Immunoactinopathies revisited: understanding clinical manifestations and biological pathways

Immune cell functionality is highly dependent on the actin cytoskeleton. The actin cytoskeleton is regulated by a complex molecular machinery that involves multiple genes. Mutations in these genes can cause inborn errors of immunity, also termed immunoactinopathies, of which Wiskott-Aldrich syndrome is the best-characterized entity. Currently, mutations in 23 genes can be considered causative of immunoactinopathies. Immunoactinopathies are rare disease entities with complex combinations of clinical manifestations, including immunodeficiency, immune dysregulation, malignancies, atopy, thrombocytopenia and bleeding, skin involvement, or congenital defects. Prompt diagnosis is crucial, because hematopoietic stem cell transplantation in an early phase can offer cure and prevent further complications. This review provides a detailed summary of the clinical experience with immunoactinopathies so far, elaborates on the most distinguishing features of immunoactinopathies by providing a clinical categorization, and links this information to the underlying biological pathways. This information may be of help to clinicians in the diagnosis of patients and to eventually improve patient care.