WAS and Wiskott-Aldrich syndrome: However, WAS knockout (WASKO) mouse models do not mimic the Plts defects found in WAS patients making it difficult to study the function of WASp in MKs and Plts physiology.11 The role of WASp in Plt development remains largely unknown with contradictory results.12,13 In an elegant study, Sabri et al. 14 identified a critical role of WASp in Plts biogenesis by inhibiting proplatelet formation through the Collagen I receptor.