 39.5%, p = 0.007), but, except for one, none of them was attributable to MSI. In contrast, incidence of CTNNB1 mutations in MSI+ and MSI− tumors no significantly differed between themselves (16.7 vs. 15.8%, p = 0.760). Interestingly, mutations in the CTNNB1 gene most frequently coexisted with mutations in the PTEN gene (7/9, 77.8%). However, this finding requires future verification on a larger group of cases. The incidence of MSI and PTEN, but not CTNNB1 mutations, was significantly more common in poorly, than in well-to-moderately, differentiated tumors (G3 vs. G1 + G2; p = 0.042, 0.039 and 0.958, respectively). Conclusion We conclude that most frequently occurring mutations in the PTEN gene may be a key event for the tumorigenesis of endometrioid endometrial carcinomas, while coexistence or absence of microsatellite instability or mutations in the CTNNB1 gene may reflect the heterogeneity of molecular mechanisms contributing to the development of these tumors.     

<Emphasis Type="Italic">p16</Emphasis><Superscript><Emphasis Type="Italic">INK4A</Emphasis></Superscript> Alterations are accompanied by aberrant protein immunostaining in endometrial carcinomas

Purpose To date, the significance of p16^INK4A tumor suppressor gene inactivation in sporadic endometrial cancer (EC) has only rarely been described. In this study, we examined the alteration type and frequency of gene alterations [point mutations, aberrant promoter methylation and loss of heterozygosity (LOH)] in 50 sporadic ECs, and correlated the genetic findings with the immunohistochemical expression of the p16^INK4A protein and the classical clinicopathological features.Methods Gene mutations were detected by PCR-SSCP-sequencing analysis, promoter hypermethylation by methylation-specific PCR (MSP), and LOH by PCR of the STS-marker c5.1.Results In total, p16^INK4A alterations were found in 14 of 50 (28%) sporadic ECs. In six (12%) cases, two alterations occurred simultaneously. Partial p16^INK4A deletions were found in four of 50 (8%) samples. There was one missense mutation (codon 70; CCCGCC) and one frameshift mutation (1-bp deletion in exon 2). Only 2 of 47 (4.2%) tumors exhibited aberrant promoter methylation. An allelic loss was detected in 12 of 50 (24%) carcinomas with a higher incidence in advanced endometrial carcinomas than in early-stage uterine tumors. p16^INK4A alterations were generally accompanied by gene silencing, confirmed by aberrant protein immunostaining (r=-0.442; P=0.001). There was a significant difference in the frequency of p16^INK4A alterations between early (stage I; 18%) and advanced (stages II–IV; 58%) ECs (P=0.022). One case showed complete protein loss, but absence of genetic alterations.Conclusions Our data indicate that p16^INK4A inactivation plays a role in the tumorigenesis of the subset of sporadic ECs, particularly in cases exhibiting an aggressive clinical behavior. We demonstrate that p16^INK4A methylation can act efficiently and similarly to other genetic alterations as one of the two necessary hits according to the Knudson two-hit hypothesis of tumor suppressor gene inactivation.     

CD34-related coexpression of <Emphasis Type="Italic">MDR1 and BCRP</Emphasis> indicates a clinically resistant phenotype in patients with acute myeloid leukemia (AML) of older age

Clinical resistance to chemotherapy in acute myeloid leukemia (AML) is associated with the expression of the multidrug resistance (MDR) proteins P-glycoprotein, encoded by the MDR1/ABCB1 gene, multidrug resistant-related protein (MRP/ABCC1), the lung resistance-related protein (LRP), or major vault protein (MVP), and the breast cancer resistance protein (BCRP/ABCG2). The clinical value of MDR1, MRP1, LRP/MVP, and BCRP messenger RNA (mRNA) expression was prospectively studied in 154 newly diagnosed AML patients ≥60 years who were treated in a multicenter, randomized phase 3 trial. Expression of MDR1 and BCRP showed a negative whereas MRP1 and LRP showed a positive correlation with high white blood cell count (respectively, p < 0.05, p < 0.001, p < 0.001 and p < 0.001). Higher BCRP mRNA was associated with secondary AML (p < 0.05). MDR1 and BCRP mRNA were highly significantly associated (p < 0.001), as were MRP1 and LRP mRNA (p < 0.001) expression. Univariate regression analyses revealed that CD34 expression, increasing MDR1 mRNA as well as MDR1/BCRP coexpression, were associated with a lower complete response (CR) rate and with worse event-free survival and overall survival. When adjusted for other prognostic actors, only CD34-related MDR1/BCRP coexpression remained significantly associated with a lower CR rate (p = 0.03), thereby identifying a clinically resistant subgroup of elderly AML patients.