Co-inheritance of mild hemophilia A and heterozygosity for type 2N von Willebrand disease: a diagnostic and therapeutic challenge

Von Willebrand disease type 2N: An update

Quantitative or qualitative defects of von Willebrand factor (VWF) are responsible for the most common inherited bleeding disorder, von Willebrand disease (VWD). Type 2N VWD is an uncommon recessive disorder that results from gene mutations located in the region coding for the binding site of VWF for factor VIII (FVIII). This narrative review describes the pathophysiology, diagnostic procedures and treatment as well as the molecular biology of type 2N VWD. Although other VWF-dependent functions like binding to platelets and collagen are preserved, FVIII plasma levels are low due to the rapid clearance of this moiety in the absence or reduction of its binding to VWF. The diagnosis of type 2N should be considered in patients with low FVIII coagulant activity (FVIII:C) and disproportionally higher VWF antigen, especially when they present with an autosomal recessive pattern of inheritance. Because an accurate diagnosis is essential for genetic counseling and optimal treatment, type 2N must be distinguished from mild/moderate hemophilia A and its carrier state. This differential diagnosis can be obtained by using the laboratory assay of the FVIII binding capacity of VWF (VWF:FVIIIB) or analysis of the FVIII binding site on the VWF gene.

Are Iranian patients with von Willebrand disease type 2N properly differentiated from hemophilia A and do they receive appropriate treatment?

: The defect function of the von Willebrand factor (VWF) in carrying factor VIII (FVIII) leads to von Willebrand disease type 2N (VWD 2N) which could be easily misdiagnosed as hemophilia A. Differentiating of VWD 2N from hemophilia A is crucial for patient treatment and genetic counseling. As a retrospective study, we aimed to evaluate the current diagnostic work-up of Iranian patients with mild/moderate deficiency of FVIII levels and the possibility of misdiagnosis of VWD 2N as hemophilia A. All patients who referred to the reference coagulation laboratory at the Iranian Blood Transfusion Organization in a 10-months period for bleeding diathesis work-up with the request of FVIII activity level were included. Clinical and laboratory phenotypes including International Society on Thrombosis and Hemostasis - Bleeding Assessment Tool, FVIII activity, VWF antigen, VWF ristocetin cofactor, and FVIII binding capacity of VWF were assessed on suspected cases for VWD 2N. In total, the results of 896 patients for investigation of VWD 2N were evaluated and five new patients were identified within unrelated families with abnormal VWF:FVIIIB levels. Four were heterozygous for VWD 2N and one homozygous whom all were misdiagnosed as hemophilia A and underwent inappropriate treatments. The median bleeding score of the VWD 2N population was nine (4-13). In Iran, probably a significant number of VWD 2N patients are misdiagnosed as hemophilia A due to insufficient test panel for subtyping of von Willebrand disease. This study also emphasized the need for inclusion of the VWF:FVIIIB in suspected hemophilia A to achieve an optimal treatment strategy.

Haemostatic patterns and bleeding scores of a genetically characterised Italian family with combined haemophilia A and type 1 von Willebrand disease

: We report on the coinheritance of mild haemophilia A and type 1 von Willebrand disease (VWD) in a genetically characterized Italian family. The proband is a 56-year-old man carrying both the c.2167G>A mutation in the factor VIII (FVIII) gene (responsible for p.A723T substitution) and the c.4751A>G mutation (p.Y1584C) in the von Willebrand factor (VWF) gene. His FVIII and VWF levels were 9.8 and 43.2 IU/dl, respectively. His bleeding symptoms included mucocutaneous bleeding, haemarthrosis, and muscle haematomas. Using the bleeding assessment tool, a questionnaire currently employed in diagnosing VWD, the patient had a bleeding score of 27 as compared with the 10.2 ± 3.4 found in patients with mild-to-moderate haemophilia A, and 0-3 in normal men. One of the proband's two daughters (both obligate carriers of haemophilia A) also harboured the VWF p.Y1584C mutation. Her FVIII and VWF levels were 45.9 and 54 IU/dl, respectively, and her bleeding score was slightly higher than normal for women (6 vs. 0-5). The other daughter had a normal bleeding score, and so did the proband's father (with type 1 VWD) and mother (haemophilia A carrier). Discrepancies between haemostatic patterns and bleeding symptoms in cases of haemophilia A, as seen in our patient, suggest the need to search for other coagulation defects, especially involving VWF, which is the carrier of FVIII. Although the presence of a VWF mutation significantly exacerbates the haemorrhagic complications in patients with mild haemophilia A, it has only mild effects on haemophilia A carriers.

Life-threatening bleeding in a patient with mild hemophilia A and heterozygosity for von Willebrand disease Type 2N

Hemophilia A and von Willebrand disease (VWD) are distinct bleeding disorders with a spectrum of clinical phenotypes. They are characterized by mutations in either factor VIII (F8) or von Willebrand factor (VWF) genes, respectively. The pattern of inheritance and appropriate laboratory evaluation differentiates these diseases, and treatment strategies for both are different. Here, we report a male patient with hemophilia A and VWD Type 2 Normandy (N) mutations who presented with life-threatening bleeding. We document his medical history, clinical course, management, and diagnostic work up.