Classification of Iranian patients with Glanzmann's Thrombasthenia using a flow cytometric method

Blood management strategies in congenital Glanzmann thrombasthenia at a hematology referral center

Background

Glanzmann thrombasthenia is associated with abnormalities in the glycoprotein IIb/IIIa receptor. This study, conducted at Ampang Hospital, Malaysia, aimed to assess outcomes of blood management strategies for Glanzmann thrombasthenia.

Methods

Ten patients with Glanzmann thrombasthenia aged 9 years (2009‒2018) were examined. Data on clinical characteristics, transfusion practices, and patient blood management were obtained from medical records. Patient blood management methods included parenteral iron, erythropoietin, hormonal pills, intrauterine progesterone contraceptive devices, tranexamic acid, and recombinant factor VIIa. Primary outcomes were hemoglobin levels and the proportion of patients who received blood transfusion. Secondary outcomes were morbidity and mortality.

Results

The median age at diagnosis was 8.2 years (range, 1‒15 yr). The female-to-male ratio was 9:1. Eight patients had type 2 disease (5‒20% of normal GPIIb/IIIa), and two patients had type 1 disease (normal GPIIb/IIIa <5%). All patients had iron deficiency. All female patients presented with significant menorrhagia. Other bleeding symptoms included epistaxis, spontaneous skin bruising, hemoptysis, gingival bleeding, knee hemarthrosis, and pelvic hematoma. No patient experienced life-threatening bleeding. Our patients had a mean hemoglobin level of 5.6 g/dL at diagnosis. All patients were optimized using non-transfusion methods as described above. Our patient had a current mean hemoglobin level of 11 g/dL. Approximately 70% (7/10) of patients did not experience receiving blood transfusions in the last 5 years. No patient experienced non-transfusion-related morbidities such as sepsis, thromboembolism, or cardiorespiratory events.

Conclusion

High cost, transfusion-related adverse events, and immunomodulation could be effectively prevented by avoiding unnecessary blood transfusions.

Evaluation of platelet surface glycoproteins in patients with Glanzmann thrombasthenia: Association with bleeding symptoms

Background & objectives:

Glanzmann thrombasthenia (GT) is a rare, inherited autosomal recessive disorder characterized by qualitative or quantitative deficiency of integrin αIIbβ3 [glycoprotein IIb (GPIIb)/IIIa, CD41/CD61] diagnosed by absent or reduced platelet aggregation to physiological agonists, namely, collagen, adenosine-di-phosphate, epinephrine and arachidonic acid. The objective of this study was to quantitate platelet surface GPs, classify GT patients and relate the results with the severity of bleeding and platelet aggregation studies.

Methods:

Fifty one patients of GT diagnosed by platelet aggregation studies were evaluated for the expression of CD41, CD61, CD42a and CD42b on platelet surface by flow cytometry. The association between the clinical phenotype based on bleeding score and GT subtype on flow cytometric evaluation was assessed.

Results:

Twenty four (47%) patients of GT were classified as type I (as CD41/CD61 were virtually absent, <5%), six (11.8%) patients as type II (5-20% CD41/CD61) and 21 (41.2%) as type III or GT variants as they had near normal levels of CD41 and CD61. Type III GT patients had significantly lower numbers of severe bleeders (P=0.034), but the severity of bleeding did not vary significantly in type I and II GT patients. In all GT patients, mean CD41 expression was found to be lower than mean CD61 expression (P=0.002).

Interpretation & conclusions:

Type I GT was found most common in our patients and with lowered mean CD41 expression in comparison with CD61. Type III GT patients had significantly lower numbers of severe bleeders, but the severity of bleeding did not vary significantly in type I and II GT patients.

Identification of Clinicopathological Spectrum, Platelet Glycoprotein IIb/IIIa complex and Platelet Antibodies in Egyptian Children with Glanzmann's Thrombasthenia

Glanzmann's thrombasthenia (GT) is a rare genetic bleeding disorder. The aim of our study was to evaluate the clinicopathological spectrum of this syndrome and to study the platelet glycoprotein IIb/IIIa complex and platelet antibodies by flow cytometry in a cohort of children with GT in a tertiary care center in Upper Egypt. Forty children with GT were assessed for the expression of GPIIb-IIIa on the platelet surface and platelet antibodies by using flow cytometry, to determine the most common GT subtypes among Egyptian children. By analysis of platelet GP IIb-IIIa by flow cytometry the classification of patients with GT in our study was type I GT (47.5%), type II GT (32.5%) and type III GT (20%). In this study, we have delineated that type I is the most common type of GT in Upper Egypt. Our data suggested that there is a good correlation between quantitative changes in the surface expression of platelet membrane glycoproteins detected by flow cytometry and the clinical severity of bleeding. Therefore, classifying of severity of bleeding in patients with GT could possibly aid the pediatricians and hematologists in the implementation of ideal prophylactic measures.

Different biochemical expression pattern of platelet surface glycoproteins suggests molecular diversity of Glanzmann's thrombasthenia in Iran

Glanzmann's thrombasthenia is a rare congenital bleeding disorder characterized by lack of platelet aggregation induced by most agonists. The disease is caused by different mutations in either GPIIb or GPIIIa genes that lead to a lack or dysfunction of the αIIbβ3. Western blot analysis was performed on the platelet lysates of 95 patients with Glanzmann's thrombasthenia who were referred to the Iranian Blood Transfusion and Hemophilia Clinic. Glanzmann's thrombasthenia was diagnosed based on clinical findings and were classified according to Glanzmann's Thrombasthenia Italian Team (GLATIT) protocol. The platelet glycoprotein expression pattern in Iranian patients with Glanzmann's thrombasthenia was studied and the relationship between the platelet glycoprotein expression levels and clinical symptoms were investigated. Loss or severe reduction of platelet GpIIb and GpIIIa were observed in majority of patients (78%). The remaining patients (22%) showed a relatively sharp decline to the normal amounts of the glycoproteins. None of the patients showed expression of CD41 without CD61. Statistical analysis showed no significant relationship between clinical symptoms and expression of platelet glycoproteins. Different patterns of platelet glycoproteins expression suggest that there is variety of mutations in the patients. Unlike the universal Glanzmann's thrombasthenia database, the majority of Iranian patients may suffer from a GpIIIa gene mutation. This study also confirmed a lack of correlation between clinical manifestation and GPIIb/IIIa expression in the patients.