Genetic polymorphisms of XRCC1 (at codons 194 and 399) in Shiraz population (Fars province, southern Iran)

Variant Alleles in XRCC1 Arg194Trp and Arg399Gln Polymorphisms Increase Risk of Gastrointestinal Cancer in Sabah, North Borneo

BACKGROUND

The XRCC1 protein facilitates various DNA repair pathways; single-nucleotide polymorphisms (SNPs) in this gene are associated with a risk of gastrointestinal cancer (GIC) with inconsistent results, but no data have been previously reported for the Sabah, North Borneo, population. We accordingly investigated the XRCC1 Arg194Trp and Arg399Gln SNPs in terms of GIC risk in Sabah.

MATERIALS AND METHODS

We performed genotyping for both SNPs for 250 GIC patients and 572 healthy volunteers using a polymerase chain reaction- restriction fragment length polymorphism approach. We validated heterozygosity and homozygosity for both SNPs using direct sequencing.

RESULTS

The presence of a variant 194Trp allele in the Arg194Trp SNP was significantly associated with a higher risk of GIC, especially with gastric and colorectal cancers. We additionally found that the variant 399Gln allele in Arg399Gln SNP was associated with a greater risk of developing gastric cancer. Our combined analysis revealed that inheritance of variant alleles in both SNPs increased the GIC risk in Sabah population. Based on our etiological analysis, we found that subjects ≥50 years and males who carrying the variant 194Trp allele, and Bajau subjects carrying the 399Gln allele had a significantly increased risk of GIC.

CONCLUSIONS

Our findings suggest that inheritance of variant alleles in XRCC1 Arg194Trp and Arg399Gln SNPs may act as biomarkers for the early detection of GIC, especially for gastric and colorectal cancers in the Sabah population.

Susceptibility to Breast Cancer and Intron 3 Ins/Del Genetic Polymorphism of DNA Double-Strand Break Repair Gene XRCC4

BACKGROUND

Since genetic variations in X-ray cross-complementing group 4 (XRCC4; OMIM: 194363) repair gene might be associated with a reduction in cellular DNA repair capacity, it is hypothesized that XRCC4 Ins/Del (I/D) polymorphism (in intron 3 of the gene; rs28360071) may be a risk factor for breast cancer. Therefore, the present case-control study was carried out.

METHODS

The present case-control study included 407 females with breast cancer and a total of 394 healthy females from the general population matched with patients according to age. Genotypic analysis for the XRCC4 I/D polymorphism was performed by PCR. In order to investigate the effect of XRCC4 I/D polymorphism on age at diagnosis of breast cancer, the Kaplan-Meier survival analysis and the Cox proportional hazards regression model were used.

RESULTS

Based on the present case-control study, the ID (OR=0.95, 95% CI: 0.69-1.31, P=0.781) and DD (OR=1.24, 95% CI: 0.84-1.83, P=0.274) genotypes were not associated with breast cancer risk compared with the II genotype. Based on the Cox regression model, there was significant association between genotypes of I/D polymorphism and age at diagnosis of breast cancer (ID+DD vs II; HR=0.79, 95% CI: 0.64-0.98, P=0.036).

CONCLUSION

Although there was no significant association between XRCC4 I/D polymorphism and risk of breast cancer, patients having the II genotype have lower age at diagnosis in comparison with patients having ID+DD genotypes.

Susceptibility to Colorectal Cancer and Two Genetic Polymorphisms of XRCC4

The X-ray complementing group 4 (XRCC4, OMIM: 194363) plays a key role in non-homologous end-joining DNA repair pathway in mammalian cells. This pathway is believed to help maintain genomic stability. In the present study, it is hypothesized that genetic polymorphisms in the NHEJ repair XRCC4 gene may be associated with an increased risk in developing colorectal cancer (CRC). We genotyped two polymorphisms of XRCC4, G-1394T (rs6869366) and intron 3 insertion/deletion (I/D; rs28360071) in 200 colorectal cancer patients as well as 256 healthy individuals, and evaluated their association with CRC. We found that in G-1394T polymorphism, neither the TG nor the GG genotypes (versus the TT genotype) were associated with the risk of developing CRC. The results of our study indicate that in comparison with the II genotype, ID and DD genotypes had no significant association with the risk of developing CRC. Subjects with TT genotype and positive family history in colorectal cancer were found to be at a much lower risk of developing CRC in comparison with the reference group (OR = 0.31, 95%CI: 0.11-0.85, P =  .023). It should be noted that participants having at least one G allele (TG+GG genotypes) were at a significantly higher risk to develop the disease compared with the reference group (OR = 9.10, 95%CI: 2.00-41.3, P = 0.004). In relation to I/D polymorphism, among participants, those with positive family history, either with ID (OR =  .78, 95%CI: 2.26-10.0, P < 0.001) or DD genotypes (OR = 5.73, 95%CI: 1.99-16.4, P = 0.001) had a significantly association with the disease. Among participants with a positive family history in CRC, the haplotype GD dramatically increased the risk of developing CRC (OR = 10.2, 95%CI: 2.28-46, P = 0.002). The results of this study indicate that G-1394T and I/D polymorphisms of XRCC4 among individuals with positive family history for colorectal cancer substantially increase the risk factor for developing colorectal cancers.

Susceptibility to gastric cancer and polymorphisms of insertion/deletion at the intron 3 of the XRCC4 and VNTR at the promoter region of the XRCC5

The genes encoding X-ray repair cross-complementing group 4 (XRCC4; OMIM: 194363) and 5 (XRCC5; OMIM: 194364) are involved in repair of DNA double-strand breaks. To investigating the associations between polymorphisms of Insertion/Deletion (I/D, rs28360071) in the intron 3 of the XRCC4 and VNTR in the promoter region of the XRCC5 and risk of gastric cancer, the present study was carried out. We included 159 (56 females, 103 males) with gastric cancer and 242 (75 females, 167 males) healthy blood donors frequency matched for age and gender. Using PCR-based methods, the genotypes of the study polymorphisms were determined. The alleles of VNTR XRCC5 polymorphism divided into two groups: L (0 and 1 repeats) and H (2 and 3 repeats) alleles. For the I/D XRCC4 polymorphism, after stratification of the subjects according to their family history (FH) of cancer, either the ID (OR = 3.19, 95%CI: 1.35-7.50, P = 0.008) or the DD genotypes (OR = 4.62, 95%CI: 1.63-13.0, P = 0.004) among positive FH persons, increased the risk of gastric cancer compared with the reference group (persons who have negative FH and II genotype). For the VNTR XRCC5 polymorphism, the LH + HH genotypes among positive FH persons, increased the risk of gastric cancer compared with the reference group (persons who have negative FH and LL genotype) (OR = 2.88, 95%CI: 1.34-6.18, P = 0.006). Sensitivity analysis showed that the above mentioned associations were not occurred due to the maldistribution of the genotypes among missing data. The present study suggests that both polymorphisms of the XRCC4 and XRCC5 might be risk factors for gastric cancer development especially among persons with positive FH.

Worldwide Distribution of Four SNPs in X-Ray and Repair and Cross-Complementing Group 1 (XRCC1)

PURPOSE

X-ray repair cross-complementing group 1 (XRCC1) repairs single-strand breaks in DNA. Several reports have shown the association of single nucleotide polymorphisms (SNPs) (Arg194Trp, Pro206Pro, Arg280His, Arg399Gln) in XRCC1 to diseases. Limited population data are available regarding SNPs in XRCC1, especially in African populations. In this study, genotype distributions of four SNPs in worldwide populations were examined and compared with those reported previously.

MATERIALS AND METHODS

Four SNPs (Arg194Trp, Pro206Pro, Arg280His, Arg399Gln) in XRCC1 from genomic DNA samples of 10 populations were evaluated by using polymerase chain reaction followed by restriction fragment length polymorphism analysis.

RESULTS

The frequency of the minor allele corresponding to the Trp allele of XRCC1Arg194Trp was higher in Asian populations than in African and Caucasian populations. As for XRCC1Pro206Pro, Africans showed higher minor allele frequencies than did Asian populations, except for Tamils and Sinhalese. XRCC1 Arg280His frequencies were similar among Africans and Caucasians but differed among Asian populations. Similarly, lower mutant XRCC1 Arg399Gln frequencies were observed in Africans.

CONCLUSIONS

This study is the first to show the existence of a certain genetic heterogeneity in the worldwide distribution of four SNPs in XRCC1.

Genetic Polymorphism of CAT C-262 T and Susceptibility to Breast Cancer, a Case-Control Study and Meta-Analysis of the Literatures

Catalase (CAT) activity is likely to be affected by functional polymorphism of C-262 T (rs1001179) in the CAT gene (OMIM: 115500). It is hypothesized that individuals with the lower expressing forms of the CAT polymorphism may be more susceptible to breast cancer. Therefore, the present case-control study and meta-analysis were carried out. The present case-control study consisted of 407 females with breast cancer and a total of 395 healthy female from population matched with patients according to age. Genotypic analysis for the CAT C-262 T polymorphism was determined by PCR. We identified 7 eligible studies, including 10,471 subjects (4,959 patients, and 5,512 healthy controls) in relation to the CAT C-262 T polymorphism and breast cancer risk. Based on the present case-control study, the CT (OR = 0.90, 95% CI: 0.66-1.22, P = 0.484) and TT (OR = 0.68, 95% CI: 0.35-1.30, P = 0.245) genotypes were not associated with breast cancer risk compared to the CC genotype. For meta-analysis including all studies, there was significant heterogeneity between studies. The overall ORs of the breast cancer risk were not associated with the CT (Q-statistic = 14.90, df = 6, P < 0.05; OR = 1.01, 95% CI: 0.92-1.09, P = 0.862) and TT (Q-statistic = 2.57, df = 6, P > 0.05; OR = 1.03, 95% CI: 0.85-1.24, P = 0.770) genotypes. There was no association between C-262 T polymorphism of the CAT and risk of breast cancer.

Genetic Polymorphism of C-262T Catalase and Susceptibility to Schizophrenia

Background: Catalase (CAT, OMIM: 115500) plays an integral role in the primary defence against oxidative stress. The T allele of the C-262T CAT polymorphism (rs1001179) is associated with lower activity of CAT. Here we investigated whether polymorphism of C-266T CAT was associated with susceptibility to schizophrenia.Methods: The present study was performed on 363 (267 males, 96 females) in-patients with schizophrenia diagnosis, and a total of 363 (266 males, 97 females) healthy controls. The C-262T CAT genotypes were determined using RFLP-PCR method.Results: Although the association between genotypes and susceptibility was not significant in both genders, there was significant interaction between gender and the TT genotype (P=0.035). The Log-rank test and the Kaplan-Meier survival analysis were used to evaluate the influence of C-262T genotypes on age at diagnosis (AAD) of schizophrenia. Mean AAD of the CC and CT+TT genotypes in males was 22.8 and 24.9 years, respectively. The difference was significant (c2=4.26, P=0.039). Difference of mean AAD of the CC (26.7 years) and CT+TT (27.3 years) genotypes among females was not significant (c2=0.02, P=0.896).Conclusion: Different associations between gender groups might be at least in part interpreted by the effect of gender on the association between C-262T polymorphism and CAT gene expression.

First survey of the two polymorphisms (Arg194Trp and Arg399Gln) in XRCC1 gene in four Afghanistan populations and comparison with worldwide data

Genetic polymorphisms in gene encoding X-ray repair cross-complementation group 1 (MIM: 194360; XRCC1) have been defined. Previous studies have revealed that there was significant difference between populations for allelic frequency of Arg194Trp (rs. 1799782) and Arg399Gln (rs. 25487) polymorphisms of XRCC1. In order to get more insight into the genetic structure of Afghanistan populations the present study was carried out. Present study was done on 656 (257 Pashtuns, 217 Tajiks, 120 Hazaras, and 62 Uzbeks) unrelated healthy Afghanis refuges living in Fars province (southern Iran). Genotypes for Arg194Trp and Arg399Gln polymorphisms of the XRCC1 were detected by RFLP-PCR method. The prevalence of the 194Trp allele in Pashtuns, Tajiks, Hazaras, and Uzbeks was 0.072, 0.085, 0.108, and 0.145, respectively. The frequency of the 399Gln in Pashtuns, Tajiks, Hazaras, and Uzbeks was 0.362, 0.378, 0.296, and 0.234, respectively. There was significant difference between these ethnic groups for the genotypic distributions of the Arg194Trp (χ(2) = 16.70, df = 6, P = 0.010) and Arg399Gln (χ(2) = 12.67, df = 6, P = 0.049) polymorphisms. Based on the complete dataset, these polymorphisms showed significant linkage disequilibrium. There was significant difference between the ethnic groups for prevalence of the haplotypes (χ(2) = 16.67, df = 6, P = 0.011). Uzbeks showed significant difference with the other ethnic groups (χ(2) = 10.09, df = 2, P = 0.006). The allelic frequencies of 194Trp and 399Gln in Pashtuns and Tajiks seem to be more similar to the Caucasians than the Asian populations. However, Uzbeks seems to be intermediate between Afghanis' Caucasian (Pashtuns and Tajiks) and Asians.

Association between exudative age-related macular degeneration and the G6721T polymorphism of XRCC7 in outdoor subjects

PURPOSE

To investigate whether the G6721T polymorphism (rs.7003908) of the non-homologous end-joining DNA repair XRCC7 gene contributes to the development of exudative age-related macular degeneration (ARMD).

METHODS

The present case-control study consisted of 111 patients with exudative ARMD and 112 sex frequency-matched healthy controls that were randomly selected from unrelated volunteers in the same clinic. Genotypes were determined by the Restriction Fragment Length Polymorphism (PCR-RFLP) based method. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for ARMD risk associated with polymorphism of XRCC7. In all analysis the GG genotype was considered to be the reference genotype.

RESULTS

There was no significant association between genotypes of XRCC7 and susceptibility to ARMD. Considering the significant difference in age distribution between cases and controls, age was used as a covariate in further analysis. After ORs were adjusted for age, the same result was observed. In the next step we stratified our subjects into outdoor and indoor groups according to their job titles. The outdoor and indoor patients were occupationally exposed to sunlight and not exposed to sunlight, respectively. Our present study showed that among indoor subjects there was no association between XRCC7 polymorphism and susceptibility to ARMD. However, among outdoor subjects, the GT + TT genotypes compared to the GG genotype increased the risk of ARMD (OR, 3.13; 95% CI, 1.04-9.39; p = 0.042).

CONCLUSIONS

Our study revealed that the T allele of the G6721T polymorphism of XRCC7 increased the risk of ARMD among outdoor subjects.

Association between polymorphisms in DNA repair genes (XRCC1 and XRCC7) and risk of preeclampsia

PURPOSE

Although the exact genes involved in preeclampsia (PE) are still not fully discovered, an important role for oxidative stress in its pathogenesis is accepted. XRCC1 (MIM: 194360) and XRCC7 (MIM: 600899) play a crucial role in the DNA repair pathways. Functional polymorphisms in XRCC1 (Arg194Trp and Arg399Gln) and XRCC7 (G6721T) may be risk factors for PE. In the present study, the association between the genetic polymorphisms of XRCC1 and XRCC7 and risk of PE is investigated.

METHODS

The present case-control study was performed on 151 preeclapmtic patients, and a total of 344 normal pregnant women, as a control group. Control women had no history of pregnancies with PE.

RESULTS

Neither polymorphism of Arg194Trp XRCC1 nor polymorphism of G6721T XRCC7 associated with the risk of PE. The Gln/Gln genotype of Arg399Gln XRCC1 polymorphism increased the risk of PE (OR=2.39, 95 % CI: 1.38-4.14, P=0.002). Statistical analysis revealed that the haplotype "194Arg-399Gln" showed higher frequency among PE patients compared to the controls (OR=1.65, 95% CI: 1.23-2.19, P=0.001).

CONCLUSIONS

The present results suggest that the 399Gln allele of the XRCC1 is significant risk factor for PE development.

Genetic variation in DNA repair gene XRCC7 (G6721T) and susceptibility to breast cancer

The human XRCC7 is a DNA double-strand break (DSBs) repair gene, involved in non-homologous end joining (NHEJ). It is speculated that DNA DSBs repair have an important role during development of breast cancer. The human XRCC7 is a NHEJ DSBs repair gene. Genetic variation G6721T of XRCC7 (rs7003908) is located in the intron 8 of the gene. This polymorphism may regulate splicing and cause mRNA instability. In the present study, we specifically investigated whether common G6721T genetic variant of XRCC7 was associated with an altered risk of breast cancer. The present study included 362 females with breast cancer. Age frequency-matched controls (362 persons) were randomly selected from the healthy female blood donors, according to the age distribution of the cases. Using RFLP-PCR based method, the polymorphism of XRCC7 was determined. The TG (OR=1.20, 95% CI: 0.83-1.74, P=0.320) and TT (OR=1.01, 95% CI: 0.67-1.53, P=0.933) genotypes had no significant effect on risk of breast cancer, in comparison with the GG genotype. Our present findings indicate that the TT and TG genotypes were not associated with an altered breast cancer risk.

Genetic polymorphisms of glutathione S-transferase T1 (GSTT1) and M1 (GSTM1) in selected populations of Afghanistan

Genetic polymorphisms in genes encoding glutathione S-transferase T1 (GSTT1, a member of class theta) and M1 (GSTM1, a member of class mu) have been defined. Previous studies have revealed that there was significant difference between populations for allelic frequency of several members of GSTs. In order to find the prevalence of null genotypes of GSTM1 and GSTT1 in Afghanis populations the present study was carried out. The total study subjects consisted of 656 unrelated healthy Afghanis refugees living in Fars province (southern Iran). From these 257, 217, 120, and 62 individuals were Pashtuns, Tajiks, Hazaras, and Uzbeks, respectively. Genetic polymorphisms for GSTT1 and GSTM1 were detected by multiplex PCR. The prevalence of null genotype of GSTM1 in Pashtuns, Tajiks, Hazaras, and Uzbeks was 42.4, 48.4, 52.5, and 40.3 %, respectively. There was no significant difference between these populations for the genotypic distribution of the GSTM1 polymorphism (χ(2) = 4.67, df = 3, P = 0.197). The frequency of GSTT1 null genotype in Pashtuns, Tajiks, Hazaras, and Uzbeks was 7.4, 25.3, 25.0, and 29.0 %, respectively. The observed difference between populations for prevalence of GSTT1 null genotype was statistically significant (χ(2) = 35.54, df = 3, P < 0.001). In comparison with European and Asian populations, Afghanistan populations like Iranian populations showed intermediate frequency for GSTT1 and GSTM1 null genotypes.

Clinical response to chemotherapy in locally advanced breast cancer was not associated with several polymorphisms in detoxification enzymes and DNA repair genes

The main aim of the present study was to investigate the association between several genetic polymorphisms (in glutathione S-transferase members and DNA repair genes) and clinical response to chemotherapy in locally advanced breast cancer. A sequential series of 101 patients were prospectively included in this study. Clinical assessment of treatment was accomplished by comparing initial tumor size with preoperative tumor size using revised RECIST guideline (version 1.1). Clinical response was regarded as a response or no response. There was no difference between non-responders and responders for the prevalence of genotypes of the study polymorphisms.

The frequency and distribution of thiopurine S-methyltransferase alleles in south Iranian population

Thiopurine methyltransferase (TPMT) catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathiopurine. Variability in TPMT activity is mainly due to genetic polymorphism. The frequency of the four allelic variants of the TPMT gene, TPMT*2 (G238C), TPMT*3A (G460A and A719G), TPMT*3B (G460A) and TPMT*3C (A719G) were determined in an Iranian population from south of Iran (n = 500), using polymerase chain reaction (PCR)-RFLP and allele-specific PCR-based assays. Four hundred seventy four persons (94.8%) were homozygous for the wild type allele (TPMT*1/*1) and twenty five people were TPMT*1/*3C (5%). One patient was found to be heterozygous in terms TPMT*1 and *2 alleles with genotype of TPMT*1/*2 (0.2%). None of the participants had both defective alleles. The TPMT*3C and *2 were the only variant alleles observed in this population. The total frequency of variant alleles was 2.6% and the wild type allele frequency was 97.4%. The TPMT*3B and *3A alleles were not detected. Distributions of TPMT genotype and allele frequency in Iranian populations are different from the genetic profile found among Caucasian or Asian populations. Our findings also revealed inter-ethnic differences in TPMT frequencies between different parts of Iran. This view may help clinicians to choose an appropriate strategy for thiopurine drugs and reduce adverse drug reactions such as bone marrow suppression.

Susceptibility to exudative age-related macular degeneration and three genetic polymorphisms of glutathione S-transferase Z1 (GSTZ1)

Purpose

To investigate whether genetic polymorphisms of GSTZ1 contribute to the development of exudative age-related macular degeneration (AMD).

Methods

The present case-control study consisted of 112 patients (44 female, 68 male) with exudative AMD and 112 sex frequency-matched healthy controls were randomly selected from unrelated volunteers in the same clinic. Genotypes were determined by polymerase chain reaction–restriction fragment length polymorphism–based method.

Results

There was no significant association between study polymorphisms and susceptibility to exudative AMD. Considering the significant difference in age distribution between cases and controls, age was used as a covariate in further analysis. After odds ratio adjustment for age, the same results were observed. The study polymorphisms showed linkage disequilibrium. Analysis revealed that there was no difference between cases and controls for the prevalence of the haplotypes of GSTZ1.

Conclusions

Our study did not support any association between susceptibility to exudative AMD and polymorphisms of GSTZ1.

Susceptibility to breast cancer and three polymorphisms of GSTZ1

Glutathione S-transferases class zeta (GSTζ) is involved in the detoxification of xenobiotic compounds and catalyzes the biotransformation of a variety of α-haloacids including dichloroacetic acid and chlorofluoroacetic acid. It has been reported that, in mice, deficiency of Gstz1 (a member of GSTζ) resulted in the generation of a constant level of oxidative stress. The present study was carried out to investigate the association between genetic polymorphisms of GSTZ1 (in promoter site G-1002A and in coding sites Glu32Lys and Gly42Arg) and risk of breast cancer. We included 106 females with breast cancer and 106 healthy females frequency matched for age. The study polymorphisms were not associated with risk of breast cancer (p>0.05). The polymorphisms of GSTZ1 showed strong linkage disequilibrium among cancer patients and control subjects (p<0.0001). There was no significant difference between cancer patients and controls for frequencies of the GSTZ1 haplotypes (p>0.05). It seems there is no meaningful relationship between the genetic polymorphisms of GSTZ1 and risk of breast cancer.

Age-related macular degeneration and genetic polymorphisms of glutathione S-transferases M1 (GSTM1) and T1 (GSTT1)

The aim of this study is to understand the multifactorial causes of age-related macular degeneration (ARMD), and, therefore, it is reasonable to investigate whether genetic polymorphisms of antioxidant enzymes (GSTM1 and GSTT1) contribute to the development of ARMD. This study consisted of 112 subjects (44 females, 68 males) with exudative ARMD, who were recruited from Khalili Hospital ophthalmic clinic in Shiraz (southern Iran), referred by vitreoretinal surgeon. Also 112 sex-matched controls (44 females, 68 males) were randomly selected from unrelated volunteers in the same clinic. We excluded patients and controls with cataract or past history of cataract surgery, asthma, past history of malignancy, cardiovascular disease that on medication and known cases of glaucoma, because these traits were associated with GSTM1 and/or GSTT1 polymorphisms. There was no association between polymorphisms of neither GSTM1 nor GSTT1 and risk of ARMD. The combination genotypes of GSTM1 and GSTT1 were not associated with the risk of ARMD. We considered the time of deterioration of vision as the time of onset of exudative ARMD. The Kaplan-Meier analysis revealed that there was significant difference between genotypes of GSTM1 (log rank statistic = 7.03, df = 1, P = 0.008). The age at onset among GSTM1 null genotype was lower than the active genotype of GSTM1. Our results support the hypothesis that the protein encoded by the GSTM1 gene might have a protective function against oxidative stress in retina. Since the age at onset is influenced by the GSTM1 polymorphism, this implies that GSTM1 is a modifier gene.

Association between N142D genetic polymorphism of GSTO2 and susceptibility to colorectal cancer

Expression pattern analysis has been revealed that glutathione S-transferase omega 2 (GSTO2, a member of class omega) is ubiquitously expressed. Over expression of GSTO2 induced apoptosis. The gene encoding GSTO2 was localized to human chromosome 10q24.3, a region that may harbor gene(s) involved in the developing of colorectal cancer. To investigate the association between GSTO2 N142D genetic polymorphism and susceptibility to colorectal cancer the present study was done. We studied 63 (26 females, 37 males) colorectal cancer patients and 126 (52 females, 74 males) healthy individuals. The control subjects were frequency matched for age and gender with the colorectal cancer group. The genotypes were performed using RFLP-PCR method. The ND and DD genotypes were not associated with risk of colorectal cancer, in comparison with the NN genotype. Family history for cancer in the first degree of relatives significantly differed between cases and controls (P = 0.012). The profiles of GSTO2 genotypes and family history in control and cancerous groups were compared to each other. Subjects with NN genotype and positive family history significantly were at high risk to develop colorectal cancer in comparison with subjects with DD or ND genotypes and negative family history (P = 0.003). Present findings indicating that GSTO2 NN genotype increase the risk of colorectal cancer in persons with positive family history for cancer in the first degree relatives.

PREVALENCE OF CONSANGUINEOUS MARRIAGES AMONG IRANIAN GEORGIANS

Consanguineous marriage – marriage between relatives – has received a great deal of attention as a potential risk factor for many adverse health outcomes. The present cross-sectional study was done in order to illustrate the prevalence and types of consanguineous marriages among Iranian Georgians living in Frydoonshahr (Isfahan province, central Iran). Data on consanguineous marriages were collected using a simple questionnaire. The total number of couples in this study was 646. Consanguineous marriage was classified by the degree of relationship between couples. First cousin marriages (14.2%) were the most common type of consanguineous marriages, followed by second cousin (7.0%), beyond second cousin (1.5%) and first cousin once removed (0.6%). The mean inbreeding coefficient (α) was calculated as 0.0104 for the population. The present study shows that the study population, as other Iranian populations, has a high level of consanguinity.

Haplotype analysis of XRCC1 (at codons 194 and 399) and susceptibility to breast cancer, a meta-analysis of the literatures

To clarify the association between XRCC1 haplotypes and susceptibility to breast cancer, a meta-analysis of case-control studies were conducted. Eligible studies were identified by searching several databases for relevant reports published before March 2010. In total, 10 studies were included in the present meta-analysis. XRCC1 haplotypes for Arg194Trp and Arg399Gln polymorphisms were included in the analysis. The association was measured using random-effect model or fixed-effect model odds ratio (OR) combined with 95% confidence intervals (CIs) according to the between studies' heterogeneity. Large between-study heterogeneity was observed (Q = 25.587, df = 9, P < 0.001). The meta-analysis showed a borderline increased risk of breast cancer associated with the Arg194-Gln399 haplotype versus the Arg194-Arg399 haplotype (OR = 1.07, 95% CI: 1.01-1.14). There was no significant association between XRCC1 haplotypes and risk of breast cancer among Caucasoid subjects. In the next step, studies were classified according to geographical locations. Studies reported form Western populations did not show heterogeneity, and the Arg194-Gln399 haplotype was not associated with risk of breast cancer in comparison with the Arg194-Arg399 haplotype (OR = 1.02, 95% CI: 0.95-1.09). Among studies reported form Asian countries, significant heterogeneity was observed. After excluding of one study which did not show linkage disequilibrium, heterogeneity between studies decreased and haplotype Arg194-Gln399 revealed significant association with increased risk of breast cancer compared with haplotype Arg194-Arg399 (OR = 1.26, 95% CI: 1.04-1.50). There was no significant association between Trp194-Arg399 haplotype and risk of breast cancer, neither in Western nor Asian countries. The present meta-analysis has indicated that the Arg194-Gln399 haplotype of XRCC1 might be a risk factor for breast cancer in Asian countries.

The association of polymorphisms in DNA base excision repair genes XRCC1, OGG1 and MUTYH with the risk of childhood acute lymphoblastic leukemia

The aim of this study was to evaluate the association of polymorphisms in genes encoding three key proteins of DNA base excision repair (BER): the OGG1 Ser326Cys, the MUTYH Tyr165Cys and the XRCC1 Arg399Gln with the risk of childhood acute lymphoblastic leukemia (ALL). Our study included 97 children patients with ALL (mean age 5.4±2.5) and 131 healthy children (mean age 6.2±2.8) used as controls. Genetic polymorphisms in BER pathway genes were examined using PCR and restriction fragment length polymorphism (RFLP). We have demonstrated that the OGG1 Cys/Cys genotype increases the risk of ALL (OR 5.36) whereas the Ser/Ser genotype variant strongly reduces the risk of this cancer among Polish children (OR 0.45). Although we did not observe the differences in single nucleotide polymorphisms (SNPs) in MUTYH and XRCC1 genes between control group and children with ALL, we have shown that the combined genotypes of examined genes can modulate the risk of childhood ALL in Polish population. We found that the combined genotype Arg/Gln-Cys/Cys of XRCC1/OGG1 (OR 3.83) as well as the Cys/Cys-Tyr/Tyr of OGG1/MUTYH (OR 6.75) increases the risk of ALL. In contrast, the combined genotype Arg/Arg-Ser/Ser of XRCC1/OGG1 (OR 0.40) as well as the Ser/Ser-Tyr/Tyr of OGG1/MUTYH (OR 0.43) played a protective role against this malignant disease. In conclusion, we suggest that polymorphisms of BER genes may be used as an important predictive factor for acute lymphoblastic leukemia in children.

Association of cytotoxic T lymphocyte-associated antigen-4 gene haplotype with the susceptibility to gastric cancer

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) was widely accepted as a pivotal molecule in downregulating T-cell mediated immune responses. In this study we investigated the polymorphisms which would impact the CTLA-4 gene expression and function to assess the association with the risk of gastric cancer. 205 gastric cancer patients and 262 healthy controls were included in the case-control study. PCR and restriction fragment length polymorphism (RFLP) methods were performed to identify the +49A/G and promoter -1661A/G polymorphisms. The promoter -1772T/C polymorphism was detected by PCR amplification refractory mutation system (ARMS) technique. A significant difference was observed between case and control groups. The frequency of +49A/G polymorphism AG and -1661A/G polymorphism GG genotype were significantly higher in patients than in controls (OR = 2.15, OR = 1.88, respectively). No significant difference was found in the allelic frequency of -1772T/C polymorphism between cases and controls (P = 0.478). By the haplotype analysis, logistic regression showed the frequency of haplotype A (GAT) and D (AGT) in the case group revealed significant difference compared with in control group (OR = 2.00, P < 0.001; OR = 1.62, P = 0.043, respectively). Our findings implied the genetic variations within CTLA-4 gene would be a critical risk factor to the susceptibility of gastric cancer.

Glutathione S-transferase genetic polymorphisms (GSTM1, GSTT1 and GSTO2) in three Iranian populations

Genetic polymorphisms in genes encoding glutathione S-transferases M1 (GSTM1; a member of class mu), T1 (GSTT1; a member of class theta) and O2 (GSTO2; a member of class omega) have been defined previously. Studies have revealed that there were significant differences between populations for allelic frequencies of GSTT1, GSTM1 and GSTO2 N412D polymorphisms. To get more insight into the genetic structure of Iranian populations the present study was done on Iranian Georgians living in Frydoonshahr (Isfahan province) and two Persian populations who living in Shiraz (Fars province) and Frydoonshahr. Study subjects consisted of 401 unrelated healthy individuals. From these 121 were Georgians. The remaining subjects were Persians from either Frydoonshahr (n = 34) or Shiraz (n = 246). The genetic polymorphism of GSTT1, GSTM1 and GSTO2 N412D was detected by PCR-based method. The frequency of GSTT1 null genotype in Georgian and Persians of Frydoonshahr and Shiraz was 15.7, 35.2 and 24.8%, respectively. There was significant difference between these populations for the distributions of the GSTT1 genotypes (chi(2) = 7.00, df = 2, P = 0.030). No significant difference was observed between these populations for polymorphisms of GSTM1 (chi(2) = 1.682, df = 2, P = 0.431) and GSTO N142D (chi(2) = 4.622, df = 4, P = 0.328). The prevalence of GSTT1 null genotype in Iranian Georgians showed significant difference with Persians and other Asian countries, but it seems to be similar with the frequency which was reported from European populations.