Elevated CD9 expression as a potential biomarker for diagnosis of Bernard-Soulier syndrome

Diagnosis of inherited platelet glycoprotein disorders is based on specific laboratory techniques such as aggregometry and flow cytometry. Flowcytometry is a powerful method, but equivocal results are produced in some cases. New cluster of differentiation markers could resolve the diagnostic dilemmas. Abnormal expression of CD9 in Bernard-Soulier syndrome (BSS) is recently reported. We aimed to determine the diagnostic significance of CD9 expression in a cohort of Iranian patients with inherited platelet glycoprotein defects. Twelve BSS, 21 Glanzmann thrombasthenia and 16 healthy controls were included in the present study. Flowcytometric diagnosis of BSS and Glanzmann thrombasthenia was made by analysis of CD41/61 and CD42a/42b CD markers. Moreover, phycoerythrin-labelled anti CD9 was examined in patients and healthy controls. The mean fluorescence intensity (MFI) of CD9 among the three groups was compared using suitable statistical methods and a P value of less than 0.05 considered statistically significant. Mean MFI of CD9 was 990.0 in BSS patients versus 421.2 and 317.3 in individuals with Glanzmann thrombasthenia and healthy controls, respectively (P < 0.05). Between the two-group comparison of means by the Mann-Whitney test revealed a P value of less than 0.001 for BSS group versus GT (2.4-fold) and BSS versus healthy controls (2.9-fold). CD9 molecule also expressed differently in patients with Glanzmann thrombasthenia in comparison with healthy controls (P < 0.001), although with a less magnitude (1.3-fold). According to our findings, CD9 is a potential biomarker for laboratory diagnosis of inherited glycoprotein defects, especially to elucidate the ambiguous results in BSS cases.