Association analysis between ARG1 gene polymorphisms and idiopathic dilated cardiomyopathy

Common variants in AGR1 genes contributed to the risk and traits of cirrhotic cardiomyopathy in Han Chinese population

Aim: This study aimed to determine the association between polymorphisms of the ARG1 gene and the risk and traits of cirrhotic cardiomyopathy (CCM). Methods: A total of 468 CCM and 1012 cirrhosis patients were enrolled, and 12 single-nucleotide polymorphisms (SNPs) in the ARG1 gene were genotyped. Differences in genotype, allele and haplotype frequencies of the SNPs between the CCM and cirrhosis groups were analyzed by chi-square test. Correlations of the genotypes of SNPs and representative traits of liver and heart function were performed using linear regression analysis. Results: SNPs rs2781666 and rs2781667 were associated with the risk of CCM in both dominant and additive inheritance models. The GG genotype frequency of rs2781666 and CC genotype frequency of rs2781667 were lower in the CCM group than in the cirrhosis group. The G-C haplotype frequency of the block consisting of rs2781666 and rs2781667 was higher and the T-T haplotype frequency was lower in CCM patients than in cirrhosis patients. SNP rs2781666 was associated with the alanine transaminase level, and rs2781667 was associated with the ARG1 level and left atrial diameter. Conclusion: SNPs rs2781666 and rs2781667 in the ARG1 gene were associated with susceptibility to and traits of CCM in the Han Chinese population.

Single Nucleotide Polymorphisms in the Arginase 1 and 2 Genes Are Differentially Associated with Circulating l-Arginine Concentration in Unsupplemented and l-Arginine-Supplemented Adults

BACKGROUND

Genetic variation in arginase may underlie variability in whole blood l-arginine concentrations in unsupplemented and l-arginine-supplemented adults.

OBJECTIVES

We aimed to study whether single nucleotide polymorphisms (SNPs) in the arginase 1 (ARG1) and arginase 2 (ARG2) genes are associated with blood l-arginine concentrations in unsupplemented and l-arginine-supplemented individuals.

METHODS

In 374 adults (mean ± SD age: 59.6 ± 14.6 y; 180 males), we analyzed SNPs in the ARG1 (rs2246012 and rs2781667) and ARG2 genes (rs3742879 and rs2759757) and their associations with blood l-arginine concentrations. We analyzed associations of haplotypes for the ARG1 gene and for the ARG1 and ARG2 genes combined with blood l-arginine concentrations in supplement users and unsupplemented participants.

RESULTS

Of study participants, 120 had low (<42 μmol/L), 133 had medium (42-114 μmol/L), and 121 had high blood l-arginine concentrations (>114 μmol/L); 58 individuals were current l-arginine supplement users. We found a significantly higher prevalence of the minor allele of ARG1 rs2246012 in supplement users with higher blood l-arginine concentrations (P = 0.03). Mean ± SEM l-arginine concentration was 263 ± 9.76 μmol/L in supplement users homozygous for the minor allele of ARG1 rs2246012 (P = 0.004); it was 70.4 ± 25.6 μmol/L in unsupplemented participants homozygous for the minor allele of ARG2 rs3759757 (P = 0.03). The ARG1 haplotype was significantly associated with blood l-arginine concentrations in supplement users (P = 0.046), whereas the combined ARG1/ARG2 haplotype was significantly associated with blood l-arginine concentrations in the cohort as a whole (P = 0.012).

CONCLUSIONS

Genetic variability in the ARG1 and ARG2 genes is associated with blood l-arginine concentrations in humans: ARG1 is associated with blood l-arginine concentrations in l-arginine supplement users, whereas ARG2 is associated with blood l-arginine concentrations in unsupplemented participants. Our study is the first to describe a possible functional relation between ARG1 and ARG2 SNPs and blood l-arginine concentrations; genetic variability in ARG1 may explain variation in blood l-arginine concentrations during supplement use and discrepant study results.

Common Variants in the ARG1 Gene Contribute to the Risk of Dilated Cardiomyopathy in the Han Chinese Population

Background: Arginase I, encoded by the ARG1 gene, is an enzyme that catalyzes the conversion of arginine to ornithine in the urea cycle; mutations in this gene has recently been reported to be associated with dilated cardiomyopathy (DCM) in Pakistan. The present study aimed to investigate the relationship between ARG1 gene mutations and DCM in the Han Chinese population. Methods: A total of 488 DCM cases and 924 matched-healthy controls were recruited. All subjects were genotyped for 12 tag single nucleotide polymorphisms (SNPs) within the ARG1 gene. Genetic association studies, including SNP and haplotype analyses, were performed. Further analyses were conducted to examine the correlations between the associated SNPs and specific clinical characteristics. Results: Only the rs2781666 and rs2781667 loci in the ARG1 gene were found to be significantly associated with DCM compared to the healthy controls. The risk of DCM at both of these loci for T allele carriers was ∼1.42-fold higher than that for carriers of the alternative alleles. There were significant differences in end-diastolic interventricular septal diameter, end-diastolic left ventricular posterior wall diameter, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and left ventricular ejection fraction among the genotype distributions of both SNPs. Furthermore, we found that the T alleles at the rs2781666 and rs2781667 loci were significantly associated with DCM in gender subgroups and the subgroup of patients <58 years of age. The haplotype T-T (rs2781666-rs2781667) also showed a significant association with DCM. Conclusion: Our results support the hypothesis that alleles and haplotypes of the ARG1 gene are significantly involved in the etiology of DCM in the Han Chinese population, but further research is necessary to elucidate the mechanism governing this association.