ISSN: 2161-1149 (Printed)
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.