Mild HA (FVIII 5%–40%) is characterized by increased bleeds mainly during surgery or after trauma, whereas severe HA (FVIII < 1%) is characterized by both spontaneous and provoked bleeds.1 Moderate HA (1%–5%) has a wide phenotype, depending on the residual FVIII activity.1 Bleeds occur mainly in joints, although they may also occur in vital organs.1 Consequently, joint bleeds lead to arthropathy and worsen quality of life.1 The gene discussed is F8; the disease is arthropathy.