Analysis of a patient with severe Hemophilia A due to a large duplication of F8 gene / 中华医学遗传学杂志

OBJECTIVE@#To report on a case with severe hemophilia A (HA) due to a large duplication of F8 gene.@*METHODS@#Inversion detection, Sanger sequencing, and multiplex ligation-dependent probe amplification (MLPA) were used to detect the mutation in the proband and his mother.@*RESULTS@#The patient, a 7-year-old boy, was diagnosed with severe HA at 8 months. No inhibitor was developed over 150 exposure days. Intronic inversion detection and Sanger sequencing have failed to identify pathogenic variants, while MLPA revealed a large duplication [Ex 1_22 dup (2 copies)] in the proband, for which his mother was a carrier [Ex 1_22 dup (3 copies)]. Large duplications of the F8 gene have so far been found in 24 HA patients, all of whom had a severe phenotype, only one had a history of inhibitors.@*CONCLUSION@#Large duplications of F8 gene are associated with severe HA. The diagnostic rate for HA may be increased by MLPA.

Detection of F8 mutations in carriers and patients with severe hemophilia A: Identification of a novel mutation / Detección de mutaciones en el gen F8 en mujeres portadoras y en pacientes con hemofilia A: Identificación de una mutación nueva

The molecular diagnosis of haemophilia A (HA) patients has many benefits including diagnosis confirmation and inhibitor risk development prediction. In female carries of a mutation, the molecular diagnosis allows for genetic counseling and prenatal diagnosis, which have become part of the comprehensive care for HA in many countries. Therefore, the aim of this study was to determine the F8 mutations in severe HA (sHA) patients and female carriers. In 12 patients with sHA, the presence of the intron 22 and intron 1 inversions was investigated using an inverse and a conventional PCR method, respectively. In patients negative for the inversions, the F8 gene was screened through conformation sensitive gel electrophoresis (CSGE) and further sequencing. The causative mutation was successfully identified in 6/12 patients, including the novel mutation p.G190C. The mothers of these six patients and those of seven other sHA patients molecularly diagnosed in a previous work were investigated for the presence of the genetic alterations found in their sons. All mothers were found to be carriers. This is the first study conducted in Venezuela which directly analyzes the F8 gene in potential carrier mothers to specifically identify the presence of the mutation that was detected in their sons, and complements a previous study on sHA patients. Our findings will facilitate the implementation of regular screening of HA carriers in our country and will allow a better care of bleeding symptoms and genetic counseling.

El diagnóstico molecular de pacientes con hemofilia A (HA) tiene múltiples beneficios, incluyendo la confirmación del diagnóstico y la predicción del riesgo de desarrollar inhibidores. En mujeres portadoras de una mutación, el diagnóstico molecular permite el consejo genético y el diagnóstico prenatal, los cuales son parte de la atención integral de HA en muchos países. Así, el objetivo de este estudio fue determinar mutaciones en el gen F8 en pacientes con HA severa (HAs) y en mujeres portadoras. En 12 pacientes con HAs, la presencia de la inversión del intrón 22 y el intrón 1 fue investigada utilizando una PCR inversa y una convencional, respectivamente. En pacientes negativos para cualquiera de las inversiones, el gen del F8 fue analizado a través de la técnica de electroforesis en gel sensible a conformación (CSGE) y posterior secuenciación. La mutación causante de la enfermedad fue identificada en 6/12 pacientes, incluyendo la mutación nueva p.G190C. Las madres de estos seis pacientes y las de otros siete pacientes de HAs diagnosticados en un estudio previo y fueron investigadas para la presencia de alteraciones genéticas encontradas en sus hijos. Todas las madres resultaron ser portadoras. Éste es el primer estudio realizado en Venezuela donde se analiza directamente el gen F8 en portadoras potenciales para identificar específicamente la presencia de una mutación que fue detectada en sus hijos, y complementa un estudio previo con pacientes HAs. Nuestros hallazgos facilitarán la implementación del análisis regular de portadoras de HA en nuestro país y permitirán un mejor cuidado de los síntomas de sangrado y consejo genético.

A homozygous female hemophilia A.

BACKGROUND: Hemophilia A (HA), being an X-linked recessive disorder, females are rarely affected, although they can be carriers. AIMS: To study the mutation in F8 gene in an extended family with a homozygous female HA. MATERIALS AND METHODS: All the seven affected members (six males and one female) were initially screened by Conformation Sensitive Gel Electrophoresis (CSGE) and direct DNA sequencing. RESULTS: A homozygous missense mutation c.1315G>A (p.Gly420Ser) was identified in exon 9 of F8 gene in homozygous state in the affected female born of 1° consanguinous marriage and in all the affected male members of the family. Her factor VIII levels was found to be 5.5%, vWF:Ag 120%. CONCLUSION: In India, as consanguineous marriages are very common in certain communities (up to 30%), the likelihood of encountering female hemophilia is higher, although this is the first case of HA out of 1600 hemophilia families registered in our Comprehensive Haemophilia Care Center. Genetic diagnosis in such cases is not necessary as all the male children will be affected and daughters obligatory carriers.

A novel mutation (4040-4045 nt. delA) in exon 14 of the factor VIII gene causing severe hemophilia A.

Hemophilia A is an X-linked congenital bleeding disorder caused by Factor VIII deficiency. Different mutations including point mutations, deletions, insertions and inversions have been reported in the FVIII gene, which cause hemophilia A. In the current study, with the use of conformational sensitive gel electrophoresis (CSGE) analysis, we report a novel 1-nt deletion in the A6 sequence at codons 1328-1330 (4040-4045 nt delA) occurring in exon 14 of the FVIII gene in a seven-year-old Iranian boy with severe hemophilia A. This mutation that causes frameshift and premature stop-codon at 1331 has not previously been reported in the F8 Hemophilia A Mutation, Structure, Test and Resource Site (HAMSTeRS) database.

Análisis de las inversiones del intrón 1 y 22 y secuenciación del gen F8 para el diagnóstico genético-molecular de hemofilia A en Chile / Introns 1 and 22 inversions and F8 gene sequencing for molecular diagnosis of hemophilia A in Chile

Background: Hemophilia A is an inherited disorder caused by alterations in factor VIII gene (F8) located on the X-chromosome, the intron 22 inversion being the most common mutation. The rest are predominantly point mutations distributed along this large gene of 26 exons. Aim: To implement a molecular diagnostic test to detect mutations in the F8 gene in Chilean patients with Hemophilia A. Material and Methods: To validate the testing methods, we analyzed samples with intron 22 and intron 1 inversion, and with point mutations previously studied, as well as one subject without Hemophilia. We also studied unrelated Chilean patients with Hemophilia A and their female relatives for carrier testing. Intron 22 and intron 1 inversions were studied by long distance polymerase chain reaction (PCR) and point mutations by sequencing the coding and promoter regions of the F8 gene. Results: The results obtained in all samples used for validation were concordant with those obtained previously. In the Chilean patients, the intron 22 inversion and point mutations previously described were observed. In 6 out of 9 patients with mild Hemophilia A we found the same mutation (Arg2159Cys) in exon 23, which has been described as prevalent in mild Hemophilia A. Conclusions: The analysis of intron 22 and intron 1 inversions, as well as of point mutations in the F8 gene will help us to confirm the diagnosis in patients with severe, moderate and mild Hemophilia A, and also it will allow us to perform carrier testing and to provide better genetic counseling.

Caracterização Molecular da Deficiência de Fator VIII em Pacientes Hemofílicos de Minas Gerais

Hemofilia A, uma doença hemorrágica ligada ao cromossomo X, é causada pela deficiência ou disfunção do fator VIII da coagulação (FVIII). A doença resulta de alterações genéticas no gene do fator VIII (F8). Clinicamente, a hemofilia A é caracterizada por hemorragias em diferentes partes do corpo e o tratamento recomendado é a reposição do fator FVIII deficiente. O desenvolvimento de anticorpos inbidores para o FVIII é a principal complicação do tratamento. Estes anticorpos neutralizam a atividade do FVIII e, portanto invalidam a terapia. Os riscos para o desenvolvimento destes anticorpos são multifatoriais e envolvem fatores genéticos e ambientais. O objetivo deste estudo foi determinar as bases moleculares da hemofilia A grave e sua correlação com o desenvolvimento de inibidores em associação com o perfil sorológico par doenças virais. As análises moleculares consistiram da determinação da inversão do íntron 1 e do íntron 22 (inv1 e inv 22), além da determinação de outras alterações genéticas presentes na região codificadora de F8.

Inicialmente, 150 pacientes, com hemofilia A grave (níveis de atividade de fator VIII inferior a 1%) registrados no Hemominas, foram selecionados para este estudo. Nós caracterizamos 50 pacientes, dos quais, 8 tinham inv1, 29 tinham inv22 e os pacientes restantes apresentaram mutações sem sentido, mutações de sentido trocado e mutações de mudança de fase de leitura. Posteriormente, um grupo de 40 pacientes, registrados no hemocentro de Campinas e com diagnóstico molecular (32 tinham inv 22 e os pacientes restantes apresentaram mutações sem sentido, mutações de sentido trocado e mutações de mudança de fase de leitura) foram arrolados em nosso estudo. Informações a cerca de inibidores e perfil sorológico de 90 pacientes foram coletadas a partir de prontuários médicos. Dados moleculares e clínicos foram comparados por meio de análises estatísticas. As análises estatísticas não revelaram uma correlação positiva entre as diferentes categorias de mutação e a presença/ausência de inibidores sob influência do perfil sorológico.

Caracterização molecular da deficiência de fator VIII em pacientes hemofílicos de Minas Gerais / Molecular characterization of factor VIII deficiency in patients with Hemophilia Minas Gerais

Hemofilia A, uma doença hemorrágica ligada ao cromossomo X, é causada pela deficiência ou disfunção do fator VIII da coagulação (FVIII). A doença resulta de alterações genéticas no gene do fator VIII (F8). Clinicamente, a hemofilia A é caracterizada por hemorragias em diferentes partes do corpo e o tratamento recomendado é a reposição do fator FVIII deficiente. O desenvolvimento de anticorpos inbidores para o FVIII é a principal complicação do tratamento. Estes anticorpos neutralizam a atividade do FVIII e, portanto invalidam a terapia. Os riscos para o desenvolvimento destes anticorpos são multifatoriais e envolvem fatores genéticos e ambientais. O objetivo deste estudo foi determinar as bases moleculares da hemofilia A grave e sua correlação com o desenvolvimento de inibidores em associação com o perfil sorológico par doenças virais. As análises moleculares consistiram da determinação da inversão do íntron 1 e do íntron 22 (inv1 e inv 22), além da determinação de outras alterações genéticas presentes na região codificadora de F8.

Inicialmente, 150 pacientes, com hemofilia A grave (níveis de atividade de fator VIII inferior a 1%) registrados no Hemominas, foram selecionados para este estudo. Nós caracterizamos 50 pacientes, dos quais, 8 tinham inv1, 29 tinham inv22 e os pacientes restantes apresentaram mutações sem sentido, mutações de sentido trocado e mutações de mudança de fase de leitura. Posteriormente, um grupo de 40 pacientes, registrados no hemocentro de Campinas e com diagnóstico molecular (32 tinham inv 22 e os pacientes restantes apresentaram mutações sem sentido, mutações de sentido trocado e mutações de mudança de fase de leitura) foram arrolados em nosso estudo. Informações a cerca de inibidores e perfil sorológico de 90 pacientes foram coletadas a partir de prontuários médicos. Dados moleculares e clínicos foram comparados por meio de análises estatísticas. As análises estatísticas não revelaram uma correlação positiva entre as diferentes categorias de mutação e a presença/ausência de inibidores sob influência do perfil sorológico.

Delivery of Factor VIII Gene into Skeletal Muscle Cells Using Lentiviral Vector

PURPOSE: This study was designed to investigate whether transduction of lentiviral vectors (LV) carrying human coagulation factor VIII (hFVIII) cDNA into skeletal muscle could increase circulating hFVIII concentrations. MATERIALS AND METHODS: A LV containing bacterial LacZ gene as a control or human FVIII gene was intramuscularly administered into the thigh muscle of 5 weeks old Sparague-Dawley rats. The plasma human FVIII concentration and neutralizing anti-FVIII antibodies were measured for up to 12 weeks in these experimental animals. RESULTS: The plasma human FVIII levels in the rats injected with LV carrying FVIII cDNA peaked at post-injection 1st week (5.19 +/- 0.14 ng/mL vs. 0.21 +/- 0.05 ng/mL in control rats , p < 0.05). Elevated hFVIII concentrations were maintained for 4 weeks (2.52 +/- 0.83 ng/mL vs. 0.17 +/- 0.08 ng/mL in control rats, p < 0.05) after a single intramuscular injection. In the Bethesda assay, neutralizing antibodies for FVIII protein were detected only in FVIII-LV injected rats by the 10th week, but not in control rats. CONCLUSION: This study suggested that a single administration of an advanced generation LV carrying the human FVIII cDNA resulted in elevation of FVIII level in immune competent rats, and that this gene transfer approach to the skeletal muscle could be an effective tool in treatment of hemophilia A.

As bases moleculares da hemofilia A

As hemofilias são doenças hemorrágicas resultantes da deficiência de fator VIII (hemofilia A) ou de fator IX (hemofilia B) da coagulação, decorrentes de mutações nos genes que codificam os fatores VIII ou IX, respectivamente. A hemofilia A é mais frequente que a hemofilia B e acomete aproximadamente 1:10.000 nascimentos masculinos. A gravidade e frequência dos episódios hemorrágicos está relacionado ao nível residual de atividade de fator VIII presente no plasma e este relaciona-se ao tipo de mutação associada à doença. A clonagem do gene do fator VIII tornou possível o conhecimento das bases moleculares da hemofilia A, sendo hoje conhecidas mais de 1.000 mutações associadas à doença. O conhecimento das bases moleculares da hemofilia A permite uma melhor compreensão da relação genótipo-fenótipo da doença, tomada de condutas clínicas diferenciadas em casos de mutações associadas a um maior risco de desenvolvimento de inibidor, determinação da condição de portadora de hemofilia em mulheres relacionadas aos pacientes, implementação de programa de aconselhamento genético/orientação familiar e melhor compreensão das relações estruturais-funcionais do gene-proteína. Este artigo propõe revisar as bases moleculares da hemofilia A, os métodos laboratoriais utilizados para a caracterização das mutações e as implicações clínicas envolvidas no diagnóstico molecular da hemofilia A.

Hemophilias are bleeding disorders due to deficiency of the blood coagulation factor VIII (hemophilia A) or factor IX (hemophilia B), resulting from mutation on the gene coding for factor VIII or factor IX. Hemophilia A is more frequent than hemophilia B and affects 1:10,000 male newborns. The severity and frequency of hemorrhagic episodes is related to residual activity of factor VIII present in the plasma and relates to the type of mutation associated with the disorder. Cloning of the factor VIII gene has enabled researchers to better understand the molecular basis of hemophilia A, accounting to date, for more than 1,000 mutations associated with the disease. This comprehensive knowledge permits an improved comprehension of the genotype-phenotype relation, establishment of clinical policies when mutations related to higher risk of inhibitors development are known, identification of hemophilia carriers in case of women related to patients, implementation of a program of genetic counseling and discovery of structural-functional relationship between gene-protein. This article aims to review the molecular basis of hemophilia A, laboratory techniques used to characterize mutations and clinical implications involved in the molecular diagnosis of hemophilia A.

An enhancer/promoter combination strengthens the expression of blood-coagulation factor VIII in non-viral expression vectors

We explored the potential of fusion of hepatic locus control region 1 (HCR-1) with HCR-2 to express B-domain-deleted human factor VIII (FVIII) in four cell lines. B-domain-deleted human FVIII expression was controlled by HCR-1/HCR-2, followed by liver specific and ubiquitous promoters. Chimera enhancer HCR-1/HCR-2, followed by cytomegalovirus (CMV) promoter, gave 2-fold more FVIII expression in all cell lines (105.6 ± 2.8 for Hek-293, 68.8 ± 3.8 for HepG2, 34.8 ± 1.3 for CHO, and 27.2 ± 1.6 ng-mL-1-106 cells-1 for L.N.) when compared to the vector with CMV alone (54.8 ± 3.3 for Hek-293, 32.4 ± 1.2 for HepG2, 18.6 ± 1.1 for CHO, and 10.1 ± 1.7 ng-mL-1-106 cells-1 for L.N.). Elongation factor 1-α gene and human CMV promoters were more efficient than the promoters from the human α-1-antitrypsin gene, and fviii was less efficient in hepatic cell lines. HCR-1/HCR-2, followed by strong promoters, increases FVIII expression in vitro. Our results underscore the importance of cis sequences for enhancing in vitro FVIII expression; this may be helpful for designing new strategies to improve heterologous expression systems.

Bases genéticas de la hemofilia A / Genetic basis of haemophilia A

La Hemofilia A es un trastorno heredado de la coagulación sanguínea, que se caracteriza por presentar niveles reducidos de Factor VIII. En pacientes con enfermedad severa, alrededor del 50 por ciento presenta la inversión del intron 22 del gen del FVIII, y en el 5 por ciento ocurre la inversión del intron 1. Además, es posible encontrar otro tipo de mutaciones, tales como, inserciones, deleciones y mutaciones missense y nonsense. Las mutaciones en el gen del FVIII se asocian a riesgo de desarrollar inhibidores del FVIII, los que provocan refractariedad a la infusión de concentrados de factor. Gracias al conocimiento genético de la hemofilia A, se ha mejorado el diagnóstico tanto de pacientes como de portadoras, así como también la producción de concentrados de factor empleados en el tratamiento.

Genética de la hemofilia humana. Diagnóstico molecular de defectos en los genes de los factores VIII y IX de coagulación / Genetics of human haemophilia. Molecular diagnosis of defects affecting coagulation factors VIII and IX

La hemofilia A (HA) y B (HB) son enfermedades hemorrágicas hereditarias ligadas al sexo causadas por defectos de los factores VIII y IX, respectivamente. Excepto grandes inversiones recurrentes involucradas en la mitad de las HA severas, el resto de las hemofilias son causadas por distintos tipos de mutaciones grandes y pequeñas. Fueron estudiadas 70 familias con HA severa (se), 6 con seHB, 1 con HA moderada-leve (m) y 2 con mHB. Primero, en seHA, se estudio la inversión del intrón 22 (Inv22) usando un nuevo abordaje basado en PCR inversa. En los casos negativos para las inversiones se estudiaron primariamente las grandes deleciones y secundariamente las mutaciones pequeñas. En familias con HA, encontramos la Inv22 en 43 por ciento de las seHAs, una única inversión del intrón 1, 10 grandes deleciones (catorce por ciento)y 23 mutaciones pequeñas (incluyendo 10 deleciones, 3 inserciones, 4 cambios nonsense, 5 missense y 1 de splicing); y en HB, 1 deleción afectando un sitio de splicing, 4 missense y 3 nonsense. Este esquema de caracterización de mutaciones permite un estudio y análisis molecular preciso de HA y HB y beneficiará tanto al asesoramiento genético como a la provisión de información clave para el diseño del tratamiento.

Molecular diagnosis of hemophilia A and B. Report of five families from Costa Rica

Hemophilia A and B are X-chromosome linked bleeding disorders caused by deficiency of the respective coagulation factor VIII and IX. Affected individuals develop a variable phenotype of hemorrhage caused by a broad range of mutations within the Factor VIII or Factor IX gene. Here, were report the results of the molecular diagnosis in a five Costa Rican families affected with Hemophilia. Methods of indirect and direct molecular diagnosis are applied in three Hemophilia A and two Hemophilia B families from Costa Rica as well as preconditions, practicability and facilities of this diagnosis. In two families with Hemophilia A and both families with Hemophilia B the causative mutation could be detected by Southern blotting, polymerase chain reaction or sequence analysis. One Hemophilia A family could only analyzed by linkage analysis using genomic markers.

Prenatal diagnosis in a haemophilia A family by both factor VIII activity and antigen measurements.

With the advent of molecular biology techniques prenatal diagnosis in haemophilia A is generally being performed by first trimester chorionic villus sampling followed by the DNA analysis using various polymorphic markers of factor VIII gene. Here we report antenatal diagnosis in a haemophilia A family performed in the second trimester by measuring both factor VIII:C and factor VIII:Ag in the fetal blood sample.

Mutations at the activated protein C cleavage sites Arg336 and Arg562 of factor VIII in Thai patients with venous thrombosis.

Venous thrombosis is a multicausal disease, more than one genetic risk factor may cooperate to effect thrombotic risk. Factor V Leiden is found to be an important hereditary risk factor for venous thromboembolism. Analogous to factor V Leiden, a point mutation at amino acid positions Arg336 and Arg562 in factor VIII may predispose patients to thrombosis. Eighty-one Thai patients with venous thrombosis and 100 Thai healthy volunteers have been studied. Neither heterozygous nor homozygous mutations were detected both thrombosis patients or normal volunteers. However, further studies with larger samples of venous thrombosis patients are recommended.

Carrier detection and prenatal diagnosis in families with haemophilia.

BACKGROUND: Haemophilias are the commonest X-linked disorders affecting approximately 1 in 10,000 male births. Detection of carrier women in families with haemophilia and subsequent antenatal diagnosis of confirmed carriers are important services for these patients and their relatives. Over the last 6 years we performed carrier detection and antenatal diagnosis in families with patients of haemophilia A and B. METHODS: During the last 6 years, 159 families with haemophilia A and B were analysed for carrier detection by DNA analysis, using various polymorphic markers of factors VIII and IX genes. The polymorphisms used were intron 18 Bcl I, intron 19 Hind III, intron 22 Xbal and DXS52/St14 of the factor VIII gene and intron I Ddel, intron 4 Taql, 3 Hhal and Residue 148 codon Mnll of the factor IX gene. There were 189 probable carriers (whose carrier status was not known) and 99 obligatory carriers (confirmed carriers by family pedigree analysis) from 102 families with haemophilia A. Of the 57 families with haemophilia B analysed, there were 98 probable and 52 obligatory carriers. All the analyses were carried out by polymerase chain reaction. For antenatal diagnosis, prior to polymorphism analysis, the sex of the foetus was detected by Y chromosome-specific amplification. RESULTS: One hundred and four females were diagnosed as carriers and 63 as non-carriers by the intragenic polymorphic markers in families with haemophilia A. Eighteen women were informative with only the extragenic marker of factor VIII gene. Four women were not informative with any of the markers used. In families with haemophilia B, 37 women were diagnosed as carriers and 34 as non-carriers by the intragenic markers and 34 were informative only with the extragenic markers. Seventeen women were not informative with any of the markers used. Of the 25 antenatal diagnoses performed (20 haemophilia A, 5 haemophilia B) using the same markers as those used in carrier detection, 14 were male foetuses and 11 female as detected by Y chromosome-specific polymerase chain reaction. Eight were affected males and 6 unaffected. Among the females, 5 were carriers and 6 normal. CONCLUSION: Using the above polymorphic markers of factors VIII and IX genes, a diagnosis could be made in the majority of families.

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.