An overview of genetic mutations in Aicardi-Goutières syndrome in Iranian population.

Aicardi-Goutières syndrome (AGS) is a rare neurodevelopmental disorder that can be misdiagnosed with infectious disorders. Molecular genetics tools and subsequent counseling have an important role in the estimation of recurrence risk and prevention of additional cases in the family. The current study provides an overview of genetic mutations in AGS in Iranian population. In a time period of 3 years, we assessed nine AGS cases and identified the underlying mutations using whole exome sequencing. Mutations were located in TREX1, IFIH1, RNASEH2B, RNASEH2A and SAMHD1 genes and inherited in either autosomal dominant or autosomal recessive manner. Since both modes of inheritance have been previously reported for AGS, appropriate genetic counseling is needed for estimation of recurrence risk in families.

Altered DNA methylation and gene expression predict disease severity in patients with Aicardi-Goutières syndrome.

Aicardi-Goutières Syndrome (AGS) is a rare neuro-inflammatory disease characterized by increased expression of interferon-stimulated genes (ISGs). Disease-causing mutations are present in genes associated with innate antiviral responses. Disease presentation and severity vary, even between patients with identical mutations from the same family. This study investigated DNA methylation signatures in PBMCs to understand phenotypic heterogeneity in AGS patients with mutations in RNASEH2B. AGS patients presented hypomethylation of ISGs and differential methylation patterns (DMPs) in genes involved in "neutrophil and platelet activation". Patients with "mild" phenotypes exhibited DMPs in genes involved in "DNA damage and repair", whereas patients with "severe" phenotypes had DMPs in "cell fate commitment" and "organ development" associated genes. DMPs in two ISGs (IFI44L, RSAD2) associated with increased gene expression in patients with "severe" when compared to "mild" phenotypes. In conclusion, altered DNA methylation and ISG expression as biomarkers and potential future treatment targets in AGS.

Collapsing Glomerulopathy as a Complication of Type I Interferon-Mediated Glomerulopathy in a Patient With RNASEH2B-Related Aicardi-Goutières Syndrome.

Aicardi-Goutières syndrome (AGS) is a well-characterized monogenic type I interferonopathy presenting with prominent neurologic manifestations. Among extraneurologic features, renal involvement has been described in only 1 patient with an IFIH1 mutation in whom membranous nephropathy developed. The pathogenic role of augmented interferon (IFN) signaling in tissues other than the central nervous system remains to be elucidated. We report a case of collapsing glomerulopathy in a 15-year-old girl affected by AGS with RNASEH2B mutation (an alanine-to-threonine change at amino acid 177), which led to kidney failure. The patient had no lupus-like features and lacked the APOL1 G1 and G2 risk alleles. Kidney biopsy showed findings consistent with collapsing glomerulopathy. MxA, a protein involved in antiviral immunity and induced by type I IFNs, was selectively expressed in CD133-positive parietal epithelial cells (PECs) but not in podocytes that stained for synaptopodin or in other glomerular cells. MxA also colocalized within pseudocrescents with CD44, a marker of PEC activation involved in cellular proliferation, differentiation, and migration and in glomerular scarring. Our findings suggest that collapsing glomerulopathy can be a complication of the type I interferonopathy AGS and that a constitutively enhanced type I IFN response in CD133-positive PECs can drive collapsing glomerulopathy.

Aicardi-Goutières syndrome: unusual neuro-radiological manifestations.

Aicardi-Goutières syndrome (AGS) is one of the expanding group of inherited congenital infection like syndromes. Here, we describe the detailed clinical and imaging findings of two sibs with AGS. Each shows scattered periventricular intracranial calcifications, severe global delay, seizures, microcephaly and spasticity. Interestingly, chilblains were observed in the two sisters as well as their parents and a paternal uncle. The brain MRI of the older sister showed marked ventricular dilatation as a result of unusual associated porencephalic cysts. Unexpectedly, unilateral cerebellar hypoplasia was also noted. In comparison, her younger sister displayed the classic atrophic changes and white matter loss of AGS. The diagnosis of AGS was confirmed by sequence analysis, which identified a previously reported homozygous RNASEH2B mutation, c.554 T > G (p.V185G). Parents were heterozygous for the same mutation. Further molecular analysis excluded mutations in potentially related manifestations of COL4A1 gene. This is the first report of chilblains associated with heterozygous RNASEH2B mutation. Further, the brain imaging findings appear particularly interesting, which until now has not been reported in any AGS patient. We discuss the possible reasons for this unusual presentation.

Molecular characterization of an intronic RNASEH2B variant in a patient with Aicardi-Goutières syndrome.

Aicardi-Goutières syndrome (AGS) is a progressive multisystem disorder including encephalopathy with significant impacts on intellectual and physical abilities. An early diagnosis is becoming ever more crucial, as targeted therapies are emerging. A deep understanding of the molecular heterogeneity of AGS can help guide the early diagnosis and clinical management of patients, and inform recurrence risks. Here, we detail the diagnostic odyssey of a patient with an early presentation of AGS. Exome and genome sequencing detected an intronic RNASEH2B variant missed in a conventional leukodystrophy NGS gene panel. RNA studies demonstrated that a c.322-17 A > G variant affected splicing and caused 16-nucleotide intronic retention in the RNASEH2B transcript, introducing an out-of-frame early termination codon. RNASEH2B expression in the patient's blood was reduced when compared to controls. Our study highlights the pathogenicity of this intronic variant and the importance of its inclusion in variant assessment.

Case Report: Novel Compound Heterozygous RNASEH2B Mutations Cause Aicardi-Goutières Syndrome.

Aicardi-Goutières Syndrome (AGS) is a rare disorder characterized by neurological and immunological signs. In this study we have described a child with a phenotype consistent with AGS carrying a novel compound heterozygous mutation in RNASEH2B gene. Next Generation Sequencing revealed two heterozygous variants in RNASEH2B gene. We also highlighted a reduction of RNase H2B transcript and protein levels in all the family members. Lower protein levels of RNase H2A have been observed in all the members of the family as well, whereas a deep depletion of RNase H2C has only been identified in the affected child. The structural analysis showed that both mutations remove many intramolecular contacts, possibly introducing conformational rearrangements with a decrease of the stability of RNase H2B and strongly destabilizing the RNase H2 complex. Taken together, these results highlight the importance of an integrated diagnostic approach which takes into consideration clinical, genetic, and molecular analyses.

Systemic inflammation and chronic kidney disease in a patient due to the RNASEH2B defect.

INTRODUCTION: Aicardi-Goutières (AGS) is a rare immune dysregulated disease due to mutations in TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR1, or IFIH1. Clinical features include basal ganglia calcifications, white matter abnormalities, and cerebral atrophy. Severe systemic inflammation and chronic kidney disease (CKD) are extremely rare in AGS. Herein, we report a patient presenting with systemic inflammation and CKD to broaden the clinical phenotype spectrum of the RNASEH2B defect. METHODS: All testing and molecular genetic analysis were performed after obtaining the informed consent of the parents. Demographic, clinical, and laboratory findings were abstracted from outpatient and inpatient encounters. Cerebral magnetic resonance imaging (MRI), computed tomography (CT) scans, and renal biopsy histopathology reports were reviewed and summarized. Whole exome sequencing (WES) was performed on peripheral blood cells. After exposure to cGAMP in vitro for 24 h, mRNA expression of 12 IFN-stimulated cytokine genes in PBMCs was assessed. Serum cytokine levels were detected by Milliplex. RESULTS: A 11-year-old girl presented with recurrent aseptic fever, arthritis, chilblains, failure to thrive, mild hearing loss, and neurological manifestations. Laboratory and immunologic findings demonstrated lymphopenia, low complement levels, positive autoantibodies, elevated levels of acute-phase reactants and inflammatory cytokines. Cerebral imaging showed cerebral atrophy, white matter abnormalities, and intracranial calcification. Renal biopsy showed glomerular sclerosis in 3 of 14 glomeruli, infiltration of lymphocytes and other mononuclear cells. WES revealed a homozygous and heterozygous mutations in RNASEH2B. Over-expression of IFN-stimulated cytokine genes was observed, including IFI44, IFI27, IFIT1, IFIT2, IFIT3, ISG15, OAS1, and SIGLEC1. CONCLUSIONS: To date, only two cases with AGS have been reported to have renal disease. Here, we describe a patient with both homozygous and heterozygous variants in RNASEH2B, presenting with neurological manifestations, persistently systemic autoinflammation, and CKD. CKD has never been reported in patients with AGS due to the RNASEH2B defect. TRIAL REGISTRATION: Not applicable; this was a retrospective study.

Late-Onset Aicardi-Goutières Syndrome: A Characterization of Presenting Clinical Features.

BACKGROUND: Aicardi-Goutières syndrome (AGS) is a genetic interferonopathy characterized by early onset of severe neurological injury with intracranial calcifications, leukoencephalopathy, and systemic inflammation. Increasingly, a spectrum of neurological dysfunction and presentation beyond the infantile period is being recognized in AGS. The aim of this study was to characterize late-infantile and juvenile-onset AGS. METHODS: We conducted a multi-institution review of individuals with AGS who were older than one year at the time of presentation, including medical history, imaging characteristics, and suspected diagnoses at presentation. RESULTS: Thirty-four individuals were identified, all with pathogenic variants in RNASEH2B, SAMHD1, ADAR1, or IFIH1. Most individuals had a history of developmental delay and/or systemic symptoms, such as sterile pyrexias and chilblains, followed by a prodromal period associated with increasing symptoms. This was followed by an abrupt onset of neurological decline (fulminant phase), with a median onset at 1.33 years (range 1.00 to 17.68 years). Most individuals presented with a change in gross motor skills (97.0%), typically with increased tone (78.8%). Leukodystrophy was the most common magnetic resonance imaging finding (40.0%). Calcifications were less common (12.9%). CONCLUSIONS: This is the first study to characterize the presentation of late-infantile and juvenile onset AGS and its phenotypic spectrum. Late-onset AGS can present insidiously and lacks classical clinical and neuroimaging findings. Signs of early systemic dysfunction before fulminant disease onset and loss of motor symptoms were common. We strongly recommend genetic testing when there is concern for sustained inflammation of unknown origins or changes in motor skills in children older than one year.

Síndrome de Aicardi-Goutieres: Diagnóstico genético en una lactante

El Síndrome de Aicardi-Goutieres (SAG) se caracteriza por una encefalopatía genética, progresiva, de inicio temprano, que se asocia a un proceso inflamatorio. Además del SNC, puede afectar a la piel, con erupciones tipo sabañones, y presentar microcefalia, talla baja, disfunción hepática, disfunción tiroidea, reactantes de fase aguda elevados, anticuerpos autoinmunes positivos y asociaciones para enfermedades sistémicas autoinmunes como él LES. El SAG presenta locus heterogénicos, con mutaciones identificadas en los genes que codifican el exonucleasa TREX1 3´â†’5´ y las tres subunidades del complejo de endonucleasa RNASEH2. Se presenta el caso de una paciente de 2 años de edad, con retraso del desarrollo psicomotor, sin otras manifestaciones sistémicas, diagnosticada como SAG, con variante c.529G(A (p.Ala177Thr) con efecto patogénico en homocigosis en el gen RNASEH2B.

Aicardi-Goutieres Syndrome (AGS) is characterized by an early-onset, progressive, genetic encephalopathy associated with an inflammatory process. In addition to the CNS, it can affect the skin, with chilblain-like eruptions, and present with microcephaly, short stature, liver dysfunction, thyroid dysfunction, elevated acute phase reactants, positive autoimmune antibodies, and associations for autoimmune systemic diseases such as SLE. SAG presents heterogeneous loci, with mutations identified in the genes encoding the TREX1 3'→5' exonuclease and the three subunits of the RNASEH2 endonuclease complex. We present the case of a female 2-year-old patient, with delayed psychomotor development, without other systemic manifestations, diagnosed as SAG, with variant c.529G>A (p.Ala177Thr) with a pathogenic effect in homozygosis in the RNASEH2B gene.