Transcript vWF Molecule

The Diagnosis of von Willebrand’s Disease
Among Iranian Women with Gynaecological
Bleeding
Baghaipour Mohammad Reza, MD,
Pediatrician, Hemophilia Fellow
history
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history
Dr Erik von Willebrand
1870-1949
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history
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history
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history
 Bleeding from mucosal tissues
 Significant bleeding in women
 Prolonged BT
 No X linked inheritance
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history
1926
First description by Erik von Willebrand
1928
5 patients described in Boston by Minot
1951
Cross transfusion by HA plasma in vWD
1964
Pool’s cryoprecipitate in vWD
1971
Immunologic difference of HA and vWD
1973
Synthesis of vWF by cultured EC
1977
First report on the use of DDAVP in vWD
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history
1981
Introduction of Haemate P in the market
1982
Epidemiology of vWD in general population
1984
1st classification based on multimer
1985
Discovery of vWF gene by four laboratories
1992
First PK trials with FVIII/vWF concentrates
1994
2nd Classification based on pathogenesis
2002
National guidelines for vWD management
2007
Molecular & clinical markers of vWD type 1
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Genetics
 vWF gene is located near the tip of the short arm of
chromosome 12, at 12p13.3 approximately 178 kb of DNA
and contains 52 exons.
 Mutations causing vWD have been identified throughout
the vWF gene ( >500 mutations)
 good correlation between the location of mutations in the
vWF gene and the subtype of vWD
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Genetics
↑
Adams13
The von Willebrand factor (vWF) protein sequence (amino acid 1–2813) is aligned with the cDNA sequence (nucleic acid 1–8439).
The vWF signal peptide is the first 22 aa, the propeptide (vWFpp) aa 23–763, and mature vWF aa 764–2800. Type 2 mutations
are primarily located in specific domains (regions) along the vWF protein. Types 2A, 2B, and 2M vWF mutations are primarily
located within exon 28 that encodes for the A1 and A2 domains of vWF. The two different types of 2A are those that have
increased proteolysis (2A2) and those with abnormal multimer synthesis (2A1). Type 2N mutations are located within the D’ and
D3 domains. Ligands that bind to certain vWF domains are identified, including FVIII, heparin, GPIb (platelet glycoprotein Ib
complex), collagen, and GPIIb/IIIa (platelet glycoprotein IIb/IIIa complex that binds to the RGD [arginine-glycine-aspartate] amino
acid sequence in vWF).
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Genetics
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Genetics
Type
1
2A
2B
2M
2N
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Inheritance
Autosomal
Autosomal
Autosomal
Autosomal
Autosomal
Autosomal
Dominant
Dominant (recessive)
Dominant
Dominant (recessive)
Recessive
Recessive
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vWF Molecule
 Vascular endothelium
 Bone marrow megakaryocyte
 Stored in secretory granules
 Stored in alpha-granules
(Weibel-Palade bodies)
 Released by stress or DDAVP
 Released by platelet
 Endoplasmic Reticulum
Dimerization
activation.
 DDAVP does not release
platelet vWF
 Golgi Apparatus
Multimerization
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vWF Molecule
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vWF Molecule
 Plasma vWF has a half-life of approximately 12 hours
(range 9–15 hours).
 vWF is present as very large multimers that are subjected
to physiologic degradation by ADAMTS13

ADAMTS13
TTP

ADAMTS13
Type 2A
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vWF Molecule
vWF blood level
 Blood type O (25%)
 Hypothyroidism
 Valproate










Old age
African-American black
Exercises, Surgery, Trauma
Pregnancy
Hyperthyroidism
Renal failure
Diabetes
Liver disease
Atherosclerosis
Inflammatory state and cancer
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vWF Molecule
Function
Hemostasis
 (1) Vascular factors
 (2) Platelet factors
 (3) Plasma factors
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vWF Molecule
Function
Hemostasis
 (1) Vasoconstriction
 (2) Platelet plug formation
 (3) Coagulation
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vWF Molecule
Function
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vWF Molecule
Function
 A3
Collagen
 A1
Gp I b
 C1
Gp II b III a
 A2
ADAMS 13
 Fibrinogen
Gp II b
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vWF Molecule
Function
• Platelet to exposed sub-endothelium
(collagen & GPIb )
• Platelet to platelet
( GP IIb/IIIa )
• Carry FVIII ( protect
from proteolysis)
Exposed subendothelium
Collagen
vWF
Platelet
GPIb
GPIIb/IIIa
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Classification
1984 ( Multimer Based )
Term
Definition
Type I
All sizes multimer, decreased Quan.
Type II
Absent of large multimer in plasma
Type II A
Absent of large multimers from Plt
and plasma, no DDAVP response
Type II B
Largest multimers present in Plt,
Appear in plasma after DDAVP
Type III
No multimers
Platelet Type - vWD
Largest multimers absent from
plasma
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Classification
1994 , 2006 ( Pathogenesis Based )
Term
Definition
Type 1 ( platelet nor/ low, IA,I-1,I-3)
Partial quantitative deficiency of vWF
Type 2
Qualitative vWF defect
Type 2A
( IIA, IB, I platelet discor, IIC,IID, IIE,
IIF, IIG, IIH, II-1, IIA-1, IIA-2, IIA-3 )
Decreased vWF-dependent platelet
adhesion with selective deficiency of highmolecular-weight Multimers
Type 2B
Increased affinity for platelet GPIb
( IIB, I New york, Malmo )
Type 2M
( IC, ID, B, Vicenza )
Decreased vWF-dependent platelet
adhesion without selective deficiency of
high-molecular-weight multimers
Type 2N
( Normandy )
Markedly decreased binding affinity for
FVIII
Type 3
Virtually complete deficiency of vWF
Pseudo- vWD ( not vWF defect )
Increased affinity of platelet GPIb for vWF
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Classification
Type 1
 Level of vWF in plasma is low.
 vWF mediates platelet adhesion and binding FVIII
normally.
 FVIII is normal or mildly decreased.
 vWF multimer gels are normal.
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Classification
Type 2 A
 Platelet adhesion is decreased because the proportion of
large vWF multimers is decreased.
 Levels of vWF:Ag and FVIII may be normal or modestly
decreased.
 vWF:Rco is markedly decreased.
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Classification
Type 2 B
 Mutations increase platelet–vWF binding and leads to the
proteolytic degradation and depletion of large vWF
multimers.
 Patients have thrombocytopenia that is exacerbated by
surgery, pregnancy, or other stress.
 RIPA is increased at low concentrations of ristocetin.
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Classification
Type 2 M
 Reduced interaction of vWF with platelet GPIb or with
connective tissue.
 Screening laboratory results are similar with type 2A
vWD and the distinction between them depends on
multimer gel electrophoresis.
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Classification
Type 2 N
 Impaired binding to FVIII, lowering FVIII levels.
 Type 2 N masquerade as an autosomal recessive H.A.
 The FVIII level is low but vWF:Ag and vWF:Rco are
normal.
 Discrimination from hemophilia A needs FVIII–vWF
binding assay.
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Classification
Type 3
 Type 3 vWD is characterized by undetectable vWF protein
and activity, and FVIII levels usually are very low.
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Epidemiology
 vWD , the most frequent inherited bleeding disorder.
 1% of General population
 Clinically significant patients = 100-200 / milion
 Mild form thought to be healthy
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Epidemiology
 vWD sub/type prevalence:
2A
2B 2
M
2N
France
30
28 8
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Italy
17
14
66
3
Germany
74
10
13
3
Average
30
30
30
10
 Type 1 , 55- 75 %
 Type 2 , 10- 30 %
 Type 3 , 5 – 20 % ( 0.5 – 6 / million )
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Epidemiology
 Non X-linked Disorder ( F ═ M )
 Type 1, 60% F
 Type 2, 55% F
 Type 3, 50% F
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Diagnosis
 Family History
 Patient medical history
 Physical exam
 Laboratory findings
 Genetics
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Diagnosis
 Family History
 Although a positive family history of documented
vWF is useful for diagnosis of vWD, such a history
is frequently not present.
 But a family history of bleeding symptoms is not
helpful.
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Diagnosis
 Physical exam
 Ecchymoses,
 Haematomas,
 Petechiae
 Evidence of liver disease (e.g. jaundice),
 Splenomegaly
 Arthropathy
 Joint and skin laxity (e.g. Ehlers-Danlos syndrome),
 Telangiectasia (e.g. hereditary haemorrhagic telangiectasia),
 Signs of anemia
 Gynaecological examination.
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Diagnosis
Common Bleedings
 Nose
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
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60% ( common in kids )
Gyn/Obs
60% ( 15% have vWD )
Teeth
50%
Ecchymosis
50%
Post surgical
25%
GI Tract
15%
Musculoskeletal 10% ( type 3 )
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Diagnosis
 Mild bleeding symptoms are very common in healthy
populations.
 Menorrhagia has good sensitivity but low specificity.
 Three findings that predict abnormal menstrual blood loss
of >80 mL include:
 Clots greater than approximately 1 inch in diameter
 Low serum ferritin
 Changing a pad or tampon more than hourly.
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Diagnosis
Bleeding Score
 The bleeding symptoms are very Important.
 The bleeding score (BS) is a quantitative index
summarizing both the number of episodes and their
severity.
 The BS has shown good sensitivity and specificity for the
diagnosis of type 1 VWD.
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Diagnosis
Bleeding Score
Rodeghiero et al,2005
A score of >3 in a male or >5 in a female is 99% specific and 64% sensitive in
identifying obligate carriers of VWD.
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Diagnosis
Bleeding Score
Tosetto A,et al,2006
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Diagnosis
Bleeding Score
Tosetto A,et al,2006
Positive BS (4 or more) has a sensitivity of 100% and a specificity of 87%.
The positive predictive value is 0.20 and the negative predictive value is 1
.
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Diagnosis
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Treatment
 DDAVP : release endogenous VWF stores through
stimulation of endothelial cells
 Plasma-derived, viral-inactivated concentrates.
 Agents that promote hemostasis and wound healing but do
not substantially alter the plasma concentration of VWF.
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Treatment
DDAVP:
 0.3 µg/kg , IV, (30–50 mL of N/S) over 30 min, peak
increments of FVIII and VWF 30 to 90 min post infusion.
 Sub cutaneous way is usually identical to IV.
 Nasal DDAVP ( Simate, 150 micro/g / dose )
 >50 kg: 2 puffs
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Treatment
DDAVP:
 Use with caution:
 Under 3 years
 vWD type1 with low PLT
 vWD type 3
 vWD type 2B ( some physicians recommend DDAVP)
 Pseudo platelet vWD
 Older age with atherosclerosis
 Uremia
 Major surgery ( long term prophylaxis is needed )
 Several doses
 Brain, ocular, and coronary artery surgeries
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Treatment
DDAVP:
 Complications:
 Headache
 Flushing
 Tachycardia
 Water intoxication ( only maintenance fluid for 24h)
 DVT
 MI
 Release of tPA ( anti fibrinolytic agents ?)
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Treatment
Cryoprecipitate
 Each bag contains about 100 IU vWF
 Virally non safe
 Volume overload
 Not available always
 Immunological reaction
 Not reliable response
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Treatment
Replacement Therapy
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Treatment
Replacement Therapy
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Treatment
Other Therapies
 Antifiibrinolytic agents
 Aminocaproic acid (25-50 mg/kg/dose QID )and Tranexamic acid
(5-10 mg/kg/dose TDS), PO or IV or topically in oral cavity.
 DIC and U.T bleeding are contraindications.
 Topical agents
 Topical bovine thrombin
 Fibrin sealant
 Topical collagen sponges
 Women Bleedings
 OCP, IUD, hysterectomy
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Treatment
Other therapies
 Platelet transfusion
:
 may control bleeding that is non- or poorly responsive to
replacement therapy with VWF concentrate.
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Menorrhagia in women with bleeding
disorders
Pictorial Blood Assessment Chart
score 100 = 80ml blood
Women with inherited bleeding
disorders
 116 women studied at Royal Free Hospital
 66 vWd
 30 carriers of hemophilia
 20 with factor XI deficiency
Prevalence rates of von Willebrand disease in
988 women presenting with menorrhagia
13% (5-24%)
Frequency of inherited bleeding disorders in
women with menorrhagia
 12% general gynecology referrals are for menorrhagia
 150 women with PBAC score > 100
 Frequency of VWD 13% compared with 0.1 to 1% in the
normal population
The frequency of bleeding symptoms in the normal
population compared
with 264 Scandinavian patients with VWD
Predictive value of bleeding symptoms in
diagnosis of type 1 VWD
Type 3
Type 2
< 10%
10-30%
Type 1
30-50%
RCof:
VWD – 0.82%
(480.000 patients?)
Please Reffer :
• Women with menorrhagia whom surgical
and Endocrinal abnormalities have been
ruled out.
•
•
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