Rapid genotypic diagnosis of type 2A von Willebrand's disease by heteroduplex analysis

We have previously reported a rapid heteroduplex-based technique which is able to identify at least 10 recurrent mutations associated with type 2A von Willebrand's disease. Thirteen patients with this disorder were genotyped by this method and a specific mutation was identified in nine cases. This simple DNA based approach can provide useful information to support data derived from phenotype tests in the initial assessment of such patients.     

An Arg545----Cys545 substitution mutation of the von Willebrand factor in type IIB von Willebrand's disease.

Type IIB is a special variant of von Willebrand's disease, characterized by an abnormal von Willebrand factor which shows an increased interaction with platelets. This interaction sometimes causes platelet aggregation and thrombocytopenia in vivo. It involves the glycoprotein-Ib (GPIb) receptor on platelets and corresponding GPIb-binding sites in the von Willebrand factor. We here demonstrate a C----T mutation at codon 1308 of the von Willebrand factor gene in 2 related patients with IIB von Willebrand's disease. The transition gives rise to a substitution of arginine by cysteine at position 545 of the mature von Willebrand factor subunit. This position is close to the GPIb- as well as the collagen- and heparin-binding domains of the von Willebrand factor. The mutation may change the conformation of the molecule in this region and activate the GPIb-binding domain, which is normally not exposed in the von Willebrand factor of circulating blood.     

Epidemiology of AIDS in females with hemophilia and other chronic bleeding disorders in the United States: comparisons with males with chronic bleeding disorders and AIDS and with nonhemophilic female blood-transfusion recipients with AIDS.

From January 1, 1981 through June 30, 1990, 32 females with chronic bleeding disorders were diagnosed with acquired immunodeficiency syndrome (AIDS) in the United States. Most (81.3%) were white and greater than or equal to 30 years of age, with a median age of 37.5 years. Eighteen (56.3%) had von Willebrand's disease. Pneumocystis carinii pneumonia was reported for 16 (50%). None had Kaposi sarcoma. The median survival time was 10.8 months, with a cumulative probability of survival at 1 year of 47.3% and at 2 years of 27.6%. We compared the demographic data and survival times of these females with those of males with a chronic bleeding disorder and AIDS, and with those of nonhemophilic females with AIDS whose exposure to the human immunodeficiency virus (HIV) was through receipt of blood transfusions, blood components, or tissue. The principal demographic difference was age distribution. The females with chronic bleeding disorders tended to be younger than the transfused, nonhemophilic females, but older than the males. The survival time from AIDS diagnosis to death for the females with chronic bleeding disorders did not differ statistically from that of the other two groups, although older nonhemophilic females whose exposure was transfusion may progress more rapidly to AIDS.     

von Willebrand disease type 2B must be always considered in the differential diagnosis of genetic thrombocytopenias with giant platelets

Type 2B von Willebrand's disease (VWD) is an inherited bleeding disorder characterized by spontaneous binding of large von Willebrand factor (VWF) multimers to platelets in vivo. This phenomenon induces the clearance of both large multimers and platelets, usually resulting in thrombocytopenia with slightly increased platelet size. We describe a newborn with a VWD type 2B due to the heterozygous missense mutation V1316M who presented the atypical feature of giant platelets in peripheral blood. Based on this observation and literature review, we suggest that the diagnosis of VWD 2B should be always considered in patients with chronic thrombocytopenia and giant platelets.     

von Willebrand's disease and menorrhagia: prevalence, diagnosis, and management

The reported prevalence of von Willebrand's disease (vWD) is increased in women with menorrhagia, with current estimates ranging from 5% to 20%. The consistent results of multiple studies suggest testing should be included in the evaluation of patients with menorrhagia, especially in unexplained cases and prior to surgical intervention. Although a cyclic variation in von Willebrand's factor levels has not been confirmed, several studies suggest lower levels during menses and the early follicular phase. Menorrhagia is one of the most common bleeding manifestations of von Willebrand's disease, reported by 60-95% of women afflicted with this bleeding disorder. Menorrhagia is typically severe, often resulting in anemia and interfering with quality of life. Despite the frequency of menorrhagia, there is no consensus on optimal management. Although oral contraceptives are frequently prescribed, there are no studies confirming their efficacy using objective measures of response. Desmopressin was associated with an 80-92% response rate in several uncontrolled studies relying on patient assessment of efficacy. However, a small, randomized trial found no significant reduction in menstrual blood flow compared with placebo. There are anecdotal reports of the successful use of antifibrinolytic agents alone and in combination with other therapies. There are no studies comparing the relative efficacy and safety of the available medical therapies for von Willebrand's disease associated menorrhagia. Until these studies are completed, treatment should be individualized based on von Willebrand's disease subtype, patient age, contraceptive needs, and personal preference.     

No inhibitor development after continuous infusion of factor concentrates in subjects with bleeding disorders undergoing surgery: a prospective study

Inhibitor development against von Willebrand factor, factor VIII or factor IX is one of the most severe complications of treating patients with von Willebrand's disease (VWD), haemophilia A or haemophilia B respectively. Continuous infusion of factor concentrate has been implicated as a risk factor for inhibitor development. This prospective study investigated inhibitor development after continuous infusion of factor concentrate for surgical procedures in subjects with VWD or a severe form of haemophilia (factor activity <1%). Observations were made on the occurrence of inhibitor formation, adverse events and virus seroconversions. Main inclusion criteria comprised a negative history of inhibitors to replacement factor concentrate, ≥50 exposure days to factor concentrate and anticipated surgery requiring replacement factor coverage for ≥3 days. Therapy began with a bolus dose of 30–50 IU kg^?1 body weight of factor concentrate followed by continuous infusion with 3–4 IU kg^?1 h^?1. Continuous infusion dose of factor concentrate was adjusted based on factor levels measured at least once daily. In 46 subjects included in the study to date, no inhibitors have been identified at discharge or follow‐up (3–4 weeks after surgery), and no thrombotic events or postoperative wound infections occurred. All subjects underwent surgery without major blood loss, and hemostatic efficacy was generally rated ‘excellent’. The results of the current study are promising, although the number of subjects is too small to make a definitive statement about the incidence of inhibitor development during continuous infusion of factor concentrate. Therefore, this study will be continued.     

Chronic arthropathy in von Willebrand's disease

Summary In von Willebrand's disease, chronic arthropathy is thought to be rare. We present four young patients, three girls and a boy, with severe von Willebrand's disease, who developed chronic progressive arthropathy due to joint haemorrhage, similar to that seen in haemophilia. Chronic joint disease is not as uncommon as is generally assumed.     

Two new candidate mutations in type IIA von Willebrand's disease (ARG834→GLY,GLY846→ARG) and one polymorphism (TYR821→CYS) in the A2 region of the von Willebrand factor

Abstract: Recently, several von Willebrand factor gene mutations resulting in type IIA von Willebrand's disease have been reported. We examined 8 patients from Sweden and Denmark with this phenotype and found two new candidate mutations and a hitherto unknown amino acid polymorphism. One patient had a de novo occurring mutation resulting in substitution of glycine for arginine 834. Previous reports have demonstrated conversion of arginine 834 to tryptophan or glutamine in IIA patients. A 2nd patient had a G(4825)→A transition, substituting arginine for glycine 846. The transition produces a sequence congruent with that of the pseudogene but several lines of evidence indicate that a sequencing error due to influence by the latter could be excluded. The remaining 6 patients had one of the earlier described substitution mutations: Ser743→Leu and Ile865→Thr. In addition, two sequence variations not linked to the phenotype were found, namely Tyr821→Cys and Val802→Leu.     

Hydroxyethyl starch induced acquired von Willebrand's disease

Hydroxyethyl starch (HES) (Hespan, DPont) is a widely used synthetic volume expander which in standard doses of up to 1.51 in 24 h has no significant effect on coagulation (Munsch et al. 1988). However, the data sheet states that in large volumes HES may alter the coagulation mechanism. We now report a case of HES induced acquired von Willebrand's disease (vWD) in which severe bleeding occurred.     

Platelet – von Willebrand factor interactions in Type IIB von Willebrand's disease

Type IIB von Willebrand's disease (vWD) is a distinct form of this disorder in which the largest multimers of the von Willebrand factor (vWF) are lacking in plasma but present in platelets. When the vasopressin analogue, l-deamino-8-D-arginine vasopressin (DDAVP), is given to patients with type IIB vWD, an abnormal vWF is released to plasma. This vWF causes thrombocytopenia in vivo and platelet aggregation in vitro. Aggregation occurs in the plasma milieu and thus at physiological fibrinogen concentration. In this study we demonstrate that IIB post-DDAVP vWF aggregated only metabolically active platelets. The platelet aggregation was completely inhibited by EDTA and PGE₁, and either inhibited or greatly weakened by ASA, demonstrating the role of divalent cations and thromboxane A₂ formation. In spite of inhibiting platelet aggregation, EDTA, PGE₁ and ASA did not prevent platelet binding of IIB post-DDAVP vWF. An antiserum against GP Ib made normal platelets less responsive to the IIB vWF although neither platelet aggregation nor vWF binding were completely prevented. The aggregation was fibrinogen-dependent and platelets from patients with Glanzmann's thrombasthenia were unresponsive. The studies provide evidence that IIB post-DDAVP vWF is bound to unstimulated platelets and that the interaction between vWF and platelets in type IIB vWD is different from ristocetin-induced as well as thrombin- and epinephrine-induced binding to platelets of normal vWF.     

Desmopressin in treatment of haematological disorders and in prevention of surgical bleeding

Stimulation with the vasopressin analogue desmopressin (DDAVP) of extrarenal arginine vasopressin (AVP) V2-receptors in endothelial cells and possible in platelets increases the circulating levels of coagulation factor VIII (FVIII), von Willebrand factor (VWF) and tissue plasminogen activator (t-PA). The purpose of this paper is to provide an updated review of current information on the efficacy and safety of DDAVP in the treatment of haemophilia, von Willebrand disease (VWD), uremia, liver cirrhosis, and in congenital or drug-induced platelet dysfunction — under surgical or non-surgical conditions. In summary, desmopressin is an effective haemostatic drug that when administered i.v., s.c. or intranasally increases plasma levels of FVIII and VWF 2–6 times and improves platelet function. It has a proven haemostatic efficacy in mild haemophilia A and VWD as well as in uremia, liver cirrhosis and in congenital and acquired, drug induced platelet dysfunction. Desmopressin has few side effects but observation is advised in small children and elderly.     

Laboratory issues in bleeding disorders

Summary.  The clinical history of the patient and of his/her relatives is the most important tool for making correct diagnosis of inherited or acquired bleeding disorders. Several attempts have been made by clinicians to evaluate the sensitivity and specificity of bleeding symptoms. Specific and detailed questionnaires have been designed to quantify the bleeding tendency of patients with von Willebrand's disease (VWD) and a bleeding score has been calculated. VWD is considered the most frequent inherited bleeding disorder according to population studies: however, due to the complexity of its diagnosis, the number of patients with correct diagnosis of VWD in many developing countries is relatively low and most cases remain still under- or misdiagnosed. Once bleeding history is carefully evaluated by means of a bleeding score, the laboratory workout should be organized to find out the specific defect of haemostasis responsible for bleeding. Since factors involved in haemostasis are many, the correct approach must include first level screening tests with the aim to identify the abnormal phase of haemostasis involved: then, second level tests should be focused on the specific factors within the abnormal step of haemostasis. Among many other acquired bleeding disorders related to clinical conditions or to the use of drugs, the acquired inhibitors of haemostasis are rare but should be immediately characterized by appropriate laboratory tests because they can be often life-threatening for the patients.     

Sp alpha I/65 hereditary elliptocytosis in North Africa

The Sp alpha I/65 variant of the spectrin has been recently described in black people with hereditary elliptocytosis (HE). The present study reports on a similar Sp alpha I/65 variant in nine North African persons belonging to four unrelated families. The abnormality was associated with a variable degree of elliptocytosis. In one case, red cell morphology was normal. In the nine carriers of the biochemical abnormality, the spectrin dimer self-association was defective. The association constant was reduced: 0.65 to 1.7 X 10(5) M-1 (controls: 4.6 +/- 0.5 X 10(5) mM-1 (n = 21)); in six cases, there was a higher level of spectrin dimer in the low ionic strength extract at 4 degrees C: 13.0 to 19.7% (controls: 6.4 +/- 2.1% (n = 7)). Limited tryptic digests of spectrin from the nine persons revealed a decrease of the 80,000-dalton alpha-1 domain, and the concomitant appearance of a peptide with a molecular weight of 65,000 daltons and an isoelectric point ranging from 5.0 to 5.1. There was a correlation between the proportion of the 65,000-dalton fragments, the defect of spectrin self-association, and the extent of morphological alteration. This is the first large series concerning a spectrin abnormality in non-black persons. In North Africa, cases of HE that are not due to a protein 4.1 defect have turned out so far to be associated with the Sp alpha I/65 variant.     

Coexistence of Haemophilia A and Von Willebrand's Disease in the Same Kindred

A clinical and laboratory investigation of a kindred in which haemophilia A and autosomal recessive von Willebrand's disease (VWD) were concomitantly present is described. 3 male patients were shown to be hemizygotes for moderate haemophilia A, one female appeared to be haemophilia A carrier and 3 males showed laboratory findings consistent with heterozygosity for autosomal recessive VWD. In one woman, the pedigree and laboratory findings suggest the possibility of double heterozygosity.     

Congenital von Willebrand's disease and clinical hypothyroidism

Data from case reports and systematic reviews suggest an association of Hypothyroidism and Acquired von Willebrand's syndrome. It is not known if congenital von Willebrand's disease is associated with hypothyroidism in a similar way. The aim of this study was to identify the association of congenital von Willebrand's disease (VWD) with clinical hypothyroidism. A total of 350 cases of congenital VWD were initially screened from our institution database from 1985 to 2010. A careful review of patient records was carried out to see if patients truly had congenital VWD and coexisting clinical hypothyroidism. Patients with uncertain diagnoses or other bleeding disorders were excluded, leading to 197 patients remaining in the final sample. A random age‐ and sex‐matched parallel control group was also obtained from the hospital database. Of 197 patients (mean age 43.8 ± 17.5 years, women 72%) of congenital VWD, 32/197 (16%) were diagnosed with clinical hypothyroidism, while only 11/197 (5.6%) of the matched controls were clinically hypothyroid. Univariate and multivariate analysis demonstrated that VWD was an independent predictor of developing clinical hypothyroidism (OR 3.45; 95% CI 1.65–7.22, P = 0.001). The proportion of patients diagnosed with clinical hypothyroidism was more in the VWD group (P < 0.0001). Our analysis shows a strong association of clinical hypothyroidism in patients with congenital VWD, but future studies will be required to delineate a pathological mechanism. In our opinion, clinicians should consider checking thyroid function in the newly diagnosed and established cases of congenital VWD.