Association study of IL2RA and CTLA4 Gene Variants with Type I Diabetes Mellitus in children in the northwest of Iran

Single-nucleotide polymorphisms as important risk factors of diabetes among Middle East population

Diabetes is a chronic metabolic disorder that leads to the dysfunction of various tissues and organs, including eyes, kidneys, and cardiovascular system. According to the World Health Organization, diabetes prevalence is 8.8% globally among whom about 90% of cases are type 2 diabetes. There are not any significant clinical manifestations in the primary stages of diabetes. Therefore, screening can be an efficient way to reduce the diabetic complications. Over the recent decades, the prevalence of diabetes has increased alarmingly among the Middle East population, which has imposed exorbitant costs on the health care system in this region. Given that the genetic changes are among the important risk factors associated with predisposing people to diabetes, we examined the role of single-nucleotide polymorphisms (SNPs) in the pathogenesis of diabetes among Middle East population. In the present review, we assessed the molecular pathology of diabetes in the Middle East population that paves the way for introducing an efficient SNP-based diagnostic panel for diabetes screening among the Middle East population. Since, the Middle East has a population of 370 million people; the current review can be a reliable model for the introduction of SNP-based diagnostic panels in other populations and countries around the world.

CTLA-4 (+49A/G) Polymorphism in Type 1 Diabetes Children of Sudanese Population

Background  Type 1 diabetes mellitus (T1DM) is an organ-specific T cell-mediated autoimmune disease, characterized by destruction of pancreatic islets. Cytotoxic lymphocyte antigen-4 ( CTLA-4 ) is a negative regulator of T cell proliferation, thus conferring susceptibility to autoimmunity.

Aims  This study aimed to investigate the association of CTLA-4 +49A/G (rs231775) polymorphism with a risk of T1DM in Sudanese children.

Methods  This a case–control study included 100 children with T1DM, referred to the pediatric clinic at referral pediatric teaching hospital in Gezira State-Sudan. Hundred unrelated healthy controls were recruited from departments in the same hospital. Genomic deoxyribonucleic acid (DNA) was extracted from Ethylenediaminetetraacetic Acid (EDTA)-preserved blood using QIAamp DNA Blood Mini Kit (QIAamp Blood) (QIAGEN; Valencia, CA). The polymerase chain reaction PCR restriction fragment length polymorphism (PCR-RFLP) and sequencing were applied for the CTLA-4 (+49A/G) genotyping. The changes accompanied the polymorphism were evaluated using relevant bioinformatics tools.

Results  The genotype and allele frequencies of the CTLA-4 (+49A/G) polymorphism were significantly different between the patients and controls ( p  = 0.00013 and 0.0002, respectively). In particular, the frequency of the G allele, GG homozygous genotype, and AG heterozygous genotype were significantly increased in patients than in controls ([28% versus 7%, odds ratio (OR) = 5.16, 95% confidence interval [CI] = 2.77–9.65, p  = 0.00] [12% versus 2%, OR = 6.68, CI = 1.46–30.69, p  = 0.01] [32% versus 10%, OR = 4.24, CI = 1.95–9.21, p  = 0.00], respectively). The presence of the G allele (homozygous) showed an influence on the signal peptide polarity, hydrophobicity, and α-helix propensity of the CTLA-protein.

Conclusion  The results further support the association of CTLA-4 (+49A/G) polymorphism and the risk of T1DM in our study population.

Genetic analysis of the relation between IL2RA/IL2RB and rheumatoid arthritis risk

Background

The biological mechanisms driving disease chronicity in rheumatoid arthritis (RA) are largely unidentified. Therefore, we aimed to determine genetic risk factors for RA.

Methods

In this case–control study, which includes samples from 499 patients and 507 healthy controls, six single‐nucleotide polymorphisms (SNPs) in interleukin‐2 receptor subunit alpha (IL2RA) and IL2RB were selected. Genotyping was performed using the Agena MassARRAY platform, and the statistical analyses were performed using the chi‐squared and Fisher's exact tests, genetic model analysis, and haplotype analysis.

Result

In the allele model, using the chi‐squared test, the result showed that rs791588 in IL2RA was associated with a decreased RA risk (odds ratios [OR] = 0.74, 95% confidence intervals [CI] = 0.62–0.89, p = 0.0014) after adjusting for age and gender. In the genetic model, logistic regression analyses revealed that rs791588 was associated with a decreased risk of RA under the codominant model, dominant model, recessive model, and log‐additive model. Stratification analysis revealed that two SNPs (rs791588 and rs2281089) were significantly associated with a reduced RA risk in an allele and genetic model after stratification by gender or age (p < 0.05). In addition, the haplotypes “C_rs12569923G_rs791588” and “C_rs12569923T_rs791588” of IL2RA was associated with an increased risk of RA adjusted by age and gender (OR = 1.35, 95% CI: 1.12–1.64, p = 0.0016; OR = 1.24, 95% CI: 1.03–1.48, p = 0.021).

Conclusion

This finding indicates that the inherited altered genetic constitution at IL2RA may predispose to a less destructive course of RA.