Immunoglobulin GM and KM genotypes in Korean patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune complex deposition. We genotyped immunoglobulin allotypes of G1M (f,z), G2M (n+,n-), G3M (b,g) and KM (1,3) in 142 Korean patients with SLE and 200 healthy controls to investigate the role of the allotypes in SLE. The allele frequency of G1M (z) was significantly higher in patients with SLE as compared to the healthy controls (94.6% vs. 84.3%, corrected P = 0.0004, OR 3.30, 95% CI 1.71-6.88). The frequency of G2M (n-) allele was also higher in patients with SLE (95.3% vs. 88.3%, corrected P = 0.008, OR = 2.71, 95% CI 1.38-5.72). Distribution of the tested allele frequencies for G3M and KM were not different between the patients and controls. In the respect of antibody production, there was increased genotype frequency of G1M (z/z) in anti-Sm(-) SLE (P = 0.023 vs. control, P = 0.042 vs. anti-Sm (+) SLE). In conclusion, particular genotypes at G1M (f,z) and G2M (n+,n-) loci are significantly associated with SLE. These immunoglobulin genes may contribute to the etiology of SLE and production of autoantibodies.