scholarly journals Moderation of hemophilia A phenotype by the factor V R506Q mutation

Blood ◽  
1996 ◽  
Vol 88 (4) ◽  
pp. 1183-1187 ◽  
Author(s):  
WC Nichols ◽  
K Amano ◽  
PM Cacheris ◽  
MS Figueiredo ◽  
K Michaelides ◽  
...  
Keyword(s):  
Protein C ◽  
Hemophilia A ◽  
Clinical Phenotype ◽  
Point Mutations ◽  
Molecular Genetic Analysis ◽  
Von Willebrand Disease ◽  
Clinical Severity ◽  
Molecular Defect ◽  
Factor V ◽  
Missense Mutations

Although many examples of unrelated hemophilia A patients carrying identical point mutations in the factor VIII (FVIII) gene have been reported, the clinical phenotype is not always the same among patients sharing the same molecular defect. Possible explanations for this discrepancy include undetected additional mutations in the FVIII gene or coinheritance of mutations at other genetic loci that modulate FVIII function. We report molecular genetic analysis of potential modifying genes in two sets of unrelated patients carrying common FVIII missense mutations but exhibiting different levels of clinical severity. Both mutations (FVIII R1689C and R2209Q) are associated with severe hemophilia A in some patients and mild/moderate disease in others. The common von Willebrand disease type 2N mutation (R91Q) was excluded as a modifying factor in these groups of patients. However, analysis of the recently described factor V (FV) R506Q mutation (leading to activated protein C resistance) identified a correlation of inheritance of this defect with reduced hemophilia A severity. Two moderately affected hemophilia A patients, each with either of two FVIII gene mutations, were heterozygous for FV R506Q, whereas two severely affected patients and two moderately affected patients were homozygous normal at the FV locus. Our results suggest that coinheritance of the FV R506Q mutation may be an important determinant of clinical phenotype in hemophilia A and that modification of the protein C pathway may offer a new strategy for the treatment of FVIII deficiency.

A Novel Mutation Glyl672→Arg in Type 2A and a Homozygous Mutation in Type 2B von Willebrand Disease

1996 ◽  
Vol 76 (02) ◽  
pp. 253-257 ◽  
Author(s):  
Takeshi Hagiwara ◽  
Hiroshi Inaba ◽  
Shinichi Yoshida ◽  
Keiko Nagaizumi ◽  
Morio Arai ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Novel Mutation ◽  
Point Mutations ◽  
Japanese Patients ◽  
Von Willebrand Disease ◽  
Homozygous Mutation ◽  
Missense Mutations ◽  
Reaction Products ◽  
Type 3 ◽  
Von Willebrand

SummaryGenetic materials from 16 unrelated Japanese patients with von Willebrand disease (vWD) were analyzed for mutations. Exon 28 of the von Willebrand factor (vWF) gene, where point mutations have been found most frequent, was screened by various restriction-enzyme analyses. Six patients were observed to have abnormal restriction patterns. By sequence analyses of the polymerase chain-reaction products, we identified a homozygous R1308C missense mutation in a patient with type 2B vWD; R1597W, R1597Q, G1609R and G1672R missense mutations in five patients with type 2A; and a G1659ter nonsense mutation in a patient with type 3 vWD. The G1672R was a novel missense mutation of the carboxyl-terminal end of the A2 domain. In addition, we detected an A/C polymorphism at nucleotide 4915 with HaeIII. There was no particular linkage disequilibrium of the A/C polymorphism, either with the G/A polymorphism at nucleotide 4391 detected with Hphl or with the C/T at 4891 detected with BstEll.

scholarly journals Molecular genetic analysis of porcine von Willebrand disease: tight linkage to the von Willebrand factor locus

Blood ◽  
1988 ◽  
Vol 72 (1) ◽  
pp. 308-313 ◽  
Author(s):  
WF Bahou ◽  
EJ Bowie ◽  
DN Fass ◽  
D Ginsburg
Keyword(s):  
Von Willebrand Factor ◽  
Molecular Basis ◽  
Gene Deletion ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Von Willebrand Disease ◽  
Molecular Defect ◽  
Human Disorder ◽  
Von Willebrand ◽  
Willebrand Factor

von Willebrand disease (vWD), one of the most common bleeding disorders in humans, is manifested as a quantitative or qualitative defect in von Willebrand factor (vWF), an adhesive glycoprotein (GP) with critical hemostatic functions. Except for the rare severely affected patient with a gene deletion as etiology of the disease, the molecular basis for vWD is not known. We studied the molecular basis for vWD in a breeding colony of pigs with a disease closely resembling the human disorder. The porcine vWF gene is similar in size and complexity to its human counterpart, and no gross gene deletion or rearrangement was evident as the pathogenesis of porcine vWD. A restriction fragment- length polymorphism (RFLP) within the porcine vWF gene was identified with the restriction endonuclease HindIII, and 22/35 members of the pedigree were analyzed for the polymorphic site. Linkage between the vWF locus and the vWD phenotype was established with a calculated LOD score of 5.3 (1/200,000 probability by chance alone), with no crossovers identified. These findings indicate that porcine vWD is due to a molecular defect within (or near) the vWF locus, most likely representing a point mutation or small insertion/deletion within the vWF gene.

scholarly journals Molecular genetic analysis of porcine von Willebrand disease: tight linkage to the von Willebrand factor locus

Blood ◽  
1988 ◽  
Vol 72 (1) ◽  
pp. 308-313 ◽  
Author(s):  
WF Bahou ◽  
EJ Bowie ◽  
DN Fass ◽  
D Ginsburg
Keyword(s):  
Von Willebrand Factor ◽  
Molecular Basis ◽  
Gene Deletion ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Von Willebrand Disease ◽  
Molecular Defect ◽  
Human Disorder ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract von Willebrand disease (vWD), one of the most common bleeding disorders in humans, is manifested as a quantitative or qualitative defect in von Willebrand factor (vWF), an adhesive glycoprotein (GP) with critical hemostatic functions. Except for the rare severely affected patient with a gene deletion as etiology of the disease, the molecular basis for vWD is not known. We studied the molecular basis for vWD in a breeding colony of pigs with a disease closely resembling the human disorder. The porcine vWF gene is similar in size and complexity to its human counterpart, and no gross gene deletion or rearrangement was evident as the pathogenesis of porcine vWD. A restriction fragment- length polymorphism (RFLP) within the porcine vWF gene was identified with the restriction endonuclease HindIII, and 22/35 members of the pedigree were analyzed for the polymorphic site. Linkage between the vWF locus and the vWD phenotype was established with a calculated LOD score of 5.3 (1/200,000 probability by chance alone), with no crossovers identified. These findings indicate that porcine vWD is due to a molecular defect within (or near) the vWF locus, most likely representing a point mutation or small insertion/deletion within the vWF gene.

The Molecular Genetics of Hemophilia A Stylianos

1987 ◽  
Author(s):  
E Antonarakis
Keyword(s):  
Amino Acids ◽  
Dna Sequences ◽  
Hemophilia A ◽  
Restriction Analysis ◽  
Point Mutations ◽  
Leader Peptide ◽  
Molecular Defect ◽  
Severe Hemophilia ◽  
Cpg Dinucleotides ◽  
Oligonucleotide Hybridization

Hemophilia A is a common X linked hereditary disorder of blood coagulation due to deficiency of factor 8. The gene for factor 8 has been cloned and characterized (Nature 312:326-342, 1984). It is divided into 26 exons and 25 introns and spans 186 kb of DNA. The CGNA is 9 kb and codes for 2351 amino acids. The first 19 amino acids comprise the secretory leader peptide and the mature excreted polypeptide consists of 2332 amino acids. The nucleotide sequence of the exons and the exon-intron junctions is known and the complete amino acid sequence has been deducedSeveral laboratories have used cloned factor 8 DNA sequences as probes to characterized mutations that are responsible for hemophilia A in certain pedigrees. These mutations have been characterized by restriction analysis, oligonucleotide hybridization, cloning and sequencing of DNA from appropriate patientsIn about 500 patients with hemophilia A examined, the molecular defect has been recognized in 39. Both gross alterations (mainly deletions) and point mutations of the factor 8 gene have been found.A total of 19 different deletions have been observed. No two unrelated pedigrees share the same exact deletion.The size of the deleted DNA varies from 1.5 kb to more than 210 kb. All but one of these deletions are associated with severe hemophilia A. A deletion of 6 kb that contains exon 22 only is associated with moderate hemophilia. Some deletions are present in patients with inhibitors to factor 8. No correlation of the size or the position of the deletions can be found with the presence of inhibitors to factor 8.A total of 20 point mutations have been characterized. All are recognized by restriction analysis and involve Taq I sites. All are mutations of CpG dinucleotides and generate nonsense or missence codons. Unrelated pedigrees have the same single nucleotide change because of independent origin of the same mutation. In many instances de novo occurrence of a point mutation has been observed. CpG dinucleotides are hot spots for mutation to TG or CA presumably because of spontaneous deamination of methylcytosine. Some point mutations are present in patients with inhibitors but no correlation of the site of mutation and inhibitor formation has been found. The nonsense mutations are present in patients with severe hemophilia A. A missense mutation (Arg Gin) in exon 26 was found in a patient with mild hemophilia while another Arg Gin mutation in exon 24 has been observed in a patient with severe disease. The creation of a donor splice site in IVS 4 of factor 8 gene has been observed in a patient with mild hemophilia.Few DNA polymorphisms within the factor 8 gene and two other closely linked polymorphisms have been used for carrier detection and prenatal diagnosis of hemophilia A. These DNA markers are useful in more than 90% of families at risk for hemophilia A.The author thanks Drs. Gitschier, Din, Olek, Pirastou, Lawn for communication of their data prior to publication.The hemophilia project at Johns Hopkins was supported by an Institutional grant and NIH grant to S.S.A. and Haig H. Kazazian, Jr.

Most Factor VIII B Domain Missense Mutations Are Unlikely to Be Causative Mutations for Hemophilia A: Implications for Factor VIII Genetic Analysis

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 513-513
Author(s):  
Kyoichi Ogata ◽  
Steven W. Pipe
Keyword(s):  
Amino Acid ◽  
Factor Viii ◽  
Hemophilia A ◽  
Coagulation Factor ◽  
Causative Mutation ◽  
Factor V ◽  
Missense Mutations ◽  
Severe Hemophilia ◽  
Single Chain

Abstract Hemophilia A results from the quantitative or qualitative deficiency of coagulation factor VIII (FVIII). FVIII is synthesized as a single-chain polypeptide of approximately 280 kDa with the domain structure A1-A2-B-A3-C1-C2. Whereas the A and C domains exhibit ~40% amino acid identity to each other and to the A and C domains of coagulation factor V, the B domain is not homologous to any known protein and is dispensable for FVIII cofactor activity. Missense mutations in the FVIII B domain have been described in patients with variable phenotypes of hemophilia A. According to the NCBI SNPs (single nucleotide polymorphism) database, 22 SNPs are reported within FVIII, 11 of which occur within the B domain. FVIII B domain variant D1241E has been reported as a missense mutation associated with mild or severe hemophilia A, yet this mutation is also present in the NCBI SNPs database. We hypothesize that D1241E and most other reported B domain missense mutations are not the causative mutation for hemophilia A in these patients but represent SNPs or otherwise non-pathologic mutations. To investigate this, we analyzed 7 B domain missense mutations that were previously found in hemophilia A patients (T751S, V993L, H1047Y, D1241E, T1353A, P1641L and S1669L). Comparative analysis showed that the amino acids at these positions are not conserved in all species and in some cases, the amino acid substitution reported in hemophilia patients is represented in the native sequence in other species. Analysis with PolyPhen Software showed that only H1047Y mutation was considered as “possibly damaging”, while the others were considered as “benign”. To investigate this further, we constructed seven plasmid vectors containing these B domain missense mutations. The synthesis and secretion of FVIII wild-type (WT) and these seven mutants were compared after transient DNA transfection into COS-1 monkey cells in vitro. Analysis of the FVIII clotting activity and antigen levels in the conditioned medium demonstrated that all mutants had FVIII activity and antigen levels similar to FVIII WT. Further, FVIII WT, H1047Y and D1241E mutants were introduced into a FVIII exon 16 knock-out mouse model of hemophilia A by hydrodynamic tailvein injection in vivo. The mouse plasma was analyzed at 24 hrs for activity and antigen expression. Mutants H1047Y and D1241E expressed at 211 mU/mL and 224 mU/mL activity with FVIII antigen levels of 97 ng/mL and 118 ng/mL, respectively, similar to FVIII WT. These results suggested that H1047Y and D1241E mutants did not lead to impairments in secretion or functional activity. We conclude that most missense mutations within the FVIII B domain would be unlikely to lead to severe hemophilia A and that the majority of such missense mutations represent polymorphisms or non-pathologic mutations. Investigators should search for additional potentially causative mutations elsewhere within the FVIII gene when B domain missense mutations are identified.

Von Willebrand Disease: A Database of Point Mutations, Insertions, and Deletions

1993 ◽  
Vol 69 (02) ◽  
pp. 177-184 ◽  
Author(s):  
David Ginsburg ◽  
Evan J Sadler
Keyword(s):  
Current System ◽  
Point Mutations ◽  
Rflp Analysis ◽  
Von Willebrand Disease ◽  
Small Subset ◽  
Molecular Defect ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Von Willebrand

SummaryThe current system for the diagnosis and classification of von Willebrand disease (vWD) is quite complex, with more than 20 distinct variants described. Over the past few years considerable progress has been made toward an understanding of vWD at the molecular level. A small cluster of mutations within the vWF A1 homologous repeat appears responsible for over 90% of type IIB vWD. A similar cluster of mutations in the vWF A2 homologous repeat accounts for the majority of type II A vWD. By RFLP analysis, several type II vWD mutations have been shown to be recurrent on distinct haplotype backgrounds, suggesting independent genetic origins (see accompanying manuscript for a complete list of known polymorphisms). Several mutations at the N-terminus of the mature vWF subunit have been identified in association with abnormal factor VIII binding. Homozygotes for this abnormal vWF present with a hemophilia-like phenotype that is autosomal recessive in inheritance. In a small subset of patients with type III vWD large gene deletions have been identified on one or both vWF alleles. Carriers heterozygous for a deleted locus and one normal vWF gene are generally asymptomatic. Nonsense mutations and other defects resulting in loss of vWF mRNA expression from one allele have also been associated with a recessive type III vWD phenotype. No distinct molecular defect responsible for classic type I vWD has yet been defined.

Three Distinct Candidate Point Mutations of the von Willebrand Factor Gene in Four Patients with Type IIA von Willebrand Disease

1992 ◽  
Vol 67 (06) ◽  
pp. 612-617 ◽  
Author(s):  
Isamu Sugiura ◽  
Tadashi Matsushita ◽  
Mitsune Tanimoto ◽  
Isao Takahashi ◽  
Tomio Yamazaki ◽  
...  
Keyword(s):  
Amino Acid ◽  
Von Willebrand Factor ◽  
Cleavage Site ◽  
Point Mutations ◽  
Pcr Amplification ◽  
Von Willebrand Disease ◽  
Missense Mutations ◽  
Allele Specific ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryType IIA von Willebrand disease (vWD) is the most common type II vWD and is characterized by the selective loss of large and intermediate sized multimers. One explanation for this disorder has been postulated to be a qualitative defect in von Willebrand factor (vWF) which results in increased susceptibility to proteolysis at the bond between residues Tyr842 and Met843. Four missense mutations that may cause type IIA vWD have recently been identified near the cleavage site. We analyzed the molecular basis for type IIA vWD in six patients. A 512 bp DNA sequence spanning the proteolytic cleavage site was targeted for PCR amplification and sequencing. We exploited a difference in restriction sites between the vWF gene and the pseudogene and have designed allele-specific oligomer used with PCR to distinguish these two genes. Three candidate missense mutations; Ser743 (TCG) → Leu (TTG), Leu799 (CTG) → Pro (CCG), and Arg834 (CGG) → Trp (TGG) were identified in 4 out of 6 patients. The amino acid substitution at Arg834 has been reported previously, but the other substitutions at Ser743 and Leu799 are novel candidate mutations locating 99 and 43 amino acids to the N-terminal side of the cleavage site, respectively. Our results indicate that amino acid substitutions located relatively distant from the cleavage site may also be involved in type IIA vWD.

Six Different Point Mutations in Seven Danish Families with Symptomatic Protein C Deficiency

1995 ◽  
Vol 73 (02) ◽  
pp. 186-193 ◽  
Author(s):  
Bent Lind ◽  
Marianne Schwartz ◽  
Sixtus Thorsen
Keyword(s):  
Splice Site ◽  
Protein C ◽  
Family Members ◽  
Point Mutations ◽  
Patient Specific ◽  
Missense Mutations ◽  
Coding Region ◽  
Protein C Deficiency ◽  
Epidermal Growth Factor Domain ◽  
Increased Risk

SummarySix different point mutations of the protein C gene are described in seven Danish families with protein C deficiency associated with an increased risk of venous thromboembolism. All affected family members are heterozygotes for the mutated protein C genotype. One mutation is a G2992→A transition at position +5 in the 5’ splice site of intron D. The other five mutations affect the protein coding region. One is a Cl432→T transition in exon III converting the highly conserved Arg15 to Trp in the Gla-domain. Another mutation is a G3157→C transversion in exon V converting the non-conserved Gly72 to Arg in the epidermal growth factor domain. The remaining three mutations are located in non-conserved amino acid positions in exon IX and affect the serine proteinase domain. The first is a G8559→C transversion converting Gly282 to Arg. The second is a C8571→T transition (present in two families) converting Arg286 to Cys. The third is a C8695→T transition converting Pro327 to Leu. In each family the protein C deficiency cosegregates or probably cosegregates (one family, G8559→C) with the mutation. All affected family members exhibit a reduction of both the antigen and the functional plasma concentration of protein C to approximately 50% of normal indicating that the mutated protein C is not present (type 1 deficiency) or only present in low amounts in plasma. Agarose gel electrophoresis followed by Western blotting shows that the Arg15→Trp substitution is associated with a normal as well as an abnormal migrating plasma protein C band. This provides positive evidence for that both the normal and mutated alleles are expressed (type 2 deficiency). The five other mutations are associated with only one band with the mobility of normal protein C. In one family a novel G1390→A transition converting the normal Ala1 to Thr was demonstrated. This mutation is not linked to the patient specific G8559→C transversion. In conclusion one splice site mutation and five different missense mutations of the protein C gene are described.

scholarly journals The Dual Regulatory Role of Amino Acids Leu480 and Gln481 of Prothrombin

2015 ◽  
Vol 291 (4) ◽  
pp. 1565-1581 ◽  
Author(s):  
Joesph R. Wiencek ◽  
Jamila Hirbawi ◽  
Vivien C. Yee ◽  
Michael Kalafatis
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Protein C ◽  
Membrane Surface ◽  
Point Mutations ◽  
Regulatory Subunit ◽  
Activate Factor ◽  
Factor V ◽  
Divalent Metal Ions

Prothrombin (FII) is activated to α-thrombin (IIa) by prothrombinase. Prothrombinase is composed of a catalytic subunit, factor Xa (fXa), and a regulatory subunit, factor Va (fVa), assembled on a membrane surface in the presence of divalent metal ions. We constructed, expressed, and purified several mutated recombinant FII (rFII) molecules within the previously determined fVa-dependent binding site for fXa (amino acid region 473–487 of FII). rFII molecules bearing overlapping deletions within this significant region first established the minimal stretch of amino acids required for the fVa-dependent recognition exosite for fXa in prothrombinase within the amino acid sequence Ser478–Val479–Leu480–Gln481–Val482. Single, double, and triple point mutations within this stretch of rFII allowed for the identification of Leu480 and Gln481 as the two essential amino acids responsible for the enhanced activation of FII by prothrombinase. Unanticipated results demonstrated that although recombinant wild type α-thrombin and rIIaS478A were able to induce clotting and activate factor V and factor VIII with rates similar to the plasma-derived molecule, rIIaSLQ→AAA with mutations S478A/L480A/Q481A was deficient in clotting activity and unable to efficiently activate the pro-cofactors. This molecule was also impaired in protein C activation. Similar results were obtained with rIIaΔSLQ (where rIIaΔSLQ is recombinant human α-thrombin with amino acids Ser478/Leu480/Gln481 deleted). These data provide new evidence demonstrating that amino acid sequence Leu480–Gln481: 1) is crucial for proper recognition of the fVa-dependent site(s) for fXa within prothrombinase on FII, required for efficient initial cleavage of FII at Arg320; and 2) is compulsory for appropriate tethering of fV, fVIII, and protein C required for their timely activation by IIa.

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