Test 14-Year-Old Boy 10-Year-Old Boy 2-Year-Old Boy Platelet count (reference range, 150-450×109/L) 1,132 893 640 Platelet aggregation Blood type A+ Blood type O+ Blood type O+ Arachidonate Absent Decreased Deaggregate ADP Absent Deaggregate Deaggregate Epinephrine Absent No secondary wave Decreased Collagen Absent Decreased Decreased Ristocetin Normal Normal Decreased PFA       Epinephrine (reference range, 70-165 s), s 182 175 Not done ADP (reference range, 50-115 s), s >212 172 Not done Factor VIII (reference range, 55%-200%), % 60 64 80 VWAg (reference range, 55%-200%), % 57 49 75 VWFAct (reference range, 55%-200%), % 43 44 56 Abbreviations: ADP: Adenosine Diphosphate; PFA: Platelet Function Analyzer; VWAg: Von Willebrand Antigen; VWFAct: Von Willebrand Factor Activity

Table 1: Pertinent Findings on Bleeding Diathesis Evaluation in 3 Siblings.