WAS and immunodeficiency disease: Mutations in the first WASP family member to be identified, namely, WASP itself, were found to be the cause of WAS, which is a recessive disorder that was initially described as a triad of symptoms, namely, thrombocytopenia, eczema and immunodeficiency [28,29,30]; furthermore, they disrupt the activity of important functional domains, leading to more severe phenotypes [31,32].