Episodic replacement of clotting factor concentrates does not prevent bleeding or musculoskeletal damage - the MUSFIH study.

PATIENTS AND METHODS: A longitudinal study was carried out in 255 children from 10 centres in nine developing countries over 5 years to assess the musculoskeletal outcome of children on episodic factor replacement. Outcome was documented by assessment of the annual joint bleeding rate (AJBR), WFH clinical and Pettersson radiological joint scores as well as the FISH score for activities. Of the 203 patients for whom data was available at the end of 5 years, 164 who had received only episodic treatment are included in this report. RESULTS: The median age at the beginning of the study was 10 years (IQR 7-12). The median clotting factor concentrate (CFC) usage was 662 IU kg-1 year-1 (IQ range: 280-1437). The median AJBR was 10 (IQ range: 5-17). The median AJBR was higher in the older children with the median being 5 for the 5 year old child, while it was 9 for the 10 year old and 11 for children older than 15. Given the episodic nature of the replacement therapy, those with a higher AJBR used significantly greater annual CFC doses (P < 0.001); The median change in WFH clinical score and Pettersson radiological score over the 5 years was 0.4/year for each, while the FISH deteriorated at a rate of 0.2/year with poor correlation of these changes with CFC dose. WFH and FISH scores were significantly worse in those with an AJBR of >3 per year (P = 0.001). The change in the Pettersson score was significantly more in those with an AJBR of >5 per year (P = 0.020). Significant changes in FISH scores were only noted after 10 years of age. CONCLUSION: Episodic CFC replacement over a large range of doses does not alter the natural course of bleeding in haemophilia or the musculoskeletal deterioration and should not be recommended as a long term option for treatment. Prophylaxis is the only way to preserve musculoskeletal function in haemophilia.

A phylogenetic analysis using full-length viral genomes of South American dengue serotype 3 in consecutive Venezuelan outbreaks reveals a novel NS5 mutation.

Dengue virus currently causes 50-100 million infections annually. Comprehensive knowledge about the evolution of Dengue in response to selection pressure is currently unavailable, but would greatly enhance vaccine design efforts. In the current study, we sequenced 187 new dengue virus serotype 3 (DENV-3) genotype III whole genomes isolated from Asia and the Americas. We analyzed them together with previously-sequenced isolates to gain a more detailed understanding of the evolutionary adaptations existing in this prevalent American serotype. In order to analyze the phylogenetic dynamics of DENV-3 during outbreak periods; we incorporated datasets of 48 and 11 sequences spanning two major outbreaks in Venezuela during 2001 and 2007-2008, respectively. Our phylogenetic analysis of newly sequenced viruses shows that subsets of genomes cluster primarily by geographic location, and secondarily by time of virus isolation. DENV-3 genotype III sequences from Asia are significantly divergent from those from the Americas due to their geographical separation and subsequent speciation. We measured amino acid variation for the E protein by calculating the Shannon entropy at each position between Asian and American genomes. We found a cluster of seven amino acid substitutions having high variability within E protein domain III, which has previously been implicated in serotype-specific neutralization escape mutants. No novel mutations were found in the E protein of sequences isolated during either Venezuelan outbreak. Shannon entropy analysis of the NS5 polymerase mature protein revealed that a G374E mutation, in a region that contributes to interferon resistance in other flaviviruses by interfering with JAK-STAT signaling was present in both the Asian and American sequences from the 2007-2008 Venezuelan outbreak, but was absent in the sequences from the 2001 Venezuelan outbreak. In addition to E, several NS5 amino acid changes were unique to the 2007-2008 epidemic in Venezuela and may give additional insight into the adaptive response of DENV-3 at the population level.

Identification of factor VIII gene mutations in patients with severe haemophilia A in Venezuela: identification of seven novel mutations.

Haemophilia A is caused by mutations in the gene encoding coagulation factor VIII (FVIII). In severe Haemophilia A (sHA), two inversions are responsible for approximately 50% of the genetic alterations (intron 22 and intron 1 inversions). The other mutations are extremely diverse and each affected family generally has its own mutation. Our aim was to detect the genetic alterations present in the FVIII gene (F8) in 54 unrelated male patients with sHA in Venezuela. We initially detected the presence of the intron 22 inversion by performing inverse PCR, and the negative patients for this inversion were analysed for the intron 1 inversion by PCR. Patients negative for both inversions were analysed using Conformation Sensitive Gel Electrophoresis for mutations in all exons, promoter region and 3'-UTR. sHA causative mutations were identified in 49 patients. Intron-22 and -1 inversions were detected in 41% and 0% of patients respectively. Besides these two mutations, 25 different mutations were identified, including nine nonsense, four small deletions, two small insertions, four missense, three splicing mutations and three large deletions. Seven novel mutations were identified, including two nonsense mutations, two small deletions, one small insertion, one missense mutation and one splicing mutation. Thirty one percent of the patients with identified mutations developed inhibitors against exogenous FVIII. This is the first report of F8 mutations in patients with sHA in Venezuela; the data from this study suggests that the spectrum of gene defects found in these patients is as heterogeneous as reported previously for other populations.

Elective surgery in patients with congenital coagulopathies and inhibitors: experience of the National Haemophilia Centre of Venezuela.

Elective surgery in patients with congenital haemophilia with inhibitors carries a high risk of bleeding. However, inhibitor patients also have a high risk of haemarthroses and other orthopaedic complications, and surgery could improve their quality of life. Successful elective surgery has been reported in inhibitor patients under haemostatic cover with plasma-derived activated prothrombin complex concentrate (pd-aPCC) or recombinant activated factor VII (rFVIIa). Recombinant FVIIa has recently become available in Venezuela and, unlike pd-aPCC, has not been associated with an anamnestic response. The aim of this study was to assess our experience using rFVIIa as a first-line and sustained treatment in elective invasive surgical procedures at the National Haemophilia Centre in Venezuela. Surgical procedures were classified as major or minor, under haemostatic cover with rFVIIa. A total of 13 patients (12 with haemophilia A with high-responding inhibitors and one with von Willebrand's disease type 3) underwent a total of 19 surgical procedures under rFVIIa cover. Thirteen procedures were classified as major surgeries. Intraoperative haemostasis was achieved in the majority of patients. Only two patients required an additional dose of rFVIIa, at 30 min and 75 min, respectively, with good results. Postoperative haemostasis was considered effective in 16 of 18 (89%) of the procedures in haemophilia A patients. Treatment was considered to be ineffective in two patients because of excessive postoperative bleeding. Data from the study provide no safety concerns, and demonstrate that rFVIIa provides effective haemostatic cover in elective surgery in patients with inhibitors; research is ongoing to determine the optimal dose for such procedures.

Factor VII deficiency: clinical manifestation of 717 subjects from Europe and Latin America with mutations in the factor 7 gene.

The congenital FVII deficiency (FVIID) is a rare haemorrhagic disorder with an autosomal recessive pattern of inheritance. Data on phenotype and the genotype from 717 subjects in Central Europe (six countries), Latin America (Costa Rica, Venezuela) and United States, enrolled in the Greifswald Registry of FVII Deficiency were analysed. We detected 131 different mutations in 73 homozygous, 145 compound heterozygous and 499 heterozygous subjects. Regional differences were observed in the mutation pattern and the clinical profile of the evaluated patients. Seventy-one per cent of homozygous and 50% of compound heterozygous subjects were symptomatic. The clinical manifestations of the homozygous subjects were characterized by intracranial haemorrhage (2%), gastrointestinal bleeding (17%), haemarthrosis (13%), epistaxis (58%), gum bleeding (38%), easy bruising (37%), haematoma (15%), haematuria (10%) and menorrhagia (19 of 26 females, 73%). The clinical variability and genotype-phenotype correlation was evaluated in the homozygous subjects. The pattern of bleeding symptoms among compound heterozygous patients was severe and similar to that of the homozygous patients. The large-scale analysis of 499 heterozygous subjects shows that 93 (19%) presented with spontaneous bleeding symptoms such as haemarthrosis (4%), epistaxis (54%), gum bleeding (14%), easy bruising (38%), haematoma (23%), haematuria (5%) and menorrhagia (19 of 45 females; 42%). The severe haemorrhages - intracranial and gastrointestinal - were not reported in heterozygous subjects. The clinical variability and the regional differences in the mutation pattern are discussed regarding care and treatment.

Chemical synoviorthesis with oxytetracycline clorhydrate (Emicine) in recurrent haemarthrosis.

This is a non-controlled experimental prospective clinical study that evaluates the satisfactory results in the chemical synovectomy (synoviorthesis) with oxytetracycline clorhydrate (Emicine, Lab. Pfizer Ltda, Guarulhos, Sao Paulo, Brazil) in recurrence haemarthrosis in different joints, demonstrating that it is an effective method in the treatment of these recurrent haemarthrosis in haemophilia. 84 patients of whom 77 concluded the full course of treatment. 82 joints were injected. The dosage injected was 5 cm(3) of the drug (25 mg) in 5 cm(3) of anaesthesia for the knee, 2 cm(3) with 1 cm(3) of anaesthesia for the elbow and 1 cm(3) plus 1 cm(3) of anaesthesia for the ankle. These injections were administered once weekly with a reinforcement in 1 month. In case of failure the same can be administered repeatedly. Subjective parameters included pain, range of movement and use of the joint involved. Pain decreased from a mean of 6.5 to 0.9 (Likert scale). Range of movement increased from 5.9 to 9 and joint use increased from 5.9 to 9.2. Objective parameters included joint diameter and range of movement. Range of movement for flexion and extension improved from 72.2 and 149.2 to 73.7 and 167, respectively, for the knees. From 57.3 and 160 to 66.6 and 170, respectively, for the shoulder. And, from 22.7 and 10.8 to 34 and 18.6, respectively, for the ankle. This procedure has multiple advantages such as immediate therapeutic effect, short period of treatment, easy technique, much less AHF coverage (30% above coagulation level), less costly than radiocolloid treatment, which make it a perfect alternative treatment for developing countries.

Inhibition of adrenaline and adenosine diphosphate induced platelet aggregation by Lansberg's hognose pit viper (Porthidium lansbergii hutmanni) venom.

The haemostatic components of venom from the genus Porthidium has been poorly studied, although it is known that severe manifestations occur when humans are envenomed, which include invasive oedema and disseminated ecchymosis. The effects of venom on blood platelets are commonly studied and are normally carried out with platelet-rich plasma (PRP). A series of crude venom dilutions was used to determine the effects of adenosine diphosphate (2 microM) and adrenaline (11 microM) induced platelet aggregation. Venom of Porthidium lansbergii hutmanni was fractioned by anionic exchange chromatography, and the fractions were also used to determine the 50% inhibition of adenosine diphosphate (ADP) and adrenaline-induced platelet aggregating dose (AD50). Crude venom has more effect in inhibiting adrenaline-induced aggregation (AD50 = 0.0043 microg) followed by the adenosine diphosphate (AD50 = 17 microg). Peaks I and II obtained by chromatography also inhibited adrenaline-induced platelet aggregation with an AD50 of 3.2 and 0.013 microg, respectively, and both peaks inhibited ADP-induced platelet aggregation with an AD50 of 10 microg. The main purpose of this work was to characterise the in vitro effects caused by P. lansbergii hutmanni crude venom and its fractions on the platelet aggregation mediated by adrenaline and ADP agonists.

The discriminant power of bleeding history for the diagnosis of type 1 von Willebrand disease: an international, multicenter study.

OBJECTIVE: The aim of this study was the validation of the criteria defining a significant mucocutaneous-bleeding history in type 1 von Willebrand disease (VWD). SUBJECTS AND METHODS: To avoid selection bias, 42 obligatory carriers (OC) of type 1 VWD were identified from a panel of 42 families with type 1 VWD enrolled by 10 expert centers. OC were identified by the presence of an offspring and another first degree relative with type 1 VWD (affected subjects, AFF). A standardized questionnaire was administered to evaluate hemorrhagic symptoms at the time of first examination, using a bleeding score ranging from 0 (no symptom) to 3 (hospitalization, replacement therapy, blood transfusion). Sensitivity, specificity, diagnostic likelihood ratios, positive and negative predictive values for the diagnosis of type 1 VWD were calculated from the data collected in OC and in 215 controls. RESULTS: Having at least three hemorrhagic symptoms or a bleeding score of 3 in males and 5 in females was very specific (98.6%) for the bleeding history of type 1 VWD, although less sensitive (69.1%). None of the misclassified OC had life-threatening bleeding episodes after diagnosis. CONCLUSIONS: We suggest that the use of a standardized questionnaire and bleeding score may be useful for the identification of subjects requiring laboratory evaluation for VWD.

Inhibition of thrombin generation in plasma by fibrin formation (Antithrombin I).

The adsorption of thrombin to fibrin during clotting defines "Antithrombin I" activity. We confirmed that thrombin generation in afibrinogenemic or in Reptilase defibrinated normal plasma was higher than in normal plasma. Repletion of these fibrinogen-deficient plasmas with fibrinogen 1 (gamma A/gamma A), whose fibrin has two "low affinity" non-substrate thrombin binding sites, resulted in moderately reduced thrombin generation by 29-37%. Repletion with fibrinogen 2 (gamma'/gamma A), which in addition to low affinity thrombin-binding sites in fibrin, has a "high affinity" non-substrate thrombin binding site in the carboxy-terminal region of its gamma' chain, was even more effective and reduced thrombin generation by 57-67%. Adding peptides that compete for thrombin binding to fibrin [S-Hir53-64 (hirugen) or gamma'414-427] caused a transient delay in the onset of otherwise robust thrombin generation, indicating that fibrin formation is necessary for full expression of Antithrombin I activity. Considered together, 1) the increased thrombin generation in afibrinogenemic or fibrinogen-depleted normal plasma that is mitigated by fibrinogen replacement; 2) evidence that prothrombin activation is increased in afibrinogenemia and normalized by fibrinogen replacement; 3) the severe thrombophilia that is associated with defective thrombin-binding in dysfibrinogenemias Naples I and New York I, and 4) the association of afibrinogenemia or hypofibrinogenemia with venous or arterial thromboembolism, indicate that Antithrombin I (fibrin) modulates thromboembolic potential by inhibiting thrombin generation in blood.

Intra-articular hyaluronic acid in the treatment of haemophilic chronic arthropathy.

We report our preliminary experience with the use of hyaluronic acid (Synvisc) in 29 joints from 25 different haemophilic patients (17 knees, six shoulders, four ankles, one elbow and one hip). All the joints were grade III of our classification, characterized by synovial thickening, axial deformities and muscle atrophy (chronic arthropathy). In view of the very satisfactory results obtained with this procedure, we have substituted Synvisc for the previous use of intra-articular long-standing corticosteroids that we had been used for some years. This method is theoretically more physiological and does not destroy the joint cartilage further, as corticosteroids can.

Synovectomy with rifampicine in haemophilic haemarthrosis.

The purpose of this paper was to assess the effectiveness of intra-articular injected rifampicine in haemophilic patients in order to achieve synovectomy by preventing repeated intra-articular bleeding. We have used this technique in haemophilic patients previously and reported our results on 13 cases [1]. Two hundred and fifty milligrams of rifampicine was injected into the elbow and ankle joints and 500 mg was injected into knee joints with 3-10 mL of lidocaine, depending on the joint size. The injections were repeated once a week for 7 weeks. Patients were only covered with antihaemophilic factor on the day of the injection at 30% above their coagulation level. We evaluated the results using two measures: subjective reports from the patient and objective assessment by the examiner. In the subjective reports the patient graded the results from their own perspective from 1 (poor) to 10 (excellent): 1-3, poor; 4-6, fair; 7-8, good; and 9-10, excellent. In the objective reports the grading was: excellent ('dry joint', full function, no haemarthrosis, no synovitis); good (clinical improvement, synovitis, reduction of haemarthroses, full function); fair synovitis (reduction of haemarthroses, no change in function); poor synovitis (persistent haemarthroses). This paper reports on the results of 38 patients with 39 joints with more that 3 years follow up, mean 1.8 years. There were 22 knees, nine elbows and eight ankles. Subjectively, there were excellent results in 21 joints (11 knees, six elbows and four ankles) good results in 15 joints (eight knees, three elbows and four ankles), fair results in two knees and a poor result in one knee. Objectively, results obtained were excellent in 20 joints (11 knees, six elbows and three ankles); good in 17 (nine knees, three elbows and five ankles); fair in one knee and poor in one knee.

Hemophilia treatment. Predicting the long-term risk of HIV exposure by cryoprecipitate.

Most of the world's haemophilia population lives in countries with few medical or financial resources. As such, they cannot easily obtain viral-inactivated clotting product. Many patients are treated with cryoprecipitate made from locally supplied blood. The reasoning for using cryoprecipitate, instead of viral-inactivated products, is based on an unspoken belief that because blood banks can provide reasonably safe products by using modern testing procedures, transmission of HIV and other blood-borne viruses is rare. However, the risk of acquiring a blood-borne infection increases with every exposure, and haemophilia patients treated with cryoprecipitate or fresh-frozen plasma are exposed to hundreds or thousands of donors during their lifetime. The risk that a person infected with HIV will donate blood during the 'window period' is directly related to the incidence of HIV in the country where the donation occurs. To demonstrate the extent of this problem, we devised a model for estimating the risk that a person with haemophilia will encounter HIV-contaminated cryoprecipitate based on the years of treatment and the underlying incidence rate of HIV among blood donors. We applied the model to two countries with different incidence rates of HIV: Venezuela and the United States. We found that a person with haemophilia who receives monthly infusions of cryoprecipitate prepared from plasma of 15 donors over a lifetime of treatment (60 years) is at significant risk of being exposed to HIV. In the United States there is a 2% risk of being exposed to HIV-contaminated blood product, and in Venezuela, the percentage of risk is 40%. Given this degree of risk, medical care providers should carefully evaluate the use of cryoprecipitate except in emergencies or when no viral-inactivated products are available.

Thrombotic dysfibrinogenemia. Fibrinogen "Caracas V" relation between very tight fibrin network and defective clot degradability.

Fibrinogen Caracas V is a thrombotic dysfibrinogenemia with an Aalpha 532 Ser-->Cys mutation characterized by a tight fibrin network formed of thin fibers responsible for a less porous clot than a normal one. In the present work, fibrinogen Caracas V is further characterized in order to understand the relationship between the structural defect and thrombophilia. This thrombotic disorder has been attributed to a tight fibrin network responsible for a decreased permeation of flow through the clot, leading to defective thrombus lysis due to a diminished availability of fibrinolytic enzymes to the inner fibrin surface. Correction of clot structure anomaly, by addition of dextran 40 to fibrinogen before clotting, induces an improvement in fibrin degradation that was attributed to an increase in porosity. The pulmonary embolism observed in this family has been related to an hyper rigidity of the clot, an anomaly that is also corrected by dextran. Furthermore, this abnormal fibrinogen binds more albumin than does normal fibrinogen, a phenomenon attributed to the mutation of serine in Aalpha-532 by cysteine. Therefore, this fibrinogen shows a striking similarity to the fibrinogen Dusart, allowing us to confirm that the alphaC-terminal part of fibrinogen plays an important role in fibrin structure, and to conclude that the anomaly of fibrin network observed in fibrinogen Caracas V is responsible for a deficient thrombus lysis.

Fibrinogen Caracas V, an abnormal fibrinogen with an Aalpha 532 Ser-->Cys substitution associated with thrombosis.

A new dysfibrinogenemia associated with thrombophilia has been identified in a Venezuelan kindred. Thrombin and Reptilase times were prolonged and the accelerating capacity of the patient's fibrin on the t-PA-induced plasminogen activation was decreased. In addition the affinity of fibrinogen for plasminogen was diminished. Permeability and electron microscopy studies revealed that the abnormal clot was made up of thin and densely packed fibres giving rise to a reduced fibrin gel porosity. This was confirmed by turbidity studies showing a decreased fibre mass/length ratio. Affected members were heterozygous for an Aalpha 532 Ser-->Cys mutation as demonstrated by genetic analyses. This abnormal fibrinogen has been designated as Fibrinogen Caracas V. The family study showed a convincing association between the mutation and thrombotic manifestations. The thrombotic tendency may be ascribed to lack of accelerating capacity of fibrin to induce fibrinolysis caused by an abnormal clot structure with thin fibres and reduced porosity.

Haemophilia therapy: assessing the cumulative risk of HIV exposure by cryoprecipitate.

Most of the world's haemophilia population live in countries with developing or emerging economies. As such, they do not have access to viral inactivated clotting product. Many are treated with cryoprecipitate made from locally supplied blood. The rationale for using cryoprecipitate instead of viral inactivated products is based on an implicit belief that because blood banks can provide reasonably safe products by using modern testing procedures, transmission of HIV and other blood-borne viruses is rare. However, the risk of acquiring a blood-borne infection is cumulative, and haemophilia patients treated with cryoprecipitate or fresh-frozen plasma are exposed to hundreds or thousands of donors during their lifetime. The risk that an HIV-infected person will be a donor during the 'window period' is directly related to the incidence of HIV in the country where the donation occurs. To illustrate the extent of this problem, we devise a model for estimating the risk that a person with haemophilia will encounter HIV-contaminated cryoprecipitate as a function of years of treatment and the underlying incidence rate of HIV among blood donors. We apply the model to two countries with different incidence rates of HIV, Venezuela and the USA. Over a lifetime of treatment (60 years), the cumulative risk of HIV exposure for a person with haemophilia receiving monthly infusion of cryoprecipitate prepared from plasma of 15 donors is significant, 2% in the USA and 40% in Venezuela. Considering the cumulative risk for transmitting HIV to patients with haemophilia through cryoprecipitate treatment, medical care providers should carefully evaluate the use of cryoprecipitate in any but emergency conditions or when no virally inactivated products are available.

ERGIC-53 gene structure and mutation analysis in 19 combined factors V and VIII deficiency families.

Combined factors V and VIII deficiency is an autosomal recessive bleeding disorder associated with plasma levels of coagulation factors V and VIII approximately 5% to 30% of normal. The disease gene was recently identified as the endoplasmic reticulum-Golgi intermediate compartment protein ERGIC-53 by positional cloning, with the detection of two founder mutations in 10 Jewish families. To identify mutations in additional families, the structure of the ERGIC-53 gene was determined by genomic polymerase chain reaction (PCR) and sequence analysis of bacterial artificial chromosome clones containing the ERGIC-53 gene. Nineteen additional families were analyzed by direct sequence analysis of the entire coding region and the intron/exon junctions. Seven novel mutations were identified in 10 families, with one additional family found to harbor one of the two previously described mutations. All of the identified mutations would be predicted to result in complete absence of functional ERGIC-53 protein. In 8 of 19 families, no mutation was identified. Genotyping data indicate that at least two of these families are not linked to the ERGIC-53 locus. Taken together, these results suggest that a significant subset of combined factors V and VIII deficiency is due to mutation in one or more additional genes.

Fibrinogen Caracas I: a dysfibrinogenemia with a hemorrhagic diathesis associated with diminished fibrin fiber diameter and reduced fibrin gel porosity.

Fibrinogen Caracas I is a dysfibrinogenemia with a mild bleeding diathesis and a defective wound healing. We have characterized this abnormal fibrinogen using transmission electron microscopy (TEM) in combination with turbidity and permeation studies. Turbidometric and permeability analysis showed that the abnormal fibrin had a significantly decreased mass:length ratio and fiber diameter. In addition, the permeability studies of plasma fibrin clots showed that the gel porosity of the abnormal fibrinogen was reduced. Images of the abnormal fibrin structure obtained using TEM showed that the fibers were thinner, much less branched and less ordered than normal fibers. Diminished fibrin fiber diameter and reduced fibrin gel porosity have been taken as hallmarks of thrombophilic dysfibrinogenemias. The results of the present study show that these features are not necessarily predictive of thrombophilia. Further studies performed on a larger number of dysfibrinogenemias need to be conducted in order to establish the implications of these parameters on the clinical outcome.

Dietary fatty acids in athero-thrombogenesis: influence of palm oil ingestion.

Dietary experiments, performed in metabolic wards, gave rise to predictive regression equations relating changes of plasma cholesterol concentration to the intake of fatty acids of the diet. It has been established that polyunsaturated fatty acids diminish and most saturated fatty acids increase plasma cholesterol concentration. This information led to expect that dietary use of palm oil may induce an unfavorable plasma lipoprotein profile. This has not been the case as shown in various dietary experiments. The reasons for this discrepancy is discussed. The influence of palm oil enriched diets on prothrombotic variables show that platelets are not affected in their function during prolonged dietary intervention. It is important to continue research on the effects of palm oil based diet on plasma fibrinogen, factor VII. There is still discordant information in this field.

Hematomas within the iliopsoas muscles in hemophilic patients: the Latin American experience.

The majority of bleeding episodes in patients who have hemophilia occur within the musculoskeletal system, primarily in the joints, but approximately 30% occur within the muscles. Iliopsoas muscle bleeding episodes are often large in volume, causing muscular function inhibition, angular deformities, and nerve involvement. Recurrent hemorrhages are common (14.2%) and neural involvement is as high as 37%. Three hundred patients are being observed in the authors' hemophilia center, 63 of whom have suffered 127 hemorrhages. Absolute bed rest and long term factor replacement are the mainstay of therapy. The experiences of physicians in other countries are appendixed to this article.

Characterization of partial gene deletions in type III von Willebrand disease with alloantibody inhibitors.

von Willebrand factor gene deletions were characterized in four patients with severe type III von Wilebrand disease and alloantibodies to von Willebrand factor. A PCR-based strategy was used to characterize the boundaries of the deletions. Identical 30 kb von Willebrand factor gene deletions which include exons 33 through 38 were identified in two siblings of one family by this method. A small 5 base pair insertion (CCTGG) was sequenced at the deletion breakpoint. PCR analysis was used to detect the deletion in three generations of the family, including two family members who are heterozygous for the deletion. In a second family, two type III vWD patients, who are distant cousins, share an approximately 56 kb deletion of exons 22 through 43. The identification and characterization of large vWF gene deletions in these type III vWD patients provides further support for the association between large deletions in both von Willebrand factor alleles and the development of inhibitory alloantibodies.