Mutations in RNU4ATAC Are Associated With Chilblain-Like Lesions and Enhanced Type I Interferon Signalling.

Mutations in the non-coding RNA gene RNU4ATAC are associated with growth restriction and complications related to antibody deficiency. Here, we report that innate immune dysfunction is a previously unrecognised feature of this disorder. In particular, painful chilblain-like lesions are common in RNU4ATAC patients and are linked to dysregulated type I interferon signalling.

Distinct pathogenic mutations in ARF1 allow dissection of its dual role in cGAS-STING signalling.

Tight control of cGAS-STING-mediated DNA sensing is crucial to avoid auto-inflammation. The GTPase ADP-ribosylation factor 1 (ARF1) is crucial to maintain cGAS-STING homeostasis and various pathogenic ARF1 variants are associated with type I interferonopathies. Functional ARF1 inhibits STING activity by maintaining mitochondrial integrity and facilitating COPI-mediated retrograde STING trafficking and deactivation.

Autoinflammatory encephalopathy due to PTPN1 haploinsufficiency: a case series.

Background: Through the agnostic screening of patients with uncharacterised disease phenotypes for an upregulation of type I interferon (IFN) signalling, we identified a cohort of individuals heterozygous for mutations in PTPN1, encoding the protein-tyrosine phosphatase 1B (PTP1B). We aimed to describe the clinical phenotype and molecular and cellular pathology of this new disease.

Methods: In this case series, we identified patients and collected clinical and neuroradiological data through collaboration with paediatric neurology and clinical genetics colleagues across Europe (Czechia, France, Germany, Italy, Slovenia, and the UK) and Israel.

Baricitinib Treatment in RNU7-1-Associated Aicardi-Goutières Syndrome in a South African Child: A Case Report.

Aicardi-Goutières syndrome (AGS) is a rare monogenic type I interferonopathy. Janus kinase (JAK) inhibition has emerged as a potential treatment for AGS. RNU7-1 is one of the most recently discovered genes for AGS, and the clinical effects of JAK inhibition in these patients have not been reported.

Reverse transcriptase inhibitors in Aicardi-Goutières syndrome: A crossover clinical trial.

Aim: To extend the findings of a previous clinical trial suggesting combined abacavir (ABC), lamivudine (3TC), and zidovudine (AZT) reduces type I interferon (IFN) signalling in Aicardi-Goutières syndrome (AGS).

Method: This was an open label, non-placebo-controlled phase II clinical trial (NCT04731103) in patients less than 16 years with any of five AGS genotypes. The effect of ABC or 3TC individually, or of combined ABC + 3TC + AZT, on IFN-stimulated gene (ISG) expression (primary outcome) and IFN-alpha protein (secondary outcome) in blood was assessed.

CNS disease associated with enhanced type I interferon signalling.

The ability to mount an interferon-mediated innate immune response is essential in protection against neurotropic viruses, but antiviral type I interferons also have neurotoxic potential. The production of type I interferons can be triggered by self-derived nucleic acids, and the brain can be susceptible to inappropriate upregulation of type I interferon signalling. Homoeostatic dysregulation of type I interferons has been implicated in rare inborn errors of immunity (referred to as type I interferonopathies) and more common neurodegenerative disorders (eg, Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis).

Autoinflammation in patients with leukocytic CBL loss of heterozygosity is caused by constitutive ERK-mediated monocyte activation.

Patients heterozygous for germline CBL loss-of-function (LOF) variants can develop myeloid malignancy, autoinflammation, or both, if some or all of their leukocytes become homozygous for these variants through somatic loss of heterozygosity (LOH) via uniparental isodisomy. We observed an upregulation of the inflammatory gene expression signature in whole blood from these patients, mimicking monogenic inborn errors underlying autoinflammation. Remarkably, these patients had constitutively activated monocytes that secreted 10 to 100 times more inflammatory cytokines than those of healthy individuals and CBL LOF heterozygotes without LOH.

Human life within a narrow range: The lethal ups and downs of type I interferons.

The past 20 years have seen the definition of human monogenic disorders and their autoimmune phenocopies underlying either defective or enhanced type I interferon (IFN) activity. These disorders delineate the impact of type I IFNs in natural conditions and demonstrate that only a narrow window of type I IFN activity is beneficial. Insufficient type I IFN predisposes humans to life-threatening viral diseases (albeit unexpectedly few) with a central role in immunity to respiratory and cerebral viral infection.

The brain microvasculature is a primary mediator of interferon-α neurotoxicity in human cerebral interferonopathies.

Aicardi-Goutières syndrome (AGS) is an autoinflammatory disease characterized by aberrant interferon (IFN)-α production. The major cause of morbidity in AGS is brain disease, yet the primary source and target of neurotoxic IFN-α remain unclear. Here, we demonstrated that the brain was the primary source of neurotoxic IFN-α in AGS and confirmed the neurotoxicity of intracerebral IFN-α using astrocyte-driven Ifna1 misexpression in mice.

Phenotypes associated with genetic determinants of type I interferon regulation in the UK Biobank: a protocol.

Background: Type I interferons are cytokines involved in innate immunity against viruses. Genetic disorders of type I interferon regulation are associated with a range of autoimmune and cerebrovascular phenotypes. Carriers of pathogenic variants involved in genetic disorders of type I interferons are generally considered asymptomatic.

Mutations in the non-catalytic polyproline motif destabilize TREX1 and amplify cGAS-STING signaling.

The cGAS-STING pathway detects cytosolic DNA and activates a signaling cascade that results in a type I interferon (IFN) response. The endoplasmic reticulum (ER)-associated exonuclease TREX1 suppresses cGAS-STING by eliminating DNA from the cytosol. Mutations that compromise TREX1 function are linked to autoinflammatory disorders, including systemic lupus erythematosus (SLE) and Aicardi-Goutières syndrome (AGS).

Biallelic NAA60 variants with impaired n-terminal acetylation capacity cause autosomal recessive primary familial brain calcifications.

Primary familial brain calcification (PFBC) is characterized by calcium deposition in the brain, causing progressive movement disorders, psychiatric symptoms, and cognitive decline. PFBC is a heterogeneous disorder currently linked to variants in six different genes, but most patients remain genetically undiagnosed. Here, we identify biallelic NAA60 variants in ten individuals from seven families with autosomal recessive PFBC.

NOTCH1-Related Leukoencephalopathy: A Novel Variant and Literature Review.

-related leukoencephalopathy is a new diagnostic entity linked to heterozygous gain-of-function variants in that neuroradiologically show some overlap with the inflammatory microangiopathy Aicardi-Goutières syndrome (AGS). To report a 16-year-old boy harbouring a novel mutation who presented neuroradiological features suggestive of enhanced type I interferon signalling. We describe five years of follow-up and review the current literature on -related leukoencephalopathy.

Mutations in the non-catalytic polyproline motif destabilize TREX1 and amplify cGAS-STING signaling.

The cGAS-STING pathway detects cytosolic DNA and activates a signaling cascade that results in a type I interferon (IFN) response. The endoplasmic reticulum (ER)-associated exonuclease TREX1 suppresses cGAS-STING by eliminating DNA from the cytosol. Mutations that compromise TREX1 function are linked to autoinflammatory disorders, including systemic lupus erythematosus (SLE) and Aicardi-Goutières syndrome (AGS).

ARF1 prevents aberrant type I interferon induction by regulating STING activation and recycling.

Type I interferon (IFN) signalling is tightly controlled. Upon recognition of DNA by cyclic GMP-AMP synthase (cGAS), stimulator of interferon genes (STING) translocates along the endoplasmic reticulum (ER)-Golgi axis to induce IFN signalling. Termination is achieved through autophagic degradation or recycling of STING by retrograde Golgi-to-ER transport.

Case report: Clinical and neuroradiological longitudinal follow-up in Leukoencephalopathy with Calcifications and Cysts during treatment with bevacizumab.

Leukoencephalopathy with Calcifications and Cysts (LCC) is a rare genetic microangiopathy exclusively affecting the central nervous system caused by biallelic mutations in . Brain magnetic resonance imaging (MRI) is often diagnostic due to the highly characteristic triad of leukoencephalopathy, intracranial calcifications, and brain cysts. Age at onset, presentation and disease evolution can all vary, ranging from pauci-symptomatic disease to rapid evolution of signs with loss of motor and cognitive abilities.