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Introduction: X-linked adrenoleukodystrophy (X-ALD) is the most common inherited peroxisomal disorder caused by variants in the ABCD1 gene. Themain phenotypes observed in men with X-ALD are primary adrenal insufficiency, adrenomyeloneuropathy, and cerebral ALD (cALD). Cerebral ALD consists of a demyelinating progressive cerebral white matter (WM) disease associated with rapid clinical decline and is fatal if left untreated. Hematopoietic stem cell transplantation is the standard treatment for cALD as it stabilizes WM degeneration when performed early in the disease. For this reason, early diagnosis is crucial, and several countries have already implemented their newborn screening programs (NBS) with the assessment of C26:0-lysophosphatidylcholine (C26:0-LPC) values as screening for X-ALD. Methods: In June 2021, an Italian group in Lombardy launched a pilot study for the implementation of X-ALD in the Italian NBS program. A three-tiered approach was adopted, and it involved quantifying the values of C26:0-LPC and other metabolites in dried blood spots with FIA-MS/MS first, followed by the more specific ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) technique and, finally, the genetic confirmation via focused NGS. Discussion: Genetically confirmed patients are set to undergo a follow-up protocol and are periodically evaluated to promptly start a specific treatment if and when the first signs of brain damage appear, as suggested by international guidelines. A specific disease monitoring protocol has been created based on literature data and personal direct experience. Conclusion: The primary aim of this study was to develop a model able to improve the early diagnosis and subsequent follow-up and timely treatment of X-ALD. Ethics: The study was approved by the local ethics committee. The research was conducted in the absence of any commercial or financial relationship that could be construed as a potential conflict of interest. [ABSTRACT FROM AUTHOR]

The paradigm type I interferonopathy Aicardi-Goutières syndrome (AGS) is most typically characterized by severe neurological involvement. AGS is considered an immune-mediated disease, poorly responsive to conventional immunosuppression. Premised on a chronic enhancement of type I interferon signaling, JAK1/2 inhibition has been trialed in AGS, with clear improvements in cutaneous and systemic disease manifestations. Contrastingly, treatment efficacy at the level of the neurological system has been less conclusive. Here, we report our real-word approach study of JAK1/2 inhibition in 11 patients with AGS, providing extensive assessments of clinical and radiological status; interferon signaling, including in cerebrospinal fluid (CSF); and drug concentrations in blood and CSF. Over a median follow-up of 17 months, we observed a clear benefit of JAK1/2 inhibition on certain systemic features of AGS, and reproduced results reported using the AGS neurologic severity scale. In contrast, there was no change in other scales assessing neurological status; using the caregiver scale, only patient comfort, but no other domain of everyday-life care, was improved. Serious bacterial infections occurred in 4 out of the 11 patients. Overall, our data lead us to conclude that other approaches to treatment are urgently required for the neurologic features of AGS. We suggest that earlier diagnosis and adequate central nervous system penetration likely remain the major factors determining the efficacy of therapy in preventing irreversible brain damage, implying the importance of early and rapid genetic testing and the consideration of intrathecal drug delivery. [ABSTRACT FROM AUTHOR]

Abstract Background Aicardi–Goutières syndrome (AGS) is a severe neurodegenerative disease with clinical features of early-onset encephalopathy and progressive loss of intellectual abilities and motor control. Gene mutations in seven protein-coding genes have been found to be associated with AGS. However, the causative role of these mutations in the early-onset neuropathogenesis has not been demonstrated in animal models, and the mechanism of neurodegeneration of AGS remains ambiguous. Methods Via CRISPR/Cas-9 technology, we established a mutant mouse model in which a genetic mutation found in AGS patients at the ADAR1 coding gene (Adar) loci was introduced into the mouse genome. A mouse model carrying double gene mutations encoding ADAR1 and MDA-5 was prepared using a breeding strategy. Phenotype, gene expression, RNA sequencing, innate immune pathway activation, and pathologic studies including RNA in situ hybridization (ISH) and immunohistochemistry were used for characterization of the mouse models to determine potential disease mechanisms. Results We established a mouse model bearing a mutation in the catalytic domain of ADAR1, the D1113H mutation found in AGS patients. With this mouse model, we demonstrated a causative role of this mutation for the early-onset brain injuries in AGS and determined the signaling pathway underlying the neuropathogenesis. First, this mutation altered the RNA editing profile in neural transcripts and led to robust IFN-stimulated gene (ISG) expression in the brain. By ISH, the brains of mutant mice showed an unusual, multifocal increased expression of ISGs that was cell-type dependent. Early-onset astrocytosis and microgliosis and later stage calcification in the deep white matter areas were observed in the mutant mice. Brain ISG activation and neuroglial reaction were completely prevented in the Adar D1113H mutant mice by blocking RNA sensing through deletion of the cytosolic RNA receptor MDA-5. Conclusions The Adar D1113H mutation in the ADAR1 catalytic domain results in early-onset and MDA5-dependent encephalopathy with IFN pathway activation in the mouse brain.

SAMHD1 (Sterile alpha motif and histidine/aspartic acid domain‐containing protein 1) is a dNTP triphosphohydrolase crucial in the maintenance of balanced cellular dNTP pools, which support genome integrity. In SAMHD1 deficient fibroblasts isolated from Aicardi‐Goutières Syndrome (AGS) patients, all four DNA precursors are increased and markedly imbalanced with the largest effect on dGTP, a key player in the modulation of telomerase processivity. Here, we present data showing that SAMHD1, by restricting the dGTP pool, contributes to telomere maintenance in hTERT‐immortalized human fibroblasts from AGS patients as well as in telomerase positive cancer cell lines. Only in cells expressing telomerase, the lack of SAMHD1 causes excessive lengthening of telomeres and telomere fragility, whereas primary fibroblasts lacking both SAMHD1 and telomerase enter normally into senescence. Telomere lengthening observed in SAMHD1 deficient but telomerase proficient cells is a gradual process, in accordance with the intrinsic property of telomerase of adding only a few tens of nucleotides for each cycle. Therefore, only a prolonged exposure to high dGTP content causes telomere over‐elongation. hTERT‐immortalized AGS fibroblasts display also high fragility of chromosome ends, a marker of telomere replication stress. These results not only demonstrate the functional importance of dGTP cellular level but also reveal the critical role played by SAMHD1 in restraining telomerase processivity and safeguarding telomere stability. [ABSTRACT FROM AUTHOR]

Introduction: Aicardi-Goutières Syndrome (AGS) is a rare encephalopathy with early onset that can be transmitted in both dominant and recessive forms. Its phenotypic covers a wide range of neurological and extraneurological symptoms. Nine genes that are all involved in nucleic acids (NAs) metabolism or signaling have so far been linked to the AGS phenotype. Recently, a link between autoimmune or neurodegenerative conditions and mitochondrial dysfunctions has been found. As part of the intricate system of epigenetic control, the mtDNA goes through various alterations. The displacement (Dloop) region represents one of the most methylated sites in the mtDNA. The term "mitoepigenetics" has been introduced as a result of increasing data suggesting that epigenetic processes may play a critical role in the control of mtDNA transcription and replication. Since we showed that RNASEH2B and RNASEH2A-mutated Lymphoblastoid Cell Lines (LCLs) derived from AGS patients had mitochondrial alterations, highlighting changes in the mtDNA content, the main objective of this study was to examine any potential methylation changes in the D-loop regulatory region of mitochondria and their relationship to the mtDNA copy number in peripheral blood cells of AGS patients with mutations in various AGS genes and healthy controls. Materials and methods: We collected blood samples from 25 AGS patients and we performed RT-qPCR to assess the mtDNA copy number and pyrosequencing to measure DNA methylation levels in the D-loop region. Results: Comparing AGS patients to healthy controls, D-loop methylation levels and mtDNA copy number increased significantly. We also observed that in AGS patients, the mtDNA copy number increased with age at sampling, but not the loop methylation levels, and there was no relationship between sex and mtDNA copy number. In addition, the D-loop methylation levels and mtDNA copy number in the AGS group showed a non-statistically significant positive relation. Conclusion: These findings, which contradict the evidence for an inverse relationship between D-loop methylation levels and mtDNA copy number, show that AGS patients have higher D-loop methylation levels than healthy control subjects. Additional research is needed to identify the function of these features in the etiology and course of AGS. [ABSTRACT FROM AUTHOR]

IntroductionAicardi-Goutières Syndrome (AGS) is a rare encephalopathy with early onset that can be transmitted in both dominant and recessive forms. Its phenotypic covers a wide range of neurological and extraneurological symptoms. Nine genes that are all involved in nucleic acids (NAs) metabolism or signaling have so far been linked to the AGS phenotype. Recently, a link between autoimmune or neurodegenerative conditions and mitochondrial dysfunctions has been found. As part of the intricate system of epigenetic control, the mtDNA goes through various alterations. The displacement (D-loop) region represents one of the most methylated sites in the mtDNA. The term "mitoepigenetics" has been introduced as a result of increasing data suggesting that epigenetic processes may play a critical role in the control of mtDNA transcription and replication. Since we showed that RNASEH2B and RNASEH2A-mutated Lymphoblastoid Cell Lines (LCLs) derived from AGS patients had mitochondrial alterations, highlighting changes in the mtDNA content, the main objective of this study was to examine any potential methylation changes in the D-loop regulatory region of mitochondria and their relationship to the mtDNA copy number in peripheral blood cells of AGS patients with mutations in various AGS genes and healthy controls.Materials and methodsWe collected blood samples from 25 AGS patients and we performed RT-qPCR to assess the mtDNA copy number and pyrosequencing to measure DNA methylation levels in the D-loop region.ResultsComparing AGS patients to healthy controls, D-loop methylation levels and mtDNA copy number increased significantly. We also observed that in AGS patients, the mtDNA copy number increased with age at sampling, but not the D-loop methylation levels, and there was no relationship between sex and mtDNA copy number. In addition, the D-loop methylation levels and mtDNA copy number in the AGS group showed a non-statistically significant positive relation.ConclusionThese findings, which contradict the evidence for an inverse relationship between D-loop methylation levels and mtDNA copy number, show that AGS patients have higher D-loop methylation levels than healthy control subjects. Additional research is needed to identify the function of these features in the etiology and course of AGS.

IntroductionX-linked adrenoleukodystrophy (X-ALD) is the most common inherited peroxisomal disorder caused by variants in the ABCD1 gene. The main phenotypes observed in men with X-ALD are primary adrenal insufficiency, adrenomyeloneuropathy, and cerebral ALD (cALD). Cerebral ALD consists of a demyelinating progressive cerebral white matter (WM) disease associated with rapid clinical decline and is fatal if left untreated. Hematopoietic stem cell transplantation is the standard treatment for cALD as it stabilizes WM degeneration when performed early in the disease. For this reason, early diagnosis is crucial, and several countries have already implemented their newborn screening programs (NBS) with the assessment of C26:0-lysophosphatidylcholine (C26:0-LPC) values as screening for X-ALD.MethodsIn June 2021, an Italian group in Lombardy launched a pilot study for the implementation of X-ALD in the Italian NBS program. A three-tiered approach was adopted, and it involved quantifying the values of C26:0-LPC and other metabolites in dried blood spots with FIA-MS/MS first, followed by the more specific ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) technique and, finally, the genetic confirmation via focused NGS.DiscussionGenetically confirmed patients are set to undergo a follow-up protocol and are periodically evaluated to promptly start a specific treatment if and when the first signs of brain damage appear, as suggested by international guidelines. A specific disease monitoring protocol has been created based on literature data and personal direct experience.ConclusionThe primary aim of this study was to develop a model able to improve the early diagnosis and subsequent follow-up and timely treatment of X-ALD.EthicsThe study was approved by the local ethics committee. The research was conducted in the absence of any commercial or financial relationship that could be construed as a potential conflict of interest.

Aicardi–Goutières syndrome (AGS) is a genetically determined early-onset progressive encephalopathy caused by mutations leading to overexpression of type I interferon (IFN) and resulting in various clinical phenotypes. A gain-of-function (GOF) mutation in the IFIH1 gene is associated with robust production of type I IFN and activation of the Janus kinase (JAK) signal transducer and activator of the transcription (STAT) pathway, which can cause AGS type 7. We detail the clinical case of an infant who initially presented with Pneumocystis jirovecii pneumonia (PCP), had recurrent respiratory infections, and was later treated with a JAK inhibitor, baricitinib, because of a genetically confirmed GOF mutation in the IFIH1 gene. This spectrum of IFIH1 GOF mutations with overlapping features of hyperinflammation and severe opportunistic infection, which mimics combined immunodeficiency (CID), has not been described before. In this case, therapy with baricitinib effectively blocked IFN-α activation and reduced STAT1 signaling but had no effect on the progression of the neurological disease.

Aicardi–Goutières syndrome (AGS) is a rare genetic disorder characterised by progressive encephalopathy, involving microcephaly, intracranial calcification, and cerebrospinal fluid lymphocytosis with increased interferon-α concentrations. The clinical features of AGS overlap with fetal cerebral anomalies caused by congenital infections, such as TORCH (toxoplasmosis, other, rubella, cytomegalovirus, and herpes), or with those of other genetic disorders showing neonatal microcephaly, including Cockayne syndrome (CS) with transcription-coupled DNA repair deficiency, and Seckel syndrome (SS) showing aberrant cell-cycle checkpoint signaling. Therefore, a differential diagnosis to confirm the genetic cause or a proof of infection should be considered. In this report, we describe an individual who showed primordial dwarfism and encephalopathy, and whose initial diagnosis was CS. First, we conducted conventional DNA repair proficiency tests for the patient derived fibroblast cells. Transcription-coupled nucleotide excision repair (TC-NER) activity, which is mostly compromised in CS cases, was slightly reduced in the patient's cells. However, unscheduled DNA synthesis (UDS) was significantly diminished. These cellular traits were inconsistent with the diagnosis of CS. We further performed whole exome sequencing for the case and identified a compound heterozygous loss-of-function variants in the SAMHD1 gene, mutations in which are known to cause AGS. As SAMHD1 encodes deoxyribonucleoside triphosphate triphosphohydrolase, we reasoned that the deoxyribonucleoside triphosphate (dNTP) pool size in the patient's cells was elevated, and the labeling efficiency of UDS-test was hindered due to the reduced concentration of phosphorylated ethynyl deoxyuridine (EdU), a nucleoside analogue used for the assay. In conclusion, UDS assay may be a useful diagnostic tool to distinguish between AGS with SAMHD1 mutations and other related diseases.

Adar null mutant mouse embryos die with aberrant double-stranded RNA (dsRNA)-driven interferon induction, and Adar Mavs double mutants, in which interferon induction is prevented, die soon after birth. Protein kinase R (Pkr) is aberrantly activated in Adar Mavs mouse pup intestines before death, intestinal crypt cells die, and intestinal villi are lost. Adar Mavs Eifak2 (Pkr) triple mutant mice rescue all defects and have long-term survival. Adenosine deaminase acting on RNA 1 (ADAR1) and PKR co-immunoprecipitate from cells, suggesting PKR inhibition by direct interaction. AlphaFold studies on an inhibitory PKR dsRNA binding domain (dsRBD)-kinase domain interaction before dsRNA binding and on an inhibitory ADAR1 dsRBD3-PKR kinase domain interaction on dsRNA provide a testable model of the inhibition. Wild-type or editing-inactive human ADAR1 expressed in A549 cells inhibits activation of endogenous PKR. ADAR1 dsRNA binding is required for, but is not sufficient for, PKR inhibition. Mutating the ADAR1 dsRBD3-PKR contact prevents co-immunoprecipitation, ADAR1 inhibition of PKR activity, and co-localization of ADAR1 and PKR in cells. [Display omitted] • Adar Mavs mice die prematurely with intestinal defects; Adar Mavs Eif2ak2 (Pkr) mice survive • ADAR1 inhibits PKR activation, and an AlphaFold interaction model was validated by mutagenesis • ADAR1 inhibition of PKR requires binding to dsRNA and a direct ADAR1 dsRBD3-PKR interaction Sinigaglia et al. demonstrate that Pkr is aberrantly activated in Adar mutant mice. ADAR1 protein inhibition of PKR activation requires a predicted direct protein interaction between ADAR1 and the PKR kinase domain. Inhibition also requires ADAR1 dsRNA binding; the mechanism reveals a new level of antiviral innate immune sensor regulation. [ABSTRACT FROM AUTHOR]

This document is a corrigendum for an article titled "Newborn screening for X-linked adrenoleukodystrophy in Italy: diagnostic algorithm and disease monitoring." The corrigendum acknowledges an error in the original article, specifically in the list of authors in the XALD-NBS study group. The corrected list of authors is provided in the corrigendum. The document emphasizes that this error does not affect the scientific conclusions of the article. [Extracted from the article]

Introduction: X-linked adrenoleukodystrophy (X-ALD) is the most common inherited peroxisomal disorder caused by variants in the ABCD1 gene. The main phenotypes observed in men with X-ALD are primary adrenal insufficiency, adrenomyeloneuropathy, and cerebral ALD (cALD). Cerebral ALD consists of a demyelinating progressive cerebral white matter (WM) disease associated with rapid clinical decline and is fatal if left untreated. Hematopoietic stem cell transplantation is the standard treatment for cALD as it stabilizes WM degeneration when performed early in the disease. For this reason, early diagnosis is crucial, and several countries have already implemented their newborn screening programs (NBS) with the assessment of C26:0-lysophosphatidylcholine (C26:0-LPC) values as screening for X-ALD., Methods: In June 2021, an Italian group in Lombardy launched a pilot study for the implementation of X-ALD in the Italian NBS program. A three-tiered approach was adopted, and it involved quantifying the values of C26:0-LPC and other metabolites in dried blood spots with FIA-MS/MS first, followed by the more specific ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) technique and, finally, the genetic confirmation via focused NGS., Discussion: Genetically confirmed patients are set to undergo a follow-up protocol and are periodically evaluated to promptly start a specific treatment if and when the first signs of brain damage appear, as suggested by international guidelines. A specific disease monitoring protocol has been created based on literature data and personal direct experience., Conclusion: The primary aim of this study was to develop a model able to improve the early diagnosis and subsequent follow-up and timely treatment of X-ALD., Ethics: The study was approved by the local ethics committee. The research was conducted in the absence of any commercial or financial relationship that could be construed as a potential conflict of interest., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Bonaventura, Alberti, Lucchi, Cappelletti, Fazzone, Cattaneo, Bellini, Izzo, Parazzini, Bosetti, Di Profio, Fiore, Ferrario, Mameli, Sangiorgio, Masnada, Zuccotti, Veggiotti, Spaccini, Iascone, Verduci, Cereda, Tonduti and XALD-NBS Study Group.)

Aicardi-Goutières syndrome (AGS) is a genetically determined early-onset progressive encephalopathy caused by mutations leading to overexpression of type I interferon (IFN) and resulting in various clinical phenotypes. A gain-of-function (GOF) mutation in the IFIH1 gene is associated with robust production of type I IFN and activation of the Janus kinase (JAK) signal transducer and activator of the transcription (STAT) pathway, which can cause AGS type 7. We detail the clinical case of an infant who initially presented with Pneumocystis jirovecii pneumonia (PCP), had recurrent respiratory infections, and was later treated with a JAK inhibitor, baricitinib, because of a genetically confirmed GOF mutation in the IFIH1 gene. This spectrum of IFIH1 GOF mutations with overlapping features of hyperinflammation and severe opportunistic infection, which mimics combined immunodeficiency (CID), has not been described before. In this case, therapy with baricitinib effectively blocked IFN-α activation and reduced STAT1 signaling but had no effect on the progression of the neurological disease., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Železnik, Soltirovska Šalamon, Debeljak, Goropevšek, Šuštar, Ključevšek, Ihan and Avčin.)

Aicardi-Goutières syndrome (AGS) is a rare genetic disorder characterised by progressive encephalopathy, involving microcephaly, intracranial calcification, and cerebrospinal fluid lymphocytosis with increased interferon-α concentrations. The clinical features of AGS overlap with fetal cerebral anomalies caused by congenital infections, such as TORCH (toxoplasmosis, other, rubella, cytomegalovirus, and herpes), or with those of other genetic disorders showing neonatal microcephaly, including Cockayne syndrome (CS) with transcription-coupled DNA repair deficiency, and Seckel syndrome (SS) showing aberrant cell-cycle checkpoint signaling. Therefore, a differential diagnosis to confirm the genetic cause or a proof of infection should be considered. In this report, we describe an individual who showed primordial dwarfism and encephalopathy, and whose initial diagnosis was CS. First, we conducted conventional DNA repair proficiency tests for the patient derived fibroblast cells. Transcription-coupled nucleotide excision repair (TC-NER) activity, which is mostly compromised in CS cases, was slightly reduced in the patient's cells. However, unscheduled DNA synthesis (UDS) was significantly diminished. These cellular traits were inconsistent with the diagnosis of CS. We further performed whole exome sequencing for the case and identified a compound heterozygous loss-of-function variants in the SAMHD1 gene, mutations in which are known to cause AGS. As SAMHD1 encodes deoxyribonucleoside triphosphate triphosphohydrolase, we reasoned that the deoxyribonucleoside triphosphate (dNTP) pool size in the patient's cells was elevated, and the labeling efficiency of UDS-test was hindered due to the reduced concentration of phosphorylated ethynyl deoxyuridine (EdU), a nucleoside analogue used for the assay. In conclusion, UDS assay may be a useful diagnostic tool to distinguish between AGS with SAMHD1 mutations and other related diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2022 Senju, Nakazawa, Shimada, Iwata, Matsuse, Tanaka, Miyazaki, Moriwaki, Mitsutake and Ogi.)