Vasculitis, autoinflammation, immunodeficiency, and hematologic defects syndrome (VAIHS) is an autosomal recessive multisystem disorder with onset in childhood. The phenotype is highly variable, but most patients have features of a systemic vascular inflammatory disorder with skin ulceration and recurrent strokes affecting the small vessels of the brain resulting in neurologic dysfunction. Other features may include recurrent fever, elevated acute-phase proteins, myalgias, lesions resembling polyarteritis nodosa, and/or livedo racemosa or reticularis with an inflammatory vasculitis on biopsy. Some patients may have renal and/or gastrointestinal involvement, hypertension, aneurysms, or ischemic necrosis of the digits. Some patients present with clinical immunodeficiency. VAIHS is caused by homozygous or compound heterozygous mutation in the ADA2 gene (CECR1) on chromosome 22q11. (OMIM)