Lack of association of CTLA-4 +49 A/G polymorphism with predisposition to type 1 diabetes in a cohort of Egyptian families

Association of Cytotoxic T-Lymphocyte Antigen-4 Gene Polymorphism with Type 1 Diabetes Mellitus: In silico Analysis of Biological Features of CTLA-4 Protein on Ethiopian Population

BACKGROUND

T1DM is a chronic organ-specific T-cell-mediated autoimmune disease characterized by the selective destruction of β-cells in the islets of Langerhans, resulting in insulin deficiency and hyperglycemia. Genes for cytotoxic T lymphocyte-associated antigen 4 have been hypothesized as possible contender genes for T1DM vulnerability. However, it has not been studied in the Ethiopian population yet.

OBJECTIVE

The aim of the study was to investigate CTLA-4 exon 1 was linked to A49G polymorphism with T1DM and its biological features of CTLA-4 among T1DM patients, in Ethiopia.

METHODS

A case-control study was done from December 2019 to March 2020 on 210 study participants (105 T1DM patients and 105 healthy controls). Polymerase Chain Reaction amplification with forward and reverse primers was followed by restriction fragment length polymorphism and gel electrophoresis to determine gene polymorphism. Bioinformatics data of SNP was retrieved from National Centers for Biotechnology Information databases. The chi-square test and logistic regression were used. Statistical significance was defined as a P-value of less than 0.05.

RESULTS

The CTLA-4 (+A49G) gene polymorphism was observed on 56 (26.7%) study participants, 39 (18.57%) of T1DM patients, and 17 (0.08%) were controls. In T1DM and controls, the frequency of the A allele was 73.3% and 89.5%, while the G allele was 26.7% and 10.5%, respectively. The G allele was found to be associated with T1DM (OR=3.1; 95% CI, 1.82 -5.32; P=0.001). Statistical analysis revealed an association between the likelihood of T1DM and GG genotype of the CTLA-4 (+A49G) gene polymorphism (OR=3.11; 95% CI, 1.37-10.90; P=0.01). Further in silico analyzed the SNP to assess its biological features.

CONCLUSION

The study showed as CTLA-4 (+A49G) gene polymorphism is linked with T1DM in the Ethiopian population.

Serum sCTLA-4 level is not associated with type 1 diabetes or the coexistence of autoantibodies in children and adolescent patients from the southern region of Saudi Arabia

Background

The soluble form of CTLA-4 (sCTLA-4) is associated with several autoimmune diseases. The aim of the study is to measure the serum sCTLA-4 levels in type I diabetic (T1DM) patients and to assess the presence of autoantibodies for a possible association.

Methods

One hundred forty-two T1DM patients were enrolled in the study. Fifty of them were serologically positive for co-existing autoantibodies. One hundred and five subjects were enrolled in the study, as non-diabetic controls (1–17 years of age; median age—10 years). The serum samples of all the subjects were analyzed with ELISA to detect the concentration of sCTLA-4 and anti-GAD/IA2 IgG. Standard statistical analysis was conducted as required.

Results

Ninety-four (66%) subjects of T1DM patients and five (4.7%) subjects of the non-diabetic group had antibodies positive for anti-GAD/IA2. Serum sCTLA-4 was low in most of the subjects of both the diabetic and control groups (p = 0.18). In the control group, nine individuals (8.6%) were positive for sCTLA-4. Similarly, only seven patients (4.9%) in the T1DM group had high levels of sCTLA-4, of which two were found to be double positive for anti-thyroid peroxidase and anti-thyroglobulin antibodies. In addition, among the T1DM patients, no significant relationships were observed between sCTLA-4 levels and age of onset (p = 0.43), disease duration (p = 0.09), or glycemic control (p = 0.32).

Conclusion

Despite the previous findings of high sCTLA-4 levels in autoimmune diseases, serum levels of sCTLA-4 are not significantly different between T1DM patients and non-diabetic adolescents. Furthermore, we did not observe any association with autoantibody presence, glycemic control, or disease duration.

Signal peptide missense variant in cancer-brake gene CTLA4 and breast cancer outcomes

The cancer-brake gene CTLA4 has a vital function in suppressing the immune responses of activated T lymphocytes. Numerous reports explored the impact of various CTLA4 variants with the predisposition for malignancies but with unconvincing findings. Hence, this study is designed to assess the association of CTLA4 (c.49A>G, rs231775) variant with the outcome of breast carcinoma. A total of 272 participants (93 BC patients and 179 cancer-free healthy volunteers) were enrolled. Genomic DNA for all participants was genotyped for CTLA4 (c.49A>G) variant via TaqMan genotyping assay. Patients with A/G genotype conferred protection against developing BC under heterozygote comparison (OR = 0.56, 95%CI = 0.31-0.98) as well dominant model (OR = 0.55, 95%CI = 0.32-0.97). AG/GG genotypes were anchored with an increased risk of nodal infiltration (OR = 2.90, 95%CI = 1.03-8.17, P = 0.037), metastasis (OR = 4.46, 95%CI = 1.18-16.8, P = 0.019), advanced clinical stage (OR = 6.54, 95%CI = 2.06-20.75, P < 0.001), recurrence (OR = 5.2, 95%CI = 1.73-15.7, P = 0.001), and shorter survival (OR = 2.54, 95%CI = 1.08-5.99, P = 0.032). In addition, functional enrichment analysis revealed the key role of CTLA4 in cancer immunosurveillance. Our findings indicated that the CTLA4 c.49A>G variant might have prognostic as well diagnostic impact in breast cancer.