Inherited bleeding disorders

Circumcision in Hemophilia: A Multicenter Experience

BACKGROUND

Hemophiliac patients and their families have social pressure to undergo circumcision, despite the potential complications. The objective of this study was to report our experience in the circumcision of hemophilia patients.

MATERIALS AND METHODS

We included 35 patients with hemophilia who had circumcision in 3 centers from January 2010 to August 2019. Their age ranged between 0.3 months and 8 years. Hemophilia a was classified as mild (n=3), moderate (n=4), and severe (n=28). Patients received 2 doses of factor VIII concentrate 50μ/kg, 1 hour before the procedure and 12 hours after it.

RESULTS

Four neonates were diagnosed with hemophilia after circumcision because of prolonged bleeding. Two patients with severe hemophilia A had bleeding after hospital discharge (6.5%). They received additional factor concentrate, and 1 patient had an extra stitch. Two patients had wound gaping (6.5%), and 1 patient had a wound infection (3.2%).

CONCLUSION

Hemophilia is not an absolute contraindication for circumcision. Circumcision of hemophilic children should be performed under appropriate conditions in hemophilia centers. Bleeding is not frequent but could be serious.

A comprehensive bioinformatic analysis of 126 patients with an inherited platelet disorder to identify both sequence and copy number genetic variants

Inherited bleeding disorders (IBDs) comprise an extremely heterogeneous group of diseases that reflect abnormalities of blood vessels, coagulation proteins, and platelets. Previously the UK-GAPP study has used whole-exome sequencing in combination with deep platelet phenotyping to identify pathogenic genetic variants in both known and novel genes in approximately 40% of the patients. To interrogate the remaining "unknown" cohort and improve this detection rate, we employed an IBD-specific gene panel of 119 genes using the Congenica Clinical Interpretation Platform to detect both single-nucleotide variants and copy number variants in 126 patients. In total, 135 different heterozygous variants in genes implicated in bleeding disorders were identified. Of which, 22 were classified pathogenic, 26 likely pathogenic, and the remaining were of uncertain significance. There were marked differences in the number of reported variants in individuals between the four patient groups: platelet count (35), platelet function (43), combined platelet count and function (59), and normal count (17). Additionally, we report three novel copy number variations (CNVs) not previously detected. We show that a combined single-nucleotide variation (SNV)/CNV analysis using the Congenica platform not only improves detection rates for IBDs, suggesting that such an approach can be applied to other genetic disorders where there is a high degree of heterogeneity.

A Morphometric Analysis of Platelet Dense Granules of Patients with Unexplained Bleeding: A New Entity of Delta-Microgranular Storage Pool Deficiency

One thousand and eighty patients, having prolonged bleeding times, frequent epistaxis, menorrhagia or easy bruising or other bleeding manifestations, and excluding those with von Willebrand's disease, were evaluated for platelet dense granule deficiency. The mean diameter of platelet dense granules was determined for all patients using image analysis. Four hundred and ninety-nine had "classic" dense (delta) granule storage pool deficiency (δ-SPD). Five hundred and eighty-one individuals (53.8%) were found to have a normal mean number of dense granules, but for some of these patients, the dense granules were smaller than for the controls. Of the patients having a normal number of dense granules, 165 (28.4%) were found to have significantly smaller granules than the platelets obtained from the control subjects. Their average granule diameter was 123.35 ± 0.86 nm, that is more than three standard deviations below the mean of the control data. Total δ-granule storage pool volumes (TDGV)/platelet were calculated using these measurements. Individuals with δ-SPD had half the number of granules (2.25 ± 0.04 DG/PL) and storage pool volume (3.88 ± 1.06 × 106 nm3) when compared to our control data (4.64 ± 0.11 DG/PL; 10.79 × 106 nm3 ± 0.42). Individuals having a bleeding history but a normal average of small dense granules had a calculated storage pool volume statistically different than controls and essentially the same storage pool volume as patients with δ-SPD. We have identified a sub-classification of δ-SPD that we have defined as micro-granular storage pool deficiency (δ-MGSPD).

Aspirin for patients undergoing major lung resections: hazardous or harmless?†

OBJECTIVES

Acetylsalicylic acid (ASA, aspirin) is a medication widely used for primary and secondary prevention of cardiovascular diseases, which are the leading cause of morbidity and mortality worldwide. Whether aspirin should be continued or paused in the perioperative period remains controversial, especially in thoracic surgical settings.

METHODS

A single-centred retrospective study comprised 486 patients. Of these, 329 patients did not use aspirin (group ASA-0) and 157 did (group ASA-1) during the perioperative period after anatomical lung resection at our hospital from January 2013 to December 2016. Major outcome measures were the amount of blood loss during the operation and during the first 5 days postoperatively (per Mercuriali's formula), as well as the amount and proportion of the blood transfusion (packed red cells) received. The need for reoperation due to a postoperative haemothorax and/or bleeding was recorded. The groups were also compared according to their rates of morbidity and mortality. Inferential statistical methods with bootstrap analysis using 1000 samples and the Mersenne Twister, a random number generator, were used.

RESULTS

There were no significant differences between the 2 groups in intraoperative bleeding [ASA-0M = 418.69 ml, standard deviation (SD) ± 364.87; ASA-1M = 399.8 ml, SD ± 323.84; P = 0.58] or in total blood loss according to Mercuriali's formula (ASA-0M = 1111.62 ml, SD ± 816.69; ASA-1M = 1115.08 ml, SD ± 682.12; P = 0.95). A total of 104 patients received transfusions up to postoperative day 5: 71 patients in the ASA-0 group received 151 blood transfusions, whereas 33 patients in the ASA-1 group received 65 blood transfusions (P = 0.66). The indication for reoperation due to bleeding (ASA-1 = 3, ASA-0 = 4; P = 0.69) was similar between the groups. There was a trend towards higher rates of postoperative complications in the ASA-1 group (risk ratio (RR) = 1.28; P = 0.055); neither cardiovascular complications nor deaths were more frequent in either of the 2 groups (P = 0.73).

CONCLUSIONS

Patients taking aspirin therapy and undergoing anatomical lung resection seem not to be at any disadvantage regarding bleeding. However, a trend towards a higher rate of postoperative complications indicates a basically increased risk for operations due to comorbidities in these patients.

High-throughput sequencing for diagnosing platelet disorders: lessons learned from exploring the causes of bleeding disorders

Inherited platelet disorders (IPDs) are a heterogeneous group of disorders caused by multiple genetic defects. Obtaining a molecular diagnosis for IPD patients using a phenotype- and laboratory-based approach is complex, expensive, time-consuming, and not always successful. High-throughput sequencing (HTS) methods offer a genotype-based approach to facilitate molecular diagnostics. Such approaches are expected to decrease time to diagnosis, increase the diagnostic rate, and they have provided novel insights into the genotype-phenotype correlation of IPDs. Some of these approaches have also focused on the discovery of novel genes and unexpected molecular pathways which modulate megakaryocyte and platelet biology were discovered. A growing number of genetic defects underlying IPDs have been identified and we will here provide an overview of the diverse molecular players. Screening of these genes will deliver a genetic diagnosis for about 40%-50% of the IPDs patients and we will compare different HTS applications that have been developed. A brief focus on gene variant interpretation and classification in a diagnostic setting will be given. Although it is true that successes in diagnostics and gene discovery have been reached, a large fraction of patients still remains without a conclusive diagnosis. In these patients, the sum of non-diagnostic variants in known genes or in potential novel genes might only be proven informative in future studies with larger patient cohorts and by data sharing among the diverse genome medicine initiatives. Finally, we still do not understand the role of the non-coding genome space for IPDs.

Platelets and platelet-derived factor Va confer hemostatic competence in complete factor V deficiency

Whole genome sequencing of an individual completely devoid of plasma- and platelet-derived factor V (FV) identified 167 variants in his F5 gene including previously identified and damaging missense mutations at rs6027 and Leu90Ser. Because the administration of fresh frozen plasma (FFP) prevents gastrointestinal bleeding in this individual, its effects on his plasma- and platelet-derived FV concentrations were assessed. The patient's plasma FV levels peaked by 2 hours following FFP administration and were undetectable 96 hours later. In contrast, increased platelet-derived FV/Va concentrations were observed within 6 hours, peaked at 24 hours, decreased slowly over 7 days, and originated from megakaryocyte endocytosis and intracellular processing of plasma FV. Ten days after transfusion, no thrombin was generated in a tissue factor-initiated whole blood clotting assay unless exogenous FV was added, consistent with the complete absence of plasma FV. In marked contrast, release of the patient's platelet-derived FV/Va (7% of normal) following platelet activation resulted in robust thrombin generation, similar to that in an individual with normal plasma- and platelet-derived FV concentrations. Thus, total FV deficiency can be corrected by plasma administration, which partially repletes and sustains the platelet cofactor pool, thereby highlighting the critical role of platelet-derived FV/Va in ensuring hemostatic competence.

Do hemophiliacs have a higher risk for dental caries than the general population?

OBJECTIVE

The aim of this study was to examine if patients with hemophilia were at increased risk for dental decay as compared to the general population.

MATERIALS AND METHODS

Census sampling was used in this case-control study to recruit cases (patients with hemophilia) and a control group individuals recruited randomly from the general population, which were matched with cases based on gender, age and place of residence. Clinical examinations included dental health and salivary assessments (flow rate, buffer capacity, caries-associated bacteria) and a structured questionnaire which inquired about socioeconomic status and dental health-related behaviors.

RESULTS

In the deciduous dentition, the overall caries experience (dmf) differed statistically significantly (P=0.003) between the hemophiliacs (2.6±2.6) and their matched healthy controls (6.1±2.5). Bivariate analyses did not reveal significant differences between cases and controls regarding salivary functions, except that higher bacteriological counts were found in healthy controls in deciduous dentitions than in patients with hemophilia (P=0.019). Children without hemophilia were from higher socioeconomic status families than hemophiliacs (P=0.004), but such differences were not found for adults (P=0.090). When compared to healthy adults, adult hemophiliacs had more gum bleeding at rest (P<0.001) as well as during their tooth brushing (P=0.007) and they also consumed more soft drinks than controls (P=0.025).

CONCLUSIONS

Better dental health was observed in children with hemophilia as compared to children without it. There were no differences in dental health between adult hemophiliacs and healthy controls from the general population. None of the linear multiple regression models confirmed hemophilia to be an additional caries risk when it was controlled for other caries determinants.

Providing young women with credible health information about bleeding disorders

BACKGROUND

Approximately 1% of U.S. women may have an undiagnosed bleeding disorder, which can diminish quality of life and lead to life-threatening complications during menstruation, childbirth, and surgery.

PURPOSE

To understand young women's knowledge, attitudes, and perceptions about bleeding disorders and determine the preferred messaging strategy (e.g., gain- versus loss-framed messages) for presenting information.

METHODS

In September 2010, a web-assisted personal interview of women aged 18-25 years was conducted. Preliminary analyses were conducted in 2011 with final analyses in 2013. In total, 1,243 women participated. Knowledge of blood disorders was tabulated for these respondents. Menstrual experiences of women at risk for a bleeding disorder were compared with those not at risk using chi-square analyses. Perceived influence of gain- versus loss-framed messages also was compared.

RESULTS

Participants knew that a bleeding disorder is a condition in which bleeding takes a long time to stop (77%) or blood does not clot (66%). Of the women, 57% incorrectly thought that a bleeding disorder is characterized by thin blood; many were unsure if bleeding disorders involve blood types, not getting a period, or mother and fetus having a different blood type. Women at risk for a bleeding disorder were significantly more likely to report that menstruation interfered with daily activities (36% vs 9%); physical or sports activities (46% vs 21%); social activities (29% vs 7%); and school or work activities (20% vs 9%) than women not at risk. Gain-framed messages were significantly more likely to influence women's decisions to seek medical care than parallel loss-framed messages. Findings suggest that the most influential messages focus on knowing effective treatment is available (86% gain-framed vs 77% loss-framed); preventing pregnancy complications (79% gain- vs 71% loss-framed); and maintaining typical daily activities during menstrual periods.

CONCLUSIONS

Lack of information about bleeding disorders is a serious public health concern. Health communications focused on gain-framed statements might encourage symptomatic young women to seek diagnosis and treatment. These findings and corresponding recommendations align with Healthy People 2020 and with CDC's goal of working to promote the health, safety, and quality of life of women at every life stage.

Descriptive epidemiology of hemophilia and other coagulation disorders in mansoura, egypt: retrospective analysis

Hemophilia represent the most severe inherited bleeding disorder (INB), it's thought to affect inviduals from all geographical areas in equal frequency. In Egypt which has a population of approximately (80million) consanguineous marriage are frequent, therefore autosomal recessive coagulation disorders reach a higher prevalence than in many other countries.The primary aim of this study was to describe the epidemiological situation of hemophilia in Mansoura, Egypt, as based on retrospective analysis of clinical records Mansoura University Children Hospital between years 2000 and 2008. The second aim was to assess the orthopedic complications and occurrence of hepatitis C in those patients and relate this status to the type of replacement therapy received prior to the study.The study included 72 children with hematological disorders registered from 2000 to 2008 in MUCH. The hemophilic patient was defined as a person with physician-diagnosed hemophilia A or B and a measured factor VIII or IX activity level of 30% or less. Persons with acquired inhibitors of FVIII or FIX excluded. Severity level was categorized as mild if the factor activity level was 6-30%, moderate if 1-5% and severe if <1% of normal.The severe presentation represents the majority in 76.7% followed by moderate severity in 17.2%. The commonest IBDs was hemophilia A affecting 44 patients, followed by Hemophilia B affecting 15 patients. The rare types were Factor XI deficiency, Factor V deficiency, Factor VII deficiency and combined FVIII, FIX and FX deficiency. The commonest orthopedic manifestation needing therapy was found among hemophilia A representing 8.3%. Hepatitis C viremia detected by PCR was found in 11.1% of patients. The bleeding complications as hematoma or hemarthrosis were the common complications. Nevertheless, 44.4% of patients had no complications, From this study we can conclude that the most common IBDs in our locality is hemophilia A followed by hemophilia B. The common presenting symptom was bleeding following male circumcision. Hepatitis C infection and arthropathy represented the main complications. The discovery of IBDs in young age children with proper supportive therapy could prevent arthropathy. Proper screening of blood and blood products reduce the risk of viral hepatitis and HIV acquisition.

Involvement of the contact phase and intrinsic pathway in herpes simplex virus-initiated plasma coagulation

SUMMARY BACKGROUND

A hemostatic response to vascular injury is initiated by the extrinsic pathway of coagulation and amplified by the intrinsic pathway. We previously reported that purified herpes simplex virus type-1 (HSV1) has constitutive extrinsic pathway tissue factor (TF) and anionic phospholipid on its surface derived from the host cell, and can consequently bypass strict cellular control of coagulation.

OBJECTIVE

The current work addresses the hypothesis that HSV1-induced plasma coagulation also involves intrinsic pathway, factor VIII (FVIII), and upstream contact activation pathway, factor XII (FXII).

RESULTS

HSV1-initiated clotting was accelerated when purified FVIII was added to FVIII-deficient plasma and in normal plasma attenuated by an inhibitory anti-FVIII antibody (Ab). High HSV1 concentrations predictably reduced the effect of FVIII due to the availability of excess viral TF. To further define TF-independent clotting mechanisms initiated by HSV1, the extrinsic pathway was disabled using factor VII-deficient plasma. The intrinsic pathway is triggered by activation of FXII associated with surface-bound kallikrein, which subsequently activates factor XI. Here we found that an inhibitor of activated FXII, corn trypsin inhibitor, and anti-FXII, anti-kallikrein and anti-FXI Abs inhibited HSV1-initiated clotting. HSV1-enhanced activation of purified FXII was confirmed by Western blot, but required prekallikrein.

CONCLUSION

The current work shows that HSV1 can trigger and amplify coagulation through the contact phase and intrinsic pathway, and suggests an additional mechanism that may contribute to vascular pathology.

Rosai-Dorfman disease with factor XII deficiency

A 17-year-old female patient presented with chronic symmetrical oligoarthritis of both knees and ankles, xerostomia, xerophthalmia, multiple bilateral lymphadenopathies in the cervical region, and bilateral parotid enlargement with the histological finding of chronic sialoadenitis. She had been already given methotrexate, chloroquine, and corticosteroids with the diagnosis of rheumatoid arthritis (RA) before referral to our outpatient clinic. Because her complaints and the lumps did not remit and she could be classified as neither RA nor primary Sjögren's syndrome (SS) according to 1987 ACR RA criteria or European preliminary criteria for SS, lymph node biopsy was repeated and revealed the diagnosis of Rosai-Dorfman disease (RDD) with the histological findings of histiocytes, phagocyting lymphocytes in enlarged sinuses, and mature plasma cells infiltrating the pulpa. All the medications were stopped after the pathological diagnosis of RDD and consulting with the Division of Hematology. She was reevaluated with magnetic resonance imaging, which showed dense infiltrative areas around knee and ankle joints, and computed tomography that showed a soft tissue mass surrounding the descending aorta and upper part of the abdominal aorta. Activated partial thromboplastin time was found to be prolonged in prebiopsy examinations, and factor XII deficiency was detected after detailed hematological evaluation. The symptoms of joint involvement were relieved with nonsteroidal antiinflammatory drugs. She has been followed-up without medication without obvious clinical or laboratory change. We herein report a patient with RDD mimicking RA and SS. We consider that RDD should be kept in mind especially in patients with resistant symptoms to conventional therapies, younger disease onset, and predominant parotid and lymph node enlargement.

The spectrum of inherited bleeding disorders in pediatrics

Inherited bleeding disorders (IBDs) are caused by quantitative and qualitative alterations of either platelets or plasma proteins involved in coagulation and fibrinolysis. Hemophilias are the most frequent IBDs; however, accumulated data from various studies reported that von Willebrand disease (VWD) is the most common cause of IBD, with an increased incidence of platelet function defects, mostly due to the increased rate of consanguinity in some communities. VWD is an inherited disorder of homeostasis due to quantitative or qualitative defect of von Willebrand factor. Data on its epidemiology and impact in developing countries are limited. The objective of this study was to assess the local prevalence of some IBD and establish the clinical and historical variables that are predictive for those bleeding disorders in pediatrics. The study involved 43 children with various bleeding manifestations and 15 age- and sex-matched controls, recruited from the Pediatrics Hematology Clinic at the National Research Centre, Sausan Mubarek children's hospital in Cairo, Egypt and the King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia. Hematological profile included platelet counts and function, prothrombin time, partial thromboplastin time, factor VIII antigen and its activity, factor IX antigen and its activity, von Willebrand factor and its activity assayed with multimeric analysis. A total of 12 (27.9%) children had VWD, 11 (25.5%) had hemophilia A, three (7%) had hemophilia B, seven (16.3%) had platelet dysfunction and 10 (23.3%) had bleeding with undiagnosed cause. Two of the VWD cases had type I, three had type II, four had type III and one case appeared to have type IIM and another to have IIB VWD. Bruising and epistaxis were the main symptoms in all children with VWD The majority of platelet dysfunction disorders were diagnosed as Glanzmann's thrombasthenia. VWD and Glanzmann's thrombasthenia should be considered not uncommon causes of IBDs in children in Egypt and Kingdom of Saudi Arabia. Routine hematological screening should be mandatory in children with positive family history of bruising and bleeding as a predictor for IBD.

Uneventful cesarean delivery with administration of factor XI concentrate in a patient with severe factor XI deficiency

Factor XI (FXI) is a procoagulant factor and antifibrinolytic agent, and its absence causes a bleeding tendency. FXI deficiency is autosomal in inheritance, with severe FXI deficiency in homozygotes and partial deficiency in heterozygotes. A 24-year-old primigravida with an uneventful pregnancy and no history of bleeding manifestations was admitted to our department at 38 weeks of gestation. Her blood count and serum biochemistry findings were normal except for a coagulation screen, which revealed a prolonged activated partial thromboplastin time (APTT) of 63 seconds (normal range, 24-35 seconds). The measured FXI coagulant activity of 8 IU/dL (reference range, 70-150 IU/dL) established a diagnosis of severe FXI deficiency. The breech presentation of the fetus prompted the decision for cesarean delivery under general anesthesia. We administered a single dose of FXI concentrate (15 IU/kg), which corrected the APTT to 34 seconds. The cesarean delivery was uncomplicated, and postpartum recovery of the mother and her baby was uneventful with no bleeding complications. The finding of an isolated prolonged APTT should prompt obstetricians to consider FXI deficiency. The appropriate use of factor FXI concentrate in managing obstetric patients with FXI deficiency can minimize potential bleeding complications and ensure an optimal outcome for both mother and neonate.

Diagnostic approach to inherited bleeding disorders

The appropriate development of hemostasis encompasses a delicate equilibrium between anti- and prothrombotic forces developing during three distinct phases (primary hemostasis, coagulation and fibrinolysis) that are closely linked to each other and precisely regulated to close vessel wounds, promote vascular healing and maintain vessel patency. Imbalance in each of these systems produces either hemorrhagic or thrombotic disorders. Inherited bleeding disorders, caused by quantitative or qualitative alterations of either platelets or plasma proteins involved in blood coagulation and fibrinolysis, may lead to serious and lifelong bleeding conditions, the severity of which is inversely associated with the degree of the underlying defect. Rapid and reliable identification of these pathologies is worthy of focus to allow the adoption of appropriate substitutive or supportive antihemorrhagic therapies. Evaluation of the hemorrhage-prone patient requires careful recording of the medical history, attention to pertinent physical findings and the discretionary use of laboratory resources. Owing to the low diagnostic efficiency of clinical history and examination, an appropriate and reliable laboratory approach, encompassing first- and second-line testing, is essential to screen, diagnose and monitor patients with bleeding diatheses. As both the analytical sensitivity and responsiveness of traditional coagulation assays to different abnormalities differ widely, each laboratory should establish individual guidelines based on field experience and on reagent and instrument characteristics. Emerging evidence indicates that the implementation of global coagulation tests, such as the thrombin generation assay and clot waveform analysis, would provide additional information for clinical decision-making for patients with inherited bleeding disorders.

Congenital combined defects of factor VII: a critical review

Factor VII deficiency is the least rare among uncommon congenital coagulation disorders. The majority of cases are isolated deficiencies. In some cases, FVII deficiency has been found to be associated with the deficiency in another coagulation factor or with non-coagulation-related abnormalities or defects. The evaluation of all published studies on the subject has shown that the FVII defect has been reported in association with FV, FVIII, FIX, FX, FXI and protein C defects. Furthermore, FVII deficiency has been described in association with bilirubin metabolism disorders, mental retardation, microcephaly, epicanthus, cleft palate and persistence of ductus arteriosus. The most interesting association appears to be that with FX. This has been shown to be due to a deletion in part of the long arm of chromosome 13. This arm contains genes coding for both FVII and FX. Interestingly, this combined coagulation defect has been found to be associated with carotid body tumors and several other malformations. Combined defects in blood coagulation often create diagnostic difficulties since results cannot be explained if a single factor deficiency is assumed. For example the combined FVII and FX defect yields a rather peculiar laboratory picture (prolonged prothrombin time and partial thromboplastin time, but normal thrombin time) that could suggest FII or FV or FX single deficiency and not FVII deficiency, indicating the need for specific factor assays whenever data are confusing. Finally, the elevated incidence of mental and skeletal malformations present in these combined defects indicates the need for a careful evaluation of all these patients lest some aspects of the defect are missed.

Clinical Impact of Oral Health Indexes in Dental Extraction of Hemophilic Patients

PURPOSE

Periodontal disease in patients with hemorrhagic disorders may lead to severe bleeding during dental treatment. This study evaluated the clinical impact of oral health indexes in hemophilic patients undergoing tooth extraction.

PATIENTS AND METHODS

Thirty-one hemophilic patients underwent teeth extractions using autologous fibrin glue and an oral antifibrinolytic drug (epsilon-aminocaproic acid). Oral health indexes (plaque, PI; gingival, GI; and decay-missing-filling-teeth, DMFT index) were evaluated before tooth extraction.

RESULTS

Postsurgical bleeding episodes were observed in 6 hemophilic patients (1 severe, 3 moderate, and 2 mild type). The PI and GI index in the bleeding group were 1.8 and 1.7, respectively, and 1.8 for both of the non-bleeding groups (PI, P = .8; GI, P = .56). The global DMFT index was 18 in the bleeding group and 19.6 in the non-bleeding group (P = .67).

CONCLUSION

The status of oral health did not interfere with bleeding caused by dental extraction of hemophilic patients.

Short- and long-term effects of therapy with interferon-alpha and pegylated interferon-alpha/ribavirin on platelet plug formation and von Willebrand factor release in patients with chronic hepatitis C

BACKGROUND

A pegylated interferon-alpha-induced decrease in platelet counts may become a limiting factor for continuation of therapy.

AIM

To evaluate the effect of pegylated interferon-alpha administration on platelet plug formation and von Willebrand factor antigen release in patients with chronic hepatitis C.

METHODS

Thirty patients with chronic hepatitis C (genotype 1; fibrosis 1-3: n = 16, cirrhosis: n = 14) received a single dose of 9 MU interferon-alpha2a, followed by weekly administration of 180 mug of pegylated interferon-alpha2a/ribavirin for 48 weeks. Platelet counts, platelet function (collagen-epinephrine-induced closure time) and von Willebrand factor antigen were measured.

RESULTS

Platelet counts and collagen-epinephrine-induced closure time decreased by 13% and 16%, respectively, 24 h after the first dose of interferon-alpha2a, and von Willebrand factor antigen levels increased by 31% (P < 0.01) compared with baseline. During a 48-week observation period, platelet counts decreased by a maximum of 33% (P < 0.001), von Willebrand factor antigen levels increased by 69% (P < 0.001) whereas collagen-epinephrine-induced closure time did not change. In noncirrhotic patients, the increase of von Willebrand factor antigen levels was maintained throughout therapy without a change in collagen-epinephrine-induced closure time. In contrast, in cirrhotics, von Willebrand factor antigen levels did not increase, while collagen-epinephrine-induced closure time was prolonged.

CONCLUSION

Single-dose interferon-alpha decreases platelet counts but improves platelet function, possibly by the release of von Willebrand factor antigen. Accordingly, long-term antiviral treatment had no effect on collagen-epinephrine-induced closure time, despite the decrease in platelet count in noncirrhotic patients. Such a compensation of decreased platelet counts by increased von Willebrand factor antigen level did not occur in cirrhotics.

Inherited thrombocytopenias: toward a molecular understanding of disorders of platelet production

PURPOSE OF REVIEW

To review the defined syndromes of inherited thrombocytopenia and discuss new genetic data for several disorders that shed light on the process of megakaryopoiesis.

RECENT FINDINGS

The genes responsible for several inherited thrombocytopenias have been recently discovered, including congenital amegakaryocytic leukemia, amegakaryocytic thrombocytopenia with radio-ulnar synostosis, familial platelet syndrome with predisposition to acute myelogenous leukemia, Paris-Trousseau, Wiskott-Aldrich syndrome, and the May-Hegglin, Sebastian, Epstein, and Fechner syndromes. These clinical syndromes, combined with studies in mouse and in vitro models, reveal the importance of these genes for normal hematopoiesis.

SUMMARY

Although inherited syndromes of thrombocytopenia are rare, characterization of mutations in these disorders has contributed greatly to our understanding of megakaryocyte and platelet development. A systematic registry of congenitally thrombocytopenic individuals would almost certainly lead to new genetic discoveries.

Infestin, a thrombin inhibitor presents in Triatoma infestans midgut, a Chagas' disease vector: gene cloning, expression and characterization of the inhibitor

This work describes the purification, gene cloning and expression of infestin, a thrombin inhibitor from midguts of Triatoma infestans. Infestin is located in the midgut and its purification was performed by anion-exchange and affinity chromatographies. The N-terminal sequence and the sequence of tryptic peptides were determined. Using RT-PCR, total RNA and infestin cDNA information, a DNA fragment was cloned which encodes a multi non-classical Kazal-type serine protease inhibitor. Isolated native infestin has two non-classical Kazal-type domains and shows an apparent molecular mass of 13 kDa, while its gene codes for a protein with four non-classical Kazal-type domains corresponding to an apparent molecular mass of 22 kDa. Two recombinant infestins, r-infestin 1-2 and r-infestin 1-4, were constructed using the vector pVT102U/alpha and expressed in S. cerevisiae. Native and r-infestin 1-2 showed very similar inhibitory activities towards thrombin and trypsin with dissociation constants of 43.5 and 25 pM for thrombin and 2.0 and 3.1 nM for trypsin, respectively. No other serine protease of the blood coagulation cascade was inhibited by the r-infestin 1-2. Surprisingly, r-infestin 1-4 inhibited not only thrombin and trypsin (K(i) of 0.8 and 5.2 nM, respectively), but also factor XIIa, factor Xa and plasmin (K(i) of 78 pM, 59.2 and 1.1 nM, respectively).

Platelet antigens. The role of human platelet alloantigens (HPA) in blood transfusion and transplantation

In this review, we describe the platelet surface molecules with special focus on the polymorphic glycoproteins giving rise to the human platelet alloantigen (HPA) system. We list the platelet glycoprotein complexes GPIa/IIa, GPIIb/IIIa, GPIb/V/IX and some other molecules, the corresponding genes that encode them and we describe their polymorphisms as well as their physiological function. Based on data obtained by serological and molecular methods, we explain how ancestral HPA alloepitopes have developed into the modern variants. We also describe the tissue distribution of these proteins, which seems to be wider than thought initially, and discuss the significance of the HPA encoding genes distribution in various populations. Methods for their determination are then described briefly Since HPA alloepitopes can induce antibodies with resulting clinical conditions such as: post-transfusion refractoriness to platelets (PTR); post-transfusion thrombocytopenic purpura (PTTP); and fetomaternal alloimmune thrombocytopenia (FMAIT), the mechanism of this alloimmunization and its prevention is described. Although the humoral arm is more important from the clinical viewpoint, the activation of the cytotoxic arm by HPA alloepitopes is also possible. These polymorphisms also seem to have a role in certain other clinical circumstances, therefore their impact on cardiovascular diseases and haemostatic disorders as well as their role in the transplantation of solid organs and bone marrow is addressed. We conclude that during the last decades, the research of the platelet membrane molecules contributed considerably to the diagnostics, prevention and therapy of the blood coagulation and haemostatic disorders, to the management of the neonatal thrombocytopenias, transfusion-related thrombocytopenias, refractoriness to platelet transfusions and autoimmune disorders. It also changed our view on the role of HPA alloepitopes in bone marrow and solid organ transplantation. In the future, this accumulated knowledge will be useful for the development of the cell-based therapies and immune modulation of both acquired and hereditary diseases.

Dental health indices and caries-related microflora in children with severe haemophilia

The purpose of this work was to investigate the prevalence of dental caries, bacterial dental plaque, gingivitis, enamel defects and caries- related microflora in children with severe haemophilia. Thirty-eight children with severe haemophilia (factor VIII and IX < 2 U dL(-1)) were recruited from Great Ormond Street Hospital for Children and matched for age, gender and ethnicity with healthy control children from the Eastman Dental Institute. Indices were recorded for decayed, missing, and filled teeth and surfaces in both the deciduous dentition (dmfs/dmft) and the permanent dentition (DMFS/DMFT). The plaque and gingivitis scores and developmental enamel defects were also recorded. The caries-related microflora was sampled and cultured for Streptococcus mutans, and Lactobacilli and Candida species. A significantly greater proportion of children with severe haemophilia were caries-free compared with the controls (36.7% vs. 13.3%; P=0.04). Both the DMFS and DMFT were significantly greater in the controls (3.6 and 2.8, respectively) compared with the haemophilia group, (0.8 and 0.7; P=0.007 and P=0.04). The plaque score for the permanent dentition only was significantly greater for the control children (24.2) compared with the haemophilia group, (10.2; P=0.04). The mean number of colony forming units of S. mutans was significantly greater in the control group compared with the haemophilia group (P=0.05). We conclude that children with severe haemophilia have a significantly lower prevalence of dental caries compared with matched, healthy controls.

Anaesthetic management of a parturient with severe congenital factor XI deficiency undergoing caesarean section for triplet pregnancy

The report describes the anaesthetic management of a Jewish patient of Ashkenazi descent with severe factor XI deficiency complicated by thrombocytopenia for caesarean section for triplets at the 35th week of gestation. Perioperative management consisted of sustained replacement therapy with fresh frozen plasma and platelets until the sixth postoperative day. General anaesthesia was used for the procedure. No other maternal or neonatal complications occurred.

Purpura in infants and children

Hemorrhage into the skin (purpura) may result from abnormalities in any of the three components of hemostasis: platelets, plasma coagulation factors, and blood vessels. The morphology, size, and distribution of the hemorrhagic lesions are helpful diagnostic features. The main causes of purpura in the newborn and the more common hemorrhagic disorders in children are reviewed.

Glanzmann's thrombasthenia revisited

Glanzmann's thrombasthenia is a rare thrombocytopathy that has been associated with fatal bleeding. This disorder is characterized by a defect in platelet aggregation. Platelet counts, morphologies, prothrombin times, and activated partial thromboplastin times are normal, however, the bleeding time is markedly prolonged. The goal of this article is to describe the pathophysiology of this disorder and to formulate a therapeutic approach to the management of hemorrhage in the thrombasthenic patient.