EIF2AK3 and cryoglobulinemia: The nature of this cell population was extensively studied also in the context of HCV related cryoglobulinemia; in both HCV related cryoglobulinemia and CVID, an anergic subset of CD21low/- B cells appears expanded and characterized by high constitutive expression of extracellular signal regulated kinase (pERK) (79–81).