CTLA4 Gene Polymorphism and its Association with Disease Occurrence, Clinical Manifestations, Serum Markers and Cytokine Levels in SLE Patients from North India

BACKGROUND: Cytotoxic T lymphocyte-associated protein-4 (CTLA-4) or CD152 is an inhibitory receptor expressed constitutively on CD4+CD25+ T regulatory lymphocytes (Treg) and transiently on activated CD4+ and CD8+ T lymphocytes. Association of CTLA4 gene polymorphisms with Systemic Lupus Erythematosus (SLE) has been reported in south Indians, but not in north Indians. This study aims to investigate CTLA4 gene polymorphism and its association with the occurrence of SLE, its clinical manifestation and serological markers in north Indians. METHODS: This cross sectional study was done in a tertiary health care centre in north India. Patients reporting to the hospital and diagnosed with systemic lupus erythematosus were included in study. +49 A/G (snp- rs231775) CTLA4 gene polymorphism was analysed in 41 SLE patients and 21 matched healthy controls by real time PCR method. ANA (Antinuclear Antibody), anti dsDNA, Interferon-γ (IFN- γ), TGF-β, IL-10 were measured by ELISA kits. Complement (C3 and C4) and immunoglobulins (IgA, IgG, IgM) estimation were done with the turbidometry method. Chi-square test was used for comparison between groups and odds ratio with 95% confidence interval was calculated to estimate the associated risk. RESULTS: A/A genotype was most common (51.2%) followed by the A/G genotype (46.3%) and G/G genotype (2.4%, detected in only 1 patient). The frequency of A allele was 74.4%, while of G allele was only 25.6%. A/G genotype SLE patients showed a higher risk (odds ratio 37.5, 95% CI- 6.048-232.51) of developing edema compared to A/A genotype patients. There was no statistically significant association of various CTLA4 genotypes with the occurrence of SLE and serum markers. CONCLUSIONS: A/A was the most common CTLA4 genotype in both SLE patients and healthy controls of north India. Contrary to the previous report in south Indians, there was no statistically significant association between CTLA4 genotype and occurrence of SLE in north Indians. Only the presence of generalised edema was found significantly associated with the A/G genotype.