Impaired function of the immune system and a low number of platelets (blood cells that are required for clotting) which causes disease in males but lies dormant in females. It is an inherited condition and thus the females may pass it on to her children. It may result in recurrent infections (due to the impaired immunity), a high tendency to bleed (due to the low platelet levels) and eczema. Symptoms develop shortly after birth or within the first year of life. It also means an increased risk of developing cancers, usually in adolescence or early adulthood. Treatment aims to relieve the symptoms.