Relationship between mutations in severe hemophilia A and risk of inhibitor development: A large single-center study

Background: One of the major problems for patients with severe hemophilia A (HA) is the development of neutralizing antibodies against factor VIII. This study aimed to analyze the molecular and clinical profiles of patients with severe HA and to determine if certain genetic variants predispose to inhibitor development in these patients. Methods: A single-center study was conducted among patients with severe HA between March 20, 2000, and June 31, 2023. Demographic data and laboratory results of patients were collected. The inverse-shifting PCR (IS-PCR) technique was initially used to screen patients for intron 22 and 1 inversions (Inv-22 and Inv-1). Results: A total of 480 patients with severe HA (408 without inhibitors and 72 with inhibitors) were enrolled in this study. The median age of the patients at the time of diagnosis was 6 months (IQR: 3 months to 18 months). Inv-22 was observed in 199 (41.5 %) of the cases. Among those patients who developed inhibitors, 53 (73.6 %) were classified as high-titer and 19 (26.4 %) as low-titer. Inv-22, positive family history of inhibitor formation, and history of intense injections revealed a statistically significant association with the risk of inhibitor development. Conclusion: The results of this study confirm the important role of different genetic variants, family history of inhibitor formation, and history of intense injections for the formation of inhibitors in patients with severe HA. This would allow us to stratify the patients which can have important clinical implications, especially in terms of their management and outcome.