Rheumatology: Current Research
Open Access

Abstract

BAFF Promoter Polymorphisms and Serum levels in Tunisian Patients with Systemic Lupus Erythematosus

Imen Sfar, Tarak Dhaouadi, Sami Turki, Lamia Ben Hassine, Adel Khedher, Narjess Khalfallah, Taieb Ben Abdallah and Yousr Gorgi

Objectives: To investigate any associations between regulatory genetic polymorphisms of the B-lymphocyte activating factor (BAFF) gene, disease susceptibility and serum soluble BAFF (s-BAFF) levels in Tunisian systemic lupus (SLE) patients.

Patients and methods: This case-control study included 124 SLE patients and 152 healthy controls. Three single nucleotide polymorphisms (SNPs) (-2841 T>C, -2701 A>T and -871 C>T) in the 5’ regulatory region of the BAFF gene were explored by PCR-RFLP. Serum BAFF levels were measured by ELISA (R&D Systems®).

Results: s-BAFF levels were elevated in SLE patients (1717.08 pg/ml) and in anti-dsDNA positive antibodies patients (1948.28 pg/ml) compared to both controls (665.82 pg/ml, p<10-8) and patients without anti-dsDNA antibodies (1281.51 pg/ml, p=0.007). In contrast, no correlation was found between global disease activity registered in SLEDAI and s-BAFF levels (p=0.7).

The -2841*C mutated allele was associated to SLE predisposition and anti-dsDNA antibody occurrence, p=0.03 and p=0.021 respectively. Single allele, genotype and haplotype association analyses showed no significant association with s-BAFF values, clinical features or SLEDAI score.

Conclusion: In Tunisian, the rs9514827 (T>C -2841) SNP in the BAFF gene promoter seems to be related to SLE susceptibility and anti-dsDNA antibodies occurrence. Even if serum s-BAFF levels were significantly higher in SLE patients and in anti-dsDNA antibody positive sera, it did not seem to be correlated with disease activity or the occurrence of lupus nephritis. Again, studied genetic markers failed to predict the serum s-BAFF levels as there was no correlation between the two parameters.