FcγRIIA, FcγRIIIA and FcγRIIIB polymorphisms in Spanish patients with systemic lupus erythematosus

Linkage studies on human families suggest that receptors for the Fc fragments of immunoglobulin G (IgG) (FcgammaRs) could be implicated in the susceptibility to, or the progression of, some autoimmune diseases. In this work we analyse the possible role of polymorphic variants of FcgammaRIIA, FcgammaRIIIA and FcgammaRIIIB genes in the susceptibility to systemic lupus erythematosus, the prototype systemic autoimmune disease. A total of 276 Spanish patients (34 male and 242 female) with systemic lupus erythematosus were included in this cross-sectional study. The FcgammaRIIA-131, FcgammaRIIIA-176 and FcgammaRIIIB-NA1/NA2 polymorphisms were investigated in the patient group as well as in 194 ethnically matched controls using polymerase chain reaction-amplification refractory mutation system (PCR-ARMS). Statistical comparisons of genotype frequencies were performed using the chi(2) test. In the case of the FcgammaRIIIB-NA1/NA2 polymorphism, an increase in the frequency of homozygous NA2/NA2 in patients was found (61.2 vs. 51.0%; P = 0.03; OR = 1.5; 95% CI = 1.03-2.24), as well as a decrease in the frequency of the NA1/NA2 genotype (28 vs. 38.7%; P = 0.02; OR = 0.6; 95% CI = 0.41-0.92). These associations were independent of patient gender and HLA-DRB1 specificities. With respect to the FcgammaRIIA-131 and FcgammaRIIIA-176 polymorphisms, no differences were found between patients and controls. Patient stratification according to their lupus-related nephritis status gave similar genotypic distribution patterns in both disease categories in all the cases.