Fc Gamma receptor IIa polymorphism in Egyptian patients with systemic lupus erythematosus

ABSTRACT

Systemic Lupus Erythematosus [SLE] is a complex, multifactorial auto-immune disease. Receptors for IgG play an important role in immune complex clearance. Several studies have identified polymorphisms of receptors for the Fc fragment of IgG [Fc Gamma R] as genetic factors influencing the susceptibility and course of such a disease. It has been also suggested that Fc Gamma RIIa polymorphism may be an important risk factor for development of lupus nephritis. This study was done to examine the frequency of Fc Gamma RIIa R/H131 polymorphism among Egyptian patients with SLE, as well as, to determine whether Fc Gamma RIIa polymorphism, represents a risk factor for both SLE susceptibility and lupus nephritis. Patients and Forty four Egyptian patients were diagnosed with SLE according to the American College of Rheumatology Criteria. Both SLE patients and healthy controls were genotyped for Fc Gamma RIIa R/H131 polymorphism using a single step allele PCR based method. No statistically significant difference was found in the frequency of FcyRlla genotypes [H/H, H/R and R/R] between SLE patients and normal controls [p > 0.05]. However, a small excess of R/R allele was seen in the SLE patients but this did not reach statistical significance [total SLE versus controls OR 1.6, 95% CI 0.69-3.7, p > 0.05]. Moreover, a possible susceptibility to lupus nephritis which may be related to Fc Gamma RIIa R/R allele was suggested in the Egyptian patients, but this also did not reach statistical significance [OR 1.6, 95% Cl0.47-5.3, p > 0.05]. No statistically significant relation was found between Fc Gamma RIIa genotypes and age, age at onset and duration of the disease [p > 0.05]. Also, no statistically significant association between clinical manifestations and Fc Gamma RIIa polymorphism was demonstrated in this study. Serological assessments demonstrated that Fc Gamma RIIa H/H131 allele was significantly associated with double-stranded DNA antibody [OR < 1.95% CI0.27-3.3, p < 0.05], while no statistically significant association was demonstrated with anti-Smith antibody [p > 0.05]. Fc Gamma RIIa polymorphism may possibly constitute a minor determinant that could influence the susceptibility to SLE and lupus nephritis. However, it seems that it does not represent a well recognized genetic risk factor neither for SLE susceptibility nor for the development of lupus nephritis in Egyptian SLE patients