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TABLE OF CONTENTS:
INTRODUCTION:........................................................................................................2
EPIDEMIOLOGY:.........................................................................................................2
MAIN CHARACTERISTIC FEATURES:....................................................................2
PATHOPHYSIOLOGY:.................................................................................................3
MOLECULAR BASIS OF SYNDROME:....................................................................2
CLINICAL PRESENTATION:......................................................................................2
LABORATORY STUDIES............................................................................................8
DIFFERENTIALS........................................................................................................11
MANAGEMENT.........................................................................................................11
PROBLEMS SPECIFIC TO WOMEN........................................................................14
PROGNOSIS:..............................................................................................................14
REFERENCES:............................................................................................................15
1
BERNARD-SOULIER SYNDROME (BSS)
INTRODUCTION:
BSS was initially explained in 1948. The initial discovery was made by 2 French
hematologists namely Jean Bernard and Jean-Pierre Soulier, and hence named the
disease accordingly1. It is a hereditary bleeding disorder. It is primarily differentiated
by means of thrombocytopenia and presence of large platelets. The initial discovery
was made in young boy, who presented with abnormal bleeding since birth and his
older sister also had bleeding disorder, which led to her death. The test results
established that there were abnormally large platelets present. These platelets were
found to be devoid of their normal function in primary platelet plug development and
thus led to prolong bleeding.
EPIDEMIOLOGY:
Frequency: it is rare disorder with expected occurrence rate of
<1/million population.
Race: common in white people and Japanese population.
Morbidity/Mortality: severity is variable ranging from mild to severe
in case of surgery and sever injury.
Sex: male female ration is same
Age: bleeding in BSS may start during infancy and can continue with
changeable severity throughout life time.
2
MAIN CHARACTERISTIC FEATURES:
The major characteristic properties of BSS are summarized as:
Autosomal recessive disorder2
Heterozygote generally donot show bleeding problems
Unusually large platelets (therefore it is also called as giant platelet disorder)2
Mild / Moderate thrombocytopenia
BM megakaryocytes show normal numbers
Prolonged skin bleeding time2
Inconsistent bleeding time with respect to thrombocytopenia2
Parental history for comparable bleeding is inconclusive
Consanguinity is frequently reported
PATHOPHYSIOLOGY:
The primary biochemical deficiency is the lack of or reduced expression of
glycoprotein Ib/IX/V complex, which is mainly present on platelet surface.
Glycoprotein Ib/IX/V complex is main receptor for binding to von Willebrand factor
(vWF), and the consequence of reduced expression is incomplete binding between
vWF and platelet membrane, specially at position of vascular damage, resulting in
imperfect platelet adhesion3.
This is confirmed by the defective or absence of platelet aggregation, when exposed
to ristocetin. Ristocetin is an antibiotic which normally causes platelets aggregation.
The final outcome is the absence of development of primary platelet plug, which
result in greater bleeding tendency. The main cause of thrombocytopenia however is
not absolutely known, but it may be related to reduce platelet life period.
3
MOLECULAR BASIS OF SYNDROME:
The GPIb/ IX/ V complex presents the most important site mediating platelet
interaction with VWF.
This complex is composed of 4 proteins:
Disulphide-linked chains of GP Ib
α - chain (135 kDa)
β – chain (25 kDa)
Non-covalently connected subunits
GPIX (22 kDa)
GPV (82 kDa)
They all contribute to same functional and structural properties signifying a common
evolutionary derivation. A number of transcripts encode these 4 polypeptide chains
but with exception of GPIb β. These genes show uninterrupted (intron - depleted)
open reading frames.
All 4 genes which encode this complex are cloned. A total of 17 different types of
BSS have been characterized up to date. This characterization is mainly on the basis
of:
Functional
Immunological
Molecular levels.
Mutations of GPIbα, GPIbβ and GPIX associated with Bernard-Soulier syndrome
are mapped to the mature protein structure and indicates missense mutations or short
deletions, nonsense mutations leading to premature stop, or mutations causing a frame
shift leading to stop. There are no reported mutations in GP V6, 17, 18
4
The different mutations are divided into 2 major groups:
First type of mutations : these are mainly located in LRR i-e Leucine
rich repeats. These mutations mainly lead to the conformational
modifications of molecules. In minority of cases, there is increased
proteases sensitivity and decrease in the receptors adhesive function.
Also these receptors are expressed at reduced levels than normal on
platelet surface membrane. Mutations affecting LRR region of GPIba,
results in variable production of the remaining chains ranging from
normal to very small amounts. While mutations affecting the LRR
region of GPIX, results in diminished production of other chains,
which suggests that GPIX has a main role in receptor complex
stability.
Second type of mutations: these result in the production of truncated
molecule which is lacking transmembrane domain, also in some cases
lacking its expression on the platelet surface as well. The additional
chains whereas are produced in residual amounts.
5
FIG1: GP I/IX/V complex
FIG 2: Mutations of (A) GPIbα (B) GPIbβ and (C) GPIX
6
CLINICAL PRESENTATION:
BSS symptoms show variable presentation between different individuals.
Signs and symptoms of disorder are frequently first observed during
childhood.
Usually common presentation of BSS is:
Cutaneous hemorrhages
o Purpura
o Bruises
Epistaxis (which may sometimes be difficult to control)
Gingival bleeding
Heavy menstural bleeding (menorrhagia)
Bleeding after parturition
Haemarthrosis
Abnormal bleeding after
o surgery
o circumcision
o dental work
Rarely blood vomitus
Presence of blood in stool (gut bleeding)
BSS poses more problem in women as compared to men and this is
mainly due to
o Menstruation and
o Child birth
7
Diagnostic Approach for BSS
LABORATORY STUDIES
The different laboratory tests for diagnosis of BSS include:
COMPLETE BLOOD COUNT (CBC):
Thrombocytopenia
Mild or moderate
Ranges from 20x109/L – near normal
Giant platelets in peripheral smear observed
80% usually larger than 2.5 µm
8 µm diameter cells also observed
8
FIG 3: Peripheral smear of patient with BSS.
BT / PFA-100 CLOSURE TIME:
Each has restricted sensitivity (~40%) still in indicative patients
Neither therefore are superior screening tests to detect functional platelet
function
BT is prolonged
PFA-100 closure time is raised
PLATELET AGGREGATION STUDIES: 7
Ristocetin induced aggregation of platelets is absent
Aggregation response is normal with additional agonists like epinephrine,
arachidonic acid, ADP and collagen.
9
FLOW CYTOMETRY:
By this technique protein expression is measured on the cell surface with the
help of monoclonal antibodies.
IN BSS
Reduced GPIb/IX/V expression
Cell surface marker is CD42b
In qualitative CD42b defect, flow cytometry is normal
10
DIFFERENTIALS
BSS should be differentiated from:
Glanzmann thrombasthenia:
May-Hegglin anomaly:
Von-Willebrand disease:
MANAGEMENT
Management of BSS mainly consists of:
Preventive measures and local care
Specific treatment
11
PREVENTIVE MEASURES:
Avoidance of anti-platelet drugs
Aspirin
NSAID’s
Dental hygiene
Mensturational bleeding hormonal control
Contraceptives
Treatment plan before surgery
Patient education
Avoid trauma
For epistaxis
Nasal packing
Gingival bleeding
Gel foam is applied soaked in tropical thrombin
Moderate / severe cases
Activity restriction is important
SPECIFIC TREATMENT CHOICES:
ANTI-FIBRINOLYTIC AGENTS:
These are mainly useful in management of menorrhagia
Also used for mild bleeding problems like bleeding from mucous
membranes for example epistaxis.
Common drugs include
o Epsilon amino caproic acid (EACA. Amicar®) is used
12
o Tranexamic acid
These are also available as mouth wash for bleeding in mouth from
o Tonsillectomy sites
o After dental extract
DESMOPRESSIN ACETATE (DDAVP) 8
It cut down the bleeding duration but in some of the patients not all
with BSS
It is helpful for small bleeding episodes
Exact mechanism is not clear
it may due to increased VWF binding with residual GP1b especially
in patients exclusive of absolute deficiency
PLATELET TRANSFUSIONS:
Should be conserved for
o surgery
o Life threatening bleeding
o Failure to other agents
Patient may produce antibodies against GP Ib/IX/V. As this complex is
present on donor platelets but not in patient’s platelets.
Recombinant activated Factor VII (rFVIIa): 9
It is used in BSS patients but with limited experience.
Precise mechanism is unknown, but increased thrombin synthesis and
fibrin deposition is observed at vascular injury site.
13
PROBLEMS SPECIFIC TO WOMEN
MENORRHAGIA:
Is the most important bleeding crisis for women following Puberty. Oral
contraceptives use can regulate menstural cycles thereby reducing heavy bleeding.
Tranexamic acid (Cyklokapron® or Amicar®) is also indicated at same time. They
mainly act by down regulating destruction of clots that formed in the body. Bleeding
is usually severe at first menstruation cycle.
PREGNANCY AND CHILD BIRTH BLEEDING:
BSS is very rare that is why there is not much documentation available about bleeding
during pregnancy and bleeding at time of parturition.
BSS expectant mother should be tracked in such treatment center having experience
in dealing such patients. They should also discuss the danger associated with epidural
in advance with the concerned physician.
PROGNOSIS:
The bleeding propensity is life-long in Bernard-Soulier syndrome (BSS) patients but
there may be reduction in bleeding tendency with age.
14
REFERENCES:
1. Bernard J. History of congenital thrombocytic hemorrhagic dystrophy. C R
Acad Sci III. 1996 Aug;319(8):727-32
2. López JA, Andrews RK, Afshar-Kharghan V, Berndt MC. Bernard-Soulier
syndrome. Blood 1998 Jun 15; 91(12):4397-418.
3. Simon D, Kunicki T, Nugent D. Platelet function defects. Haemophilia. 2008
Nov; 14(6):1240-9.
4. Andrews R, Berndt M, Lopez J. The glycoprotein Ib-IX-V complex. In:
Michelson AD, editor. Platelets.2nd edition. San Diego, CA: Academic Press;
2006. pp. 145–64
5. Lanza F. Bernard-Soulier syndrome (hemorrhagiparous thrombocytic
dystrophy) Orphanet J Rare Dis. 2006; 1:46.
6. Kahn ML, Diacovo TG, Bainton DF, Lanza F, Trejo J, Coughlin SR.
Glycoprotein V-deficient platelets have undiminished thrombin responsiveness
and do not exhibit a Bernard-Soulier phenotype. Blood. 1999;94(12):4112–21
7. Ramasamy I. inherited bleeding disorders. Disorders of platelet adhesion and
aggregation. Crit Rev Oncol Hematol. 2004; 49 (1) : 1-35
8. Franchini M. The use of desmopressin as a hemostatic agent. Am J Hematol,
2007 Aug; 82(8): 731-5.
9. Peters M, Heijboer H. treatment of a patient with Bernard Soulier syndrome
and recurrent nosebleeds with recombinant Factor VIIa. Thrombosis and
Hemostasis 1998; 352
15