WAS and Wiskott-Aldrich syndrome: The levels of WASp expression correlate negatively with the severity of the disease; accordingly, low levels produce milder forms such as X-linked thrombocytopenia, whereas the absence of the protein results in the most serious manifestations of Wiskott-Aldrich syndrome (Albert et al., 2010; Jin et al., 2004; Zhu et al., 1997).