University of Utah CME Statement Willebrand.pdf · 2014-04-10 · University of Utah CME Statement...
Transcript of University of Utah CME Statement Willebrand.pdf · 2014-04-10 · University of Utah CME Statement...
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University of Utah CME Statement
• The University of Utah School of Medicine adheres to ACCME Standards regarding industry support of continuing medical education.
• Speakers are also expected to openly disclose intent to discuss any off-label, experimental, or investigational use of drugs, devices, or equipment in their presentations.
• This speaker has nothing to disclose.
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Laboratory Diagnosis of Von Willebrand Disease
Delu Zhou MD PhD Pathology Resident University of Utah March 18th 2013
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Objectives
After attending this seminar, the attendee are expected to be able to:
•Explain common symptoms and genetic causes of von Willebrand disease.
•Describe the common laboratory assays used to diagnose von Willebrand disease.
•List common subtypes of von Willebrand disease.
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Topics
1. Introduction of von Willebrand factor and von Willebrand disease
2. Common diagnostic tests for von Willebrand disease and interpretation
3. Case studies
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Topics
1. Introduction of von Willebrand factor and von Willebrand disease
2. Common diagnostic tests for von Willebrand disease and interpretation
3. Case studies
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vWF is synthesized in endothelial cells as a monomer that is subsequently made into multimers that are secreted.
vWF is a critical protein in blood clotting
Von Willebrand factor (vWF)
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The majority of vWF is circulating in the blood plasma.
A pool of vWF is also stored in the endothelial cells and megakaryocytes, the precursors of platelets.
Von Willebrand factor (vWF)
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Von Willebrand factor (vWF)
Mature vWF Propeptide
FVIII GPIb Collagen GPIIb/IIIa
vWD Guidelines, NHLBI
FVIII: Factor VIII
GPIb: platelet glycoprotein Ib
GPIIb/IIIa: platelet glycoprotein IIb/IIIa
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De Meyer S F et al. Stroke 2012;43:599-606
Von Willebrand factor (vWF)
vWF is a multimeric protein composed of dimeric building blocks.
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Body Reactions to Bleeding
1. Constriction of blood vessels
Robbins and Cotran Pathologic Basis of Disease 8th edition
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Body Reactions to Bleeding
2. Adhesion of platelets
Robbins and Cotran Pathologic Basis of Disease 8th edition
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Body Reactions to Bleeding
3. Formation of fibrin reinforces platelets
Robbins and Cotran Pathologic Basis of Disease 8th edition
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vWF Plays Two Major Roles
vWF tethers the platelet to exposed collagen
vWF serves as a carrier protein for factor VIII
Kumar: Robbins Basic Pathology, 9th ed.
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Von Willebrand disease (vWD)
Von Willebrand disease (vWD) was first described in 1926 by a Finnish physician named Dr. Erik von Willebrand.
Quantitative deficiency of vWF or to functional deficiencies of vWF
Autosomal inheritance pattern / Males and females are affected equally
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Von Willebrand disease (vWD)
The first manuscript describing a
haemorrhagic disorder in people who
were living on the Aland islands off the
coast of Finland.
Dr. Erik von Willebrand
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Von Willebrand disease (vWD)
His first case was a little girl, who was five years old
when first examined.
She was one of 12 siblings, all but two of whom had
had bleeding symptoms.
Her parents had severe nose bleedings.
The girl herself had had several severe episodes of
bleeding from the nose and lips, and following tooth
extractions. At the age of 13, she bled to death during
her fourth menstrual period.
The history of von Willebrand disease. Haemophilia.
Volume 5 (s2), p7–11, May 1999
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Von Willebrand disease (vWD)
Most frequent inherited bleeding disorder
Estimated prevalence of 1% in general population
Clinically significant vWD: 100 persons per million population
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Clinical Manifestations
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vWD Classification
Type 1: Partial quantitative deficiency of vWF
Mild-moderate disease
70% of cases
Type 2: Qualitative deficiency of vWF
Mild to moderate disease
25% of cases
Type 3: Total or near total quantitative deficiency of vWF
Severe disease
5% of cases
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vWD Classification
Type 1: Partial quantitative deficiency of vWF
Mild-moderate disease
70%
Type 2: Qualitative deficiency of vWF
Mild to moderate disease
25%
Type 3: Total or near total quantitative deficiency of vWF
Severe disease
5%
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Type 2A ↓vWF-dependent platelet adhesion with selective deficiency of high molecular weight vWF multimers
Type 2B Increased vWF affinity for platelet GPlb; ± ↓platelet numbers
Type 2M ↓vWF-dependent platelet adhesion without selective deficiency of high molecular weight vWF multimers
Type 2N Markedly decreased vWF binding affinity for FVIII
vWD Classification
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Topics
1. Introduction of von Willebrand factor and von Willebrand disease
2. Common diagnostic tests for von Willebrand disease and interpretation
3. Case studies
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Initial vWD testing
von Willebrand Factor Antigen
von Willebrand Factor Activity (Ristocetin Cofactor)
Factor VIII Activity
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von Willebrand Factor Antigen
vWF:Ag Immunological assay that measures the concentration of the vWF protein in plasma. Methodology: Microlatex Particle-Mediated Immunoassay
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Principle of Latex Immunoassay
http://tiger.kobiljak.msu.edu/WebSites/Web_Path/webpath/microbio/microbe/serology.htm
Turbidity
Absorbance
Ab-coated Latex
Particles
Patient Plasma
Added Ag-Ab Binding
and Precipitation
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von Willebrand Factor Activity (Ristocetin Cofactor)
• vWF:RCo
• Measures the ability of a patient’s plasma to agglutinate platelets in the presence of the antibiotic Ristocetin.
• Methodology: Platelet Agglutination
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von Willebrand Factor Activity (Ristocetin Cofactor)
Kumar: Robbins Basic Pathology, 9th ed.
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• Ristocetin is an antibiotic
• Side effect: activates vWF and induces platelet agglutination and cause thrombocytopaenia
• Removed from the market
von Willebrand Factor Activity (Ristocetin Cofactor)
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Principles of von Willebrand Factor Activity Assay
Platelets
Ristocetin
vWF
Platelet
Agglutination
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In quantitative vWF deficiency (types 1 and 3), it parallels the vWF antigen
In qualitative vWF deficiency resulting in decreased affinity for platelets (types 2A and 2M), vWF RCo is more severely affected compared to vWF antigen.
Principles of von Willebrand Factor Activity Assay
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However this assay is not a true 'functional' assay but rather the interaction of vWF with the Gp1b platelet receptor in the presence of ristocetin.
Principles of von Willebrand Factor Activity Assay
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Factor VIII Activity
Functional clot-based assay
Measures the activity of factor VIII
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Result Interpretation
Type 1: Partial quantitative deficiency of vWF
Condition vWF:RCo (%)
vWF:Ag (%)
FVIII (%)
Ratio of vWF:RCo/vWF:Ag
Normal 51-215 52-214 56-191 >0.5-0.7
Type 1 <30 <30 ↓ or Normal
>0.5-0.7
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Result Interpretation
Type 3: Total quantitative deficiency of vWF
Condition vWF:RCo (%)
vWF:Ag (%)
FVIII (%)
Ratio of vWF:RCo/vWF:Ag
Normal 51-215 52-214 56-191 >0.5-0.7
Type 3 <10 <10 ↓ ↓ ↓ N/A
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Result Interpretation Type 2A: ↓vWF-dependent platelet adhesion with selective deficiency of high molecular weight vWF multimers
Condition vWF:RCo (%)
vWF:Ag (%)
FVIII (%)
Ratio of vWF:RCo/vWF:Ag
Normal 51-215 52-214 56-191 >0.5-0.7
Type 2A <30 30-200 ↓ or Normal
<0.5-0.7
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Result Interpretation Type 2B: Increased vWF affinity for platelet GPlb; ± ↓platelet numbers
Ristocetin-Induced Platelet Aggregation (RIPA)
Type 2B: Increased platelet aggregation at low dose of ristocetin
Condition vWF:RCo (%)
vWF:Ag (%)
FVIII (%)
Ratio of vWF:RCo/vWF:Ag
Normal 51-215 52-214 56-191 >0.5-0.7
Type 2B <30 30-200 ↓ or Normal
Usually <0.5-0.7
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Result Interpretation Type 2M: ↓vWF-dependent platelet adhesion without selective deficiency of high molecular weight vWF multimers
Condition vWF:RCo (%)
vWF:Ag (%)
FVIII (%)
Ratio of vWF:RCo/vWF:Ag
Normal 51-215 52-214 56-191 >0.5-0.7
Type 2M <30 30-200 ↓ or Normal
<0.5-0.7
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Result Interpretation Type 2N: Markedly decreased vWF binding affinity for FVIII
vWF:FVIII binding (vWF:FVIIIB) assay
Condition vWF:RCo (%)
vWF:Ag (%)
FVIII (%)
Ratio of vWF:RCo/vWF:Ag
Normal 51-215 52-214 56-191 >0.5-0.7
Type 2N 30-200 30-200 ↓ ↓ >0.5-0.7
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von Willebrand Factor Multimers
vWF monomer is about 250 kD
vWF is released from endothelial cells to the plasma as a multimers ranging from 500-20,000 kD
Analysis of vWF multimeric forms by this procedure is predominantly designed to evaluate type II vWD
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Principle of Gel Electrophoresis and Western Blot
http://www.virology.ws/wp-content/uploads/2010/07/western_blot.jpg
Chemiluminescence
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http://www.nhlbi.nih.gov/guidelines/vwd/3_diagnosisandevaluation.htm
Principle of Gel Electrophoresis and Western Blot
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Principle of Gel Electrophoresis and Western Blot
NP vWD
Type 1
NP NP vWD
Type
2A
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Genetic testing
Type-specific sequencing tests
vWD Guidelines, NHLBI
Exon 28 Propeptide
cleavage site
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Genetic testing
von Willebrand Disease, Type 2A (VWF) Sequencing Exon 28 with
Reflex to 9 Exons 2005480
Method: Polymerase Chain Reaction/Sequencing
von Willebrand Disease, Type 2B (VWF) Sequencing 2005486
Method: Polymerase Chain Reaction/Sequencing
von Willebrand Disease, Type 2M (VWF) Sequencing 2005490
Method: Polymerase Chain Reaction/Sequencing
von Willebrand Disease, Type 2N (VWF) Sequencing 2005494
Method: Polymerase Chain Reaction/Sequencing
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Topics
1. Introduction of von Willebrand factor and von Willebrand disease
2. Common diagnostic tests for von Willebrand disease and interpretation
3. Case studies
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Case 1
A one-year-old girl was referred to our hospital for prolonged oral bleeding following a mouth wound. Physical examination revealed many bruises. There was no documented familial history of hemorrhage.
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Case 1 Lab Results:
Platelet count: 346 (229-465 K/ul)
aPTT (Partial Thromboplastin Time): 68 s (24-35 s)
vWF:Ag <10% (0-6 years: 52-214%)
vWF:RCo <10% (0-6 years: 51-215%)
Factor VIII 7% (0-6 years: 56-191%)
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Case 1
What is the most likely diagnosis:
A. vWD type 1
B. vWD type 2A
C. vWD type 2M
D. vWD type 3
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Case 1
What is the most likely diagnosis:
A. vWD type 1
B. vWD type 2A
C. vWD type 2M
D. vWD type 3
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Case 1
• vWD Type 3
• Recessive disorder
• vWF protein is virtually undetectable
• Absence of vWF causes a secondary deficiency of FVIII and a subsequent severe combined defect in blood clotting and platelet adhesion
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Case 2
A 6-year-old boy with frequent nosebleeds.
Physical examination revealed occasional ecchymosis (subcutaneous hemorrhage / purple discoloration of the skin).
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Case 2
Lab Results:
Platelet count: 360 K/ul (229-465 K/ul)
aPTT (Partial Thromboplastin Time): 30 s (24-35 s)
vWF:Ag 21% (0-6 years: 52-214%)
vWF:RCo 20% (0-6 years: 51-215%)
Factor VIII 60% (0-6 years: 56-191%)
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Case 2
Ctrl Patient
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Case 2
What is the most likely diagnosis:
A.vWD type 1
B.vWD type 2A
C.vWD type 2B
D.vWD type 3
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Case 2
What is the most likely diagnosis:
A.vWD type 1
B.vWD type 2A
C.vWD type 2B
D.vWD type 3
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Case 2
• vWD Type 1
• Mild to moderate disease
• Mild quantitative deficiency of vWF
• vWF is functionally normal
• Usually autosomal dominant
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Case 3
A 5-year-old boy recent had gingival bleeding and nosebleed.
Lab Results:
Platelet count: 289 K/ul (229-465 K/ul)
aPTT (Partial Thromboplastin Time): 85 s (24-35 s)
vWF:Ag 156% (0-6 years: 52-214%)
vWF:RCo 135% (0-6 years: 51-215%)
Factor VIII 8% (0-6 years: 56-191%)
Genetic testing ruled out Hemophilia A (FVIII deficiency)
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Case 3
What is the most likely diagnosis:
A.vWD type 1
B.vWD type 2A
C.vWD type 2N
D.vWD type 3
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Case 3
What is the most likely diagnosis:
A.vWD type 1
B.vWD type 2A
C.vWD type 2N
D.vWD type 3
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Case 3
vWD Type 2N Markedly decreased affinity of vWF for FVIII Results in markedly reduced FVIII level. vWF:FVIII binding (vWF:FVIIIB) assay
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Summary
von Willebrand factor (vWF)
• Large multimeric protein
• Two major functions:
1. Tethers the platelets to exposed collagen during
injuries
2. Serves as a carrier protein for Factor VIII
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Summary
von Willebrand disease (vWD)
• Most frequent inherited bleeding disorder
• Autosomal inheritance pattern
• Quantitative: Types 1 and 3
• Qualitative: Types 2A, 2B, 2M and 2N
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Summary Laboratory tests for vWD
Initial vWD testing
• vWF:Ag
• vWF:RCo
• FVIII activity
Further testing
• vWF multimer analysis
• Ristocetin-induced platelet aggregation (RIPA)
• vWF:FVIII binding (vWF:FVIIIB) assay
• Genetic testing
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Acknowledgements
Dr. Ashwood
Dr. Smock
Dr. Meikle
Dr. Rockwood
Dr. Frank
Dr. Genzen
Dr. Fang
Dr. Hopkins
Jeanne
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References The history of von Willebrand disease. Haemophilia. Volume 5 (s2), p7–11, May
1999
The Diagnosis, Evaluation, and Management of von Willebrand Disease. vWD
Guidelines. NIH/NHLBI
Berntorp E. Von Willebrand Disease. Pediatr Blood Cancer. 2013;60:S34–S36
James PD and Goodeve AC. Genetics in Medicine. Volume 13 (5), May 2011
G Castaman, et al. Von Willebrand's disease in the year 2003: towards the
complete identification of gene defects for correct diagnosis and treatment.
Haematologica 2003 Jan 88: 94-108
ARUP consult