Background: Rheumatoid arthritis (RA) is a chronic,
autoimmune inflammatory illness. Proinflammatory cytokines
play a crucial role in the development of RA by inducing an
inflammatory response. One of these cytokines is interleukin-21
(IL-21), which regulates B-cell proliferation, plasma
differentiation, and immunoglobulin synthesis; consequently, IL21's actions on B cells may take part in the development of
autoimmune disorders. Aim of the study: to investigate the
association between plasma IL-21 gene polymorphism and
susceptibility to RA in Egyptian patients and to find out its
relation to disease activity. Methods: The case-control study was
performed on 100 subjects; divided into two groups: Group(I):70
RA patients, Group (II):30 healthy matched controls. Through
history taking, clinical examination and assessment of IL-21 gene
rs2055979 by quantitative Real-Time PCR (qRT-PCR).
Evaluation of disease activity by using the Disease Activity
Score (DAS-28 score). Results: RA patients were significantly
associated with a higher frequency of rs2055979 AA genotype
and A allele (p= 0.023, 0.028) with risk to RA development
(OR=2.759, 2.040 respectively). IL-21 genotypes AA and CA
were significantly associated with higher DAS-28 when
compared to the CC genotype (p≤0.05). On regression analysis,
IL21 dominant models were considered independent risk
predictors of higher RA disease activity (