<unk>  include a vast range of heterogenous diseases characterized by elevated<unk><unk>  number (>2x109/L) in peripheral blood for more than 6 months in the absence of any clear etiology. The majority of patients are asymptomatic, although when present, symptoms are very variable.
Chronic lymphoproliferative disorder of NK cells
Congenital defects of phagocytes
Congenital disorders of the bone marrow
Critical illness-related corticosteroid insufficiency
Defects in intrinsic and innate immunity
Acquired disorders of the bone marrow
Natural killer cell deficiency
IgG4-related systemic disease