Polymorphism of β2-glycoprotein I at codons 306 and 316 in patients with systemic lupus erythematosus and antiphospholipid syndrome

TLDR: The prevalence of mutations in the fifth domain of β2GPI in patients with SLE and/or APS were similar to those previously reported for the general population, and Heterozygosity for either mutation does not influence the incidence of aPL, but in patientsWith SLE, the mutation at exon 8 may predispose to thrombosis as an independent factor.

Abstract: Objective To determine the frequency of mutations in the phospholipid binding domain of β2-glycoprotein I (β2GPI) in patients with systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS), and to analyze the clinical correlations of such mutations with thromboembolic complications. Methods Exons 7 and 8 of β2GPI, which encode for its fifth domain, were amplified by polymerase chain reaction, and the presence of mutations was determined by restriction digestion and single-strand conformation polymorphism analysis. A clinical correlation with these mutations and the presence of antiphospholipid antibodies (aPL), lupus anticoagulant (LAC), anti-β2GPI antibody, and the development of thromboembolic complications was performed using chi-square and Fisher's exact tests. Results From a total of 143 patients studied, we found that 5.6% were heterozygous for the mutation at exon 7 (codon 306), and 7.7% were heterozygous for the mutation at exon 8 (codon 316). No homozygous subjects were found for either mutation. No significant correlation between these mutations and the presence of aPL, LAC, or anti-β2GPI antibodies was found. In patients with SLE (n = 95), 4 of 6 patients with exon 8 mutation had thrombosis, compared with 22 of 82 patients without the mutation (P = 0.043). Conclusion The prevalence of mutations in the fifth domain of β2GPI in these patients with SLE and/or APS were similar to those previously reported for the general population. Heterozygosity for either mutation does not influence the incidence of aPL, but in patients with SLE, the mutation at exon 8 may predispose to thrombosis as an independent factor.