TNF-α-308 promoter G/A and PTPN22 (1858 C/T) genes polymorphisms in Egyptian patients with systemic lupus erythematosus

Abstract

Tumor necrosis factor alpha (TNF-α) promoter gene polymorphism at position 308 and that of the protein tyrosine phosphatase nonreceptor type 22 (PTPN22) at position 1858 C/T have been inconsistently implicated as genetic risk factors for systemic lupus erythematosus (SLE) in some populations. We investigated the possible association of these polymorphisms with SLE susceptibility, and whether serum TNF-α level is related to different genotypes and disease activity in Egyptian SLE patients. TNF-α-308 G/A and PTPN22 C1858T polymorphisms were determined by PCR-restriction fragment length polymorphism analysis in 40 SLE patients and 40 unrelated healthy controls. Serum TNF-α level was measured by ELISA method. The median serum TNF-α was significantly higher in SLE patients than in controls (P < 0.001). A significant positive correlation was detected between serum TNF-α and SLE activity index (r = 0.723, P < 0.001). There was no significant difference in TNF-α-308 G/A genotypes or allele frequency between SLE cases and controls (P = 0.108 and P = 0.133, respectively). Diabetes was the only clinical feature in SLE patients that showed significant higher frequency with GA genotype than with GG genotype (P = 0.001). Risk estimation for the TNF-α-308 genotypes was of no significant (odds ratio = 2.429; 95 % CI = 0.8–7.2; P = 0.108). Concerning PTPN22 1858 C/T, there was no significant difference in PTPN22 C/T genotypes or allele frequency between SLE cases and controls (P = 0.152 and P = 0.155, respectively). TNF-α-308 G/A and PTPN22 (1858 C/T) polymorphisms do not exhibit a significant influence on the susceptibility of SLE in Egyptian patients. However, serum TNF-α level could be a sensitive marker of SLE disease activity.