von Willebrand's disease: a report from a meeting in the Åland islands

von Willebrand factor neutralizing and non-neutralizing alloantibodies in 213 subjects with type 3 von Willebrand disease enrolled in 3WINTERS-IPS

BACKGROUND

Type 3 von Willebrand disease (VWD) is the most severe form of this disease owing to the almost complete deficiency of von Willebrand factor (VWF). Replacement therapy with plasma-derived products containing VWF or recombinant VWF rarely cause the development of alloantibodies against VWF that may be accompanied by anaphylactic reactions.

OBJECTIVE

The objective of this study was to assess the prevalence of anti-VWF alloantibodies in subjects with type 3 VWD enrolled in the 3WINTERS-IPS.

METHODS

An indirect in-house enzyme-linked immunosorbent assay has been used to test all the alloantibodies against VWF. Neutralizing antibodies (inhibitors) have been tested with a Bethesda-based method by using a VWF collagen binding (VWF:CB) assay. Samples positive for anti-VWF antibodies were further tested with Bethesda-based methods by using the semiautomated gain-of-function glycoprotein-Ib binding (VWF:GPIbM) and a VWF antigen (VWF:Ag) enzyme-linked immunosorbent assay.

RESULTS

In total, 18 of the 213 (8.4%) subjects tested positive for anti-VWF antibodies and 13 of 213 (6%) had VWF:CB inhibitors. These 13 were among the 18 with anti-VWF antibodies. Of the 5 without VWF:CB inhibitors, 3 had non-neutralizing antibodies, 1 only inhibitor against VWF:GPIbM, and one could not be tested further. Ten of the 13 subjects with VWF:CB inhibitors also had VWF:GPIbM inhibitors, 6 of whom also had VWF:Ag inhibitors. Subjects with inhibitors were homozygous for VWF null alleles (11/14), homozygous for a missense variant (1/14), or partially characterized (2/14).

CONCLUSIONS

Anti-VWF antibodies were found in 8.4% of subjects with type 3 VWD, whereas neutralizing VWF inhibitors were found in 6%, mainly in subjects homozygous for VWF null alleles. Because inhibitors may be directed toward different VWF epitopes, their detection is dependent on the assay used.

Gynaecological issues in women with bleeding disorders: CSL Behring Symposium

The symposium focused on issues around surgery, ovulation bleeding, health-related quality of life (HRQoL) and pelvic pain in women with bleeding disorders.

Surgery

Young women with congenital bleeding disorders, especially those with severe forms, are more likely to experience gynaecological and obstetric disorders than unaffected women. Surgery may be required to manage heavy menstrual bleeding (HMB), ovulatory bleeding, endometriosis and delivery. Major surgery should be undertaken only in hospitals with a haemophilia centre and 24-hour laboratory capability. Correction of haemostasis, either by desmopressin, coagulation factor or platelet transfusion, is essential for a successful outcome of surgery. Management of pregnancy requires a multidisciplinary approach; the mode of delivery is based on the consensus of gynaecologist and haematologist, and with respect to the patient’s diagnosis.

Ovulation bleeding

Women with bleeding disorders are at risk for excessive gynaecological bleeding associated with menstruation, ovulation, pregnancy and delivery. Ovulation bleeding is associated with the rupture of ovarian cysts and causes abdominal pain; complications include haemoperitoneum, fertility problems and ovarian torsion. Management includes hormonal and haemostatic therapies, in combination if necessary, and surgery as a last resort. Current management is based on experience in a relatively small number of cases and more clinical data are needed.

Health-related quality of life

In addition to experiencing joint and tissue bleeds, women experience psychosocial and medical issues associated with menstruation, pregnancy, labour and delivery. HMB has the greatest impact, and is associated with impaired HRQoL in almost all and dissatisfaction with the burden of treatment. There is a need for focused psychosocial support and a specific tool for the assessment of HRQoL in women with bleeding disorders.

Pelvic pain

Gynaecological causes of pelvic pain in women with bleeding disorders include dysmenorrhoea, mid-cycle pain, bleeding into the corpus luteum and endometriosis. There is no correlation between bleeding tendency and endometriosis severity; however, screening for a bleeding disorder should be considered. Pharmacological management may be hormonal or non-hormonal. Gonadotrophin-releasing hormone agonists offer an alternative to surgery for women with severe bleeding disorders who have endometriosis. Paracetamol is the preferred early analgesic option. Endometrial ablation controls heavy bleeding and pelvic pain but is not recommended for women with large fibroids or a large endometrial cavity. Hysterectomy is an option of last resort. Education for health professionals should include raising awareness about the management of pain in women with bleeding disorders.

Use of a Pediatric Bleeding Questionnaire in the Screening of Von Willebrand Disease in Young Females at Menarche in the Primary Care Setting

Von Willebrand disease (VWD), the most common inherited bleeding disorder, is caused by deficiency or dysfunction in von Willebrand factor. Assessment of hemorrhagic symptoms is essential for early diagnosis, although bleeding histories are taken in a nonstandardized manner. Validated bleeding assessment tools provide objectivity in evaluating bleeding patterns of females at menarche and may improve provider confidence in screening for VWD. Utilizing a pretest/posttest design, in this project we implemented and evaluated the use of a pediatric bleeding questionnaire in eight pediatric primary care clinics for 3 months. Results indicate improved provider knowledge, confidence, and skills after implementation. The importance and quality of the tool were rated highly by the providers, while the ease of use was rated low. Providers were satisfied with the practice change and believed that it improved their clinical abilities. The use of this tool can improve VWD screening in this practice setting.

[Von Willebrand disease. Molecular biology and diagnosis]

BACKGROUND

Von Willebrand disease is the most common inherited disorder of the coagulation proteins in humans. There are three types: 1, 2A, 2B, 2N, 2M and 3. It is associated with mutations on chromosome 12 in the region p13.2, encoding the von Willebrand factor (VWF), which is synthesized in endothelial cells and megakaryocytes.

DISCUSSION

The VWF gene has been characterised using molecular biology techniques, which have acquired an important role in diagnosis von Willebrand disease, as well as in the investigation of alterations in other genes, which may be involved in regulating the synthesis, processing, and secretion of VWF. However, there are still no strategies to integrate the molecular biology diagnostic tests available. Analysis of VWF multimers is a methodology that meets the characteristics for diagnosis, but it is not easy to standardise. Considering that even in tertiary centres in our country, von Willebrand patients do not have a definitive diagnosis, it is necessary to implement these methodologies to study and improve diagnosis.

CONCLUSIONS

Von Willebrand disease is highly heterogeneous due to the molecular mechanisms that produce the various clinical and laboratory phenotypes. In Mexico there are few studies related to this disease; therefore it is essential to conduct a comprehensive study including clinical, basic, and special testing laboratory tests, in order to establish a correct diagnosis, develop new therapeutic approaches, and offer the appropriate medical care and genetic counselling.

Utility of a Paediatric Bleeding Questionnaire as a screening tool for von Willebrand disease in apparently healthy children

von Willebrand disease (VWD), an inherited bleeding disorder caused by deficiency or dysfunction of von Willebrand factor (VWF) is diagnosed when a personal and often a family history of excessive mucocutaneous bleeding is present along with abnormal laboratory studies. An accurate assessment of haemorrhagic symptoms is key in suspecting VWD but presents a challenge especially in children due to overlap between normal and abnormal bleeding. Bleeding questionnaire (BQ) scores have been validated in adults and have recently been validated in children with VWD for assessing bleeding severity. However, there are limited data supporting their use prospectively in healthy children with bleeding complaints.

AIM

The objectives of this study were to obtain normative data from children and validate a paediatric BQ (PBQ) to determine the discriminative ability of its total score and its individual components for identifying children likely to have VWD.

METHODS

The PBQ was administered to 1281 multiethnic, healthy children between 30 days and 18 years of age presenting to a general paediatric office and to 35 children with VWD based on VWF antigen, activity and multimer pattern.

RESULTS

When children with total BQ scores of 3 or more were predicted to have VWD, the sensitivity was 97.2%, the specificity was 97.1%, the positive predictive value was 48.6% and the negative predictive value was 99.9%.

CONCLUSIONS

The PBQ may help discriminate a significant bleeding history from trivial bleeding, may be integrated into the primary care algorithm for evaluating children suspected with VWD.

Third Åland islands conference on von Willebrand disease, 26-28 September 2012: meeting report

The first meeting of international specialists in the field of von Willebrand disease (VWD) was held in the Åland islands in 1998 where Erik von Willebrand had first observed a bleeding disorder in some members of a family from Föglö and a summary of the meeting was published in 1999. The second meeting was held in 2010 and a report of the meeting was published in 2012. Topics covered included progress in understanding of VWD over the last 50 years; multimers; classification of VWD; pharmacokinetics and laboratory assays; genetics; treating the paediatric patient; prophylaxis; geriatrics; gene therapy and treatment guidelines. This third meeting held over 3 days covered the structure and function of von Willebrand factor (VWF); type 1 VWD, the most common form of the disease; a lifespan of pharmacokinetics in VWD; detecting inhibitors in VWD patients; and special challenges in understanding and treating the female VWD patient.

Alloantibodies in von Willebrand disease

The development of alloantibodies against von Willebrand factor (VWF) represents a rare but serious complication of treatment of von Willebrand disease (VWD), occurring in ~5% to 10% of type 3 VWD patients. Affected patients can present with a range of symptoms, including lack or loss of hemostatic response to infused VWF concentrates up to anaphylactic reactions in rare cases. It is classically reported in multitransfused patients and occurs most frequently in patients with partial or complete VWF gene deletions. A positive family history of anti-VWF antibodies also appears to be a risk factor. There is a lack of standardization of laboratory methods for antibody identification and characterization. Issues of variability in laboratory approaches as well as the rarity of the complication act as a barrier to future studies. Recombinant factor VIII as well as bypassing agents and immune tolerance have been reported as effective treatments; however, aside from case reports, little exists in the literature to guide management. The imminent clinical availability of recombinant VWF has prompted a resurgence of interest in this area. Additional study is warranted to address the deficiencies in our understanding of this treatment complication.