Abstract
Abstract
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.