Complement BF variability did not influence the development of RA in the studied patients, but BF variants may act as markers of disease prognosis, such as development of EAMs, corroborating with the role of the alternative pathway in the pathogenesis of RA.
We did not find significant differences in Bf and C4 allotype frequencies in RA patients subdivided according to severity of the disease into a mild group and a progressive group.
This finding suggests that auto-antibody-defined subgroups of RA may be genetically heterogeneous with respect to Bf and confirms the status of Bf SS phenotype as a marker for RA susceptibility and/or severity.
The frequencies of Bf*S in DR4 positive and DR4 negative RA were similar so that the findings were not accounted for by linkage disequilibrium between DR4 and Bf*S.