Quantitative flow cytometric analysis of the GPIb/IX/V complex on the platelet surface. The mean fluorescence intensity (MFI) values were converted into number of molecules per platelet based on the calibration bead standard curve. A normal control as well as a standard bead is run alongside with each patient. The number of molecules of each of the 3 glycoproteins per platelet in both affected and unaffected members fall within the ranges obtained for normal control subjects (GPIb, 34.000 ± 9000; GPIX, 26.000 ± 6000; GPV, 12.000 ± 4000; n = 1).