CTLA-4 polymorphisms in Thai patients with rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis

Studies on polymorphisms of the cytotoxic T lymphocytes associated antigen-4 (CTLA-4) genes in rheumatic disease patients are limited in Southeast Asia. This pilot study aimed to determine CTLA-4 polymorphisms in Thai patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SSc), and correlate them with serology.

One-hundred RA, 70 SLE and 50 SSc patients, and 99 healthy controls (HCs) were included in this study. Polymorphisms of the CTLA-4 gene at +49A/G, -318C/T, -1661A/G and -1722T/C loci were determined by polymerase chain reaction restriction fragment length polymorphism methods. Patient serum samples were determined as follows: RA (rheumatoid factor [RF] and anticyclic citrullinated peptide [anti-CCP]), SLE (antinuclear antibodies [ANA], anti-double-stranded DNA [anti-dsDNA], anti-Smith [anti-Sm], anti-ribonucleoprotein [anti-RNP], and anti-Sjögren's syndrome antigen A [SSA]), and SSc (ANA, anti-RNP, anti-SSA, anti-topoisomerase-1 [anti-Scl70], and anti-centromere antibodies [ACA]).

Among the 4 loci studied (+49A/G, -318C/T, -1661A/G and -1722T/C) only the A allele frequency at the +49A/G was significantly higher in the RA patients than their HCs (47.25% vs 35.86%, P = .029, odds ratio [OR] 1.60; 95% CI 1.04-2.47). It also was significantly higher in the subgroup of RA patients with positive RF and anti-CCP than their HCs (47.50% vs 35.86%, P = .020, OR 1.62; 95% CI 1.06-2.47 and 48.89% vs 35.86%, P = .012, OR 1.71; 95% CI 1.11-2.64, respectively). No polymorphisms at these 4 loci were observed in SLE or SSc patients.

The A allele at +49A/G locus of the CTLA-4 gene was associated with RA in Thais.