['Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a CD28-family receptor expressed on T-cells which suppresses T cell proliferation. CTLA-4 -318C/T polymorphism is involved in regulation of CTLA-4 expression.', 'The study aimed to investigate the genetic association of CTLA-4 -318C/T polymorphism with rheumatoid arthritis (RA) and the activity and severity of the disease in the Egyptian population.', 'A single nucleotide polymorphism (rs5742909) in CTLA-4 was genotyped in 100 RA patients and 100 healthy controls using polymerase chain reaction-restriction fragment length polymorphism. Diagnostic tests were measured for RA patients.', 'The frequency of T allele in RA patients was significantly higher than in the control subjects (p\u2009=\u20090.002). CT and TT genotypes had high C-reactive protein, erythrocyte sedimentation rate and disease activity score 28 while CC genotype had a high rheumatoid factor.'] Is cytotoxic T-lymphocyte-associated protein 4 gene polymorphism related to rheumatoid arthritis in Egyptian population?