Microbial nucleic acid recognition serves as the major stimulus to an antiviral response, implying a requirement to limit the misrepresentation of self nucleic acids as non-self and the induction of autoinflammation. By systematic screening using a panel of interferon-stimulated genes we identify two siblings and a singleton variably demonstrating severe neonatal anemia, membranoproliferative glomerulonephritis, liver fibrosis, deforming arthropathy and increased anti-DNA antibodies. In both families we identify biallelic mutations in DNASE2, associated with a loss of DNase II endonuclease activity. We record increased interferon alpha protein levels using digital ELISA, enhanced interferon signaling by RNA-Seq analysis and constitutive upregulation of phosphorylated STAT1 and STAT3 in patient lymphocytes and monocytes. A hematological disease transcriptomic signature and increased numbers of erythroblasts are recorded in patient peripheral blood, suggesting that interferon might have a particular effect on hematopoiesis. These data define a type I interferonopathy due to DNase II deficiency in humans.

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The type I cryoglobulins (CGs) account for 10-15% of all cryoglobulins and are found in patients with hematological disorders. We here describe the largest series of seven cases of type I cryoglobulinemia associated with multiple myeloma (MM) and provide a detailed review of the literature associated with this disorder, with the aim of improving the future diagnosis and therapeutic management of this rare disease. Six of the cases in our series were men aged 28-69 years, and most of the subject patients had an immunoglobulin G (IgG) monoclonal component and stage I indolent MM that manifested as cryoglobulin-related symptoms. The patients were all karyotypically normal. Clinical manifestations in this group were: skin lesions (five cases, 71.4%), rheumatologic failure (four cases, 57.1%), neurological abnormalities (two cases, 28.6%), mixed cutaneous/rheumatologic/renal defects (one case, 14.3%) and one case in which the cryoglobulinemia was asymptomatic. Two patients experienced acute renal failure but underwent a full recovery following treatment for MM. We conclude from our analysis that treatment approaches for severe type I cryoglobulinemia should involve plasmapheresis at the onset to achieve a rapid control of the CG-related symptoms, and that specific MM treatments should be introduced also at an early stage to avoid cryoglobulinemia relapse. In this context, bortezomib and lenalidomide are potentially the most effective therapeutic agents.