Polymorphisms of the interleukin-4 gene in Chinese patients with systemic lupus erythematosus in Taiwan

We aimed to evaluate the relationship between two polymorphisms of the IL4 gene (-590T/C and intron 3) and systemic lupus erythematosus in Chinese patients in Taiwan. This study included 91 patients with systemic lupus erythematosus (SLE) and 163 unrelated, age matched healthy controls living in the same area. The typing of -590T/C and intron 3 VNTR (variable number of tandem repeats) polymorphisms were performed by PCR-RFLP and PCR, respectively. Allelic frequencies and carriage rates between SLE patients and controls were compared, and the relationship between allelic frequencies and clinical manifestations of SLE was evaluated. The genotype frequencies of IL-4 intron 3 were found to differ significantly between SLE patients with and without discoid rash (chi-square test, P = 0.035). The allelic frequency of intron 3 RP 1 was significant different in the patients with discoid rash when compared to patients without this clinical feature (OR = 3.70, 95% CI 2.04-6.72, chi(2) test, P = 0.029). The RP1/RP1 homozygous carriage was significantly associated with patients with discoid rash when compared to patients without this clinical feature (OR= 6.04, 95% CI 2.81-12.95, P=0.01). The allelic frequency of -590T was significant different in the patients with discoid rash when compared to patients without this clinical feature (OR = 3.44, 95% CI 1.88-6.31, chi-square test, P=0.04). The T/T homozygous carriage was significantly associated with patients with discoid rash when compared to patients without this clinical feature (OR=5.41, 95% CI 2.50-11.68, P=0.02). We describe a novel association between RP1/RP1 and T/T homozygous carriage and patients with discoid rash. The role of the intron 3 polymorphism of the IL4 gene in SLE remains unclear and further substantiation based on larger patient samples is needed.