Objective: To retrospectively analyze the clinical data of 5 cases of hemophilia A (HA) complicated with recombinant factor Ⅷ (FⅧ) inhibitor formation

so as to guide the treatment of HA. Methods: The clinical characteristics of 5 cases of HA complicated with FⅧ inhibitor formation were retrospectively analyzed

and the mutation of hemophilia-related genes was detected by polymerase chain reaction (PCR) technology and DNA sequencing analysis. Results: All of the 5 patients were male and received gene FⅧ on-demand treatment in other hospitals. Five cases were tested for HA genes in the children and mothers

and all were due to maternal inheritance. The median age at inhibitor discovery was 24 months. Five cases were unwilling to induce immune tolerance therapy after the bleeding was stopped. Case 1 received low-dose emecizumab prophylaxis

case 3 and 4 received on-demand treatment with four-factor prothrombin complex concentrate

case 2 continued standard prophylaxis with third-generation recombinant FⅧ

and case 5 received low-dose prophylaxis with third-generation recombinant FⅧ. The follow-up period was (7.60±1.75) months until Jan. 2021. The inhibitor in 3 children with high titer was still >5 BU/mL

and the inhibitor in 2 children had returned to normal state. Conclusion: Inhibitors may occur in children with severe HA treated with FⅧ

and the production of inhibitor is closely related to both genetic and therapeutic factors. After bleeding events in HA children with inhibitor

the appropriate hemostatic scheme should be selected as far as possible according to the bleeding situation of the child and the specific situation of the family

so as to reduce the risk of disability and death.