Fibronectin gene polymorphisms are associated with the development of B-cell lymphoma in type II mixed cryoglobulinemia

Objective: To analyse fibronectin (FN) gene polymorphisms in type II mixed cryoglobulinemia syndrome (MCsn), an immune-complex mediated systemic vasculitis linked to hepatitis C virus (HCV) infection and characterised by rheumatoid factor (RF) positive B-cell proliferation at high risk for the progression into non-Hodgkin's lymphoma (NHL). Methods: Samples from 74 patients with MCsn (type II serum cryoglobulins and clinical signs of vasculitis) were studied. In all, 58 (78.4%) patients were HCV-positive. In total, 21 (28.4%) patients developed a B-cell NHL during the course of MCsn. A total of 72 patients with HCV-negative and MC-unrelated NHL and 110 healthy blood donors (HBDs) were taken as controls. HaeIIIb and MspI FN gene polymorphisms were analysed by PCR and specific restriction enzyme digestions, following reported procedures. Plasma FN levels were analysed by ELISA, whenever possible. Results: HaeIIIb and MspI allele and genotype frequencies did not differ between MCsn patients and HBDs. Of note, the DD-MspI (OR = 5.99; CI 1.77-20.261, p = 0.0039) and the AA-HaeIIIb (OR = 4.82, CI 1.42-16.39, p = 0.0176) homozygosis appeared significantly associated with the development of B-cell NHL in MCsn patients, with the HaeIIIb A allele possibly conferring an increased risk of NHL in the general population (OR = 1.72, CI 1.128-2.635, p = 0.0133). None of the other MCsn-related clinical manifestations were significantly associated with a particular genetic pattern. No association between FN plasma levels and FN genotypes was found. Conclusion: Genotyping for MspI and HaeIIIb FN gene polymorphisms may be clinically relevant to define the risk of lymphoma development in MCsn.