**3. Epidemiology**

It has been estimated that one in every 100,000 male births leads to Wiskott-Aldrich Syndrome, and in families without a history of the disease, the average age of diagnosis is 24 months [4, 5]. In the United States, the estimated incidence of WAS is one in 250,000 male births. Whereas WAS still is a rare disease, it is more common than other immunodeficiency syndromes such as hyper-IgM syndrome or SCID which have an estimated incidence of about one in 1,000,000 live births. It is thought WAS accounts for 1.2% of all inherited immunodeficiencies in the United States [6]. Up to now, the impact of any ethnic or geographical factor on its incidence has not been reported. Because of misdiagnosing of mild cases, these conditions may be presumed as idiopathic thrombocytopenia purpura [4].
