Inhibitor development in patients with congenital factor VII deficiency, a study on 50 Iranian patients.

: Congenital factor VII (FVII) deficiency is a rare bleeding disorder with an estimated prevalence of 1 per 500 000 in the general population. On-demand replacement therapy is the main therapeutic choice in patients with congenital FVII deficiency. Inhibitor formation against exogenous FVII is very rare and can cause challenges in the management of the disorder. The present study was conducted to assess the prevalence of FVII inhibitor in 50 patients with congenital FVII deficiency under on-demand or prophylaxis treatment by recombinant activated FVII. All patients with confirmed congenital FVII deficiency were assessed for inhibitor development in regular intervals. Inhibitor titer was determined by a modified Nijmegen-Bethesda assay. The study results were analyzed by SPSS software. Among all cases, two patients (4%) developed an FVII inhibitor. Case 1 was a 14-year-old boy with severe FVII deficiency (FVII activity <1%) with regular prophylaxis. The patient was a high-responder with high-titer FVII inhibitor (170 Bethesda Unit). This patient, who had a history of intracranial hemorrhage, had undergone brain surgery three times. The second patient was a 70-years old man with on-demand therapy that also developed a high-titer inhibitor (10 Bethesda Unit). This patient had experienced easy bruising and endured a few surgeries for his brain tumor and, finally, succumbed to the disease. Although the inhibitor formation is a rare phenomenon, it may result in a significant challenge to manage the affected patients.