Assessing bleeding in von Willebrand disease with bleeding score

Gingival bleeding is a useful clinical feature in the diagnosis of hereditary bleeding disorders in children

The search for hereditary bleeding disorders (HBD) prior to invasive procedures in children is primarily based on personal and family bleeding history. Although several scores are available, they have only been evaluated in specific situations or in adults. Our monocentric retrospective study aimed to analyze the association between clinical history and four scores (HEMSTOP, PBQ, ISTH-BAT, TOSETTO) and the diagnosis of MHC in children referred to the University Hospital of Montpellier for hemostasis investigations. A total of 117 children were retrospectively included in the study. Of these, 57 (49%) were diagnosed with HBD, with 30 having primary bleeding disorders and 27 having coagulation disorders. The diagnosis of HBD was significantly associated with gingival bleeding, which was present in 30% of HBD patients. In our population, only the HEMSTOP score showed an association with the diagnosis of HBD, but it was positive in only 48% of patients. By including gingival bleeding as a factor, we modified the HEMSTOP score, which increased its sensitivity from 0.45 to 0.53. When examining primary bleeding disorders, the modified HEMSTOP score, with the inclusion of gingival bleeding, enables us to diagnose 63% of patients (see Fig. 1).    Conclusion: Therefore, gingival bleeding should be considered a useful factor in bleeding history for HBD diagnosis. Adding this symptom to a screening score such as HEMSTOP improves its sensitivity. To confirm our findings, a prospective study is required.    Trial registration: Study registration number: NCT05214300. What is Known: • Screening for hereditary bleeding disorder diseases is a necessity and a challenge in children. • Minor disorders of primary hemostasis are the most common, but often escape standard coagulation tests. What is New: • Gingival bleeding is a frequent symptom that is easy to investigate and may point to a primary hemostasis disorder. • Adding the gingival bleeding item to a routine screening score such as HEMSTOP improves sensitivity.

Targeting von Willebrand disease: the current status and future directions of management therapies

INTRODUCTION

von Willebrand disease (VWD) is the commonest inherited bleeding disorder, and is typically caused by deficits in the quantity or quality of von Willebrand factor (VWF).

AREAS COVERED

This review describes the main clinical, diagnostic, and therapeutic aspects of VWD, with particular attention to its management. In addition, standard and avant-garde replacement therapies based on the use of VWF are discussed.

EXPERT OPINION

The goal of treatment for VWD is to reverse the double hemostatic defect resulting from the abnormal or reduced expression of VWF and the concomitant factor VIII (FVIII) deficiency. Treatment consists of managing any bleeds and both short-term prophylaxis (i.e. for surgery or invasive procedures) and long-term prophylaxis. While desmopressin is suitable for most patients with type 1 VWD, VWF/FVIII concentrates are the treatment of choice for the other types of VWD. Beside plasma-derived VWF/FVIII concentrates, whose safety and efficacy have been demonstrated by several clinical trials, products containing only VWF, obtained by plasma fractionation and recombinant DNA technology, have become available and marketed more recently. The clinical use of these VWF-only products is particularly attractive in the setting of surgery and long-term prophylaxis, such as the prevention of recurrent gastrointestinal bleeding in cases of angiodysplasia.

Platelet Aggregation Assays Do Not Reliably Diagnose Platelet Delta Granule Storage Pool Deficiency

Background

Patients with platelet dysfunction disorders present with a variety of mucocutaneous bleeding symptoms including easy bruising, frequent epistaxis, bleeding gums upon tooth brushing and for women, heavy menstrual bleeding. Available laboratory assays to evaluate platelet function include the platelet function analyzer (PFA) and in larger centers with coagulation laboratories, light transmission platelet aggregometry (LTA) analyses. Both assays are known to have a number of limitations, especially in the diagnosis of platelet delta granule storage pool deficiency (δ-SPD). δ-SPD is an underdiagnosed condition caused by decreased numbers of platelet dense granules (DGs) and is best diagnosed by electron microscopy (EM). Patients with platelet δ-SPD have a decreased response to low levels of the agonist adenosine diphosphate (ADP) in the second wave of light transmittance with LTA or decreased ADP secretion by fluorescence lumiaggregometry. There are few reports that have evaluated patients with δ-SPD and their respective LTA results. One report published in 1987 described normal LTA assays in 23% of patients with δ-SPD; a more recent report described LTA as having the sensitivity to detect only about 52% of patients with δ-SPD. The purpose of our study was intended to review the LTA and EM results of patients suspected of having a platelet function disorder at our institution for comparison with previously published studies.

Methods

Our study included 344 patients who had been evaluated by both LTA and whole mount EM. Aggregometry utilized five agonists: ADP, epinephrine, collagen, arachidonic acid, and ristocetin. DGs were enumerated in 100 whole-mounted platelets to determine a mean number of dense granules per platelet (DGs/PL).

Results

Seventy-seven percent of our patients were found to have δ-SPD (264/344); 68% (179/264) of these subjects had an abnormal platelet LTA. Thirty-two percent (85/264) of our patients had normal LTA results but were found to have δ-SPD with a mean of 2.54 ± 0.15 DG/PL (normal = 4 - 6 DG/PL).

Conclusion

These data confirm previous reports suggesting the utilization of LTA alone in patients with histories of unexplained bleeding may miss the diagnosis of platelet δ-SPD. It is, therefore, prudent to assess platelet DG number by EM, especially if platelet LTA assessment is normal.

Inflammatory Biomarkers in Postural Orthostatic Tachycardia Syndrome with Elevated G-Protein-Coupled Receptor Autoantibodies

A growing body of evidence suggests that postural orthostatic tachycardia syndrome (POTS) may be an autoimmune disorder. We have reported in a previous manuscript that 89% of POTS patients (n = 55) had elevations in G-protein-coupled adrenergic A1 receptor autoantibodies and 53% had elevations in muscarinic acetylcholine M4 receptor autoantibodies, as assessed by ELISA. Patients with autoimmune disorders have been reported with a variety of elevated cytokines and cytokines (such as rheumatoid arthritis); thus, we evaluated a limited number of cytokines/chemokines in POTS patients with elevated adrenergic and muscarinic receptor autoantibodies. We utilized the plasma of 34 patients from a previous study; all of the patients (100%) had autoantibodies against the A1 adrenergic receptor and 55.9% (19/34) had autoantibodies against the M4 muscarinic acetylcholine receptor. In particular, the plasma cytokine/chemokine levels were measured as biomarkers of inflammation by Quantibody^® technology (Raybiotech, Peachtree Corners, GA, USA). We also evaluated the platelet dense granule numbers, as these patients frequently complain of symptoms related to platelet dysfunction. Patients were predominantly young females who displayed a multitude of co-morbidities but generally reported viral-like symptoms preceding episodes of syncope. Eighty five percent (29/34) had platelet storage pool deficiency. Patients had elevations in five of ten cytokine/chemokines biomarkers (IL1β, IL21, TNFα, INFγ, and CD30), whereas two biomarkers had decreased levels (CD40L and RANTES). Our observations demonstrate that POTS patients known to have autoantibodies against the G-protein-coupled adrenergic A1 receptor have abnormal plasma concentrations of inflammatory cytokines.

Role of oculocerebrorenal syndrome of Lowe (OCRL) protein in megakaryocyte maturation, platelet production and functions: a study in patients with Lowe syndrome

Lowe syndrome (LS) is an oculocerebrorenal syndrome of Lowe (OCRL1) genetic disorder resulting in a defect of the OCRL protein, a phosphatidylinositol-4,5-bisphosphate 5-phosphatase containing various domains including a Rho GTPase-activating protein (RhoGAP) homology domain catalytically inactive. We previously reported surgery-associated bleeding in patients with LS, suggestive of platelet dysfunction, accompanied with a mild thrombocytopenia in several patients. To decipher the role of OCRL in platelet functions and in megakaryocyte (MK) maturation, we conducted a case-control study on 15 patients with LS (NCT01314560). While all had a drastically reduced expression of OCRL, this deficiency did not affect platelet aggregability, but resulted in delayed thrombus formation on collagen under flow conditions, defective platelet spreading on fibrinogen and impaired clot retraction. We evidenced alterations of the myosin light chain phosphorylation (P-MLC), with defective Rac1 activity and, inversely, elevated active RhoA. Altered cytoskeleton dynamics was also observed in cultured patient MKs showing deficient proplatelet extension with increased P-MLC that was confirmed using control MKs transfected with OCRL-specific small interfering(si)RNA (siOCRL). Patients with LS also had an increased proportion of circulating barbell-shaped proplatelets. Our present study establishes that a deficiency of the OCRL protein results in a defective actomyosin cytoskeleton reorganisation in both MKs and platelets, altering both thrombopoiesis and some platelet responses to activation necessary to ensure haemostasis.

Catalytic dysregulation of SHP2 leading to Noonan syndromes affects platelet signaling and functions

Src homology 2 domain-containing phosphatase 2 (SHP2), encoded by the PTPN11 gene, is a ubiquitous protein tyrosine phosphatase that is a critical regulator of signal transduction. Germ line mutations in the PTPN11 gene responsible for catalytic gain or loss of function of SHP2 cause 2 disorders with multiple organ defects: Noonan syndrome (NS) and NS with multiple lentigines (NSML), respectively. Bleeding anomalies have been frequently reported in NS, but causes remain unclear. This study investigates platelet activation in patients with NS and NSML and in 2 mouse models carrying PTPN11 mutations responsible for these 2 syndromes. Platelets from NS mice and patients displayed a significant reduction in aggregation induced by low concentrations of GPVI and CLEC-2 agonists and a decrease in thrombus growth on a collagen surface under arterial shear stress. This was associated with deficiencies in GPVI and αIIbβ3 integrin signaling, platelet secretion, and thromboxane A2 generation. Similarly, arterial thrombus formation was significantly reduced in response to a local carotid injury in NS mice, associated with a significant increase in tail bleeding time. In contrast, NSML mouse platelets exhibited increased platelet activation after GPVI and CLEC-2 stimulation and enhanced platelet thrombotic phenotype on collagen matrix under shear stress. Blood samples from NSML patients also showed a shear stress-dependent elevation of platelet responses on collagen matrix. This study brings new insights into the understanding of SHP2 function in platelets, points to new thrombopathies linked to platelet signaling defects, and provides important information for the medical care of patients with NS in situations involving risk of bleeding.

von Willebrand Factor and Management of Heart Valve Disease: JACC Review Topic of the Week

For decades, numerous observations have shown an intimate relationship between von Willebrand factor (VWF) multimer profile and heart valve diseases (HVD). The current knowledge of the unique biophysical properties of VWF helps us to understand the longstanding observations concerning the bleeding complications in patients with severe HVD. Not only does the analysis of the VWF multimer profile provide an excellent evaluation of HVD severity, it is also a strong predictor of clinical events. Also of importance, VWF responds within minutes to any significant change in hemodynamic valve status, making it an accurate marker of the quality of surgical and transcatheter therapeutic interventions. The authors provide in this review a practical, comprehensive, and evidence-based framework of the concept of VWF as a biomarker in HVD, advocating for its implementation into the clinical decision-making process besides usual clinical and imaging evaluation. They also delineate critical knowledge gaps and research priorities to definitely validate this concept.

Diagnostic work up of patients with increased bleeding tendency

Introduction

The diagnostic trajectory of patients with increased bleeding tendency can be very costly and time‐consuming. In addition, previous studies have shown that half of these patients remain without final diagnosis despite all efforts.

Aim

This study aimed to improve insight into the current diagnostic process of these patients.

Methods

A total of 117 adult patients, referred to an academic hospital because of being suspected to have an increased bleeding tendency, were included. Different parameters were compared between patients receiving final diagnosis, patients without final diagnosis but a high Tosetto bleeding assessment tool (BAT) score (classified as bleeding of unknown cause, or BUC) and a control group consisting of patients without final diagnosis and a low BAT score.

Results

The BAT score was significantly higher in patients in the BUC group as compared to patients reaching final diagnosis (8.1 vs 4.9). Interestingly, the two subcategories most prevalently increased were surgery and post‐partum haemorrhage‐associated bleeding (surgery: 2.1 vs 1.1; post‐partum haemorrhage: 0.7 vs 0.0). Laboratory screening results were more often abnormal in patients reaching final diagnosis compared to patients remaining without diagnosis and a high BAT score (n = 32 (78%) vs n = 14 (46%), 95% CI 1.5‐12), especially concerning the PFA (=27 (66%) vs n = 10 (33%), 95% CI 1.4‐10) and von Willebrand factor activity levels (n = 11 (27%) vs n = 1 (3%), 95% CI 1.3‐91).

Conclusion

Isolated high bleeding score on surgical or post‐partum bleeding correlates with a lower chance of receiving final diagnosis. Withholding extensive haemostatic testing should be considered. Better screening and confirmative haemostatic assays are still needed.

A simplified flow cytometric method for detection of inherited platelet disorders-A comparison to the gold standard light transmission aggregometry

Background

Flow cytometric platelet activation has emerged as an alternative diagnostic test for inherited platelet disorders. It is, however, labor intensive and few studies have directly compared the performance of flow cytometric platelet activation (PACT) to light transmission aggregometry (LTA). The aims of this study were 1/ to develop a simplified flow cytometric platelet activation assay using microtiter plates and 2/ to correlate the outcome to gold standard method LTA, and to clinical bleeding assessment tool scores (BAT score).

Methods

The PACT method was developed in microtiter plates using adenosine diphosphate (ADP), collagen-derived peptide (CRP-XL) and thrombin receptor activator for peptide 6 (TRAP-6) as agonists. Antibodies against GPIIb-IIIa activation epitope (PAC1), P-selectin (CD62P) and lysosome-associated membrane glycoprotein 3 (LAMP3; CD63) were used as platelet activation markers. Sixty-six patients referred to the coagulation unit for bleeding symptoms were included in this single-center observational study. Platelet activation was determined by PACT and LTA. The results of both methods were correlated to BAT score.

Results

A two-by-two analysis using Cohen’s kappa analysis gave moderate agreement between LTA and PACT (82%, kappa = 0.57), when PACT analysis with ADP and CRP-XL was compared to LTA. Using LTA as reference method, positive predictive value was 70% and negative predictive value was 87%. A substantial number of patients had high BAT score and normal LTA and PACT results. Patients with abnormal LTA or PACT results had higher BAT score than patients with normal results, but the difference was not significant.

Conclusions

The performance in microtiter plates simplified the PACT method and enabled analysis of more patients at the same time. Our results indicate that with modification of the current PACT assay, a higher negative predictive value can be obtained. Furthermore, with comparable result to LTA the PACT could be used as a screening assay for inherited platelet disorders.

Assessment of the Stability of von Willebrand Profile Clotting Factors and Platelet Dense Granule Testing Following Air Transport

The purpose of this study was to determine the reliability of test results dependent upon blood and plasma sample stability when shipped by airfreight courier for reference laboratory assessment. Of particular interest was evaluation of von Willebrand profile assays and platelet dense granule storage pool analysis. Peripheral venous blood was obtained from healthy volunteers. von Willebrand factor (VWF) activity, VWF antigen, and factor VIII coagulant activity assays were performed immediately following venipuncture with additional aliquots of plasma frozen and stored at −70°C for subsequent analysis 48 hours later. One frozen aliquot was shipped via airfreight for analysis 48 hours later, with another frozen aliquot that remained on-site. Blood was also collected to enumerate platelet dense granules to determine whether shipment would affect results. Statistical analysis of all test results demonstrated significant correlation between immediately assayed samples and samples that were stored for 48 hours at −70°C (P < .0001), or frozen and shipped on dry ice (P < .0001) for analysis upon return to our laboratory. No difference was found in the mean number of platelet dense granules between samples retained in our laboratory or samples analyzed upon return of shipment (P = .751).

Bleeding score in type 1 von Willebrand disease patients using the condensed MCMDM-1 vWD validated questionnaire

BACKGROUND

Assessment of the severity of bleeding symptom has led to the evolution of bleeding assessment tools which are now validated.

AIMS

To administer the condensed molecular and clinical markers for the diagnosis and management of type 1 von Willebrand disease VWD (MCMDM-1 vWD) questionnaire to the Omani type 1 vWD patients and correlate it with the laboratory parameters.

METHODS

Patients and controls were personally interviewed and the condensed MCMDM-1 vWD questionnaire administered by a single investigator. Bleeding score (BS) was calculated, based on the presence or absence of the bleeding symptoms according to a standard validated questionnaire in both the patients and the controls.

RESULTS

The median age of the patient cohort was 27 (range, 7-49) years with 60.87% of females. The median time to administer condensed MCMDM-1 BS questionnaire was 11 minutes (interquartile range-IQR;7,16). Overall, bleeding from the oral cavity was the most predominant symptom (63%). The median BS was 5 (IQR;1,8) although individual scores ranged between 0 and 29. However, there was no statistically significant difference in BS between genders (males: median 4; IQR 1,6 and females: median 5, IQR 1,10) (P > .05, Kruskal-Wallis test) The Spearman's correlation value of BS was weak with FVIII:C levels and von Willebrand Ristocetin co-factor activity; very weak with von Willebrand Antigen level, and moderate with vonWillebrand Collagen Binding activity being -0.29, -0.28, -0.14 and -0.43, respectively.

CONCLUSION

The BS reflects the severity of bleeding among the vWD patients. Although the BS was abnormal, it did not correlate significantly with the surrogate laboratory parameters [P > .05].

Bleeding score in Type 1 von Willebrand disease patients using the ISTH-BAT questionnaire

BACKGROUND

Bleeding assessment tools have evolved in the last decade to standardize the assessment of the severity of bleeding symptom in a consistent way. In 2010, the International Society on Thrombosis and Hemostasis-Bleeding Assessment Tool (ISTH-BAT) was developed and validated.

AIMS

Our aim was to administer ISTH-BAT questionnaire to the Omani patients with type 1 VWD and obtain the bleeding score (BS). We also studied the severity of their bleeding symptoms and correlated it with the BS as well as with the laboratory parameters.

METHODS

Forty-eight type I VWD index cases and 52 normal subjects were interviewed and the ISTH-BAT questionnaire administered. The BS was calculated based on a history of bleeding symptoms from 12 different sites according to the standard ISTH-BAT questionnaire. Laboratory parameters were obtained from patient's medical records.

RESULTS

The mean age of this cohort was 27 years (range, 6-49) with 60% being females. The median time to administer this questionnaire was 10 minutes with an interquartile range (IQR) from 8 to 17 minutes. Overall, the median BS was 7 (IQR; 2,11) although individual scores ranged between 0 and 36. The BS was negatively correlated with VWF: Ag, VWF: RCo, and VWF: CB and the Spearman's correlation coefficient "rho" was, respectively, -0.15, -0.08, and -0.22.

CONCLUSION

The ISTH-BAT BS is designed to reflect the severity of bleeding. Our results demonstrate the inherent variability of this bleeding pattern. We also found that the ISTH-BAT BS significantly correlated with VWF: Ag and VWF: CB.

Thrombocytopenia and CD34 expression is decoupled from α-granule deficiency with mutation of the first growth factor-independent 1B zinc finger

Essentials The phenotypes of different growth factor-independent 1B (GFI1B) variants are not established. GFI1B variants produce heterogeneous clinical phenotypes dependent on the site of mutation. Mutation of the first non-DNA-binding zinc-finger causes a mild platelet and clinical phenotype. GFI1B regulates the CD34 promoter; platelet CD34 expression is an indicator of GFI1B mutation.

SUMMARY

Background Mutation of the growth factor-independent 1B (GFI1B) fifth DNA-binding zinc-finger domain causes macrothrombocytopenia and α-granule deficiency leading to clinical bleeding. The phenotypes associated with GFI1B variants disrupting non-DNA-binding zinc-fingers remain uncharacterized. Objectives To determine the functional and phenotypic consequences of GFI1B variants disrupting non-DNA-binding zinc-finger domains. Methods The GFI1B C168F variant and a novel GFI1B c.2520 + 1_2520 + 8delGTGGGCAC splice variant were identified in four unrelated families. Phenotypic features, DNA-binding properties and transcriptional effects were determined and compared with those in individuals with a GFI1B H294 fs mutation of the fifth DNA-binding zinc-finger. Patient-specific induced pluripotent stem cell (iPSC)-derived megakaryocytes were generated to facilitate disease modeling. Results The DNA-binding GFI1B variant C168F, which is predicted to disrupt the first non-DNA-binding zinc-finger domain, is associated with macrothrombocytopenia without α-granule deficiency or bleeding symptoms. A GFI1B splice variant, c.2520 + 1_2520 + 8delGTGGGCAC, which generates a short GFI1B isoform that lacks non-DNA-binding zinc-fingers 1 and 2, is associated with increased platelet CD34 expression only, without quantitative or morphologic platelet abnormalities. GFI1B represses the CD34 promoter, and this repression is attenuated by different GFI1B zinc-finger mutations, suggesting that deregulation of CD34 expression occurs at a direct transcriptional level. Patient-specific iPSC-derived megakaryocytes phenocopy these observations. Conclusions Disruption of GFI1B non-DNA-binding zinc-finger 1 is associated with mild to moderate thrombocytopenia without α-granule deficiency or bleeding symptomatology, indicating that the site of GFI1B mutation has important phenotypic implications. Platelet CD34 expression appears to be a common feature of perturbed GFI1B function, and may have diagnostic utility.

Novel insights into the clinical phenotype and pathophysiology underlying low VWF levels

Critical clinical questions remain unanswered regarding diagnosis and management of patients with low von Willebrand factor (VWF) levels (30-50 IU/dL). To address these questions, the Low VWF Ireland Cohort (LoVIC) study investigated 126 patients registered with low VWF levels. Despite marginally reduced plasma VWF levels, International Society of Thrombosis and Haemostasis Bleeding Assessment Tool (ISTH BAT) confirmed significant bleeding phenotypes in the majority of LoVIC patients. Importantly, bleeding tendency did not correlate with plasma VWF levels within the 30 to 50 IU/dL range. Furthermore, bleeding phenotypes could not be explained by concurrent hemostatic defects. Plasma factor VIII to VWF antigen (VWF:Ag) ratios were significantly increased in LoVIC patients compared with controls (P < .0001). In contrast, VWF propeptide to VWF:Ag ratios >3 were observed in only 6% of the LoVIC cohort. Furthermore, platelet-VWF collagen binding activity levels were both significantly reduced compared with controls (P < .05). In response to 1-desamino-8-D-arginine vasopressin (DDAVP), peak VWF:Ag levels exceeded 100 IU/dL in 88% of patients and was sustained >100 IU/dL after 4 hours in 72% of subjects. In conclusion, our novel data suggest that low VWF levels can be associated with significant bleeding and are predominantly due to reductions in VWF synthesis and/or constitutive secretion. Although enhanced VWF clearance may contribute to the pathophysiology in some individuals, the absolute reduction in VWF plasma half-life is usually mild and not sufficient to significantly impact upon the duration of DDAVP-induced VWF response. This trial was registered at www.clinicaltrials.gov as #NCT03167320.

Quality of Life in Children and Adolescents With Rare Bleeding Disorders in Southern Iran

The aim of this study is to evaluate quality of life (QOL) in patients with rare bleeding disorders (RBDs). In this cross-sectional study, 52 consecutive children aged between 4 and 18 years old with RBDs registered at the Haemophila Center of Fars province in Southern Iran were investigated from January to April 2015. Quality of life was evaluated using Haemo-QOL questionnaire. Final score is defined between 0 and 100, and higher score of QOL shows worse condition. P value less than .05 was considered statistically significant. Mean age of the patients was 13.96 ± 4.50 and ranged from 4 to 18 years old including 28 males and 24 females. Family and friends were the 2 most impaired domains of Haemo-QOL in these patients. In univariate analysis, bleeding severity based on bleeding score, health status, and being bothered by the disease showed statistically significant correlations with QOL of the patients ( P < .05). In multiple linear regression models, only degree of being bothered by the disease was determined as an independent influencing factor on QOL. Taking together, Haemo-QOL of children with RBDs was better than what was reported in patients with hemophilia in our region, but it was worse than that reported in patients with hemophilia in other developing and developed countries. Due to chronic feature of bleeding disorders, more attention to different aspects of the disease, especially in 2 dimensions of family and friends through considering educational and psychological program for the patients and their family, are recommended to improve QOL of the patients with RBDs.

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.

Genetic analysis in Factor XI deficient patients from central China: identification of one novel and seven recurrent mutations

Factor XI (FXI) deficiency is a rare bleeding disorder with a range of manifestations from asymptomatic to trauma related bleeding. To identify mutations in FXI-deficient patients and characterize the phenotype-genotype relationship, we studied six patients and their 18 family members in central China. Five patients were identified by presurgical or routine laboratory screening but had no bleeding symptoms. Only one patient exhibited excessive injury- and surgical-related bleeding. Eight mutations were detected, including five nonsense mutations (p.Tyr369*, p.Arg72*, p.Gln281*, p.Trp519*, and p.Trp246*), two missense mutations (p.Thr40Ile and p.Ala430Thr), and a 4-bp deletion in a splice site (c.1136-4delGTTG); one mutation was novel (p.Thr40Ile). In vitro, the p.Thr40Ile mutant protein exhibited impaired secretion and function. Five of the patients were homozygous or compound heterozygous, but only one nonsense mutation was found in Patient 2. In these patients, bleeding tendency was not correlated with FXI levels or with a single heterozygous mutation. Thrombin generation tests could not distinguish the bleeder from non-bleeders. In conclusion, we reported 8 mutations in the FXI gene (F11) leading to FXI deficiency. Moreover, the functional consequences of a novel mutation leading to FXI deficiency have been elucidated. More cases are needed to find any signature of founder effect in the Chinese population and its potential relationship with other Asian population.

Predictors of von Willebrand disease diagnosis in individuals with borderline von Willebrand factor plasma levels

BACKGROUND

In individuals with borderline von Willebrand factor (VWF) plasma levels, second-level tests are required to confirm or exclude von Willebrand disease (VWD). These tests are time-consuming and expensive.

OBJECTIVE

To assess which parameters can predict VWD diagnosis in individuals with borderline VWF levels (30-60 IU dL(-1) ).

METHODS

Nine hundred and fifty individuals with bleeding episodes or abnormal coagulation test results were investigated with first-level tests (blood count, prothrombin time, activated partial thromboplastin time, blood clotting factor VIII, VWF ristocetin cofactor activity [VWF:RCo], and VWF antigen), and 93 (62 females and 31 males; median age, 28 years; interquartile range 15-44) had borderline VWF:RCo levels. All underwent second-level investigations to confirm or exclude VWD. A multivariable logistic regression model was fitted with sex, age, bleeding score, family history, VWF:RCo and ABO blood group as predictors, and used to predict VWD diagnosis.

RESULTS

Forty-five of the 93 individuals (48%) had VWD (84% type 1). A negative linear relationship between VWF:RCo levels and risk of VWD diagnosis was present, and was particularly evident with blood group non-O [adjusted odds ratio 7.00 (95% confidence interval [CI] 1.48-33.11) for every 5 IU dL(-1) decrease in VWF:RCo]. The other variable clearly associated with VWD diagnosis was female sex (adjusted odds ratio 5.76 [95% CI 1.47-22.53]). The area under the receiver operating characteristic curve of the full logistic model was 0.89 (95% CI 0.82-0.95).

CONCLUSIONS

In individuals with borderline VWF, the two strongest predictors of VWD diagnosis are low VWF:RCo levels (particularly in those with blood group non-O) and female sex. This predictive model has a promising discriminative ability to identify patients with borderline VWF levels who are likely to have VWD.

Modern Patient Blood Management in Arthroplasty

One of the oldest and still commonest procedures in clinical practice, allogeneic blood transfusion (ABT), is not fully supported by available evidence. In the last few decades, increasing concerns about unfavorable outcomes associated with ABT, anticipation of future insufficient blood supply, and awareness of the cost (direct and indirect) of transfusion have led to the promotion of patient blood management (PBM) as a cost-effective strategy, beneficial for patients as well as for society (Shander et al. 2010). PBM programs utilize a series of measures with a proven ability to reduce ABT and to be cost-effective. Despite that the impact of PBM on patient clinical outcomes needs to be fully defined and future studies are needed, PBM should be adopted as a new standard of care.

How I treat type 2 variant forms of von Willebrand disease

Type 2 von Willebrand disease (VWD) includes a wide range of qualitative abnormalities of von Willebrand factor structure and function resulting in a variable bleeding tendency. According to the current classification, 4 different subtypes can be identified, each with distinctive phenotypic and therapeutic characteristics. Current available laboratory methods allow a straightforward approach to VWD subtyping, and although the precise molecular characterization remains complex, it is not required for appropriate treatment of the vast majority of cases. Desmopressin can be useful only in a few type 2 cases compared with patients with actual quantitative deficiency (type 1), most often in variants with a nearly normal multimeric pattern (type 2M). However, since no laboratory test accurately predicts response to desmopressin, a trial test should always be performed in all type 2 VWD patients, with the exception of type 2B ones. Replacement therapy with plasma-derived von Willebrand factor-factor VIII concentrates represents the safe mainstay of treatment of all patients, particularly those not responding to desmopressin or requiring a sustained hemostatic correction because of major surgery or bleeding. A significant patient bleeding history correlates with increased bleeding risk and should be considered in tailoring the optimal antihemorrhagic prophylaxis in the individual patient.

Evaluation of Thrombin Generation Assay in Patients With Hemophilia

We evaluated the correlation between thrombin generation (TG) parameters with bleeding symptoms and disease severity in patients with hemophilia. In this cross-sectional study, 59 patients with hemophilia without inhibitors and regardless of their severity were randomly selected from southern Iran and TG assays were conducted. Bleeding score (BS) was calculated by performing a clinical evaluation using Tosetto questionnaire. Only lag time showed a statistically significant correlation with BS ( rs = .316, P = .016). All TG parameters except peak showed association with disease severity ( P < .05). Endogenous thrombin potential showed a significant correlation with factor activity level ( rs = .459, P < .001). Both lag time and start tail showed significant negative correlations with factor activity level ( rs = −0.488, P < .001 and rs= − .289, P < .026, respectively). Although most of the TG parameters evaluated were not significantly correlated with the BS of patients with hemophilia, the majority of TG parameters were significantly associated with factor activity level and disease severity.

Phenotypic and genotypic characterization of 10 Finnish patients with von Willebrand disease type 3: discovery of two main mutations

Severe von Willebrand's disease (VWD) type 3 is a rare autosomal-recessively inherited bleeding disorder, showing considerable genotypic heterogeneity. We investigated the phenotype in correlation with the genotype in Finnish type 3 VWD patients. Ten patients previously diagnosed with VWD type 3 treated at the Coagulation Disorder Unit in Helsinki University Hospital were re-evaluated for bleeding tendency and treatment. Phenotypic characterization included coagulation and platelet function testing confirming the diagnosis. The genotype was assessed by initial screening for the common c.2435delC mutation and subsequently if needed, by analysing all 51 coding exons of the von Willebrand factor gene. Our result confirmed the diagnosis of type 3 VWD for all 10 patients. We discovered two common mutations: nine of the 20 alleles (45%) were found to carry the c.2435delC frameshift mutation, previously described to be frequent in countries surrounding the Baltic Sea. The nonsense mutation c.4975C>T (p.R1659X) was found on 8/20 (40%) of the alleles. In addition, three novel mutations, a potential splice site mutation (c.874+2T>C) and two frameshift mutations (c.1668delC and c.2072delCCinsG) were found. Seven patients were homozygous and three compound heterozygous for the reported mutations. This study indicates that mainly two mutations (c.2435delC and p.R1659X) cause the majority of type 3 VWD in Finland. This result sets future standards for the genetic testing among the Finnish type 3 VWD population.

Bleeders, bleeding rates, and bleeding score

Bleeding symptoms are frequently reported even in otherwise healthy subjects, and differentiating a normal subject from a patient with a mild bleeding disorder (MBD) can be extremely challenging. The concept of bleeding rate, that is, the number of bleeding episodes occurring within a definite time, could be used as the unifying framework reconciling the bleeding risk observed in congenital and acquired coagulopathies into a single picture. For instance, primary prevention trials have shown that the incidence of non-major bleeding symptoms in normal subjects is around five per 100 person-years, and this figure is in accordance with the number of hemorrhagic symptoms reported by normal controls in observational studies on hemorrhagic disorders. The incidence of non-major bleeding in patients with MBDs (e.g. in patients with type 1 VWD carrying the C1130F mutation) is also strikingly similar with that of patients taking antiplatelet drugs, and the incidence in moderately severe bleeding disorders (e.g. type 2 VWD) parallels that of patients taking vitamin K antagonists. The severity of a bleeding disorder may therefore be explained by a bleeding rate model, which also explains several common clinical observations. Appreciation of the bleeding rate of congenital and acquired conditions and of its environmental/genetic modifiers into a single framework will possibly allow the development of better prediction tools in the coming years and represents a major scientific effort to be pursued.

Bleeding scores: are they really useful?

Given the commonality of bleeding symptoms in the general population and the diagnostic limitations of available laboratory testing for mild bleeding disorders, there has been increasing interest in a more precise quantification of bleeding symptoms. The Vicenza bleeding score (and its successor, Molecular and Clinical Markers for the Diagnosis and Management of Type 1 von Willebrand disease [MCMDM-1 VWD]) and its pediatric counterpart, the Pediatric Bleeding Questionnaire, are validated research tools that have demonstrated their ability to discriminate between healthy subjects and those with VWD. These instruments collect data regarding both the presence and severity of a variety of bleeding symptoms and generate a bleeding score by summing the severity of all symptoms reported by a subject. More recent work demonstrates the promise of these tools as a diagnostic aid in the evaluation of patients with a suspected inherited mild bleeding disorder, as well as the development of a condensed score with increased clinical applicability. This review focuses on the development of these bleeding assessment tools, recent publications applying and refining these instruments, and current limitations of bleeding scores. Needed research studies and potential clinical applications of bleeding scores are also discussed. The ultimate goal would be for bleeding scores to be integrated with the results of standardized laboratory testing to allow for a universal diagnostic approach to patients with suspected bleeding disorders.

Prospective evaluation of a pediatric bleeding questionnaire and the ISTH bleeding assessment tool in children and parents in routine clinical practice

BACKGROUND

Diagnosing mild bleeding disorders (BDs) in children is difficult. Bleeding scores (BSs) have been proposed for obtaining standardized quantitative histories.

OBJECTIVES

To compare the Canadian pediatric bleeding questionnaire (PBQ) with the new ISTH bleeding assessment tool (ISTH BAT) for the determination of BS in a routine pediatric outpatient setting.

METHODS

One hundred children with a suspected BD were enrolled in this cross-sectional study. Bleeding scores were calculated for all children and their natural parents. For all children, extensive laboratory investigations were performed.

RESULTS

Based on laboratory tests, 56 children were diagnosed as having no BD, 11 were diagnosed with possible VWD, 12 with VWD 1, 11 with VWD 2, five with possible platelet defects, and five with mild factor deficiencies. Both questionnaires were able to discriminate between no BD and VWD (P = 0.0001), but the area under the receiver characteristics curve to detect any mild BD was only 0.76. Despite the inherited nature of the BD, a family score did not increase the ability to discriminate between no BD and VWD (P = 0.2052). There was no significant difference between the two tools used (P = 0.3253) or simple qualitative criteria, such as yes/no questions regarding bleeding (P = 0.3477).

CONCLUSIONS

The two tools translated into German did not differ substantially. Both were able to discriminate between no BD and a possible BD with acceptable accuracy. A BS of < 2 makes a BD unlikely. Simple qualitative criteria were similar; however, to allow comparison of studies and follow-up in patients over time, we recommend the ISTH BAT.

Critical von Willebrand factor A1 domain residues influence type VI collagen binding

BACKGROUND

von Willebrand factor (VWF) binds to subendothelial collagen at sites of vascular injury. Laboratory testing for von Willebrand disease (VWD), however, does not always include collagen binding assays (VWF:CB) and standard VWF:CB assays use type I and/or type III collagen rather than type VI collagen.

OBJECTIVES

We report here on several mutations that exclusively alter binding to type VI collagen.

PATIENTS/METHODS

Healthy controls and index cases from the Zimmerman Program for the Molecular and Clinical Biology of VWD were analyzed for VWF antigen (VWF:Ag), VWF ristocetin cofactor activity and VWF:CB with types I, III and VI collagen. VWF gene sequencing was performed for all subjects.

RESULTS

Two healthy controls and one type 1 VWD subject were heterozygous for an A1 domain sequence variation, R1399H, and displayed a selective decreased binding to type VI collagen but not types I and III. Expression of recombinant 1399H VWF resulted in absent binding to type VI collagen. Two other VWF A1 domain mutations, S1387I and Q1402P, displayed diminished binding to type VI collagen. An 11 amino acid deletion in the A1 domain also abrogated binding to type VI collagen.

CONCLUSIONS

VWF:CB may be useful in diagnosis of VWD, as a decreased VWF:CB/VWF:Ag ratio may reflect specific loss of collagen binding ability. Mutations that exclusively affect type VI collagen binding may be associated with bleeding, yet missed by current VWF testing.

Predictors of von Willebrand disease in children

BACKGROUND

Bleeding and bruising are common symptoms for which children are referred to a pediatric hematologist. Although bleeding scores have been validated to quantify bleeding risk in adults, there are no similar definitive data in children. The aim was to describe presenting bleeding symptoms in children and evaluate if these bleeding symptoms were predictive of von Willebrand disease (VWD) or low von Willebrand factor (VWF).

PROCEDURE

We performed a retrospective chart review of consecutive pediatric patients referred for perceived bleeding symptoms to the coagulation clinic at The Children's Hospital of Pittsburgh of UPMC. All underwent a uniform bleeding symptom inventory and hemostatic testing. Single and multiple variable logistic regression models were created to predict either VWD, low VWF, or nonspecific defective platelet aggregation, using the predictor variables of family bleeding history, mucocutaneous bleeding, cutaneous bleeding, and surgical bleeding, based on The International Society on Thrombosis and Hemostasis (ISTH) bleeding definitions.

RESULTS

Of 298 pediatric patients evaluated, 8% had VWD (VWF:RCo and VWF:Ag ≤ 30 IU/dl) and 34% had low VWF (VWF:RCo and VWF:Ag 30-50 IU/dl). Further, 16% had a nonspecific platelet aggregation disorder, 41% had normal hemostatic testing, and 1% had factor VIII or IX deficiency. In single and multiple variable logistic regression analysis, neither a personal or family bleeding history at presentation, nor the presence of two or more bleeding symptoms were predictive of VWD, low VWF, or nonspecific defective platelet aggregation.

CONCLUSIONS

These findings suggest that qualitative assessment of bleeding symptoms alone is not useful in children.

Evaluation of the new INNOVANCE® PFA P2Y cartridge in patients with impaired primary haemostasis

Recently, the INNOVANCE® PFA P2Y (P2Y) cartridge of the PFA-100® system (Siemens Healthcare Diagnostics, Marburg, Germany) has been developed for the monitoring of adenosine diphosphate (ADP) P2Y(12) receptor inhibition in patients under dual antiplatelet therapy. The aim of this study was to evaluate the influence of pre-existing defects in primary haemostasis on the P2Y cartridge independent from specific antiplatelet medication. Therefore, the closure time (CT) of the P2Y cartridge was measured in a cohort of 176 patients with assumed bleeding disorders and compared with the results of established methods for the assessment of primary haemostasis. Von Willebrand disease (VWD) was found in 25 patients (14%). The detection rate of the P2Y cartridge regarding VWD was 64% and lower compared to the two conventional cartridges (collagen/epinephrine cartridge, CEPI, 80%; collagen/ADP cartridge, CADP, 76%). In the subgroup of VWD patients with VWF:RCo < 60 IU/dL (n = 22), the correlation analysis and the inter-rater agreement revealed only limited accordance with the two established cartridges. The correlation with the CADP cartridge (C(r) = 0.767, R(2) = 0.461; Kappa = 0.41) was higher than the correlation with the CEPI cartridge. Except for severe forms, platelet function disorders (9 patients, 5%) did not prolong the CT of the P2Y cartridge. Interestingly, the P2Y cartridge was less interference-prone to unspecific medications (23 patients, 13%). As the main conclusion, it must be taken into account that low von Willebrand factor activity can significantly influence the CTs of the P2Y cartridge when using it for the monitoring of antiplatelet therapy.

Screening for von Willebrand disease: contribution of an automated assay for von Willebrand factor activity

Measuring von Willebrand factor (VWF) activity is essential to the diagnosis of von Willebrand disease (VWD). The VWF activity is usually assessed based on measurement of the ristocetin cofactor (VWF:RCo). However, that test is technically challenging and has high intra- and inter-assay variabilities. The HemosIL VWF activity (VWF:AC) is a fully automated assay, recently proposed as a good alternative to VWF:RCo for VWD diagnosis. This study was undertaken to assess this new method. First, the analytical performance of VWF:AC on an automated coagulo-meter (ACLTop) was determined, and then this new method was compared with VWF:RCo and the platelet function analyzer (PFA100) for 160 patients referred for VWD screening. The VWF:AC achieved acceptable precision with within-run and between-run coefficients of variation ranging from 2.3% to 14.1%, and linearity from 10% to 100%. Despite some marked differences between VWF:AC and VWF:RCo for 10 plasmas tested, their agreement for VWD diagnosis was good. The VWF:AC had sensitivity similar to that of PFA100 (close to 100%), but better specificity (97.7% vs. 66% or 60%, depending on the cartridge used). The good analytical performance, and the sensitivity and specificity of VWF:AC to detect VWF deficiency renders it a suitable method for VWD screening. Our findings support VWF:AC use for the diagnostic work-up of VWD, paying close attention to concomitant clinical signs and bleeding score, as recommended for VWD.

Gynecological and obstetrical manifestations of inherited bleeding disorders in women

Patients affected by bleeding disorders present a wide spectrum of clinical symptoms that vary from a mild or moderate bleeding tendency to significant episodes. Women with inherited bleeding disorders are particularly disadvantaged since, in addition to suffering from general bleeding symptoms, they are also at risk of bleeding complications from regular haemostatic challenges during menstruation, pregnancy and childbirth. Moreover, such disorders pose important problems for affected women due to their reduced quality of life caused by limitations in activities and work, and alteration of their reproductive life. These latter problems include excessive menstrual bleeding or menorrhagia, miscarriage, bleeding complications during pregnancy and after delivery and their related complications such as acute or chronic anaemia. The management of these women is difficult because of considerable inter-individual variation. Moreover, reliable information on clinical management is scarce, only a few available long term prospective studies of large cohorts provide evidence-based guideline about diagnosis and treatment.

Application of UKHCDO 2004 guidelines in type 1 von Willebrand Disease--a single centre paediatric experience of the implications of altered or removed diagnosis

Diagnosis of type I von Willebrand Disease (VWD) can be challenging. In 2004, the United Kingdom Haemophilia Centre Doctors' Organisation (UKHCDO) proposed more stringent diagnostic criteria to replace the 1995 guidelines. To determine the true number of cases of type 1 VWD in a single paediatric centre, the 2004 UKHCDO Guideline for the diagnosis of VWD was used to evaluate 114 patients on our type 1 VWD register. Clinical and laboratory data were collected and analysed to see whether they met the criteria for type 1 VWD. Only 8% remained on the type 1 VWD register. 18% have been classified as 'possible type 1 VWD'. Twenty five surgical procedures have since been performed on patients from the group in which the diagnosis was removed without any haemostatic support or bleeding complications. Reaction to the removal of the VWD diagnosis or delivery of an alternative diagnosis was positive for most patients and families. This study is the first to assess the impact of the 2004 UKHCDO Guidelines on the diagnosis of VWD. It provides evidence that the prevalence of type 1 VWD may actually be closer to that of haemophilia instead of the previously reported 1-3% of the general population. We propose that all centres should review their patients with a diagnosis of VWD to revalidate this disease that claims to be our most common inherited bleeding disorder.

A cost-effectiveness analysis of coagulation testing prior to tonsillectomy and adenoidectomy in children

BACKGROUND

The American Society of Pediatric Otolaryngology recommends pre-operative coagulation testing only when indicated by history or physical exam. Nevertheless, many surgeons test all children scheduled for tonsillectomy and/or adenoidectomy (T&A). Studies of pre-operative screening have had conflicting results. A decision analysis model was constructed to address the costs and health outcome states of pre-operative screening strategies in children.

PROCEDURE

A 14-day Markov model evaluated three strategies: (1) test all children for coagulation disorders; (2) test only those children with a pertinent history; and (3) perform no pre-operative testing. A literature search and a review of national databases estimated probabilities, costs, and utility data. Parameters then were varied widely in sensitivity analyses. Using a societal perspective and a cycle length of 1 day, we compared the strategies based on total costs and quality-adjusted life years (QALYs).

RESULTS

Total costs for the strategies were $3,200 for testing all children, $3,083 for testing only those with a history finding, and $3,077 for not testing. Total utilities were 0.02579, 0.02654, and 0.02659 QALYs, respectively. Cost-effectiveness ratios were most sensitive to variation in the cost of post-operative care and the probability of post-operative bleeding. The strategy of not testing was dominant in all sensitivity analyses.

CONCLUSIONS

Our results demonstrate that not performing preoperative testing is the most cost-effective strategy. This was persistent in sensitivity analyses, indicating that the model was robust. These data may be helpful to institutions and organizations to formulate policies regarding pre-operative coagulation for children without previous diagnoses of bleeding disorders.

Enzymes that hydrolyze adenine nucleotides in platelets and polymorphisms in the alpha2 gene of integrin alpha2beta1 in patients with von Willebrand disease

Von Willebrand disease (VWD) is one of the most common inherited bleeding diseases caused by a qualitative or quantitative deficiency of the von Willebrand factor (FvW). FvW is a multimeric glycoprotein synthesized by megakaryocytes and endothelial cells and it is present in the subendothelial matrix, blood plasma, platelets, and endothelium. This glycoprotein plays an important role in thrombus formation by initiating platelet adhesion to sites of injury as well as platelet aggregation. The aim of this study was to evaluate the activities of enzymes that hydrolyze adenine nucleotides in platelets, ristocetin-induced platelet aggregation (RIPA), and polymorphisms of the alpha2 gene of alpha2beta1 integrin from VWD patients. Platelet nucleoside triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase, and ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) activities were verified in 14 VWD patients. For RIPA determination, a final concentration of 1.25 mg/ml of ristocetin was used. Polymorphisms of the alpha2 gene were analyzed through PCR. Platelet NTPDase and E-NPP were decreased in VWD patients. 5'-Nucleotidase activity was not statistically significant between controls and VWD patients. RIPA was significantly reduced, with an allelic frequency of 78.57% for 807C in VWD patients. Our results indicated reduced platelet NTPDase and E-NPP activities which might be related to the low platelet adhesiveness. The prevalence of the 807C allele might account for the variability in bleeding in VWD.

Gynaecological and obstetrical problems in women with different bleeding disorders

The aim of this case-control study was to analyse the prevalence of gynaecological, obstetrical and other more general bleeding symptoms in 114 women affected by various inherited bleeding disorders, who were compared with 114 apparently healthy women. Retrospective information were collected by means of two specific questionnaires, one on gynaecological and obstetrical bleeding symptoms, with special focus on the presence of menorrhagia as defined by a pictorial blood loss assessment chart (PBAC); and the other on general bleeding symptoms, whose severity was graded by means of the bleeding score (BS). Compared to normal women, the whole group of women with inherited bleeding disorders had a higher prevalence of excessive bleeding at menarche (25% vs. 5%, P < 0.0001) and menorrhagia (59% vs. 46%, P = 0.06). Affected women also had a higher frequency than controls of general bleeding symptoms that scored as severe by a BS > or = 12 (49% vs. 0%, P < 0.0001). In affected women, the BS increased according to the severity of the haemostasis defect. In conclusions, the BS and the PBAC are simple tools to evaluate the severity of general bleeding symptoms and menorrhagia in women with inherited bleeding disorders. These instruments may help to identify those women for whom a therapeutic intervention is warranted.

Optimizing treatment of von Willebrand disease by using phenotypic and molecular data

The wide clinical spectrum of von Willebrand disease (VWD), its complex pathophysiology and its classification into distinct quantitative (type 1 or type 3) and qualitative (type 2) types with further subtle distinctions have prevented most clinicians from establishing a straightforward approach to diagnosing and treating this inherited bleeding disorder. The results of studies involving large cohorts of patients with a wide range of bleeding manifestations and variable von Willebrand factor (VWF) reduction have recently become available. These data have allowed the proposal of minimal criteria for a clinically useful diagnosis and for differentiating patients with mild VWD from subjects with borderline or only slightly reduced VWF levels who will not benefit from a specific diagnosis. These criteria are based on measurement of VWF ristocetin cofactor (VWF:RCo), VWF antigen (VWF:Ag), factor VIII and a standardized bleeding score (BS). Demonstration of the inheritance of the disorder could help to classify patients for whom insufficient hemostatic challenges may produce a falsely reassuring BS (like in children). Using this approach, mild VWD appears to be mostly composed of type 1 cases. Complemented by the results of desmopressin trial infusion, these parameters form the basis for a clinically oriented classification of all forms of VWD and may be useful for selecting the best treatment according to the severity of the disease. Although few molecular data have revealed practical utility, there is no doubt that the clarification of the molecular pathophysiology of VWD has allowed the unification of this complex disorder into a simple conceptual framework. This framework underlies the proposed utilization of simple phenotypic markers for optimizing treatments in individual patients.

Variability in bleeding phenotype in Amish carriers of haemophilia B with the 31008 C-->T mutation

The aim of this study was to characterize the variability of bleeding phenotype and its association with plasma factor IX coagulant activity (FIX:C) in haemophilia B carriers in a large Amish pedigree with a unifying genetic mutation, C-to-T transition at base 31008 of the factor IX gene (Xq27.1-27.2). A cross-sectional survey of haemophilia B carriers included a multiple choice questionnaire evaluating symptoms of mucocutaneous bleeding, joint bleeding and bleeding after haemostatic stress [menstruation, postpartum haemorrhage (PPH), dental extractions and invasive surgeries]. Severity of bleeding was graded as 0 to 4, 0 being no bleeding whereas 4 being severe bleeding. Association between total bleeding scores and the FIX:C was evaluated. Sixty-four haemophilia B carriers participated in this study. Median age: 18 years (range 1-70 years); median bleeding score: 1 (range 0-8). Besides PPH, isolated symptoms of bruising, epistaxis, menorrhagia and postsurgical bleeding including dental extraction were not associated with lower FIX:C. Bleeding score >/=3 was associated with involvement of at least two bleeding sites and a lower mean FIX:C of 42 +/- 10.3% (95% CI 36.4-47.7) while a score >3 had involvement of </=2 sites and higher mean FIX:C of 54.9 +/- 21.5% (95% CI 49-61), P = 0.005. Subcutaneous haematoma formation and bleeding after haemostatic stress requiring treatment were associated with bleeding scores >/=3. Phenotypic variability existed among the carriers of haemophilia B who belonged to a single pedigree carrying a single unifying mutation. The utility of bleeding scores to define bleeding phenotype precisely in haemophilia B carriers needs further evaluation.