Regular Prophylactic Treatment with Factor IX P® in a Patient with Severe Factor X Deficiency.

Background: Congenital factor X deficiency, a rare coagulation disorder with variable severity, is an inherited autosomal recessive disorder. The incidence of homozygous factor X deficiency is ~ 1 in 1 million of the general population. The gene encoding for factor X is found adjacent to that encoding for factor VII on chromosome 13q34. Bleeding sites vary according to the severity of the deficiency. Mucocutaneous soft tissue hemorrhages, including menorrhagia in women, are common. Hemarthros, exsanguinating postoperative hemorrhage, pseudotumors, and hemorrhages of the central nervous system have been reported in severely affected patients. Mildly affected patients experience easy bruising and excessive bleeding after trauma or surgery. Treatment options consist of fresh frozen plasma (FFP), prothrombin complex concentrates (PCC) containing factor X or pasteurized Factor IX P® (ZLB Behring). Disadvantage of FFP is the large infusion volume, potential viral transmission, and no standardized factor X content. These aspects, in addition to the thrombotic risk, also need to be addressed for the PCCs. Factor IX P®, which is virus inactivated, contains almost equal amounts of factor IX (1200 IU) and X (800 IU) and suits therefore well for the treatment of factor X deficiency.

Case report: We report on our experience of prophylactic treatment with Factor IX P® in a 31-year-old male with severe factor X deficiency (< 1%) associated with a homozygous Cys350Phe mutation in exon 8 on chromosome 13. After birth the patient experienced severe mucosal bleedings and haematomas and later on various joint bleedings with consecutive hemophilic arthropathy. Initially he received FFP on demand and later regular prophylaxis with PCC (containing 600 IU factor X) 2 to 3 times a week (~ 20–25 IU/kg/bw), age at onset of prophylaxis ~ 7 years. The patient is positive for HIV, HCV, and HBV (known since 1984). He is now on regular prophylaxis with Factor IX P® since 7 months. The prophylaxis is given 2 times a week in doses of ~ 20 IU/kg bw. The trough level after 72 hours was 12% using PCC and 20% using Factor IX P®. The patient reported on joint pain when factor X activities were below 20%. The rate of joint pain episodes is lower when using Factor IX P® two times a week as compared to PCC two to three times a week. Orthopedic and dental surgery were performed using Factor IX P® concentrate with excellent hemostatic effect, no thromboembolic complications, and no adverse drug reactions.

In conclusion, prophylactic treatment with Factor IX P® in severe factor X deficient patients appears to be an effective and safe therapeutic option.