Glanzmann Thrombasthenia in Saudi Arabia Prof. Layla A. M. Bashawri Imam Abdulrahman Bin Faisal University
INTRODUCTION Named after the Swiss Pediatrician Eduardo Glanzmann in 1918 who described bleeding symptoms associated with a normal platelet count, (“weak platelets”) described as hereditary hemorrhagic thrombasthenia. Glanzmann thrombasthenia is a bleeding disorder marked by prolonged bleeding time, normal platelet count and absence of platelet aggregation in response to platelet agonists ADP, collagen, arachidonic acid and thrombin, impaired or absent clot retraction. Transmitted as an autosomal recessive trait with consanguinity reported and intercommunity marriages in affected patients.
PATHOGENESIS Platelets from GT patients show quantitative or qualitative abnormalities of platelet membrane glycoprotein (GP) IIb – IIIa complex, also called integrin IIb 3, which mediates aggregation of activated platelets. GPIIb/IIIa ( IIb and 3) subunits are prominent integral components of the platelet membrane that form heterodimers containing specific sites for platelet cohesion. The IIb 3 integrin serves as a platelet receptor for fibrinogen, fibronectin, vitronectin and VWF.
Classification of Glanzmann Thrombasthenia Type I Disease Patients with no platelet aggregation, absent or severely deficient fibrinogen binding, absent clot retraction and platelet GP IIb/IIIa levels < 5%. Type II Disease Patients with no platelet aggregation, fibrinogen binding present, normal or moderately deficient clot retraction and GP IIb/IIIa levels in the 10 – 20% range. Variant Disease Patients with no or very abnormal aggregation but in most cases with GPIIb or GP IIIa gene defects allowing GPIIb/IIIa expression more than 50%, variable fibrinogen binding and clot retraction.
Molecular Biology The two genes encoding GPIIb (ITGA2B) and GPIIIa (ITGB3) are closely associated at chromosome 17q21. The GT associated mutations that have been identified at the molecular level has substantially increased in recent years enabling the development of an Internet database (GT Database). Inherited genetic mutations in ITGA2B, ITGB3 result in a heterogeneity of the Thrombasthenia phenotypes.
Molecular Biology These defects have been shown to lead to disruption of GPIIb / IIIa synthesis, receptor assembly and / or function. Leading to prevention of GPIIb / IIIa from binding to its major adhesive ligands VWF and Fibrinogen to mediate platelet aggregation.
To date more than 100 distinct genetic defects have been described ranging from point mutations, small deletions and insertions to large deletions and inversions occurring with even distribution on both genes.
Molecular Biology First Molecular Analysis of ITGB3 gene in Saudi Arabia (Tarek Owaidah et al) 1 novel germline mutation in exon 13, results in premature stop codon and protein truncation. Blood 2011,118:1136
Genetic Basis
Incidence: Rare worldwide, (reported incidence 1/1000,000),occurs in regions where consanguineous marriages are common, groups of patients have been identified. e.g. India, Iraqi-Jews and Arabs in Palestine, and in Jordan and Saudi Arabia.
In Saudi Arabia: A previous report from our institution in 1988 revealed a high incidence of this disorder in the EP (12/34). (This makes it probably the second hemorrhagic disorder to HA in EP). A study in Riyadh in 1995-96, 18/168. (where it was the 3 rd H.BD). even type II reported in 1990. 1997 (16 Saudi patients over 11 years EP). Madinah: (24 over 16 years 1992 – 2008) Tarawah A.
Saudi Arabia Riyadh 44 patients (R. Alnounou 2005-2009). GT1-34, GT2-6, GT3-4. Riyadh 2011 , 51 patients for Molecular Analysis. Tarek Owaidah etal
CLINICAL FEATURES Easy and spontaneous bruising. Mucous membrane bleeding. Subcutaneous hematomas Petechiae uncommon, but purpura and ecchymoses may be striking Rare hemarthrosis Fatal hemorrhages Clinical heterogeneity, an extreme variability in the clinical symptoms
Clinical Severity GT is certainly a severe hemorrhagic disease nevertheless bleeding, severity is unpredictable. Emphasized by the inconsistency between siblings who presumably share the same genetic defect.
Diagnosis and Lab. Investigations The condition shares common clinical and laboratory features as with other platelet disorders. Careful analysis of the medical history and family history. CBC, PBS, PT, aPTT
DIAGNOSIS AND LAB. INVESTIGATIONS Platelet Count: N,PBS: MPV:N BT usually markedly prolonged. Tests of platelet functions: Platelet aggregation: ADP, epinephrine, thrombin, AA, Collagen, No aggregation Ristocetin aggregation. (subnormal in our cases) Clot retraction: absent or reduced (rarely normal)
DIAGNOSIS PFA highly sensitive test. The PFA assay is prolonged among patients with GT. Flow cytometry can be beneficial, under flow cytometric analysis CD41 and CD 61 are markedly decreased or absent.
Flow cytometry is the current method of choice for confirmation of the diagnosis procedures exist both for quantitative assessment of the residual GPIIb/IIIa content of platelets and for testing the inability of variant GT; GPIIb/IIIa to express activation- dependent epitopes (recognized by the absence of binding of monoclonal antibodies such as PAC-I or FITC- fibrinogen ).
DIAGNOSIS The best way to diagnose GT is through mutation analysis. Genomic DNA sequencing of the 45 exons comprising the IIb- 3 unit, along with the splice sites of the ITGB3 and ITGA2B gene, should be investigated, and the established mutations be confirmed with a second DNA sample analysis.
DIFFERENTIAL DIAGNOSIS By Laboratory Tests: Mainly: VWD: VIII assay, VWF, PFT BSS: Platelet count, PBS, PFT Afibrinogenaemia: same PFT but muscle haemorrhages, intra- abdominal hemorrhages, fetal wastage, PT, PTT, TT, fibrinogen level.
Overall, the diagnosis of GT includes presence of a normal platelet count, absent platelet aggregation in response to all physiologic stimuli (is pathognomonic for GT), and abnormal clot retraction is rarely observed in other disorders. Prolonged bleeding time and PFA time.
Eastern Province Study (KFHU) In this study 31 patients were diagnosed with Glanzmann thrombasthenia. (Retrospective review from Coagulation laboratory, Hematology Clinic, medical records department). Clinical data, family history were recorded. Laboratory Investigations included CBC, PBS, bleeding time, APTT, PT, Clot Retraction and Platelet Aggregation. In some of our patients flow cytometric analysis of platelet glycoproteins was carried out.
RESULTS 31 Patients, 17 males, 14 females, were Saudi patients (most from eastern province and from the southern part of the Kingdom). Positive history of first degree consanguinity was observed and there was a positive family history also.
Summary: Clinical Features Patient Age now Gender Age at Clinical Presentation (Years) Presentation 1. 55 M early childhood Gum bleeding, bled at circumcision, hemarthrosis 2. 28 M 1 year Epistaxis, bruises 3. 26 M 20 days Bled at circumcision; Haemoarthrosis Bruises 4. 31 M 2 years old Buccal mucosa / Melena, epistaxis, bruises, chronic gum bleeding 5. 23 M early childhood Epistaxis; Bruises
Summary: Clinical Features Patient Age now Gender Age at Clinical Presentation (Years) Presentation 6. 22 M early childhood Epistaxis 7. 25 M 11 months Bruises, blunt injury to Right eye. 8. 21 M 1-1/2 Because of prolonged BT before Circumcision 9. 18 F 1 month Petchial rash at 1 month, bleeding with tooth eruption, hemoptysis with cough (URTI) 10. 18 F 9 months Gum bleeding
Summary: Clinical Features Patient Age now Gender Age at Clinical Presentation (Years) Presentation 11. 54 M 7 years Circumcision bleeding, Epistaxis, Hematuria, Rectal bleeding 12. 37 F 4 years Epistaxis, Menorrhagia, GIT bleeding, Petechial, Ecchymosis, Haemoarthrosis, 13. 35 F early childhood Uncontrolled menorrhagia, gum bleeding, delayed wound healing 14. 38 F 7 years Melena; menorrhagia; rectal bleeding; gum bleeding; epistaxis; haemoarthrosis; Hematuria 15. 45 (died) M early childhood Severe GIT bleeding
Summary: Clinical Features Patient Age now Gender Age at Clinical Presentation (Years) Presentation 16. 37 F early childhood Menorrhagia 17. 40 M early childhood Gum bleeding; epistaxis 18. 38 F early childhood Menorrhagia; Petechiae 19. 51 F early childhood Menorrhagia; Epistaxis 20. 81 M early childhood Epistaxis
Summary: Clinical Features Patient Age now Gender Age at Clinical Presentation (Years) Presentation 21. 34 F early childhood Menorrhagia, bruises; gum bleeding 22. 38 M early childhood Gum bleeding 23. 39 M early childhood Epistaxis; Gum bleeding 24. 40 F early childhood Petechiae; menorrhagia 25. 36 F early childhood Epistaxis
Summary: Clinical Features Patient Age now Gender Age at Clinical Presentation (Years) Presentation 26. 37 F early childhood Menorrhagia; epistaxis 27. 35 M early childhood Gum bleeding; Epistaxis 28. 35 M early childhood Epistaxis 29. 46 (Died) F 5 years Severe GIT bleeding, Menorrhagia 30. 40 M early childhood Epistaxis 31. 38 F early childhood Bruises, Menorrhagia
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