Can BAFF promoter polymorphism be a predisposing condition for HCV-related mixed cryoglobulinemia?
To the editor: Mixed cryoglobulinemia (MC) is a benign but prelymphomatous condition whose clinical manifestations are secondary to systemic immune complex–related vasculitis, which is the final step in a complex process initiated by unregulated B-cell expansion. MC is strongly associated with hepatitis C virus (HCV) infection.1 In fact, a majority of MC patients (> 90%) exhibit HCV markers, and approximately 50% of HCV patients exhibit a wide range of MC markers/symptoms, varying from asymptomatic serum cryoglobulins to MC syndrome (MCS), symptoms of which include weakness, arthralgias, and purpura.2 Several mechanisms involved in the pathogenesis of HCV-related MC have been proposed, but the reasons why cryoglobulins appear in only half of all HCV patients are still unclear. Suggested key determinants include host genetic background or viral factors. B cell–activating factor (BAFF, or B-lymphocyte stimulator) is a recently discovered TNF- family member whose essential role in B-lymph
