This document summarizes a study that characterized mutations causing Glanzmann's thrombasthenia (GT) in Iranian patients. The study identified 3 novel mutations in the genes encoding platelet glycoprotein IIb/IIIa (GPIIb/IIIa) from DNA analysis of 20 GT patients. The mutations included 2 frameshift mutations resulting in premature protein termination or splice site alterations, and a substitution mutation disrupting the GPIIb/IIIa structure and preventing platelet aggregation. The study contributes to understanding the genetic basis of GT and its variable clinical manifestations.

1. Molecular Characterization of Glazmann’s Thrombasthenia in
Iran: identification of three novel mutations

2. Platelets and Hemostasis
Glanzmann’s Thrombansina
Methods
Results and Discussion
Conclusion
Content

3. Platelets (Thrombocytes)
Produced in BM
No nucleus
Hemostasis
Resting Plt
Activated Plt

5. Platelets (Thrombocytes)

6. Platelet Functional Disorder

7. Glanzmann’s Thrombasthenia (GT)
- Autosomal recessive coagulation disorder (bleeding disorder)

8. Glanzmann’s Thrombasthenia (GT)
- Men and women affected equally
- Genetic defect located on chromosome 17
- Impaired platelet aggregation is the hallmark of GT

9. Glanzmann’s Thrombasthenia (GT)
- Quantitative and/or qualitative defect of platelet glycoprotein IIb/IIIa (GPIIb/IIIa)

10. Glanzmann’s Thrombasthenia (GT)
- Nonsense and missense mutations

11. Glanzmann’s Thrombasthenia Symptoms
Petechia Epistaxis Gum bleeds

12. Methods
20 patients (GT)
Blood sampling, DNA extraction, and analysis by spectrophotometer
Amplification by touch-down PCR
Conformation Sensitive Gel
Electrophoresis heteroduplex PCR
DNA Sequencing

13. Results and Discussion
Mutation Identification
1

14. Glanzmann’s Thrombasthenia (GT) Types
2

15. Results and Discussion
Mutation Identification

16. Results and Discussion
Mutation Identification

17. Results and Discussion
Mutation Identification
* Point mutations and polymorphism in GPIIb/IIIa complex
* Missense and nonsense mutations cause premature
termination or splice site defects.
* Ligand binding activity, rate of the complex expression, and the
receptor activation impaired depending on the site of mutation

18. Discussion
* 3 novel mutations and 2 novel polymorphisms were recognized
during the examination of entire coding regions of ITGA2B and ITGB3
genes.
* Frameshift mutations resulted in premature termination
or splice site alteration.
- The beginning of exon 9 of ITGB3 and exon 1 of ITGA2B.
- The middle of exon 12 of ITGB3

19. Discussion
* 2 novel synonymous polymorphisms (silent mutation)
- exon 10 of IGTB3 no effect on plt (aggregation or adhesion)
* Substitution mutation on exon 5 of IGTB3 disrupt
GPIIb/IIIa structure and LBA prevents plts aggregation
* Type I GT no GPIIb/IIIa expression on their plts.
* Another polymorphism (missense gene alteration) in the
extracellular domain of B3

20. Conclusion
* The platelet membrane glycoprotein IIb/IIIa complex mutations
lead to Glanzmann's thrombasthenia. A large variety of mutations
and polymorphisms are responsible for the aberrant expression and
defective activity of this heterodimeric complex.
* Mutation screening was analyzed using conformation-sensitive
gel electrophoresis heteroduplex PCR, and DNA sequencing.

21. Thank You