en Pediatric Hematology & Oncology Pediatric Hematology & Oncology پژوهشي Original Article Background: Bernard-Soulier syndrome is a rare inherited bleeding disease caused by quantitative or qualitative defect of GPIb/IX/V, a platelet complex that binds the Von Willebrand factor. The expression of GPIb-IX-V complex can be evaluated by flow cytometry and confirmed by the absence of ristocetin-induced platelet aggregation in platelet-rich plasma. The main aim of the present study was to classify Iranian Bernard-Soulier syndrome patients by a flow cytometric method, and to evaluate the correlation between platelet immunophenotype and clinical findings among patients. Patients and Methods: The surface expression level of GPIb-IX-V on platelets was assessed in fifteen Bernard-Soulier syndrome patients, using a panel of antibodies using a quantitative flow cytometry method. The results of the physical examination, family history and clinical presentation were also recorded by a physician. Result: The present study showed that all the patients suffer from a severe form of GPIb-IX-V complex deficiency. The study also found no correlation between the platelet surface glycoprotein expression and severity of bleeding among patients. Conclusion: Severe quantitative defect is the most common subtype among Iranian patients with Bernard-Soulier syndrome. Platelet Immunophenotyping alone does not determine the severity of hemorrhage in patients with Bernard-Soulier syndrome. Key words: Bernard Soulier Syndrome, GPIb-IX-V, flow cytometry, bleeding. Bernard Soulier Syndrome, GPIb-IX-V, flow cytometry, bleeding. 3 9 http://ijbc.ir/browse.php?a_code=A-10-9-15&slc_lang=en&sid=1 Hadjati S 10031947532846002636 10031947532846002636 No Farsinejad A 10031947532846002637 10031947532846002637 No Faranoush M 10031947532846002638 10031947532846002638 Yes Gharehbaghian A 10031947532846002639 10031947532846002639 No Amirizadeh N 10031947532846002640 10031947532846002640 No Toogeh Gh 10031947532846002641 10031947532846002641 No