The biallelic variable number of tandem repeats of the tumor necrosis factor receptor 2 promoter in systemic lupus erythematosus

Abstract

The objective of this study was to investigate whether the variable number of tandem repeats (VNTR) of the tumor necrosis factor receptor 2 (TNFR2) promoter is associated with susceptibility to systemic lupus erythematosus (SLE) and its clinical phenotypes. A biallelic VNTR within a 42-bp region in the TNFR2 gene promoter was determined by polymerase chain reaction in 88 SLE patients and 95 healthy control subjects. Clinical manifestations were analyzed in each patient and correlated with the genotypes. When the TNFR2 promoter VNTR was compared between Korean and Caucasian healthy controls with respect to allele frequencies, there was a significant difference (alleles 1 and 2: 39, 151 in Koreans vs 60, 138 in Caucasians, respectively; chi-squared test 4.38; 2 df; P=0.036). The genotype distribution of the TNFR2 promoter VNTR did not differ between SLE patients and control subjects (1.1, 1.2, and 2.2 genotypes 7, 14, 67 vs 5, 29, and 61 controls, respectively; chi-squared test 5.19; 2 df; P=0.061). According to the TNFR2 promoter genotypes in the lupus patients, clinically there was no significant difference in age at onset, anti-dsDNA titer, C4 level, systemic lupus erythematosus disease activity index (SLEDAI), Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index, or autoantibodies. However, the 1.1 genotype group showed the lowest C3 level and more frequent renal involvement than the 1.2 and 2.2 genotype groups. In conclusion, an ethnic difference in the TNFR2 promoter VNTR has been found and the biallelic VNTR of the TNFR2 promoter may be associated with clinical phenotypes in SLE.