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Type 3 von Willebrand disease (VWD3) is a rare and severe bleeding disorder characterized by often undetectable von Willebrand factor (VWF) plasma levels, a recessive inheritance pattern, and heterogeneous genotype. The objective of this study was to identify the VWF defects in 265 European and Iranian patients with VWD3 enrolled in 3WINTERS-IPS (Type 3 Von Willebrand International Registries Inhibitor Prospective Study). All analyses were performed in centralized laboratories. The VWF genotype was studied in 231 patients with available DNA (121 [115 families] from Europe [EU], and 110 [91 families] from Iran [IR]). Among 206 unrelated patients, 134 were homozygous (EU/IR = 57/77) and 50 were compound heterozygous (EU/IR = 43/7) for VWF variants. In 22 patients, no or only one variant was found. A total of 154 different VWF variants (EU/IR = 101/58 [5 shared]) were identified among the 379 affected alleles (EU/IR = 210/169), of which 48 (EU/IR = 18/30) were novel. The variants p.Arg1659*, p.Arg1853*, p.Arg2535*, p.Cys275Ser, and delEx1_Ex5 were found in both European and Iranian VWD3 patients. Sixty variants were identified only in a single allele (EU/IR = 50/10), whereas 18 were recurrent (≥3 patients) within 144 affected alleles. Nine large deletions and one large insertion were found. Although most variants predicted null alleles, 21% of patients carried at least 1 missense variant. VWD3 genotype was more heterogeneous in the European population than in the Iranian population, with nearly twice as many different variants. A higher number of novel variants were found in the Iranian VWD3 patients.

Background Type 3 von Willebrand's disease (VWD) patients present markedly reduced levels of von Willebrand factor and factor VIII. Because of its rarity, the bleeding phenotype of type 3 VWD is poorly described, as compared to type 1 VWD. Aims To evaluate the frequency and the severity of bleeding symptoms across age and sex groups in type 3 patients and to compare these with those observed in type 1 VWD patients to investigate any possible clustering of bleeding symptoms within type 3 patients. Methods We compared the bleeding phenotype and computed the bleeding score (BS) using the MCMDM-1VWD bleeding questionnaire in patients enrolled in the 3WINTERS-IPS and MCMDM-1VWD studies. Results In 223 unrelated type 3 VWD patients, both the BS and the number of clinically relevant bleeding symptoms were increased in type 3 as compared to type 1 VWD patients (15 versus 6 and 5 versus 3). Intracranial bleeding, oral cavity, hemarthroses, and deep hematomas were at least five-fold over-represented in type 3 VWD. A more severe bleeding phenotype was evident in patients having von Willebrand factor antigen levels

Background\ud The phenotypic diagnosis of von Willebrand disease (VWD) is a multistep process with classification dependent on the quantification of von Willebrand factor (VWF) multimeric structure. VWF multimer analysis is a technically challenging, lengthy and non‐standardised assay, usually performed in specialist laboratories. Recently, a new semi‐automated multimer assay, the Hydragel 5 von Willebrand multimers (H5VWM) has become available.\ud \ud Objectives\ud This study, performed in two European centres, compared existing in‐house multimer assays to the H5VWM in individuals with and without VWD.\ud \ud Results\ud Overall agreement of 91.1% was observed in 74 individuals with normal VWF levels, 57 patients grouped as type 1 VWD, 33 type 2A, 16 type 2B, 28 type 2M, 11 type 2N. Patients tested following Desmopressin or VWF concentrate, with thrombotic thrombocytopenic purpura and acquired von Willebrand syndrome were also evaluated. Many of the discrepancies between methods were in patients with genetic mutations linked to more than one type of VWD including p.R1374C/H and p.R1315C. Quantifiable multimer results were available within one working day. Densitometry improved the interpretation of the multimers with slight structural variations that were not apparent by visual inspection of the in‐house method.\ud \ud Conclusions\ud 5VWM was a rapid, sensitive, standardised assay which used existing technology and could be included as an initial screen of VWF multimers in a VWD diagnostic algorithm in conjunction with traditional multimer analysis.

Next generation DNA sequencing (NGS) has the potential to improve the diagnostic and prognostic utility of newborn screening programmes. This study assesses the feasibility of automating NGS on dried blood spot (DBS) DNA in a United Kingdom National Health Service (UK NHS) laboratory. An NGS panel targeting the entire coding sequence of five genes relevant to disorders currently screened for in newborns in the UK was validated on DBS DNA. An automated process for DNA extraction, NGS and bioinformatics analysis was developed. The process was tested on DBS to determine feasibility, turnaround time and cost. The analytical sensitivity of the assay was 100% and analytical specificity was 99.96%, with a mean 99.5% concordance of variant calls between DBS and venous blood samples in regions with &ge, 30&times, coverage (96.8% across all regions, all variant calls were single nucleotide variants (SNVs), with indel performance not assessed). The pipeline enabled processing of up to 1000 samples a week with a turnaround time of four days from receipt of sample to reporting. This study concluded that it is feasible to automate targeted NGS on routine DBS samples in a UK NHS laboratory setting, but it may not currently be cost effective as a first line test.

ispartof: JOURNAL OF THROMBOSIS AND HAEMOSTASIS vol:17 issue:8 pages:1253-1260 ispartof: location:England status: published

The fifth Åland Island meeting on von Willebrand disease (VWD) was held on the Åland Islands, Finland, from 22 to 24 September 2016 – 90 years after the first case of VWD was diagnosed in a patient from the Åland Islands in 1926. This meeting brought together experts in the field of VWD to share knowledge and expertise on current trends and challenges in VWD. Topics included the storage and release of von Willebrand factor (VWF), epidemiology and diagnostics in VWD, treatment of VWD, angiogenesis, and VWF inhibitors.

Background Congenital afibrinogenemia (OMIM #202400) is a rare coagulation disorder that was first described in 1920. It is transmitted as an autosomal recessive trait that is characterized by absent levels of fibrinogen (factor I) in plasma. Consanguinity in Pakistan and its neighboring countries has resulted in a higher number of cases of congenital fibrinogen deficiency in their respective populations. This study focused on the detection of mutations in fibrinogen genes using DNA sequencing and molecular modeling of missense mutations in all three genes [Fibrinogen gene alpha (FGA), beta (FGB) and gamma (FGG)] in Pakistani patients. Methods This descriptive and cross sectional study was conducted in Karachi and Lahore and fully complied with the Declaration of Helsinki. Patients with fibrinogen deficiency were screened for mutations in the Fibrinogen alpha (FGA), beta (FGB) and gamma (FGG) genes by direct sequencing. Molecular modeling was performed to predict the putative structure functional impact of the missense mutations identified in this study. Results Ten patients had mutations in FGA followed by three mutations in FGB and three mutations in FGG, respectively. Twelve of these mutations were novel. The missense mutations were predicted to result in a loss of stability because they break ordered regions and cause clashes in the hydrophobic core of the protein. Conclusions Congenital afibrinogenemia is a rapidly growing problem in regions where consanguinity is frequently practiced. This study illustrates that mutations in FGA are relatively more common in Pakistani patients and molecular modeling of the missense mutations has shown damaging protein structures which has profounding effect on phenotypic bleeding manifestations in these patients.

Molecular genetic tools are widely applied in inherited bleeding disorders. New genes involved in haemorrhagic disorders have been identified by genome wide linkage analysis on families with a specific phenotype. LMNA1 or MCFD in combined FV/FVIII-deficiency and VKORC1 in vitamin K coagulation factor deficiency type 2 are two examples. Identification of the causative gene mutation has become standard for most bleeding disorders. Knowledge of the causative mutation allows genetic counselling in affected families and most importantly adds to the pathophysiological understanding of phenotypes. Haemophilia A represents a model as the F8 gene mutation predicts the risk of developing an inhibitor and more recently also the bleeding phenotype. In this review novel genetic diagnostic strategies for bleeding disorders are outlined and inhibitor formation is presented as an example for clinical relevant phenotype/genotype correlation studies.

Molecular genetic analysis of families with hemophilia and other heritable bleeding disorders is a frequently requested laboratory investigation. In the United Kingdom, laboratories undertaking genetic testing must participate in a recognized external quality assessment scheme for formal accreditation. The UK National External Quality Assessment Scheme (UK NEQAS) for heritable bleeding disorders was established in its current format in 2003, and currently has 27 registered participants in the United Kingdom, the European Union (EU), and the non-EU countries. Two exercises per annum are circulated to participants comprising either whole blood or DNA isolated from cell lines, and laboratories are allowed 6 weeks to analyze the samples and generate a report. Reports are assessed by a panel comprising clinicians and scientists with expertise in this area. Samples to date have involved analysis of the F8 gene (10 exercises), the F9 gene (4 exercises), and the VWF gene (3 exercises) and have comprised a wide spectrum of mutations representing the routine workload encountered in the molecular genetics laboratory. The majority of laboratories in each exercise passed, but a small number did not and reasons for failing included clerical errors, genotyping inaccuracies, and a failure to correctly interpret data. Overall we have seen an improvement in quality of reports submitted for assessment, with a more concise format that will be of value to referring clinicians and counsellors. Informal feedback from participants has been very positive.

Congenital defects of platelets or plasma proteins involved in blood coagulation generally lead to bleeding disorders. In some of these disorders, patients with a severe phenotype are prone to spontaneous bleeds with critical consequences. This situation occurs more commonly in haemophilia A and haemophilia B and to a certain extent in severe forms (type 3) of von Willebrand disease. Defects in other plasma coagulation proteins and platelet factors are relatively rare, with an incidence of ≤ 1: 1-2 million. Molecular genetic studies of the human coagulation factors, especially factors VIII and IX, have contributed to a better understanding of the biology of these genetic disorders, the accurate detection of carriers and genetic counselling, and have also fostered new therapeutic strategies. This article reviews the evolution of genetics over the last five decades as a tool for bleeding disorder investigations, the recent advances in molecular techniques that have contributed to improved genetic diagnosis of this condition, and the development and utility of proficiency testing programmes and reference materials for genetic diagnosis of bleeding disorders.

Summary Haemophilia A is caused by a reduction in clotting factor VIII (FVIII). FVIII coagulant activity (FVIII:C) can be measured by three methods; the one-stage activated partial thromboplastin time-based clotting assay, the two-stage Xa generation-based clotting assay and the chromogenic Xa generation-based assay. The FVIII:C of most patients with haemophilia A are concordant regardless of the assay method employed. Up to a third of patients show assay discrepancy, usually with the two-stage and chromogenic assays being much lower than the one-stage assay. Very rarely, patients have been reported with lower one-stage compared to two-stage and chromogenic assays, but here we report that the mutation p.Tyr365Cys accounts for most of these patients and, at least in the UK, is not rare. We have identified this mutation in 23 different families. Affected male index individuals had a lower mean one-stage FVIII:C of 27 iu/dl compared to two-stage FVIII:C mean of 77 iu/dl. Affected individuals had minimal or absent bleeding symptoms and when these were present they were usually in patients with another co-inherited bleeding disorder. Affected individuals often had surgery without the need to correct the one-stage FVIII:C.

The UK treatment strategy for von Willebrand disease (VWD) is based on consensus guidelines produced by the United Kingdom Haemophilia Centre Doctors' Organization (UKHCDO) relating to the diagnosis and management of VWD. Selection of therapeutic products suitable for treatment of this complex inherited bleeding disorder is based on the observed response. Desmopressin (DDAVP), an analog of vasopressin, is the recommended treatment in individuals who respond to this drug on trial infusion. DDAVP clearly has no effect in type 3 VWD but may have variable clinical effect in individuals with other subtypes or may be contraindicated in some cases. In patients where DDAVP treatment is unsuitable, replacement factor concentrate containing von Willebrand factor (VWF) is the recommended alternative. Relevant concentrates are available for all patients in the United Kingdom, and treatment is administered by a network of 67 hemophilia treatment centers that also provide specialist care for individuals diagnosed with VWD. Patients diagnosed with the condition are registered on a national inherited bleeding disorder database administered by the UKHCDO on behalf of the Department of Health to aid in service planning and commissioning. Genetic testing is employed in the United Kingdom in certain situations, which is also performed in accordance with current UKHCDO guidelines.

von Willebrand disease is a common inherited bleeding disorder characterized by excessive mucocutaneous bleeding. Characteristic bleeding symptoms include epistaxis, easy bruising, oral cavity bleeding, menorrhagia, bleeding after dental extraction, surgery, and/or childbirth, and in severe cases, bleeding into joints and soft tissues. There are three subtypes: types 1 and 3 represent quantitative variants and type 2 is a group of four qualitative variants: (1) type 2A-characterized by defective von Willebrand factor-dependent platelet adhesion because of decreased high-molecular-weight von Willebrand factor multimers, (2) type 2B-caused by pathologically increased von Willebrand factor-platelet interactions, (3) type 2M-caused by decreased von Willebrand factor-platelet interactions not based on the loss of high-molecular-weight multimers, and (4) type 2N-characterized by reduced binding of von Willebrand factor to factor VIII. The diagnosis of von Willebrand disease requires specialized assays of von Willebrand factor and/or molecular genetic testing of von Willebrand factor. Severe bleeding episodes can be prevented or controlled with intravenous infusions of virally inactivated plasma-derived clotting factor concentrates containing both von Willebrand factor and factor VIII. Depending on the von Willebrand disease type, mild bleeding episodes usually respond to intravenous or subcutaneous treatment with desmopressin, a vasopressin analog. Other treatments that can reduce symptoms include fibrinolytic inhibitors and hormones for menorrhagia.

Background: The type 3 Von Willebrand International RegistrieSInhibitor Prospective Study (3WINTERS-IPS) is a no-profit, investigator initiated, multicenter, European-Iranian observational, retrospective and prospective study on patients with diagnosis of type 3 VWD. Patients with type 3 von Willebrand Disease (VWD3) have markedly reduced levels of von Willebrand factor (VWF) and very severe bleeding phenotype. Due to the recessive inheritance pattern, VWD3 is by definition a rare bleeding disorder (1:Million) but its prevalence may increase in countries like Iran with consanguineous marriages. Aim: To identify the VWF genetic defects in a cohort of European and Iranian patients with previously diagnosed VWD3 enrolled into the 3WINTERS-IPS project. Methods: Patients classified locally as VWD3 were enrolled in the study following informed consent. 141 patients were from 9 different European countries and 119 patients were from the Islamic Republic of Iran. Plasma/buffy-coat samples were sent to expert labs to confirm patient's laboratory phenotype and to perform molecular analysis. PCR and Sanger sequencing/ next generation sequencing and multiplex-ligation dependent probe amplification were used in Hamburg, Sheffield and Milan to confirm previously identified variants or to seek previously unidentified variants. Results: DNA samples from 122 patients from Europe and 114 patients from Iran were analyzed at the molecular level. Of the 236 VWD3 patients under evaluation 24 are still in progress. Of the 212 fully evaluated patients 139 were homozygous (EU/IR=46/93) and 43 were compound heterozygous (EU/IR=36/7). In the remaining 30 patients no variants were identified in 19 samples (EU/IR=6/13) and only one variant was found in the remaining 11 cases (EU/IR=10/1). 135 (EU/IR=82/53) different gene defects were identified among the 375 (EU/IR=174/201) alleles found in this study. Of these 135 variants identified 51(EU/IR=22/29) were not reported on the www.ensembl.org database. The distribution of the different type of variants identified in the two populations is shown in the Figure. The two charts are showing quite similar percentages of the variants identified, with a main exception for the Small deletions and Small insertions. Only five variants are shared among the two populations. Three of these are the "hotspot" variants at the Arg codon, p.Arg1659* (EU/IR=9/8), p.Arg1853* (EU/IR=2/3) and p.Arg2535* (EU/IR=1/2). However, a missense variant , p.Cys275Ser (EU/IR=1/2) and a large deletion, delEx1_Ex5 (EU/IR=1/2) were also found in both populations. Fifteen variants were recurrent and were found in 154 alleles, whereas 49 variants were found only once in the heterozygous state (EU/IR=40/9) and 50 variants were found only twice, mainly in the homozygous state (EU/IR=25/25). Six large deletions were identified (delEx1_Ex3, delEx1_Ex5, delEx14_Ex15, delEx17, delEx35_Ex52 and delEx1_Ex52) and a duplication (dupEx1_Ex28), nevertheless 52 alleles with missense variants were identified (EU/IR=20/32). Discussion: As expected, the majority of the Iranian patients were found to be homozygous (Homozygous/Compound Heterozygous=93/7) reflecting a high rate of consanguinity, nevertheless half of the European patients were found to be homozygous (Homozygous/Compound Heterozygous=46/36). The European populations demonstrated a higher heterogeneity of variants with 82 different variants among the 175 mutated alleles vs 53 different variants among the 201 mutated alleles identified in the Iranian population. Nevertheless, a higher number of previously unreported variants was found in the Iranian population (29) vs the European one (22), probably due to bias of previous investigations performed in European patients. Figure Figure. Disclosures Peyvandi: Ablynx: Other: Member of Advisory Board, Speakers Bureau; Shire: Speakers Bureau; Roche: Speakers Bureau; Grifols: Speakers Bureau; Grifols: Speakers Bureau; Novo Nordisk: Speakers Bureau; Sobi: Speakers Bureau; Sobi: Speakers Bureau; Novo Nordisk: Speakers Bureau; Kedrion: Consultancy; Novo Nordisk: Speakers Bureau; Octapharma US: Honoraria; Novo Nordisk: Speakers Bureau; Sobi: Speakers Bureau; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Kedrion: Consultancy; Novo Nordisk: Speakers Bureau; Kedrion: Consultancy; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Octapharma US: Honoraria; Shire: Speakers Bureau; Roche: Speakers Bureau; Kedrion: Consultancy; Kedrion: Consultancy; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Octapharma US: Honoraria; Octapharma US: Honoraria; Sobi: Speakers Bureau; Roche: Speakers Bureau; Octapharma US: Honoraria; Shire: Speakers Bureau; Sobi: Speakers Bureau; Roche: Speakers Bureau; Roche: Speakers Bureau; Shire: Speakers Bureau; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Grifols: Speakers Bureau; Grifols: Speakers Bureau; Grifols: Speakers Bureau; Shire: Speakers Bureau. Schneppenheim:CSL Behring: Consultancy; SHIRE: Consultancy. Berntorp:Octapharma: Consultancy; CSL Behring: Consultancy; Shire: Consultancy, Other: honoraria for lecturing . Eikenboom:CSL: Research Funding. Mannucci:Bayer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kedrion: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Grifols: Speakers Bureau; Alexion: Speakers Bureau; Baxalta/Shire: Speakers Bureau; Novo Nordisk: Speakers Bureau. Mazzucconi:Baxalta-Shire: Consultancy, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Novartis,: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Novo Nordisk: Consultancy, Speakers Bureau; CSL Behring: Consultancy, Speakers Bureau. Oldenburg:Swedish Orphan Biovitrum: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Grifols: Honoraria, Membership on an entity's Board of Directors or advisory committees; Biogen Idec: Honoraria, Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Biotest: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; CSL Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Patients with type 3 von Willebrand Disease (VWD) usually have markedly reduced FVIII/VWF levels and very severe bleeding manifestations but, because of their rarity, their bleeding phenotype is poorly described. We aimed at evaluating the distribution of bleeding symptoms in patients with type 3 VWD, comparing them with previously available data from a cohort of type 1 patients, and describing site-specific clustering of bleeding symptoms in these patients. We analyzed clinical data from the type 3 Von Willebrand International RegistrieS Inhibitor Prospective Study (3WINTERS-IPS),a no-profit, investigators initiated, multicenter, European-Iranian observational, retrospective and prospective study on patients with diagnosis of type 3 VWD. Aims of the 3WINTERS-IPS is 3-fold: a) to identify the main phenotypic and molecular characteristics of a large cohort of VWD patients; b) to evaluate the risk factors responsible for the severe bleeding phenotype; c) to assess the efficacy and safety of the treatment with VWF concentrates with or without FVIII including the risk of anti-VWF antibodies. Retrospective information on bleeding symptoms at presentation was collected using the MCMDM-1 VWD bleeding questionnaire, and bleeding severity summarized as bleeding score. Individual bleeding symptoms were considered as relevant when having a score >1 (hence requiring medical attention). Data was compared with that retrieved from the MCMDM-1 VWD study database on patients affected by type 1 VWD (index cases and affected family members). The study enrolled a total of 260 patients, of which we analysed 243 patients with available bleeding score at recruitment. The median age at study inclusion was 29 years (interquantile range, 26.5 years); 140 were females (53.8%). There were 108 patients of Iranian descent, while the remaining of patients were from Europe. The median number of bleeding symptoms was 5, and the median bleeding score was 15 (interquantile range, 13). Only 7/243 patients (2.8%) had a single bleeding symptom. Epistaxis was the most frequent relevant symptom, being present in 195 patients (80.2%), followed by menorrhagia in 99 females (70.7%). Males had a higher frequency of hemarthroses and hematomas than females (53.4% vs 42.1% and 40.8% vs 27.1%, respectively). When comparing the clinical presentation of type 3 vs. type 1 VWD, clearly increased bleeding scores were evident for all age-classes and even in paediatric cases. The association between symptoms having a relative frequency >20% is presented in the circle diagram, showing that some symptoms appeared to cluster with others in a variable degree (e.g., menorrhagia with epistaxis, hemarthrosis or oral cavity bleeding; post-extraction bleeding again with epistaxis, hemarthrosis or oral cavity bleeding; surgical bleeding or gastrointestinal bleeding with epistaxis alone). These findings confirm the severity of type 3 VWD and extend the knowledge of symptoms distribution in the widest available cohort of type 3 VWD patients. Disclosures Tosetto: Stago, Novo-Nordisk, BMS: Speakers Bureau; Werfen: Other: Member of Advisory Board, Speakers Bureau. Berntorp:Octapharma: Consultancy; CSL Behring: Consultancy; Shire: Consultancy, Other: honoraria for lecturing . Eikenboom:CSL: Research Funding. Mazzucconi:Baxalta-Shire: Consultancy, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Novartis,: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Novo Nordisk: Consultancy, Speakers Bureau; CSL Behring: Consultancy, Speakers Bureau. Oldenburg:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Biogen Idec: Honoraria, Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria, Membership on an entity's Board of Directors or advisory committees; Grifols: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; CSL Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biotest: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Swedish Orphan Biovitrum: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Peyvandi:Kedrion: Consultancy; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Shire: Speakers Bureau; Roche: Speakers Bureau; Shire: Speakers Bureau; Kedrion: Consultancy; Kedrion: Consultancy; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Grifols: Speakers Bureau; Roche: Speakers Bureau; Octapharma US: Honoraria; Octapharma US: Honoraria; Sobi: Speakers Bureau; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Kedrion: Consultancy; Shire: Speakers Bureau; Roche: Speakers Bureau; Roche: Speakers Bureau; Novo Nordisk: Speakers Bureau; Shire: Speakers Bureau; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Grifols: Speakers Bureau; Shire: Speakers Bureau; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Grifols: Speakers Bureau; Novo Nordisk: Speakers Bureau; Octapharma US: Honoraria; Octapharma US: Honoraria; Sobi: Speakers Bureau; Grifols: Speakers Bureau; Grifols: Speakers Bureau; Kedrion: Consultancy; Sobi: Speakers Bureau; Roche: Speakers Bureau; Novo Nordisk: Speakers Bureau; Novo Nordisk: Speakers Bureau; Novo Nordisk: Speakers Bureau; Sobi: Speakers Bureau; Octapharma US: Honoraria; Sobi: Speakers Bureau. Schneppenheim:SHIRE: Consultancy; CSL Behring: Consultancy. Tiede:Alnylam, Bayer, Biogen Idec, Biotest, Bristol-Myers-Squibb, Boehringer Ingelheim, CSL Behring, Leo Pharma, Novo Nordisk, Octapharma, Pfizer, Roche, Shire, and SOBI: Consultancy; Alnylam, Bayer, Biogen Idec, Biotest, Bristol-Myers-Squibb, Boehringer Ingelheim, CSL Behring, Leo Pharma, Novo Nordisk, Octapharma, Pfizer, Roche, Shire, and SOBI: Honoraria; Alnylam, Bayer, Biogen Idec, Biotest, Bristol-Myers-Squibb, Boehringer Ingelheim, CSL Behring, Leo Pharma, Novo Nordisk, Octapharma, Pfizer, Roche, Shire, and SOBI: Research Funding.

Summary. Haemophilia A and B in one individual may arise from co-incident inheritance of independent mutations in the F8 and F9 genes. However, this association is rare and has been studied poorly at a genetic level. We report a male patient with abnormal bleeding and reduced factor VIII:C (26 IU dL−1) and factor IX:C (35 IU dL−1). This index case harboured a F8 c.979C>G transversion (predictive of p.Leu327Val) and a F9 c.845A>G transition (predictive of p.His282Arg) which have been previously associated with mild haemophilia A and B, respectively. Identical F8 and F9 mutations were identified in the mother and maternal grandmother. However, an affected maternal uncle showed only the F8 c.979C>G mutation, indicating haemophilia A alone. The sister of the index case was heterozygous only for F9 c.845A>G, indicating carriership of haemophilia B alone. The non-Mendelian inheritance of F8 c.979C>G and F9 c.845A>G in this kindred is consistent with recombination between F8 and F9 and illustrates the large recombination distance between these loci. Recognition of this phenomenon was essential for accurate genetic counselling in this kindred.

P>The relationships between the Platelet Function Analyzer (PFA)-100 and von Willebrand factor (VWF) levels and bleeding score (BS) were evaluated within a multicentre project on Molecular and Clinical Markers for the Diagnosis and Management of type 1 von Willebrand disease (MCMDM-1VWD). PFA-100 closure time, either with epinephrine (EPI) or adenosine diphosphate (ADP)-cartridges, was measured in 107 index cases, 105 affected and 71 unaffected family members, and 79 healthy controls. By regression analysis VWF levels were strongly related to both closure times, with a non-linear progression. In a multiple stepwise regression model, age- and sex-adjusted PFA-100 ADP and VWF ristocetin cofactor activity (VWF:RCo) were independently associated with BS. Most of the variation of BS was predicted by PFA-100 ADP and VWF:RCo alone. In the subgroup of patients with subtle abnormalities of the multimeric pattern, VWF was invariably reduced and closure time prolonged in almost all of them. Neither PFA-100 ADP nor EPI closure times appeared to significantly improve the diagnostic capability of VWF antigen (VWF:Ag) measurement. Thus, in an unselected population a normal PFA-100 would be useful to exclude VWD, but whether it could replace the more specific VWF assay in patients with significant mucocutaneous bleeding symptoms remains to be investigated prospectively.

SUMMARY: Deficient or defective coagulation factor VIII (FVIII) and von Willebrand factor (VWF) can cause bleeding through congenital deficiency or acquired inhibitory antibodies. Recent studies on type 1 von Willebrand's disease (VWD), the most common form of the disease, have begun to explain its pathogenesis. Missense mutations of varying penetrance throughout VWF are the predominant mutation type. Other mutation types also contribute while about one-third of patients have no mutation identified. Enhanced clearance and intracellular retention contribute to pathogenic mechanisms. Chromogenic substrate (CS) methods to determine FVIII coagulant activity have several advantages over one-stage methods, which include minimal influence by variable levels of plasma components, notably lupus anticoagulant. Direct proportionality between FVIII activity and FXa generation results in high resolution at all FVIII levels, rendering the CS method suitable for measuring both high and low levels of FVIII activity. FVIII inhibitors in patients with inherited or acquired haemophilia A present several challenges in their detection and accurate quantification. The Nijmegen method, a modification of the Bethesda assay is recommended for inhibitor analysis by the International Society on Thrombosis and Haemostasis. Understanding potential confounding factors including heparin and residual FVIII in test plasma, plus optimal standardization can reduce assay coefficient of variation to 10-20%.These areas are all explored within this article.

von Willebrand disease (VWD) is a common autosomally inherited bleeding disorder associated with mucosal or trauma-related bleeding in affected individuals. VWD results from a quantitative or qualitative deficiency of von Willebrand factor (VWF), a glycoprotein that is essential for primary haemostasis and that carries and protects coagulation factor VIII (FVIII) in the circulation. Through characterization of the phenotype and identification of mutations in the VWF gene in patients with VWD, understanding of the genetics and biochemistry of VWF and VWD has advanced considerably. The importance of specific regions of VWF for its interaction with other components of the vasculature has been revealed, and this has facilitated the formal classification of VWD into three subtypes based upon quantitative (types 1 and 3) and qualitative (type 2) deficiency of VWF. The underlying genetic lesions and associated molecular pathology have been identified in many cases of the qualitative type 2 VWD variants (2A, 2B, 2M, 2N) and in the severe quantitative deficiency, type 3 VWD. However in the partial quantitative deficiency, type 1 VWD, the picture is less clear: there is a variable relationship between plasma levels of VWF and bleeding, there is incomplete penetrance and variable expressivity within affected families, the causative molecular defect is unknown in a substantial number of cases, and even in those cases where the causative mutation is known, the associated molecular pathology is not necessarily understood. This guideline aims to provide a framework for best laboratory practice for the genetic diagnosis of VWD, based upon current knowledge and understanding.

Inherited bleeding, thrombotic and platelet disorders (BPDs) are diseases affecting approximately 300 individuals per million births. With the exception of haemophilia and von Willebrand disease patients, a molecular analysis for patients with a BPD is often unavailable. Many specialised tests are usually required to reach a putative diagnosis and they are typically performed in a step-wise manner to control costs. This approach causes delays and a conclusive molecular diagnosis is often never reached which can compromise treatment and impede rapid identification of affected relatives. To address this unmet diagnostic need, we designed a high-throughput sequencing (HTS) platform targeting 63 genes relevant for BPDs. The platform can call single nucleotide variants (SNVs), short insertions/deletions (indels) and large copy number variants (CNVs), though not inversions, which are subjected to automated filtering for diagnostic prioritization, resulting in an average of 5.34 candidate variants per individual. We sequenced 159 and 137 samples respectively from cases with and without previously known causal variants. Among the latter group, 61 cases had clinical and laboratory phenotypes indicative of a particular molecular etiology while the remainder had ana priorihighly uncertain etiology. All previously detected variants were recapitulated and, when the etiology was suspected but unknown or uncertain, a molecular diagnosis was reached in 56 of 61 and only eight of 76 cases, respectively. The latter category highlights the need for further research into novel causes of BPDs. The ThromboGenomics platform thus provides an affordable DNA-based test to diagnose patients suspected of having a known inherited BPD.

Since its first description in 1926, the precise nature and indeed significance of von Willebrand factor (VWD) in the area of human bleeding has been unsure and often controversial. The recognition of VWD as a distinct entity in blood and the cloning of the von Willebrand factor (VWF) gene in the 1980s encouraged both phenotypic and genotypic studies, culminating in 1994 with the recognition, by the VWF subcommittee of the Scientific and Standardization Committee (SSC) of International Society of Thrombosis and Haemostasy (ISTH), of three types of VWD, characterized by severe plasma VWF deficiency (type 3), functionally deficient plasma VWF (type 2) and reduced (below normal) levels of plasma VWF, which is functionally essentially normal (type 1; 70% of all cases). Since then, whereas gene analysis has recognized VWF gene (VWF) mutations in most individuals with type 3 and type 2 disease, the latter mutations correlating well with recognized functional domains within the VWF protein, few mutations have been reported in cases with type 1 VWD. This led to speculation that other factors, particularly ABO blood group, may be primarily responsible for the majority of such patients, perhaps combined with a generic bleeding tendency throughout the normal population. Recent large studies in Europe and Canada have considerably clarified this situation, revealing that the majority of type 1 VWD is associated with mutations within VWF. The role of these mutations in the aetiology of the disease opens up new approaches to the study of the diagnosis and treatment of the condition. Conversely, the lack of a change in the VWF gene in many recruited families will lead to enhanced efforts to identify non-VWF gene causes both at the genetic and epigenetic level.

Background: Presence of bleeding symptoms, inheritance and reduced von Willebrand factor (VWF) contribute to the diagnosis of type 1 von Willebrand disease (VWD). However, quantitative analysis of the importance of VWF antigen (VWF:Ag) and ristocetin cofactor activity (VWF:RCo) levels in the diagnosis is lacking. Objectives: To evaluate the relative contribution of VWF measurement to the diagnosis of VWD. Patients and methods: From the MCMDM-1VWD study cohort, 204 subjects (considered as affected by VWD based on the enrolling Center diagnoses and the presence of linkage with the VWF locus) were compared with 1155 normal individuals. Sensitivity, specificity and diagnostic positive likelihood ratios (LR) of VWF:Ag and VWF:RCo were computed. Results: ABO blood group was the variable most influencing VWF levels, but adjustment of the lower reference limit for the ABO group did not improve sensitivity and specificity of VWF:Ag or VWF:RCo. The lower reference limit (2.5th percentile) was 47 IU dL(-1) for both VWF:Ag and VWF:RCo and showed similar diagnostic performance [receiver-operator curve area: 0.962 and 0.961 for VWF:Ag and VWF:RCo, respectively; P = 0.81]. The probability of VWD was markedly increased only for values below 40 IU dL(-1) (positive LR: 95.1 for VWF:Ag), whereas intermediate values (40 to 60 IU dL(-1)) of VWF only marginally indicated the probability of VWD. Conclusions: Although the conventional 2.5 lower percentile has good sensitivity and specificity, only VWF:Ag or VWF:RCo values below 40 IU dL(-1) appear to significantly indicate the likelihood of type 1 VWD. The LR profile of VWF level could be used in a diagnostic algorithm.

von Willebrand disease (VWD) is the most common inherited bleeding disorder, and type 1 VWD is the most common VWD variant. Despite its frequency, diagnosis of type 1 VWD remains the subject of debate. In order to study the spectrum of type 1 VWD in the United States, the Zimmerman Program enrolled 482 subjects with a previous diagnosis of type 1 VWD without stringent laboratory diagnostic criteria. von Willebrand factor (VWF) laboratory testing and full-length VWF gene sequencing was performed for all index cases and healthy control subjects in a central laboratory. Bleeding phenotype was characterized using the International Society on Thrombosis and Haemostasis bleeding assessment tool. At study entry, 64% of subjects had VWF antigen (VWF:Ag) or VWF ristocetin cofactor activity below the lower limit of normal, whereas 36% had normal VWF levels. VWF sequence variations were most frequent in subjects with VWF:Ag

Inherited deficiencies of plasma proteins involved in blood coagulation generally lead to lifelong bleeding disorders, whose severity is inversely proportional to the degree of factor deficiency. Haemophilia A and B, inherited as X-linked recessive traits, are the most common hereditary hemorrhagic disorders caused by a deficiency or dysfunction of blood coagulation factor VIII (FVIII) and factor IX (FIX). Together with von Willebrand's disease, a defect of primary haemostasis, these X-linked disorders include 95% to 97% of all the inherited deficiencies of coagulation factors. The remaining defects, generally transmitted as autosomal recessive traits, are rare with prevalence of the presumably homozygous forms in the general population of 1:500,000 for FVII deficiency and 1 in 2 million for prothrombin (FII) and factor XIII (FXIII) deficiency. Molecular characterization, carrier detection and prenatal diagnosis remain the key steps for the prevention of the birth of children affected by coagulation disorders in developing countries, where patients with these deficiencies rarely live beyond childhood and where management is still largely inadequate. These characterizations are possible by direct or indirect genetic analysis of genes involved in these diseases, and the choice of the strategy depends on the effective available budget and facilities to achieve a large benefit. In countries with more advanced molecular facilities and higher budget resources, the most appropriate choice in general is a direct strategy for mutation detection. However, in countries with limited facilities and low budget resources, carrier detection and prenatal diagnosis are usually performed by linkage analysis with genetic markers. This article reviews the genetic diagnosis of haemophilia, genetics and inhibitor development, genetics of von Willebrand's disease and of rare bleeding disorders.

SummaryMolecular genetic analysis of families with haemophilia and other inherited bleeding disorders is nowa common laboratory investigation. In contrast to phenotypic testing in which strict quality control is adhered to, in haemophilia molecular genetic testing there has been a lack of any external quality assurance schemes. In 1998 the UK National External Quality Assessment Scheme (UK NEQAS) established a pilot quality assurance scheme for molecular genetic testing in haemophilia. Results from three initial surveys highlighted problems with the quality of samples when used to screen for the intron 22 inversion within the F8 gene. The scheme was re-launched in 2003, and since that time there have been five exercises involving whole blood or immortalised cell line DNA. The results together with an overall summary of the exercise are subsequently returned to participants. Exercises to date have focused exclusively on haemophilia A and QA, material has included screening for the intron 1 and intron 22 inversions as well as sequence analysis. A paper exercise circulated in 2003 highlighted problems with the format of reports and, following feedback to participants, onlya single error has been made in the subsequent four exercises. Participating laboratories now receive QA material every six months. Immortalised cell line material was introduced in 2005 and was shown to perform well. This will allow expansion of the scheme and a reduction in the dependence on blood donation.

The guideline group was selected to be representative of UKbased medical experts. MEDLINE and EMBASE were searched systematically for publications in English from 2002 using the key word Willebrand. The writing group produced the draft guideline, which was subsequently reviewed by the A United Kingdom Haemophilia Centre Doctors Organization (UKHCDO) advisory committee, a British Committee for Standards in Haematology (BCSH) sounding board of approximately 50 UK haematologists, and the BCSH executive; comments were incorporated where appropriate. The ‘GRADE’ system was used to quote levels and grades of evidence, details of which can be found in at http://www.bcshguidelines.com/BCSH_PROCESS/EVIDENCE_LEVELS_AND_ GRADES_OF_RECOMMENDATION/43_GRADE.html. The objective of this guideline is to provide healthcare professionals with clear guidance on the diagnosis and management of patients with von Willebrand disease.

The aim of molecular genetic analysis in families with haemophilia is to identify the causative mutation in an affected male as this provides valuable information for the patient and his relatives. For the patient, mutation identification may highlight inhibitor development risk or discrepancy between different factor VIII assays. For female relatives, knowledge of the familial mutation can facilitate carrier status determination and prenatal diagnosis. Recent advances in understanding mutations responsible for haemophilia and methods for their detection are presented. For reporting of such mutations, participation in external quality assessment ensures that essential patient and mutation details are routinely included and that pertinent information is incorporated in the interpretation. Fil: de Brasi, Carlos Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentina. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas "Mariano R. Castex"; Argentina Fil: El Maarri, O.. Universitat Bonn; Alemania Fil: Perry, D. J.. Universitat Bonn; Alemania Fil: Oldenburg, J.. Universitat Bonn; Alemania Fil: Pezeshkpoor, B.. Universitat Bonn; Alemania Fil: Goodeve, A.. Sheffield Children’s NHS Foundation Trust; Reino Unido. Sheffield University Medical School; Reino Unido

SummaryA cohort of 79 previously untreated patients (PUPs) with moderatesevere haemophilia A (baseline Factor VIII

Conformation sensitive gel electrophoresis (CSGE) was confirmed as an effective procedure for screening the factor IX (FIX) gene by detecting 10/10 previously known FIX gene mutations. The FIX genes of a further 11 haemophilia B patients with unknown mutations were then screened and an abnormal CSGE profile was identified in all cases. Subsequent DNA sequencing demonstrated one of these to be a novel mutation (31133insT, Arg338Fs), the remaining 10 having been previously reported on the haemophilia B database. Mutation screening of the FIX gene using CSGE was demonstrated to be a rapid and efficient means of carrier analysis in families with haemophilia B.

SummaryUsing an ELISA-based method to detect type 2N von Willebrand disease (VWD), we found two individuals with absent FVIII binding. Direct sequencing of the FVIII binding region of the von Willebrand factor (VWF) gene showed that one individual had an R854Q substitution whilst the other had a T791M substitution. The very low FVIII binding and the VWF:Ag levels in both individuals suggested a second defect on the other VWF allele. Conformation sensitive gel electrophoresis of polymerase chain reaction amplified DNA was used to detect an additional change in the VWF gene of each patient. Direct sequencing confirmed a previously unreported G to A transition in the donor splice site in intron 25 of both individuals which should result in a null allele. This was confirmed by mRNA analysis. These two individuals therefore have compound heterozygous VWD in which the only expressed allele has a type 2N mutation. In our population, such compound heterozygosity appears to be a significant cause of type 2N VWD.

Childhood lymphoblastic leukemia (ALL) is usually assumed to have been permanently eradicated in patients in long-term remission, but occasionally can recur after many years. To learn more about the problem, we studied a group of children whose leukemia had been in remission for 10 or more years before relapse and tried to determine whether they had true recurrences or second malignancies. We studied children treated on Medical Research Council ALL protocols between 1970 and 1984 and followed up by the Clinical Trial Service Unit in Oxford. Detailed clinical and laboratory data was collected from the centers concerned on all who were reported to have had a recurrence of their leukemia after 10 or more years from the time of achieving first complete remission (CR1). To prove that the relapse was a true recurrence rather than a second or secondary leukemia, DNA extracted from archived marrow smears was subjected to polymerase chain reaction (PCR) analysis for the presence of an identical Ig heavy chain (IgH) or T-cell receptor (TCR) gene rearrangement at initial diagnosis and subsequent relapse. A total of 1,134 of 2,746 children had survived 10 years or more (range, 10 to 24 years) in CR1 and of those, 12 (approximately 1%) had subsequently relapsed. Relapse blast cells were shown to express the common ALL antigen (CD 10) in all cases and an identical clonal IgH or TCR gene rearrangement was found on PCR analysis of DNA from diagnosis and relapse in all eight cases where DNA extraction was successful. A further program of therapy was successful in inducing a second CR in all patients, four of whom have succumbed to a second relapse after 12 to 27 months. The remaining eight are in continuing CR2 at a follow-up of 12 to 108 months (median, 52) from relapse. Although the risk of relapse of childhood ALL after 10 years in remission appears to be small (around 1%), it persists. This raises questions about how blasts can survive quiescent for so long and when we can truly be confident of cure, if ever.

SummaryCausative mutations in the factor VIII gene of seven unrelated patients with severe haemophilia A were identified using the mutation screening procedure conformation sensitive gel electrophoresis (1) and characterised by direct sequencing. Female family members of all patients had requested either carrier status determination or prenatal diagnosis. However, lack of the factor VIII gene inversion, a prior family history or informative polymorphisms prevented diagnosis in these families. Identification of a mutation in each family enabled female carrier status to be determined in all cases. Six mutations were previously unreported. One Afro-Caribbean patient had two sequence changes; A670 2G and A6769G. The latter, resulting in Met2238Val and previously reported as a FVIII mutation, was shown to be polymorphic with a 42% heterozygosity rate in an Afro-Caribbean population. Conformation sensitive gel electrophoresis was found to be technically simple and efficient at locating previously unknown FVIII gene mutations.

The deficiency or abnormal function of von Willebrand factor (VWF) causes von Willebrand disease (VWD), the most frequent inherited bleeding disorder. The laboratory diagnosis of VWD can be difficult as the disease is heterogeneous and an array of assays is required to describe the phenotype. Basic classification of quantitative (type 1 and 3) and qualitative (type 2) VWD variants requires determination of VWF antigenic (VWF:Ag) levels and assaying of VWF ristocetin cofactor (VWF:RCo) activity, determining the capacity of VWF to interact with the platelet GPIb-receptor. Knowing the VWF:RCo activity is essential for identifying, subtyping and monitoring VWD, but the assay is poorly standardized and many protocols do not fulfil the clinical need in all situations. This has led to the development of novel activity assays, independent of ristocetin, with enhanced assay characteristics. Results from the first independent clinical evaluations are promising, showing that they are reliable and suitable for VWD diagnosis. The qualitative type 2 VWF deficiency can be further divided into four different subtypes (A, B, M and N) using specific assays that explore other activities or the size distribution of VWF multimers. These methods are discussed herein. However, in a number of patients it may be difficult to correctly classify the VWD phenotype and genetic analysis may provide the best option to clarify the disorder, through mutation identification.

SummaryThe risk of developing factor VIII inhibitor antibodies in haemophilia A may relate both to factor VIII genotype and genes within the HLA complex known to influence immune response. We investigated a cohort of 176 patients with severe haemophilia A and with either high-level inhibitors (>10BU/ml) or with no history of an inhibitor, stratified according to the presence or absence of the factor VIII gene intron 22 inversion.HLA DRB1, DQA1 and DQB1 polymorphisms were determined by PCR. HLA frequencies from 137 United Kingdom controls were used for comparison. HLA phenotype frequency differences, expressed as odds ratios with 95% confidence intervals were as follows: HLA- DRB*1501, DQB 1*0602 and DQA1*0102 were all increased in frequency in patients with inhibitors, only DQA1*0102 reaching statistical significance (OR 2.7,1.2-5.9). These alleles form part of an established HLA haplotype. The frequencies of HLA-DRB 1*1501, DQB1*0602 and DQA1*0102 were particularly raised in patients with inhibitors and a factor VIII gene intron 22 inversion, although again only DQA1*0102 achieved significance (OR 3.1, 1.0-10.1). The frequency of DRB 1*01, DQB 1 *0501, DQA 1*0101 were also increased in inhibitor patients lacking the intron 22 inversion although this failed to achieve statistical significance. This data suggests that HLA class II profile constitutes a weak risk factor for developing inhibitor antibodies to factor VIII. This may be more pronounced in patients with an intron 22 inversion.

The activity of the factor VIII coagulation protein can be measured by three methods: a one or two-stage clotting assay and a chromogenic assay. The factor VIII activity of most individuals with mild hemophilia A is the same regardless of which method is employed. However, approximately 30% of patients show marked discrepancies in factor VIII activity measured with the different methods. The objective of this study was to investigate the incidence of assay discrepancy in our center, assess the impact of alternative reagents on factor VIII activity assays and determine the usefulness of global assays of hemostasis in mild hemophilia A. Factor VIII activity was measured in 84 individuals with mild hemophilia A using different reagents. Assay discrepancy was defined as a two-fold or greater difference between the results of the one-stage and two-stage clotting assays. Rotational thromboelastometry and calibrated automated thrombography were performed. Assay discrepancy was observed in 31% of individuals; 12% with lower activity in the two-stage assay and 19% with lower activity in the one-stage assay. The phenotype could not always be predicted from the individual’s genotype. Chromogenic assays were shown to be a suitable alternative to the two-stage clotting assay. Thromboelastometry was found to have poor sensitivity in hemophilia. Calibrated automated thrombography supported the results obtained by the two-stage and chromogenic assays. The current international guidelines do not define the type of assay to be used in the diagnosis of mild hemophilia A and some patients could be misclassified as normal. In our study, 4% of patients would not have been diagnosed on the basis of the one-stage factor VIII assay. Laboratories should use both one stage and chromogenic (or two-stage) assays in the diagnosis of patients with possible hemophilia A.

Von Willebrand disease is a common autosomal inherited bleeding disorder caused by quantitative or qualitative defects of von Willebrand factor, a multi-adhesive protein that binds platelets to exposed subendothelium and carries factor VIII in circulation. As a result of von Willebrand factor deficiency or abnormality, levels of factor VIII, the protein deficient in hemophilia A, may be variably reduced. Clinical manifestations are mainly represented by mucous membrane and of soft tissue bleeding. Their severity is variable depending on the degree of von Willebrand factor and factor VIII reduction. While a clear-cut diagnosis is easy in severe von Willebrand factor reductions, the advantage of pursuing a definite diagnosis in mild or dubious cases should be weighed against the risk of over-medicalization. The aim of treatment is to correct the dual defect of hemostasis caused by the abnormal/reduced von Willebrand factor and the concomitant deficiency of factor VIII. Desmopressin is the treatment of choice for type 1 von Willebrand disease patients with factor VIII and von Willebrand factor levels of 10 U/dL or over who have proved responsive to a test-infusion with the compound. Von Willebrand factor/factor VIII concentrates are needed when desmopressin is ineffective (mainly type 2 and 3 von Willebrand disease).

Almost half of all cases of severe hemophilia A are caused by recurrent DNA inversions, which disrupt the factor VIII (FVIII) gene. These inversions generally occur between a region of intron 22 (int22h) and one of two homologous copies of this region, located 300 to 400 kb telomeric to the FVIII gene. They are routinely detected by a Bcl I Southern blot assay in which the sizes of two of the three normal hybridization bands are characteristically altered. However, atypical hybridization patterns have been observed, and this report describes the first detailed analysis of a hemophilia A patient with such a pattern. The abnormal result was found to be caused by a novel FVIII inversion involving an extra copy of int22h from a site only 70 to 200 kb telomeric of the FVIII gene. Polymerase chain reaction (PCR) allowed one of the inversion junctions to be analyzed, showing that the int22h sequence at this inversion junction was truncated. This patient and his novel inversion provide further evidence that int22h is associated with instability in Xq28.

von Willebrand's disease (VWD) is probably the most common bleeding disorder, with some studies indicating that up to 1% of the population may have the condition. Over recent years interest in VWD has fallen compared to that of haemophilia, partly the result of focus on blood-borne diseases such as HIV and hepatitis. Now the time has come to revisit VWD, and in view of this some 60 international physicians with clinical and scientific interest in VWD met over 4 days in 2010 in the Aland islands to discuss state-of-the-art issues in the disease. The Aland islands are where Erik von Willebrand had first observed a bleeding disorder in a number of members of a family from Foglo, and 2010 was also the 140th anniversary of his birth. This report summarizes the main papers presented at the symposium; topics ranged from genetics and biochemistry through to classification of VWD, pharmacokinetics and laboratory assays used in the diagnosis of the disease, inhibitors, treatment guidelines in different age groups including the elderly who often have comorbid conditions that present challenges, and prophylaxis. Other topics included managing surgeries in patients with VWD and the role of FVIII in VWF replacement, a controversial subject.

Nucleotide variations not changing protein sequences are considered silent mutations; accumulating data suggest that they can, however, be important in human diseases.We report an altered splicing process induced by a silent substitution (c.7056CT) in the von Willebrand factor gene in a case of type 1 von Willebrand disease originally classified as lacking von Willebrand factor mutations.The c.7056CT synonymous substitution introduces a new donor splice site within exon 41, leading to messenger RNA lacking nucleotides 7055-7081 (c.7055_7081del). The encoded von Willebrand factor protein is predicted to lack amino acids 2352-2360 in the B2 domain. The patient's von Willebrand disease phenotype was characterized by reduced plasma and platelet von Willebrand factor, which was normal in function and multimer structure. In vitro expression studies demonstrated that co-transfection of equimolar c.7055_7081del and wild-type von Willebrand factor (mimicking the patient's heterozygous state) induced a 50% lower von Willebrand factor secretion than the wild type, while almost no von Willebrand factor secretion was seen with the mutated von Willebrand factor alone. The secreted von Willebrand factor was structurally and functionally normal, suggesting that the c.7056CT substitution behaves like a loss-of-function allele.This is the first report of a synonymous von Willebrand factor substitution being responsible for von Willebrand disease. Our findings suggest the need to reconsider the role of von Willebrand factor polymorphisms in von Willebrand disease.

Background: Accurate measurement of von Willebrand factor (VWF) is a critical requirement for the diagnosis of von Willebrand disease (VWD). Aim of the study: To evaluate the diagnostic efficiency of a rapid quantitative test for the measurement of VWF antigen (VWF:Ag) in type 1 VWD. Patients and methods: VWF: Ag was measured with an ELISA in a robotic instrument, as a reference method, and with a fully automated latex-immunoassay (LIA) on an ACL 9000 analyser in 1,716 subjects enrolled within the Molecular and Clinical Markers for Diagnosis and Management of Type 1 von Willebrand Disease (MCMDM-1VWD) Study. Among these subjects, 1,049 were healthy controls, 281 healthy family members and 386 affected members from 127 European families with type 1 VWD. Results: The assay linearity range was 10-125 IU/dL for LIA (R-2 = 0.99) and 5-133 IU/dL for ELISA (R-2 = 0.99). The inter-assay CV for low VWF levels (similar to 30 IU/dL) was 2% for the LIA test and 8.7 % for ELISA. The sensitivity for detection of type 1 VWD affected members was 86% and the specificity 91% for LIA, 87% and 90% for ELISA. A receiver-operator (ROC) analysis disclosed only a marginal difference between the two tests, LIA having a slightly greater area under the curve (0.94 vs. 0.93, p = 0.03). Conclusion: VWF: Ag LIA compared well to standard ELISA in this large population of patients and controls, showing better CV. However the lower detection limit for the VWF: Ag LIA compared to the VWF: Ag ELISA means that the LIA assay is less good at discriminating between type 3 VWD and moderate type 1 VWD. (C) 2010 Elsevier Ltd. All rights reserved.

There has been much recent data published on type 1 von Willebrand disease (VWD) predominantly from three multi-centre cohort studies. These data have influenced a revision of the classification of type 1 VWD and have important implications for the management of this disorder. Patients with low von Willebrand factor (VWF) levels tend to have VWF mutations and VWD is transmitted predictably within families. In patients with VWF levels close to the lower end of the normal range, candidate mutations are found less often, ABO blood group is a more important factor and the disease has variable heritability within families. The importance of bleeding symptoms, in addition to VWF levels, in the diagnosis of type 1 VWD has been highlighted.

The decreased survival of von Willebrand factor (VWF) in plasma has been implicated as a mechanism in a subset of type 1 von Willebrand disease (VWD) patients. We have previously reported that the ratio of plasma levels of VWF and its propeptide (VWFpp) can be used to identify patients with reduced VWF survival. In this study, we report the assay of VWFpp and VWF:Ag in 19 individuals recruited from 6 European centers within the MCMDM-1VWD study. Eight individuals had a VWF:Ag level less than 30 IU/dL. Seven of these patients had a robust desmopressin response and significantly reduced VWF half-life that was predicted by a markedly increased steady-state plasma VWFpp/VWF:Ag ratio. VWF mutations previously associated with reduced VWF survival were identified in each of the 7 individuals. Thus, a substantially increased ratio of steady-state VWFpp/VWF:Ag predicted a reduced VWF half-life in patients with markedly decreased VWF:Ag levels. These data indicate that a reduced VWF survival is found in a subpopulation of patients with type 1 VWD. The systematic assay of both plasma VWF and the VWF propeptide in moderately severe type 1 VWD patients may identify patients with a reduced VWF survival phenotype.