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J C Eikenboom

Publications and source records attributed to J C Eikenboom.

At least 19 recordsLinked to original sources
PubMed2001

Type 1 von Willebrand disease mutation Cys1149Arg causes intracellular retention and degradation of heterodimers: a possible general mechanism for dominant mutations of oligomeric proteins.

Some families affected by von Willebrand disease type 1 show high penetrance with exceptionally low von Willebrand factor (VWF) levels. Previously, a mutation associated with this dominant phenotype, Cys1149Arg, was found to decrease the secretion of coexpressed normal VWF, and the mutation was proposed to cause intracellular retention of pro-VWF heterodimers. To demonstrate heterodimer formation, a model was developed in which subunits could be distinguished immunologically and by size. Recombinant VWF lacking domain A1 (dA1), A3 (dA3), or both (dA13) was secreted efficiently as a full range of multimers. Cotransfection of Cys1149Arg and dA13 resulted in the secretion of multimeric VWF containing about 250 kd (Cys1149Arg) and about 210 kd (dA13). Cell lysates contained pro-VWF forms of Cys1149Arg and dA13. Immunoprecipitation with an antidomain A1 antibody recovered both subunits in heterodimers, and subunit ratios were consistent with random dimerization. Similar results were obtained for cotransfection of Cys1149Arg and dA1. Normal VWF has a Cys1149-Cys1169 intrachain bond. When cotransfected with normal VWF, Cys1149Arg or the double mutant Cys1149Arg+Cys1169Ser caused a similar decrease in VWF secretion, suggesting that an unpaired Cys1169 does not explain the intracellular retention of Cys1149Arg. VWF Cys1149Arg was not secreted from BHK cells but was degraded intracellularly within about 4 hours, and the proteasome inhibitor lactacystin delayed its clearance more than 16 hours. Thus, dominant von Willebrand disease type 1 may be caused by heterodimerization of mutant and normal subunits in the endoplasmic reticulum followed by proteasomal degradation in the cytoplasm. A similar dominant negative mechanism could cause quantitative deficiencies of other multisubunit proteins.

Amino Acid Substitution↗
PubMed2001

High factor VIII antigen levels increase the risk of venous thrombosis but are not associated with polymorphisms in the von Willebrand factor and factor VIII gene.

High factor VIII levels increase the risk of venous thromboembolism, but the mechanisms that cause high factor VIII levels are unclear. In 301 thrombosis patients and 301 matched healthy controls, factor VIII antigen (VIII:Ag) levels > or = 150 IU/dl increased the thrombosis risk more than fivefold. We investigated whether high factor VIII:Ag levels result from a genetic variation in the factor VIII or von Willebrand factor (VWF) genes. Six polymorphisms in the VWF gene and two CA-repeats in the factor VIII gene were not associated with plasma VWF levels, factor VIII:Ag levels, or thrombosis risk. Our data do not support the hypothesis that a single functional sequence variation in the factor VIII or VWF gene explains the majority of high factor VIII levels and thrombotic risk.

Biomarkers↗
PubMed2001

Congenital von Willebrand disease type 3: clinical manifestations, pathophysiology and molecular biology.

von Willebrand disease type 3 is the most severe form of this condition. Patients present with a moderate-to-severe bleeding tendency. The plasma von Willebrand factor level in these patients is very low or undetectable. Although rare, von Willebrand disease type 3 is of major interest because of its severe clinical presentation, the need for replacement therapy and the risk of occurrence of alloantibodies after the infusion of plasma concentrates. The inheritance of type 3 disease is typically autosomal recessive. The parents are often consanguineous, although compound heterozygous inheritance does occur. The molecular basis of von Willebrand disease type 3 has recently been studied in detail, several molecular defects being identified. This chapter will focus on the clinical and molecular aspects of type 3 von Willebrand disease.

Humans↗
PubMed2001

A standard nomenclature for von Willebrand factor gene mutations and polymorphisms. On behalf of the ISTH SSC Subcommittee on von Willebrand factor.

Examination of the entire von Willebrand factor (VWF) gene for mutations, particularly in types 1 and 3 von Willebrand disease (VWD) is becoming more widely practised. The sequence of the entire VWF gene will soon be compiled as a single sequence. For these reasons, a clearly defined nomenclature to use for numbering the VWF nucleotide and amino acid sequence is required. The following recommendations are made for VWF numbering. VWF cDNA nucleotide sequence should be numbered from the A of the initiator ATG as the +1 position. Genomic DNA should be prefixed with a "g" and also numbered from this position. Amino acid (aa) numbering should be from the initiator methionine as the +1 position with sequential numbering of aa throughout VWF. To avoid confusion with previously used numbering schemes for mature VWF, which started from serine 764 of pre-pro VWF, the use of the single letter amino acid code is recommended.

Humans↗
PubMed2000

Heightened proteolysis of the von Willebrand factor subunit in patients with von Willebrand disease hemizygous or homozygous for the C2362F mutation.

We studied the proteolytic pattern of the mutant von Willebrand factor (VWF) in four patients with von Willebrand disease (VWD) who were either homozygous or hemizygous for the mutation C2362F. A significant decrease in the native fragment of 225 kDa was evident in all the patients, together with a marked increase in the 176 and 140 kDa fragments, a pattern usually observed in type 2A VWD. The proteolytic pattern measured in four heterozygotes for C2362F was within the normal range, suggesting that the mutant VWF C2362F present in the plasma of these patients may be protected from proteolysis by normal VWF.

Genotype↗
PubMed2000

Autosomal dominant type 1 von willebrand disease due to G3639T mutation (C1130F) in exon 26 of von Willebrand factor gene: description of five Italian families and evidence for a founder effect.

Twenty-four apparently unrelated Italian patients with autosomal dominant type 1 von Willebrand disease (VWD) and a clear autosomal pattern of inheritance of bleeding symptoms were screened for the C1149R and C1130F mutations. None of the patients had the C1149R mutation; three patients and four affected relatives were heterozygous for the C1130F mutation. The mutation appeared to be linked to a single haplotype, defined by five genetic markers [variable number tandem repeat (VNTR) I and II in intron 40, RsaI in exons 13 and 18 and HphI in exon 28], suggesting a founder effect. The patients responded well to desmopressin infusion. The C1130F mutation might have a dominant negative effect on the secretion of the normal protein that desmopressin would appear to overcome.

Deamino Arginine Vasopressin↗
PubMed2000

Heritability of elevated factor VIII antigen levels in factor V Leiden families with thrombophilia.

Factor VIII activity (factor VIII:C) and factor VIII antigen (factor VIII:Ag) levels above 150 IU/dl are associated with a five- to sixfold increased risk of venous thrombosis compared with levels < 100 IU/dl. These high levels are present in 25% of patients with a first episode of deep-vein thrombosis and in 11% of healthy controls. von Willebrand factor (VWF) and blood group are important determinants of the factor VIII level in plasma and therefore contribute to thrombotic risk, while factor VIII appears to be the final effector. Previously, we found familial clustering of factor VIII:C levels in women, which remained after adjustment for VWF and blood group. In the present study, we analysed the familial influence on factor VIII:Ag levels exceeding 150 IU/dl in 12 large families with thrombophilia in which high factor VIII:Ag levels contribute to thrombotic risk. As expected, blood group was a main determinant of the plasma factor VIII level: 58 relatives (32%) had factor VIII levels above 150 IU/dl and 50 (86%) of these had blood group non-O. After adjustment for blood group and age, we found an association between factor VIII:Ag levels in sister pairs (0.35, P = 0.003), brother pairs (0.35, P = 0.003), brother-sister pairs (0.35, P < 0.001) and in mother-son pairs (0.45, P = 0.02), but not in father-daughter or father-son pairs. The familial aggregation test was strongly positive for factor VIII:Ag levels (P < 0.001) and remained so after adjustment for the influence of blood group. We conclude that high factor VIII:Ag levels are a highly prevalent risk factor for venous thrombosis and contribute to risk in families with thrombophilia, and that these high levels are likely to be genetically determined by factors other than just blood group.

Adolescent↗
PubMed2000

Factor V antigen levels and venous thrombosis: risk profile, interaction with factor V leiden, and relation with factor VIII antigen levels.

Clotting factor V has a dual function in coagulation: after activation, procoagulant factor V stimulates the formation of thrombin, whereas anticoagulant factor V acts as a cofactor for activated protein C (APC) in the degradation of factor VIII/VIIIa, thereby reducing thrombin formation. In the present study, we evaluated whether plasma factor V levels, either decreased or increased, are associated with venous thrombosis. High procoagulant factor V levels may enhance prothrombinase activity and increase the thrombosis risk. Low anticoagulant factor V levels could reduce APC-cofactor activity in the factor VIII inactivation (APC-resistant phenotype), which might also promote thrombosis. Low factor V levels in combination with factor V Leiden could lead to a more severe APC-resistant phenotype (pseudohomozygous APC resistance). To address these issues, we have measured factor V antigen (factor V:Ag) levels in 474 patients with thrombosis and 474 control subjects that were part of the Leiden Thrombophilia Study (LETS). Factor V:Ag levels increased by 7.6 U/dL for every successive 10 years of age. Mean factor V:Ag levels were 134 (range 41 to 305) U/dL in patients and 132 (range 47 to 302) U/dL in controls. Neither high nor low factor V:Ag levels were associated with venous thrombosis. We found that factor V:Ag and factor VIII antigen levels in plasma were correlated, but factor V did not modify the thrombotic risk of high factor VIII levels. The normalized APC ratio was not influenced by the factor V:Ag level in subjects with or without factor V Leiden. We conclude that neither low nor high factor V:Ag levels are associated with venous thrombosis and that factor V:Ag levels do not mediate the thrombotic risk associated with high factor VIII levels.

Adolescent↗
PubMed1999

Increased levels of factor VIII and fibrinogen in patients with venous thrombosis are not caused by acute phase reactions.

Factor VIII activity (factor VIII:C) levels > or =150 IU/dl are associated with a 5- to 6-fold increased risk of venous thrombosis compared to levels <100 IU/dl, and fibrinogen levels > or =5.0 g/l increase the thrombosis risk 4-fold. These high levels are present in 25% resp. 3% of the patients with a first episode of venous thrombosis. These findings were based on measurements after the thrombotic event, so the factor VIII and fibrinogen levels in thrombosis patients may have been influenced by acute phase reactions or ongoing inflammatory responses. In the present study we measured plasma C-reactive protein (CRP) as a sensitive marker of an acute phase reaction in 474 thrombosis patients and 474 age- and sex-matched healthy controls, that were part of the Leiden Thrombophilia Study (LETS). Mean and median CRP levels were higher in thrombosis patients than in the controls, suggesting inflammation in some patients. CRP affected both factor VIII and fibrinogen levels, in patients and controls alike. After adjustment for the effect of CRP, high factor VIII:C levels still increased the thrombosis risk 6-fold and high fibrinogen levels 4-fold, which is for both very similar to the risk before correction for CRP levels. These results show that although systemic inflammation may be present in some of the patients, elevated levels of factor VIII:C and fibrinogen were in general not caused by acute phase reactions. This further supports a causal relationship between both high factor VIII:C and fibrinogen levels and venous thrombosis.

Acute-Phase Reaction↗
PubMed1999

Inconsistency of association between type 1 von Willebrand disease phenotype and genotype in families identified in an epidemiological investigation.

In a previous epidemiological investigation among schoolchildren of Northern Italy, a conservative 1% prevalence of type 1 von Willebrand disease (VWD) was found. Diagnosis was based on a positive family history and low von Willebrand factor (VWF) ristocetin cofactor activity. To investigate whether the type 1 VWD phenotype as detected by our original methodology cosegregates with one or more specific alleles of the VWF gene, we have performed genotype analysis in affected subjects and their family members. Eleven of the 14 subjects previously identified as having VWD, all with mild personal bleeding symptoms, agreed to participate in the genetic study. Remarkably, the laboratory measurements of the previous investigation were completely confirmed in 10 of the 11 subjects. Clear cosegregation of the VWD type 1 and a specific VWF allele was observed in one family and was likely in the family of two other pro-bands. In three additional propositi and their families a possible association of the phenotype with a VWF allele was found. No association was observed in the remaining five subjects and their families. During 13-year follow-up few additional bleeding episodes were recorded among investigated subjects, most often occurring in the one family manifesting clear cosegregation. The results of this study illustrate that a personal and family bleeding history and persistently low VWF ristocetin cofactor activity, fitting the usual criteria for type 1 VWD, may not cosegregate with genetic markers at the VWF gene locus. Thus the prevalence of VWD defined as a disorder involving the VWF locus might be overestimated in population study. However, phenotypic diagnosis still remains fundamental to identify patients at risk of bleeding. Further research should clarify whether in families with more severe clinical and laboratory phenotype a clear association with markers of VWF is found.

Alleles↗
PubMed1998

Familial clustering of factor VIII and von Willebrand factor levels.

Recently, we found that high levels of clotting factor VIII (>150 IU/dl) are common and make an important contribution to thrombotic risk. The determinants of high factor VIII:C are unclear and might be partly genetic. Therefore, we tested the influence of age, blood group and von Willebrand factor (VWF) levels on factor VIII:C levels, and investigated whether factor VIII:C levels are genetically determined. We performed an analysis of 564 female relatives of hemophilia A patients, who had visited our center for genetic counseling. In univariate analysis, AB0 blood group, age and VWF antigen (VWF:Ag) levels all influenced factor VIII:C levels. After adjustment for the effect of VWF:Ag levels, both blood group and age still had an effect on factor VIII:C levels. In sister pairs, the Pearson correlation coefficient between factor VIII:C levels was 0.17 (p = 0.024) and this correlation remained positive (0.15, p = 0.046) after correction for the influence of VWF:Ag. In mother-daughter pairs, no correlation of factor VIII:C levels was found. The correlation of VWF:Ag levels in sisterpairs was 0.41 (p <0.001) and in mother-daughter pairs 0.44 (p <0.001), in line with the assumption that VWF:Ag levels are under control of autosomal genes. Familial influence on plasma factor VIII:C and VWF:Ag levels was investigated with a recently developed familial aggregation test. This test verifies whether familial aggregation of a particular parameter exists in a set of pedigrees. In 435 women from 168 families, factor VIII:C as well as VWF:Ag levels correlated significantly within families, which suggests a familial influence. The familial aggregation was more prominent for VWF:Ag levels than for factor VIII:C levels, possibly because the genetic effect on VWF:Ag levels is larger than on factor VIII:C levels. Our results support the presence of a familial influence on factor VIII:C as well as on VWF:Ag levels.

Adult↗
PubMed1998

Characterization of the genetic defects in recessive type 1 and type 3 von Willebrand disease patients of Italian origin.

The genetic defects causing recessive type 1 and type 3 von Willebrand disease (VWD) in eight families from the northern part of Italy have been investigated. Mutations were identified in 14 of the 16 disease-associated von Willebrand factor (VWF) genes. Only one mutation, a stop codon in exon 45, was previously reported. Several new mutations were identified: one cytosine insertion in exon 42, one guanine deletion in exon 28, one probably complete VWF gene deletion, one substitution in the 3' splice site of intron 13, one possible gene conversion, and three candidate missense mutations. One missense mutation, the substitution of a cysteine in exon 42, was identified in all type 3 VWD patients that were previously characterized as a subgroup with significant increase of factor VIII procoagulant activity after desmopressin infusion. This paper demonstrates again that the molecular defects of quantitative VWD are diverse and located throughout the entire VWF gene.

DNA Mutational Analysis↗
PubMed1996

Dominant type 1 von Willebrand disease caused by mutated cysteine residues in the D3 domain of von Willebrand factor.

No defects have been reported in moderately severe type 1 von Willebrand disease (vWD) with a clear autosomal dominant inheritance pattern, and the mechanism underlying this form of vWD remains obscure. We have studied a type 1 vWD family with such a dominant phenotype. The entire coding sequence of the von Willebrand factor (vWF) gene was analyzed by direct sequencing of DNA fragments amplified by polymerase chain reaction. Only one candidate mutation T(3445)-->C in exon 26 was detected that predicts a replacement of cysteine (C) at position 386 of the mature vWF subunit by arginine (R). Both mutant and normal vWF alleles were expressed as shown by analysis of platelet mRNA. This substitution segregates with vWD in the family and was not found in 100 unrelated individuals. The recombinant mutant vWF(C386R) was characterized by expression in 293T cells. The secretion of vWF(C386R) was greatly impaired due to retention in the endoplasmic reticulum. In cotransfections of normal and mutant vWF constructs, the vWF(C386R) subunits caused a dose-dependent decrease in the secretion of vWF. The multimer pattern remained nearly normal and consistent with a dominant vWD type 1 phenotype. The importance of the cysteine residues in the D3 domain of vWF in the pathogenesis of dominant type 1 vWD was further shown by the detection of another cysteine mutation, Cys367-->Phe, in two additional unrelated patients with a similar dominant type 1 vWD phenotype. We conclude that the loss of cysteine pairing in the D3 domain, leaving one free cysteine, can induce a purely quantitative deficiency of vWF by dominantly suppressing the secretion of normal vWF.

Alleles↗
PubMed1995

Usefulness of patient interview in bleeding disorders.

BACKGROUND: It is not known which questions in a medical interview are most informative for diagnosing mild bleeding disorders, and what the value is of the entire interview in screening for hemostatic disorders. METHODS: A questionnaire was sent to 222 patients with a proven bleeding disorder, to 134 patients suspected of a bleeding disorder but whose hemostasis proved normal, and to 341 healthy volunteers. A first comparison, between patients with a bleeding disorder and patients with bleeding complaints whose hemostasis proved normal, mimics the situation in a department of hematology where patients are referred because of complaints. The second comparison, between patients with a proven bleeding disorder and healthy volunteers, may serve as a model for the situation where the interview is used as a screening tool to detect patients with a bleeding disorder in a population where there is no prior suspicion, eg, before surgical intervention. For each question we calculated a univariate odds ratio, multivariate odds ratios, and a positive and negative likelihood ratio. With a receiver operating characteristic curve analysis we evaluated the value of a simple vs an elaborate interview. RESULTS: Ninety-two percent of the questionnaires were returned. For both comparisons the most informative questions were questions about bleeding disorders in the family and traumatic events, with the exception of delivery. Noninformative questions were frequent gumbleeds and blood in the urine. A receiver operating characteristic curve analysis revealed that a simple interview has a high discriminating power in a screening situation, whereas in a referred situation even an elaborate interview has a low performance. CONCLUSIONS: A simple interview is useful as a screening tool for the dentist or surgeon. In a specialized hematology center with referred patients, however, the interview is of little value in identifying patients with a bleeding disorder.

Blood Coagulation Disorders↗