High Titer Inhibitor-Acquired Hemophilia A Treated With Human FVIII Concentrate in Limited Resource: A Case Report

@#Acquired hemophilia A (AHA) is a rare condition that affects one in a million people each year, and there are not many diagnostics or therapeutic agents available for treatment due to its rarity. This is a case report of a 61-year-old woman who presented with a spontaneous subcutaneous hematoma and multiple extensive bruises in her extremities. There was no prior history of bleeding disorders, and the laboratory results showed an isolated aPTT prolongation with no correction after mixing studies, and a reduction in FVIII activity level along with a high FVIII inhibitor titer (928BU). Furthermore, the diagnosis of idiopathic AHA was made after other secondary causes had been ruled out, and the patient received human FVIII concentrate instead of bypassing agents due to its availability. The patient still experienced clinical improvement despite using this alternative. AHA is currently managed using both hemostasis agents and inhibitor eradication, and they come with several limitations. Human FVIII concentrate therapy is still an option in situations with limited resources, even though it is not recommended in patients with high inhibitor titer levels.

Estudio de la relación entre el grupo sanguíneo eritrocitario ABO con los niveles del factor von Willebrand en pacientes diagnosticados con la enfermedad / Study of the relationship between the ABO erythrocyte blood group with the von Willebrand factor levels in patients diagnosed with the disease

Resumen La presencia o ausencia de los antígenos del sistema ABO entre otros factores se han relacionado con los niveles plasmáticos del factor von Willebrand (VWF) debido a su influencia en la proteólisis por la ADAMTS 13; la actividad de este sistema eritrocitario puede incidir en eventos trombóticos o hemorrágicos. El propósito de este estudio fue determinar si los pacientes diagnosticados con la enfermedad de von Willebrand pertenecían al grupo sanguíneo O y si los niveles de VWF y FVIII eran más bajos que los de los grupos no-O. El grupo sanguíneo fue identificado por un método directo en tubo y el VWF y FVIII se midieron mediante ensayos de coagulación. Se analizó un total de 64 pacientes, el 29,4% eran mayores de 40 años, el 100% presentaron valores más bajos del VWF que los grupos no-O, el 64% de los pacientes presentaron una concentración del FVIII de 6-49% inferior al rango normal establecido y el 78,51% fueron tipificados como del grupo sanguíneo O. El análisis estadístico demostró una relación estadísticamente significativa entre los niveles de VWF y el grupo sanguíneo. Se determinó que existe una relación entre el sistema ABO y el VWF-FVIII (p<0,05); sin embargo, esto no significa que sea la única causa de la existencia de un nivel bajo del factor. Estos datos indican la necesidad de mayores estudios en la población de pacientes con la enfermedad y la necesidad de determinar los tipos de von Willebrand y su relación con el grupo sanguíneo.

Abstract The presence or absence of antigens of the ABO system, among other factors, have been related to plasma levels of von Willebrand factor (VWF) due to its influence on proteolysis by ADAMTS 13. The activity of this erythrocyte system may influence on thrombotic or hemorrhagic events. The purpose of this study was to determine if the patients diagnosed with von Willebrand disease belonged to the O blood group and the VWF and FVIII levels were lower than those of the other blood groups. The blood group was identified by direct tube method and the VWF and FVIII were measured by coagulation tests. A total of 64 patients were analised, 29.4% were older than 40, 100% presented lower values of VWF than the non-O groups. A total of 64% of the patients presented a lower concentration of 6-49% in FVIII at the established normal range and 78.51% were typified as blood group O. Statistical analysis showed a statistically significant relationship between VWF levels and blood group. It was determined that there is a relationship between the ABO system and the VWF-FVIII (p<0.05). However, this does not mean that is the only cause of the existence of a low level of these factors. These data indicate the need for further studies in the population of patients with von Willebrand disease in order to determine the von Willebrand types and their relationship with the blood group.

Resumo A presença ou ausência dos antígenos do sistema ABO, entre outros fatores, tem sido relacionada aos níveis plasmáticos do fator de von Willebrand (VWF) devido à sua influência na proteólise pelo ADAMTS 13; a atividade desse sistema eritrocitário pode afetar eventos trombóticos ou hemorrágicos. O objetivo deste estudo foi determinar se os pacientes com diagnóstico de doença de von Willebrand pertenciam ao grupo sanguíneo O e se os níveis de VWF e FVIII eram inferiores aos dos grupos não-0. O grupo sanguíneo foi identificado por um método direto em tubo e o VWF e o FVIII foram medidos por testes de coagulação. Foram analisados 64 pacientes, 29,4% tinham idade superior a 40 anos, 100% apresentaram valores mais baixos do VWF que os grupos não-O e 64% dos pacientes apresentaram concentração de FVIII 6-49% menor à faixa normal estabelecida, e 78,51% foram tipificados como do grupo sanguíneo O. A análise estatística mostrou uma relação estatisticamente significativa entre os níveis de VWF e o grupo sanguíneo. Foi determinado que existe uma relação entre o sistema ABO e o VWF-FVIII (p<0,05), no entanto, isso não significa que seja a única causa da existência de um baixo nível do fator. Esses dados indicam a necessidade de novos estudos na população de pacientes com a doença e a necessidade de determinar os tipos de von Willebrand e sua relação com o grupo sanguíneo.

Validación del ensayo FVIII: C cromogénico en una plataforma automatizada

El objetivo de este trabajo fue realizar la validación analítica del método cromogénico (FVIII:Ccro) en la plataforma ACL TOP y correlacionarlo con el método coagulable en una etapa (FVIII:Ccoag). El estudio de validación (EP5-A2, EP6-A2 y comparación de métodos por EP-9) se realizó para la curva de rango normal-bajo (CRNB): aproximadamente entre 10-150 UI/dL de FVIII y de rango muy bajo (CRMB): aproximadamente entre 0-10 UI/dL. Los resultados de repetitividad (CVr) y precisión intermedia (CVi) fueron menores del 6% y comparables a los informados por el fabricante para otras plataformas. El rango de medición analítica fue de 11-129 UI/dL con CRNB, y se extrapoló a 0,3 UI/dL al utilizar la CRMB. Para la CRNB FVIII:Ccro mostró buena correlación con FVIII:Ccoag: r: 0,98, pendiente: 0,982 (0,961-1,003), ordenada al origen: -0,3 (-1,1-0,5), sesgo: -2,0%. Para CRMB se obtuvo un r de 0,96, pendiente: 0,921 (0,855-0,988), ordenada al origen: -0,07 (-0,35-0,20), sesgo: -10,2%. Sólo 4 pacientes presentaron niveles discrepantes entre ambos métodos. La determinación de FVIII:C por el método cromogénico automatizado en la familia ACL TOP fue comparable con FVIII coagulable en una etapa en el rango analítico evaluado. El FVIII:Ccro automatizado puede utilizarse para el diagnóstico y seguimiento del tratamiento de los pacientes hemofílicos.

The objective of this work was to perform the analytical validation of the chromogenic method (FVIII:Ccro) on the ACL TOP platform correlating with one stage assay (FVIII:Ccoag). The validation study (EP5-A2, EP6-A2 and comparison of methods by EP-9) was performed for the low-normal range curve (CRNB): approximately between 10-150 IU/dL of FVIII and very low range (CRMB): approximately between 0-10 IU/dL. The results of CVr (repeatability) and CVi (intermediate precision) were lower than 6% and comparable to those reported by the manufacturer for other platforms. The analytical measurement range was 11-129 IU/dL, extrapolated to 0.3 IU/dL using the CRMB. For CRNB FVIII:Ccro showed good correlation with FVIII:Ccoag: r: 0.98, slope: 0.982 (0.961-1.003), intercept: -0.3 (-1.1-0.5), bias: -2.0%. For CRMB: r: 0.96 was obtained, pending: 0.921 (0.855-0.988), intercept: -0.07 (-0.35-0.20), bias: -10.2%. Only 4 patients presented discrepant levels between both methods. The automated chromogenic FVIII assay in the ACL TOP family is comparable with one stage coagulable FVIII in the analytical range studied. The FVIII:Ccro automated can be used for the diagnosis and monitoring of the treatment of hemophilic patients.

O objetivo deste trabalho foi a validação analítica do método cromogênico (FVIII:Ccro) na plataforma ACL TOP correlacionando-se com o método coagulável numa etapa (FVIII:Ccoag). O estudo de validação (EP5-A2, EP6-A2 e comparação de métodos por EP-9) foi realizado para a curva de faixa normal-baixa (CRNB) aproximadamente entre 10 e 150 Ul/dL de FVIII e de faixa muito baixa (CRMB): aproximadamente entre 0 e 10 UI/dL. Os resultados de Repetitividade (CVr) e precisão intermediária (CVi) foram inferiores a 6% e comparáveis aos descritos pelo fabricante para outras plataformas. A faixa de medição analítica foi de 11-129 UI/dL com CRNB extrapolando-se para 0,3 UI/dL utilizando a CRMB. Para a CRNB FVIII:Ccro houve boa correlação com o FVIII: Ccoag: r: 0,98, inclinação: 0,982 (0,961-1,003), ordenada na origem: -0,3 (-1,1-0,5), Viés: -2,0%. Para CRMB: foi obtido um r: 0,96, pendente: 0,921 (0,855-0,988), ordenado na origem: -0,07 (-0,35-0,20), Viés: -10,2%. Apenas quatro pacientes apresentaram níveis discrepantes entre os dois métodos. A determinação de FVIII:C pelo método cromogênico automatizado na família ACL TOP foi comparável ao FVIII coagulável em um estágio na faixa analítica avaliada. FVIII: O FVIII:Ccro automatizado pode ser utilizado para o diagnóstico e seguimento do tratamento dos pacientes hemofílicos.

Evaluation of coagulation factor activity and sterility of thawed fresh frozen plasma during storage up to 5 days at 4°C

@#Introduction: Fresh frozen plasma (FFP) is a blood component containing functional quantities of all coagulation factors stored at -18°C or below. FFP has to be thawed and transfused as soon as possible to prevent the loss of certain coagulation factor activities and to minimise microbial contamination. Materials and Methods: Thirty units of FFP kept at -20°C were thawed using a 37°C water bath and immediately sampled for baseline Factor II (FII), Factor VIII (FVIII) and fibrinogen activity levels and sterility testing. Each unit was then divided into two smaller bags (i.e. Bag I and Bag II) and kept at 4°C. At 6 hours and Day 3, representative samples were taken from Bag I for coagulation factor activity assays, while at Day 5 representative samples were taken from Bag II for coagulation factor activity assays and sterility testing. Results: FII activities at the four time points were 73.43%, 73.73%, 71% and 69.8%, respectively, while FVIII activities were 177.63%, 144.37%, 80.8% and 70.97%, respectively. Fibrinogen levels at the four time points were 3.24 g/L, 3.24 g/L, 3.21 g/L and 3.20 g/L, respectively. All samples were free from microbial contamination even at Day 5. Conclusion: The mean reduction in FII and fibrinogen activities on Day 5 was 5% and 1%, respectively. However, FVIII activity declined significantly by approximately 60% at Day 5. Despite these reductions, thawed plasma stored for up to 5 days at 4°C is still suitable for use as the coagulation factor activity levels still exceed the minimum release criteria recommended in quality assurance regulations.

Surgery in Patients with Von Willebrand Disease : A Single Center Experience / 임상소아혈액종양

BACKGROUND: Von Willebrand disease (VWD) is the most common inherited bleeding disorder. Surgery, even relatively minor procedures, in patients with moderate to severe qualitative and quantitative deficiencies of von Willebrand factor (VWF) can be associated with a life-threatening risk of excessive bleeding. The purpose of this study was to evaluate the safety and efficacy of VWF/FVIII in patients with von Willebrand disease before surgery and determine the efficacy of VWF/FVIII.METHODS: We reviewed the results of surgical procedures in patients with VWD at Kyung Hee University Hospital at Gangdong, between September 2009 and January 2016. VWF/FVIII concentrates were administrated preoperatively to all patients.RESULTS: Between September 2009 and January 2016 at our center, eight surgical procedures were performed successfully and no severe complications were observed in the seven patients with VWD. Four orthopedic procedures, one laparoscopic appendectomy, one ovary cystectomy, one strabotomy, and one dental extraction were performed. The median duration of hospitalization was seven days. VWF/FVIII concentrates were administered prior to all procedures, including the dental extraction. In all cases, uncontrolled bleeding and thromboembolic complications were not observed.CONCLUSION: Patients with VWD who require surgery can be treated efficiently and safely with VWF/FVIII concentrates. There is excellent tolerance, efficacy and safety in preventing excessive bleeding during surgery. When administering VWF/FVIII concentrates, treatment should be monitored with VWF Ag, VWF:RCo and FVIII plasma levels.

Surgery in Patients with Von Willebrand Disease : A Single Center Experience / 임상소아혈액종양

BACKGROUND: Von Willebrand disease (VWD) is the most common inherited bleeding disorder. Surgery, even relatively minor procedures, in patients with moderate to severe qualitative and quantitative deficiencies of von Willebrand factor (VWF) can be associated with a life-threatening risk of excessive bleeding. The purpose of this study was to evaluate the safety and efficacy of VWF/FVIII in patients with von Willebrand disease before surgery and determine the efficacy of VWF/FVIII. METHODS: We reviewed the results of surgical procedures in patients with VWD at Kyung Hee University Hospital at Gangdong, between September 2009 and January 2016. VWF/FVIII concentrates were administrated preoperatively to all patients. RESULTS: Between September 2009 and January 2016 at our center, eight surgical procedures were performed successfully and no severe complications were observed in the seven patients with VWD. Four orthopedic procedures, one laparoscopic appendectomy, one ovary cystectomy, one strabotomy, and one dental extraction were performed. The median duration of hospitalization was seven days. VWF/FVIII concentrates were administered prior to all procedures, including the dental extraction. In all cases, uncontrolled bleeding and thromboembolic complications were not observed. CONCLUSION: Patients with VWD who require surgery can be treated efficiently and safely with VWF/FVIII concentrates. There is excellent tolerance, efficacy and safety in preventing excessive bleeding during surgery. When administering VWF/FVIII concentrates, treatment should be monitored with VWF Ag, VWF:RCo and FVIII plasma levels.

Human coagulation factor VIII domain-specific recombinant polypeptide expression

BACKGROUND: Hemophilia A is caused by heterogeneous mutations in F8. Coagulation factor VIII (FVIII), the product of F8, is composed of multiple domains designated A1-A2-B-A3-C1-C2. FVIII is known to interact with diverse proteins, and this characteristic may be important for hemostasis. However, little is known about domain-specific functions or their specific binding partners. METHODS: To determine F8 domain-specific functions during blood coagulation, the FVIII domains A1, A2, A3, and C were cloned from Hep3B hepatocytes. Domain-specific recombinant polypeptides were glutathione S-transferase (GST)- or polyhistidine (His)-tagged, over-expressed in bacteria, and purified by specific affinity chromatography. RESULTS: Recombinant polypeptides of predicted sizes were obtained. The GST-tagged A2 polypeptide interacted with coagulation factor IX, which is known to bind the A2 domain of activated FVIII. CONCLUSION: Recombinant, domain-specific polypeptides are useful tools to study the domain-specific functions of FVIII during the coagulation process, and they may be used for production of domain-specific antibodies.

Análisis del costo y la efectividad de los esquemas de administración de factores de coagulación para el manejo de niños con hemofilia A en México / Cost-effectiveness analysis of prophylaxis vs. ''on demand'' approach in the management in children with hemophilia A in Mexico

Introducción. La hemofilia A es causada por la deficiencia del factor VIII. El tratamiento consiste principalmente en aumentar la concentración del FVIII en la sangre utilizando productos de remplazo. El objetivo de este trabajo fue estimar los beneficios clínicos y económicos del manejo profiláctico con factor VIII en niños con hemofilia A en México. Métodos. Se realizó la evaluación económica del manejo profiláctico (PROF) y del tratamiento sobre demanda (SD). Las estrategias comparadas fueron el manejo profiláctico -consistente en FVIII recombinante 25 UI/kg cada tercer día- vs. tratamiento sobre demanda -consistente en FVIII derivado de plasma 40 UI/kg. Se reportó el número de sangrados evitados (SE). Se empleó una tasa de descuento del 5%. Los resultados se expresaron en pesos mexicanos. Resultados. El costo de incremental de PROF respecto a SD fue de $7,727,554 pesos. El manejo con PROF ofrece una reducción de 112 SE frente al manejo de SD (162.9 vs. 50.7). El costo por SE fue de $68,876 pesos. Conclusiones. Un abordaje con PROF mejora la calidad de vida respecto al manejo SD y reduce el número de hemorragias que enfrentan los niños con hemofilia A. PROF es una alternativa costo-efectiva (RCEI $68,876 pesos) para reducir sangrados de acuerdo con la disponibilidad de pago establecida por las autoridades de salud en México.

Background. Hemophilia A is due to a deficiency of factor VIII. Treatment consists primarily of increasing the concentration of FVIII in the blood using replacement products. The aim of this study was to estimate the clinical and economic benefits of prophylactic management with factor VIII in children with hemophilia A in Mexico. We undertook this study to estimate the clinical and economic benefits of prophylactic management (PROF) with factor VIII (FVIII) in children with severe hemophilia in Mexico. Methods. We carried out an economic evaluation of PROF vs. treatment on demand (OD). The strategies compared were management with PROF consisting of recombinant FVIII (rFVIII) 25 IU kg every other day vs. OD management consisting of plasma-derived FVIII (pdFVIII) 40 IU kg. A Markov model was performed with a time horizon of 16 years in patients with severe hemophilia for 2 years, reporting the number of events of bleeding averted (BA). We used a discount rate of 5%. The results are expressed in Mexican pesos (2012). Results. The incremental cost of PROF regarding SD was $7,727,554 pesos. PROF management provides a reduction of 112 BA vs. OD management (162.9 vs. 50.7). Cost per BA was $68,876 pesos. Conclusions. Management with PROF reduces the number of bleeding events facing children with hemophilia A compared to OD management. PROF is a cost-effective alternative to reduce bleeding ($68,876 pesos per BA) according to the willingness to pay established by health authorities in Mexico.

A patient with acquired hemophilia A induced by clopidogrel

Acquired hemophilia A (AHA) is a rare bleeding disorder caused by autoantibodies against factor VIII (FVIII). Treatment with clopidogrel is a cause of AHA, but its clinical course is unknown. Recently, we treated a 65-year-old man who was hospitalized for cerebellar infarction and had a prolonged activated partial thromboplastin time (aPTT) with soft tissue oozing after 3 weeks of clopidogrel use. We terminated clopidogrel administration and transfused the patient with fresh frozen plasma. However, the aPTT increased up to 98.8 seconds, and the FVIII and FVIII inhibitor levels were <1% and 5.4 Bethesda units/mL, respectively. Clopidogrel-associated AHA was considered, and we began steroid treatment. Two months later, FVIII, FVIII inhibitor, and aPTT values were normalized. No further bleeding or aPTT prolongation has been reported during the 2-year follow-up period. AHA should be considered in patients taking clopidogrel and experiencing bleeding, unless the platelet count and coagulation screen are normal.

Manejo de la enfermedad de von Willebrand en ginecología y obstetricia: revisión cualitativa de la literatura / A qualitative review of the literature regarding managing Von willebrand disease in obstetrics and gynaecology

Introducción: la enfermedad de Von Willebrand es el trastorno de la coagulación con mayor prevalencia de mujeres en edad fértil y, por lo tanto, es el trastorno genético de la hemostasia más frecuente en la práctica ginecológica y obstétrica. Objetivo: hacer una revisión de la enfermedad de Von Willebrand en pacientes de ginecología y obstetricia con especial énfasis en la fisiopatología, el diagnóstico y el tratamiento. Metodología: se realizó una búsqueda bibliográfica en las bases de datos electrónicas MEDLINE/Pubmed, Elsevier, Interscience, EBSCO, Scopus, SciELO de 1980 al 2009, Cochrane Pregnancy and Childbirth Group (septiembre 30 del 2009) y libros de texto impresos. Resultados: el diagnóstico se basa en una cuidadosa anamnesis y pruebas de laboratorio de detección y confirmatorias. La correcta identificación de los diferentes tipos y subtipos es importante desde el punto de vista terapéutico. El tratamiento requiere medicaciones específicas como la desmopresina, concentrados de factor VIII y terapias coadyuvantes. No existe evidencia para contraindicar la vía vaginal del parto, sin embargo, se debe individualizar cada caso en particular. Conclusión: las mujeres con trastornos de la coagulación presentan durante la menarquia, la gestación, el parto y el puerperio un riesgo mayor de sangrado lo que hace obligatoria una adecuada evaluación y un manejo multidisciplinario durante el embarazo.

Introduction: Von Willebrand disease (vWD) is a disorder of the coagulation, being more prevalent in fertile females and is thus the most frequently occurring genetic haemostasis disorder in obstetric and gynaecological practice. Objective: reviewing the literature concerning vWD in obstetric and gynaecology patients, placing special emphasis on the disease’s physiopathology, diagnosis and treatment. Methodology: a bibliographic search was made of MEDLINE electronic databases via pubmed, Elsevier, Interscience, EBSCO, Scopus and SciELO from 1980 to 2009. The Cochrane Pregnancy and Childbirth Group (September 30th 2009) and printed texts and books were also consulted. Results: diagnosis was based on careful anamnesis and detection and confirmatory laboratory tests. Correct identification of different types and subtypes is important from a therapeutic point of view. Treatment requires specific medication such as desmopressin, factor VIII concentrates and coadjuvant therapies. No evidence was found to contraindicate vaginal birth route; however, each particular case must be taken individually. Conclusion: females suffering from coagulation disorders present a greater risk of bleeding during menarche, pregnancy, giving birth and the puerperium. This means that suitable evaluation and multidisciplinary management must be mandatory during pregnancy.

Anticuerpos anti-FVIII: su evaluación por citometría de flujo / Anti FVIII antibodies: evaluation by flow cytometry

En este trabajo se describe un sistema para evaluar y caracterizar los anticuerpos anti-FVIII en pacientes con Hemofilia A Severa (HAS) que reciben el Factor como tratamiento de sustitución. Consiste en el empleo combinado de microesferas y Citometria de Flujo (CF). El rFVIII fue acoplado a microesferas de 2 µm de diámetro (m-FVIII) las cuales se incubaron con diluciones de plasma o suero de pacientes con (n=13) o sin (n=17) inhibidor, pacientes en Tratamiento Inmunotolerante (TIT)(n=5) y dadores normales (N) (n=12). Los anticuerpos se revelaron con anti-lgG humana, anti-lgG1, anti-lgG2, anti-IgG3 o anti-lgG4 biotiniladas, seguido por streptavidina-ficoeritrina. Se registraron los valores de Intensidad de Fluorescencia Media (IFM). Microesferas sin FVIII (m-Control) se utilizaron como control. El resultado se expresó como índice: (IFM de m-FVIII/IFM de m-Control) multiplicado por la inversa de la dilución de máxima respuesta. Se determinó el porcentaje de contribución de cada subclase de IgG. Los resultados presentaron un 86 por ciento de concordancia con la prueba de Bethesda y un 80 por ciento con ELISA. El método fue útil para el seguimiento de los pacientes durante el TIT. La IgG4 prevaleció en pacientes con alto título y al comienzo del TIT. La CF es fácil y rápida y requiere sólo 200 µl de muestra.

In this study, a Flow Cytometry (FC) system is described for detecting and characterizing antibodies (inhibitors) to Factor VIII (FVIII) in Severe Haemophilia A (SHA) patients following FVIII infusion. A combination of microspheres and Flow Cytometry (FC) was employed. First, rFVIII was coupled to microspheres of 2 µm of diameter (m-FVIII). Then, they were reacted with dilutions of plasma or serum of patients with (n=13) or without (n=17) inhibitors. Five patients receiving Immunotolerant Treatment (ITI) and 12 normal donors were included. Microspheres without rFVIII were used as control (m-Control). Captured anti-FVIII antibodies were detected using biotinylated anti-Human IgG, IgG1, IgG2, IgG3 or IgG4 followed by streptavidin-phycoerythrin. FC analysis was performed recording Mean Fluorescence Intensity (MFI). Results were given as an Index: the highest MFI ratio between m-FVIII and m-Control multiplied by the inverse of the corresponding plasma dilution. The contribution of each IgG subclass was expressed as percentage. FC results had 86 per cent and 80 per cent of coincidence with the Bethesda method and ELISA respectively. The test was useful to measure anti-FVIII antibodies during the ITI. IgG4 was the prevalent IgG subclass in patients with high level of inhibitors and previously to ITI. FC was easy, fast and requires only 200 µl of sample.

Identification of FVIII gene mutations in patients with hemophilia A using new combinatorial sequencing by hybridization.

BACKGROUND: Standard methods of mutation detection are time consuming in Hemophilia A (HA) rendering their application unavailable in some analysis such as prenatal diagnosis. OBJECTIVES: To evaluate the feasibility of combinatorial sequencing-by-hybridization (cSBH) as an alternative and reliable tool for mutation detection in FVIII gene. PATIENTS/METHODS: We have applied a new method of cSBH that uses two different colors for detection of multiple point mutations in the FVIII gene. The 26 exons encompassing the HA gene were analyzed in 7 newly diagnosed Italian patients and in 19 previously characterized individuals with FVIII deficiency. RESULTS: Data show that, when solution-phase TAMRA and QUASAR labeled 5-mer oligonucleotide sets mixed with unlabeled target PCR templates are co-hybridized in the presence of DNA ligase to universal 6-mer oligonucleotide probe-based arrays, a number of mutations can be successfully detected. The technique was reliable also in identifying a mutant FVIII allele in an obligate heterozygote. A novel missense mutation (Leu1843Thr) in exon 16 and three novel neutral polymorphisms are presented with an updated protocol for 2-color cSBH. CONCLUSIONS: cSBH is a reliable tool for mutation detection in FVIII gene and may represent a complementary method for the genetic screening of HA patients.

Transient Acquired Hemophilia Associated with Mycoplasma Pneumoniae Pneumonia

Acquired hemophilia is a rare disorder caused by autoantibodies to factor VIII (FVIII) (also referred to as factor VIII inhibitors or anti-FVIII) and may be associated with pregnancy, underlying malignancy, or autoimmune disorders. A 33-month-old girl who presented with hematochezia and ecchymotic skin lesions was diagnosed with Mycoplasma pneumoniae pneumonia by serology and polymerase chain reaction. Hematologic studies showed a prolonged activated partial thromboplastin time (aPTT), partially corrected mixing test for aPTT, reduced levels of FVIII, and the presence of antibodies against FVIII. She was treated conservatively with prednisone and intravenous immunoglobulin (IVIG) without FVIII transfusion and recovered without sequelae. This report provides the first description of acquired hemophilia due to anti-FVIII in association with M. pneumoniae in Korea. We discuss this case in the context of the current literature on acquired hemophilia in children.

Synthesis of recombinant blood coagulation factor VIII (FVIII) heavy and light chains and reconstitution of active form of FVIII

FVIII is synthesized as a single chain precursor of approximately 280 kD with the domain structure of A1-A2-B-A3-C1-C2 and it circulates as a series of metal ion-linked heterodimers that result from cleavages at B-A3 junction as well as additional cleavages within B domain. Factor VIII is converted to its active form, factor VIIIa, upon proteolytic cleavages by thrombin and is a heterotrimer composed of the A1, A2, and A3-C1-C2 subunits. A1 subunits of factor VIIIa terminates with 36 residue segment (Met337-Arg372) rich in acidic residues. This segment is removed after cleavages at Arg336 by activated protein C, which results in inactivation of the cofactor. In the present study, site-directed mutagenesis of FVIII at Arg336 to Gln336 was performed in order to produce an inactivation resistant mutant rFVIII (rFVIIIm) with an extended physiological stability. A recombinant mutant heavy chain of FVIII (rFVIII-Hm; Arg336 to Gln336) and wild-type light chain of FVIII (rFVIII-L) were expressed in Baculovirus-insect cell (Sf9) system, and a biologically active recombinant mutant FVIII (rFVIIIm) was reconstituted from rFVIII-Hm and rFVIII-L in the FVIII-depleted human plasma containing 40 mM CaCl2. The rFVIIIm exhibited cofactor activity of FVIIIa (2.85 x 10(-2) units/mg protein) that sustained the high level activity during in vitro incubation at 37 degrees C for 24 h, while the cofactor activity of normal plasma was declined steadily for the period. These results indicate that rFVIIIm (Arg336 to Gln336) expressed in Baculovirus-insect cell system is inactivation resistant in the plasma coagulation milieu and may be useful for the treatment of hemophilia A.