Surface expression of activation dependent platelet membrane glycoproteins (CD62P, PAC-1, CD63 and CD40L) was not enhanced in the PKU group compared to the control group: CD62 P (percentage of positive platelets) as [median; interquartile range] in the PKU group versus control group: [(2.0; 1.6–2.7) versus (2.1; 1.57–2.8), p = 0.86] and PAC-1 (percentage of positive platelets) as [median; interquartile range]: [(0.46; 0.32–0.68) versus (0.55; 0.42–0.71), p = 0.29] (Fig 2A). This evidence concerns the gene CD63 and phenylketonuria.