Reduced PPF in MKs from cases. (A) Flow cytometry analysis of day 10 MK for markers CD41 and CD42 showed no difference in maturation between control and case MKs. (B) The same cultures showed evidence of reduced PPF (arrows). (C) PPF was quantified after MK spreading on fibrinogen and staining for VWF for 6 unrelated controls and 7 cases. Linear mixed model with a fixed effect for case/control status, a random effect for pedigree and a random effect for sample. The P value under the null hypothesis in which that the fixed effect is equal to 0 is shown.