Genetic polymorphisms of XRCC1 and leukemia risk: a meta-analysis of 19 case-control studies

Age- and Gender-Independent Association of XRCC1 Arg399Gln Polymorphism with Chronic Myeloid Leukemia

Purpose

DNA damage to hematopoietic progenitor cells is an essential factor for leukemia development as a failure of the host DNA repair system to fix errors in DNA. This study aimed to assess the association of XRCC1 gene polymorphisms including Arg194Trp, Arg399Gln, and Arg280His with the risk of development of CML in Sudanese population.

Patients and Methods

The present study was conducted on 186 newly diagnosed patients with CML, aged 19–70 years (118 males and 68 females; mean age of 46.15±13.91 years) and 186 normal healthy controls (123 males and 63 females; mean age of 44.94±8.97 years). Polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) assay was utilized to analyze the XRCC1 (Arg194Trp, Arg399Gln, and Arg280His) gene polymorphisms.

Results

The genotypic frequencies of Arg399Gln polymorphism in cases were 131 (70.4%) homozygous Arg/Arg, 46 (24.7%) homozygous Gln/Gln, and 9 (4.8%) heterozygous Arg/Gln as compared to the controls ie, 153 (82.3%), 73 (14.5%), and 6 (3.2%), respectively. The Arg399Gln variant genotypic frequencies significantly differed between the cases and controls (χ² = 7.249, P = 0.027). By comparison, no statistically significant difference was observed in the variant genotype frequencies between the cases and controls in terms of Arg194Trp and Arg280His polymorphisms.

Conclusion

XRCC1 Arg399Gln gene polymorphism might have an important role in increasing the risk of chronic myeloid leukemia among Sudanese patients. Furthermore, all tested three polymorphisms showed no association of risk of the development of CML with age and gender.

[Acute lymphoblastic leukemia: a genomic perspective]

In parallel to the human genome sequencing project, several technological platforms have been developed that let us gain insight into the genome structure of human entities, as well as evaluate their usefulness in the clinical approach of the patient. Thus, in acute lymphoblastic leukemia (ALL), the most common pediatric malignancy, genomic tools promise to be useful to detect patients at high risk of relapse, either at diagnosis or during treatment (minimal residual disease), and they also increase the possibility to identify cases at risk of adverse reactions to chemotherapy. Therefore, the physician could offer patient-tailored therapeutic schemes. A clear example of the useful genomic tools is the identification of single nucleotide polymorphisms (SNPs) in the thiopurine methyl transferase (TPMT) gene, where the presence of two null alleles (homozygous or compound heterozygous) indicates the need to reduce the dose of mercaptopurine by up to 90% to avoid toxic effects which could lead to the death of the patient. In this review, we provide an overview of the genomic perspective of ALL, describing some strategies that contribute to the identification of biomarkers with potential clinical application.

Associations between XRCC1 Gene Polymorphisms and Coronary Artery Disease: A Meta-Analysis

Genetic variations that influence DNA repair efficiency may contribute to coronary artery disease (CAD) susceptibility. Previous studies have investigated whether there was evidence of an association between polymorphisms at the X-ray repair cross complementing 1 (XRCC1) gene and susceptibility to CAD, but findings have been inconclusive. We identified eligible studies through a comprehensive literature search to determine whether an association exists between XRCC1 gene polymorphisms and CAD susceptibility. Findings were assessed using the odds ratio (OR) and corresponding 95% confidence interval (CI), which were calculated using a fixed- or random-effects model, based on the heterogeneity of the studies. Ten eligible studies were finally included in this meta-analysis. Our pooled analysis found that XRCC1 polymorphisms were significantly associated with CAD susceptibility under recessive (Arg194Trp: OR = 1.47, 95% CI = 1.13-1.93; Arg399Gln: OR = 1.45, 95% CI = 1.12-1.89), homozygous (Arg194Trp: OR = 1.37, 95% CI = 1.03-1.81; Arg399Gln: OR = 1.56, 95% CI = 1.19-2.05), and allele (Arg399Gln: OR = 1.18, 95% CI = 1.06-1.32) genetic models. Following subgroup analysis by ethnicity, in Asian populations, we found evidence of associations between the XRCC1 Arg194Trp polymorphism and CAD under recessive and homozygous genetic models, and between the XRCC1 Arg399Gln polymorphism and CAD under recessive, homozygous, and allele genetic models. Subgroup analysis stratified by control source revealed associations between the Arg194Trp and Arg399Gln polymorphisms and susceptibility to CAD under recessive and homozygous modes of inheritance, respectively. In addition, subgroup analysis stratified by sample size found that findings of the Arg194Trp polymorphism in large sample sizes were comparable to those found using pooled eligible studies. Based on our meta-analysis, we concluded that the XRCC1 gene polymorphisms, Arg194Trp and Arg399Gln, are associated with CAD susceptibility, specifically in Asian populations. However, additional, comprehensive and well-designed studies are warranted to confirm these findings.

The association between XRCC1 Arg399Gln polymorphism and risk of leukemia in different populations: a meta-analysis of case-control studies

Background

Associations between Arg399Gln single-nucleotide polymorphism (SNP) in the XRCC1 gene and leukemia susceptibility have been studied extensively, however, the results are inconsistent. The aim of this study was to determine these associations using meta-analytical methods.

Methods

A meta-analysis was performed to examine the associations between XRCC1 Arg399-Gln SNP and leukemia risk. A literature search of PubMed and Web of Science databases was conducted to identify relevant studies published up to March 10, 2015. The references of the retrieved articles were also screened. All the statistical analyses were conducted using Review Manager software.

Results

The XRCC1 Arg399Gln SNP was found to be associated with increased childhood risk of acute lymphoblastic leukemia among Asians under the dominant (odds ratio [OR] 2.11, 95% confidence interval [CI] 1.50–2.97, P<0.0001), allele contrast (OR 1.72, 95% CI 1.33–2.23, P<0.0001), and homozygote contrast (OR 2.34, 95% CI 1.25–4.36, P=0.008) models. However, no association was found in Caucasians between the SNP and risk of either chronic myeloid leukemia or chronic lymphocytic leukemia under any contrast model.

Conclusion

The findings of the current meta-analysis indicate that the XRCC1 Arg399Gln SNP is a risk factor for childhood lymphoblastic leukemia in Asians.

Inherited genetic variation in childhood acute lymphoblastic leukemia

Although somatically acquired genomic alterations have long been recognized as the hallmarks of acute lymphoblastic leukemia (ALL), the last decade has shown that inherited genetic variations (germline) are important determinants of interpatient variability in ALL susceptibility, drug response, and toxicities of ALL therapy. In particular, unbiased genome-wide association studies have identified germline variants strongly associated with the predisposition to ALL in children, providing novel insight into the mechanisms of leukemogenesis and evidence for complex interactions between inherited and acquired genetic variations in ALL. Similar genome-wide approaches have also discovered novel germline genetic risk factors that independently influence ALL prognosis and those that strongly modify host susceptibility to adverse effects of antileukemic agents (eg, vincristine, asparaginase, glucocorticoids). There are examples of germline genomic associations that warrant routine clinical use in the treatment of childhood ALL (eg, TPMT and mercaptopurine dosing), but most have not reached this level of actionability. Future studies are needed to integrate both somatic and germline variants to predict risk of relapse and host toxicities, with the eventual goal of implementing genetics-driven precision-medicine approaches in ALL treatment.

Polymorphism of XRCC1, XRCC3, and XPD genes and risk of chronic myeloid leukemia

The genetic polymorphisms of X-ray repair cross complementing group 1 (XRCC1), X-ray repair cross complementing group 3 (XRCC3), and xeroderma pigmentosum complementation group D (XPD) repair genes may lead to genetic instability and leukemogenesis. The purpose of the study was to evaluate the association between XRCC1 Arg399Gln, Arg280His and Arg194Trp, XRCC3 Thr241Met, and XPD Lys751Gln polymorphisms and the risk of developing CML in Romanian patients. A total of 156 patients diagnosed with CML and 180 healthy controls were included in this study. We found no association between CML and XRCC1 or XRCC3 variant genotypes in any of the investigated cases. A significant difference was observed in the variant genotype frequencies of the XPD Lys751Gln polymorphism between the patients with CML and control group (for variant homozygous genotypes, OR = 2.37; 95% CI = 1.20–4.67; P value = 0.016 and for combined heterozygous and variant homozygous genotypes, OR = 1.72; 95% CI = 1.10–2.69; P value = 0.019). This was also observed when analyzing the variant 751Gln allele (OR = 1.54; 95% CI = 1.13–2.11; P value = 0.008). Our results suggest that the XPD Lys751Gln variant genotype increases the risk of CML.