TNF and arthropathy: Indeed, we found significant associations between circulating levels of TNF-α and multiple clinical parameters of HA, including the number of hemarthroses, the grade of synovial hypertrophy, and the clinical WFH score and US score, which altogether suggest a role for TNF-α in the progression of blood-induced arthropathy and its possible suitability in the future as a biomarker of disease severity that could potentially be used to identify patients with progressing joint disease.