Polymorphisms in Coagulant and Inflammatory Genes Modify the Phenotype of Severe Hemophilia A and B.

Among patients with severe hemophilia (<1% factor level), 10–15% are known to have a clinically mild phenotype. The basis for this phenomenon is unclear. We hypothesized that functionally significant polymorphisms in the coagulant, inflammatory and immunoregulatory genes may affect the phenotype of severe hemophilia. A total 114 patients with hemophilia A (n=95) and hemophilia B (n=19) were studied. All these patients were on minimal on-demand treatment. Patients were evaluated for the frequency and site of hemorrhage. Their clinical and radiological joint scores were documented. They were categorized as ‘mild’ (<1 affected joint and < 5 bleeds in the preceding year, n=15) or ‘severe’ (>1 affected joint and >5bleeds, n=99). Functional polymorphisms in the coagulant system (human platelet alloantigen; tissue factor; fibrinogen; factors II; V; VII; XIIIA; thrombin activable fibrinolysis inhibitor (TAFI); endothelial protein C receptor; endothelial nitric oxide synthase 3; tissue plasminogen activator; plasminogen activator inhibitor; tissue factor pathway inhibitor; protein C and S; thrombomodulin), known procoagulant factors (methylene tetrahydrofolate reductase gene), inflammatory cytokine genes (tumor necrosis factor alpha; transforming growth factor beta; interleukin (IL) 10; IL 6; IL 1beta; IL 1 beta receptor antagonist; tumor necrosis factor beta), immunoregulatory cytokine genes (interferon gamma; HLA B27; FC gamma receptor), MDM2, angiotensin converting enzyme and HFE genes were genotyped. The mean age in the two groups was 18.5 & 14.85, p=0.124. The clinical features showing significant difference are shown in the table. Of the polymorphisms studied, the FVII RQ/QQ (lower levels) (RR-3.99, p=0.022, 95% CI 1.2–13.4), TNF alpha-308AA/AG (pro-inflammatory) (RR-3.4, p=0.037, 95% CI, 1.07–10.7), TGF beta Codon 10 CC/CT (pro-inflammatory) (RR-2.8, p=0.07, 95% CI, 0.91–8.3), have been associated with a severe phenotype while MDM2GG (anti-inflammatory, RR-0.3, p=0.038, 95% CI, 0.1–0.93) was associated with a milder phenotype. We hypothesize that the bleeding frequency in severe hemophilia may be increased due to relatively lower FVII levels and a combination of cytokine driven pro-inflammatory state involving TNF alpha, TGF beta and MDM2 would cause destruction of the cartilage resulting in elaboration of metalloproteinases from chondrocytes leading to the development of arthropathy.