Impact of genetic and non-genetic factors on phenotypic diversity in NBAS-associated disease.

Biallelic pathogenic variants in neuroblastoma-amplified sequence (NBAS) cause a pleiotropic multisystem disorder. Three clinical subgroups have been defined correlating with the localisation of pathogenic variants in the NBAS gene: variants affecting the C-terminal region of NBAS result in SOPH syndrome (short stature, optic atrophy, Pelger-Huët anomaly), variants affecting the Sec 39 domain are associated with infantile liver failure syndrome type 2 (ILFS2) and variants affecting the ß-propeller domain give rise to a combined phenotype. However, there is still unexplained phenotypic diversity across the three subgroups, challenging the current concept of genotype-phenotype correlations in NBAS-associated disease. Therefore, besides examining the genetic influence, we aim to elucidate the potential impact of pre-symptomatic diagnosis, emergency management and other modifying variables on the clinical phenotype. We investigated genotype-phenotype correlations in individuals sharing the same genotypes (n = 30 individuals), and in those sharing the same missense variants with a loss-of-function variant in trans (n = 38 individuals). Effects of a pre-symptomatic diagnosis and emergency management on the severity of acute liver failure (ALF) episodes also were analysed, comparing liver function tests (ALAT, ASAT, INR) and mortality. A strong genotype-phenotype correlation was demonstrated in individuals sharing the same genotype; this was especially true for the ILFS2 subgroup. Genotype-phenotype correlation in patients sharing only one missense variant was still high, though at a lower level. Pre-symptomatic diagnosis in combination with an emergency management protocol leads to a trend of reduced severity of ALF. High genetic impact on clinical phenotype in NBAS-associated disease facilitates monitoring and management of affected patients sharing the same genotype. Pre-symptomatic diagnosis and an emergency management protocol do not prevent ALF but may reduce its clinical severity.

GAS1 Promotes Ferroptosis of Liver Cells in Acetaminophen-Induced Acute Liver Failure.

Purpose: Acute liver failure (ALF) is a clinically fatal disease that leads to the rapid loss of normal liver function. Acetaminophen (APAP) is a leading cause of drug-induced ALF. Ferroptosis, defined as iron-dependent cell death associated with lipid peroxide accumulation, has been shown to be strongly associated with APAP-induced liver injury. Growth arrest-specific 1 (GAS1) is a growth arrest-specific gene, which is closely related to the inhibition of cell growth and promotion of apoptosis. However, the functional role and underlying mechanism of GAS1 in APAP-induced ferroptosis remain unknown. Methods: We established liver-specific overexpression of GAS1 (GAS1AAV8-OE) mice and the control (GAS1AAV8-vector) mice by tail vein injection of male mice with adeno-associated virus. APAP at 500 mg/kg was intraperitoneally injected into these two groups of mice to induce acute liver failure. The shRNA packaged by the lentivirus inhibits GAS1 gene expression in human hepatoma cell line HepaRG (HepaRG-shNC and HepaRG-shGAS1-2) and primary hepatocytes of mice with liver-specific overexpression of GAS1 were isolated and induced by APAP in vitro to further investigate the regulatory role of GAS1 in APAP-induced acute liver failure. Results: APAP-induced upregulation of ferroptosis, levels of lipid peroxides and reactive oxygen species, and depletion of glutathione were effectively alleviated by the ferroptosis inhibitor, ferrostatin-1, and downregulation of GAS1 expression. GAS1 overexpression promoted ferroptosis-induced lipid peroxide accumulation via p53, inhibiting its downstream target, solute carrier family 7 member 11. Conclusion: Collectively, our findings suggest that GAS1 overexpression plays a key role in aggravating APAP-induced acute liver injury by promoting ferroptosis-induced accumulation of lipid peroxides.

The Diagnostic and Therapeutic Value of NCAPG as a Proposed Biomarker Candidate in Acute Liver Failure.

BACKGROUND: Acute Liver Failure (ALF) is a difficult problem to solve in clinical practice. The presence of non-SMC condensin I complex subunit G (NCAPG) has previously been linked to vascular invasion of digestive system tumors, foreshadowing poor prognosis. Its role in ALF biology, however, remains unknown. This article explores the role of NCAPG as a potential biomarker candidate for the accurate diagnosis and targeted treatment of ALF. METHODS: The study included transcription data (GSE14668, GSE38941, GSE62029, GSE96851, and GSE120652) of ALF, normal tissues, and clinical samples, where NCAPG was selected as the differential gene by the "DESeq2" R package to analyze the immune cell functions and signal pathways. Furthermore, RT-qPCR and Western blot analyses were used to confirm the RNA and protein levels of NCAPG in ALF cell models, respectively. RESULTS: Bioinformatics analysis revealed that NACPG was up-regulated in ALF tissues, and the functional signaling pathway was primarily associated with immune infiltration. Based on the results of clinical samples, we suggest that NCAPG was overexpressed in ALF tissues. We also found that the expression of NCAPG increased with the degree of liver injury in vitro. Enrichment analysis suggested that NCAPG influenced ALF as a PI3K/AKT pathway activator. CONCLUSION: Our study suggests that NCAPG is a preliminary tool for the diagnosis of ALF. It can affect ALF via the PI3K/AKT pathway and is a potential therapeutic target to improve prognosis.

MicroRNA-29a-3p Prevents Drug-Induced Acute Liver Failure through Inflammation-Related Pyroptosis Inhibition.

OBJECTIVE: Little is known about the role of microRNA-29a-3p (miR-29a-3p) in inflammation-related pyroptosis, especially in drug-induced acute liver failure (DIALF). This study aimed to identify the relationship between miR-29a-3p and inflammation-related pyroptosis in DIALF and confirm its underlying mechanisms. METHODS: Thioacetamide (TAA)- and acetaminophen (APAP)-induced ALF mouse models were established, and human samples were collected. The expression levels of miR-29a-3p and inflammation and pyroptosis markers were measured by quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, or immunochemical staining in miR-29a-3p knock-in transgenic mouse (MIR29A(KI/KI)) DIALF models. In addition, RNA sequencing was conducted to explore the mechanisms. RESULTS: MiR-29a-3p levels were decreased in TAA- and APAP-induced DIALF models. MiR-29a-3p prevented DIALF caused by TAA and APAP. RNA sequencing and further experiments showed that the protective effect of miR-29a-3p on DIALF was mainly achieved through inhibition of inflammation-related pyroptosis, and the inhibition was dependent on activation of the PI3K/AKT pathway. In addition, miR-29a-3p levels were reduced, and pyroptosis was activated in both peripheral blood mononuclear cells and liver tissues of DIALF patients. CONCLUSION: The study supports the idea that miR-29a-3p inhibits pyroptosis by activating the PI3K/AKT pathway to prevent DIALF. MiR-29a-3p may be a promising therapeutic target for DIALF.

[Liver transplantation for the treatment of acute liver failure in 3 cases with NBAS gene deficiency and literature review].

Objective: To investigate the clinical efficacy of liver transplantation in the treatment of acute liver in children with NBAS gene deficiency disease and their outcome. Methods: This retrospective study enrolled children with NBAS gene deficiency who were admitted to the Children's Hospital of Fudan University for liver transplantation from January 2013 to June 2022. The clinical data were collected and analyzed. Medical literature published before June 2022 was searched with the keywords of "NBAS" "neuroblastoma amplified sequence recurrent" "acute liver failure" "SOPH syndrome" "short stature with optic nerve atrophy" "Pelger-Huët anomaly" in PubMed, China National Knowledge Infrastructure and Wanfang database. Results: Liver transplantation was performed in 3 patients (2 males and 1 female) with NBAS deficiency. All patients presented with fever-triggered recurrent acute liver failure. The genetic detection found compound heterozygous NBAS gene pathogenic variants in them. The total episodes of acute liver failure before liver transplantation were 11, 2, and 4 respectively, and the age at liver transplantation was 3.5, 2.3, and 2.0 years respectively. During liver transplantation, patient 1 was in the convalescent phase of acute liver failure, patient 2 was in the acute phase, presenting with hepatic encephalopathy (grade V) and respiratory failure, and patient 3 was considered to be in the acute phase. After liver transplantation, patient 1 recovered normal liver function within 1 month and had no liver transplantation-related complications. Patient 2 had secondary epilepsy, intellectual disability, movement disorder, and transiently elevated transaminases. Patient 3 died of severe infection within 1 month. There was no literature in Chinese, 6 in English, 8 NBAS-deficient patients who were treated with liver transplantation. Total 11 patients presented with fever-triggered recurrent acute liver failure. Their age at liver transplantation ranged from 0.9 to 5.0 years. Postoperative complications occurred in 3 patients. Until the last visit, they were followed up for 0.7 to 14.0 years. Total 2 patients died and the 9 surviving patients did not develop acute liver failure. Conclusions: Liver transplantation is effective for the treatment of acute liver failure associated with NBAS gene disease. However, postoperative complications of liver transplantation may occur. The timing of liver transplantation still needs further research.

Genotypic and phenotypic spectrum of infantile liver failure due to pathogenic TRMU variants.

PURPOSE: This study aimed to define the genotypic and phenotypic spectrum of reversible acute liver failure (ALF) of infancy resulting from biallelic pathogenic TRMU variants and determine the role of cysteine supplementation in its treatment. METHODS: Individuals with biallelic (likely) pathogenic variants in TRMU were studied within an international retrospective collection of de-identified patient data. RESULTS: In 62 individuals, including 30 previously unreported cases, we described 47 (likely) pathogenic TRMU variants, of which 17 were novel, and 1 intragenic deletion. Of these 62 individuals, 42 were alive at a median age of 6.8 (0.6-22) years after a median follow-up of 3.6 (0.1-22) years. The most frequent finding, occurring in all but 2 individuals, was liver involvement. ALF occurred only in the first year of life and was reported in 43 of 62 individuals; 11 of whom received liver transplantation. Loss-of-function TRMU variants were associated with poor survival. Supplementation with at least 1 cysteine source, typically N-acetylcysteine, improved survival significantly. Neurodevelopmental delay was observed in 11 individuals and persisted in 4 of the survivors, but we were unable to determine whether this was a primary or a secondary consequence of TRMU deficiency. CONCLUSION: In most patients, TRMU-associated ALF was a transient, reversible disease and cysteine supplementation improved survival.

Characterization of a novel non-canonical splice site variant (c.886-5T>A) in NBAS and description of the associated phenotype.

BACKGROUND: Biallelic pathogenic variants in the neuroblastoma-amplified sequence (NBAS) gene manifest in a broad spectrum of disorders, including, but not limited to recurrent acute liver failure, skeletal dysmorphism, susceptibility to infections, and SOPH syndrome with its cardinal symptoms of short stature, optic atrophy, and Pelger-Huët anomaly. We aimed to present clinical and genetic characteristics of two sisters (20 and 15 years old) who were diagnosed with optic atrophy and cone dystrophy in childhood. Genome sequencing revealed two novel variants in NBAS in compound heterozygous state in both sisters, namely a 1-bp deletion predicted to result in a premature termination codon (c.5104del; p.(Met1702*)), and a non-canonical splice site variant of unclear significance (c.886-5T>A; p.?). RESULTS: Clinical examination and history revealed cone dystrophy, optic atrophy, and Pelger-Huët anomaly, but no short stature, recurrent acute liver failure, or susceptibility to infections. RNA analysis revealed that the c.886-5T>A variant results in two aberrant transcripts that are predicted to lead to in frame amino acid changes in the ß-propeller region of the protein. CONCLUSION: We hypothesize that the phenotype of our subjects, which appears to be at the end of the spectrum of NBAS-related disorders, could be explained by residual protein function mediated by the non-canonical splice site variant c.886-5T>A. Our study contributes to the existing knowledge on the genotypic and phenotypic spectrum of NBAS-related disorders.

MicroRNA-378 inhibits hepatocyte apoptosis during acute liver failure by targeting caspase-9 in mice.

BACKGROUND: Acute liver failure (ALF) is a severe and potentially lethal clinical syndrome. It has been demonstrated that micro ribonucleic acids (miRNAs) are crucial mediators of nearly all pathological processes, including liver disease. OBJECTIVE: The present study investigates the role of miR-378 in ALF. An ALF mouse model was induced using intraperitoneal injections of d-galactosamine/lipopolysaccharide (d-GalN/LPS). A hepatocyte cell line and miR-378 analogue were used in vitro to investigate the possible roles of miR-378 in ALF. METHODS: The expressions of miR-378 and predicted target genes were measured via reverse transcription-quantitative polymerase chain reaction and western blotting, and cell apoptosis was assayed using flow cytometry. RESULTS: Compared with mice in the control group, the mice challenged with d-GalN/LPS showed higher levels of alanine aminotransferase, aspartate aminotransferase, tumour necrosis factor-alpha and interleukin-6, more severe liver damage and increased numbers of apoptotic hepatocytes. Hepatic miR-378 was distinctly downregulated, while messenger RNA and protein levels of cysteinyl aspartate specific proteinase 9 (caspase-9) were upregulated in the ALF model. Furthermore, miR-378 was downregulated in d-GalN/TNF-induced hepatocyte cells, and miR-378 was found to inhibit hepatocyte apoptosis by targeting caspase-9. CONCLUSION: Together, the present results indicate that miR-378 is a previously unrecognised post-ALF hepatocyte apoptosis regulator and may be a potential therapeutic target in the context of ALF.

Deficiency of Ninjurin1 attenuates LPS/D-galactosamine-induced acute liver failure by reducing TNF-α-induced apoptosis in hepatocytes.

Nerve injury-induced protein 1 (Ninjurin1, Ninj1) is a membrane protein that mediates cell adhesion. The role of Ninj1 during inflammatory response has been widely investigated in macrophages and endothelial cells. Ninj1 is expressed in various tissues, and the liver also expresses high levels of Ninj1. Although the hepatic upregulation of Ninj1 has been reported in human hepatocellular carcinoma and septic mice, little is known of its function during the pathogenesis of liver diseases. In the present study, the role of Ninj1 in liver inflammation was explored using lipopolysaccharide (LPS)/D-galactosamine (D-gal)-induced acute liver failure (ALF) model. When treated with LPS/D-gal, conventional Ninj1 knock-out (KO) mice exhibited a mild inflammatory phenotype as compared with wild-type (WT) mice. Unexpectedly, myeloid-specific Ninj1 KO mice showed no attenuation of LPS/D-gal-induced liver injury. Whereas, Ninj1 KO primary hepatocytes were relatively insensitive to TNF-α-induced caspase activation as compared with WT primary hepatocytes. Also, Ninj1 knock-down in L929 and AML12 cells and Ninj1 KO in HepG2 cells ameliorated TNF-α-mediated apoptosis. Consistent with in vitro results, hepatocyte-specific ablation of Ninj1 in mice alleviated LPS/D-gal-induced ALF. Summarizing, our in vivo and in vitro studies show that lack of Ninj1 in hepatocytes diminishes LPS/D-gal-induced ALF by alleviating TNF-α/TNFR1-induced cell death.

MKK4 Knockdown Plays a Protective Role in Hemorrhagic Shock-Induced Liver Injury through the JNK Pathway.

Hemorrhagic shock (HS) triggers tissue hypoxia and organ failure during severe blood loss, and the liver is sensitive to HS. Mitogen-activated protein kinase kinase 4 (MKK4) activates the c-Jun NH2-terminal kinase (JNK) pathway, and its expression is upregulated in the serum of HS patients and mouse livers at 1 h post-HS. However, the function of MKK4 in HS-induced liver injury is unclear. The role of MKK4 was investigated in vivo using rat models of HS. Before HS, lentivirus harboring shRNA against MKK4 was injected into rats via the tail vein to knock down MKK4 expression. HS was induced by bloodletting via intubation of the femoral artery followed by resuscitation. The results showed that MKK4 knockdown reduced HS-induced apoptosis in the liver by decreasing Bax expression and the cleavage of caspase 3 and promoting Bcl-2 expression. Moreover, the generation of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) in the liver was promoted, while superoxide dismutase (SOD) activity was inhibited by HS. However, the effect of HS on oxidative stress was abrogated by MKK4 knockdown. Furthermore, MKK4 knockdown restored MMP and complex I and complex III activities and promoted ATP production, suggesting that HS-induced mitochondrial dysfunction in the liver was ameliorated by MKK4 knockdown. The inhibitory effect of MKK4 knockdown on the phosphorylation and activation of the JNK/c-Jun pathway was confirmed. Overall, MKK4 knockdown may suppress oxidative stress and subsequent apoptosis and improve mitochondrial function in the liver upon HS by inhibiting the JNK pathway. The MKK4/JNK axis was shown to be a therapeutic target for HS-induced liver injury in this study.

HNF4α overexpression enhances the therapeutic potential of umbilical cord mesenchymal stem/stromal cells in mice with acute liver failure.

Human umbilical cord mesenchymal stem/stromal cells (hUMSCs) hold promise for treating acute liver failure (ALF). Here, we investigated the therapeutic effect of hUMSCs overexpressing hepatocyte nuclear factor 4α (HNF4α), a transcription factor important for maintaining hepatocyte identity and hepatic functions, in ALF, compared with hUMSCs without overexpression of HNF4α (CON-hUMSCs). The cells were administered into mice via the tail vein for 24 h before exposure to lipopolysaccharide/d-galactosamine (LPS/d-GalN) for 6 h by intraperitoneal injection. HNF4α-hUMSCs ameliorated liver injury in ALF better than CON-hUMSCs. The overexpression of HNF4α enhanced the transcription of interleukin (IL)-10 and promoted M2 macrophage polarization through the IL-10/signal transducer and activator of transcription 3 (STAT3) pathway. HNF4α-hUMSCs could exert a more pronounced therapeutic effect on ALF than CON-hUMSCs, providing a novel therapy for ALF.

Mesenchymal stem cells derived from different perinatal tissues donated by same donors manifest variant performance on the acute liver failure model in mouse.

BACKGROUND: Mesenchymal stem cells (MSCs) derived from different tissues have variant biological characteristics, which may induce different performances in the treatment of diseases. At present, it is difficult to know which type of MSC is most suitable for acute liver failure (ALF), and there is no parallel study to compare MSCs from different tissues of the same donor. METHODS: In this study, we derived MSCs from three different perinatal tissues of the same donor: cord lining (CL), cord-placenta junction (CPJ) and fetal placenta (FP), respectively, for compared gene expression profiles by transcriptome sequencing, and ability of proliferation and immune regulation in vitro. In addition, the therapeutic effects (e.g., survival rate, histological evaluation, biochemical analysis) of CL-MSCs, FP-MSCs and CPJ-MSCs on ALF mouse model were compared. RESULTS: The transcriptome analysis showed that FP-MSCs have significantly high expression of chemokines compared to CPJ-MSCs and CL-MSCs, similar to the q-PCR result. Of note, we found that CPJ-MSCs and FP-MSCs could improve the survival rate of mice with ALF induced by carbon tetrachloride, but CL-MSCs had no difference with Sham group. Moreover, we also found that biomarkers of ALF (e.g., MDA, SOD and GSH-px) significantly improved post-CPJ-MSCs and FP-MSCs treatment, but not CL-MSCs and Sham group. However, CL-MSCs treatment leads to inflammatory reaction in the early stage (day 3) of ALF treatment but not found with other groups. CONCLUSIONS: It is important to select the MSCs derived from different tissues with variant performance for therapeutic purpose, and the CPJ-MSCs and FP-MSCs cells can significantly improve the syndrome of ALF which is highly recommended for a potential therapeutic options for ALF.

Hepatocyte Bcl-3 protects from death-receptor mediated apoptosis and subsequent acute liver failure.

Acute liver failure (ALF) is a rare entity but exhibits a high mortality. The mechanisms underlying ALF are not completely understood. The present study explored the role of the hepatic B cell leukemia-3 (Bcl-3), a transcriptional regulator of nuclear factor-kappa B (NF-κB), in two independent models of ALF. We employed a recently developed transgenic mouse model in a C57BL6/J background comparing wild-type (WT) and transgenic littermates with hepatocyte-specific overexpression of Bcl-3 (Bcl-3Hep) in the ALF model of d-galactosamine (d-GalN) and lipopolysaccharide (LPS). Additionally, the apoptosis-inducing CD95 (FAS/APO-1)-ligand was explored. Bcl-3Hep mice exhibited a significant protection from ALF with decreased serum transaminases, decreased activation of the apoptotic caspases 8, 9, and 3, lower rates of oxidative stress, B-cell lymphoma 2 like 1 (BCL2L1/BCL-XL) degradation and accompanying mitochondrial cytochrome c release, and ultimately a decreased mortality rate from d-GalN/LPS compared to WT mice. d-GalN/LPS treatment resulted in a marked inflammatory cytokine release and stimulated the activation of signal transducer and activator of transcription (STAT) 3, c-Jun N-terminal kinases (JNK) and extracellular signal-regulated kinase (ERK) signaling comparably in the hepatic compartment of Bcl-3Hep and WT mice. However, in contrast to the WT, Bcl-3Hep mice showed a diminished rate of IkappaB kinase-beta (IKK-ß) degradation, persistent receptor interacting protein kinase (RIPK) 1 function and thus prolonged cytoprotective nuclear factor-kappa B (NF-κB) p65 signaling through increased p65 stability and enhanced transcription. Likewise, Bcl-3 overexpression in hepatocytes protected from ALF with massive hepatocyte apoptosis induced by the anti-FAS antibody Jo2. The protection was also linked to IKK-ß stabilization. Overall, our study showed that Bcl-3 rendered hepatocytes more resistant to hepatotoxicity induced by d-GalN/LPS and FAS-ligand. Therefore, Bcl-3 appears to be a critical regulator of the dynamics in ALF through IKK-ß.

Case report: A novel cause of acute liver failure in children: A combination of human herpesvirus-6 infection and homozygous mutation in NBAS gene.

Etiologies of acute liver failure in children can be multiple factors including virus infection, drug-induced damage, and different pathogens. Next-generation sequencing (NGS) is an emerging method for pan-pathogen screening. Here we reported a case of acute liver failure in a 15-month-old male, using NGS and gene sequencing to determine the cause of acute liver failure may be caused by pathogens, drug-induction and pathogenic variant gene.

CCR2-overexpressing mesenchymal stem cells targeting damaged liver enhance recovery of acute liver failure.

BACKGROUND: Mesenchymal stem cell (MSC) transplantation is emerging as a promising cell therapeutic strategy in acute liver failure (ALF) clinical research. The potency of MSCs to migrate and engraft into targeted lesions could largely determine their clinical efficacy, in which chemokine/receptor axes play a crucial role. Unfortunately, the downregulation of chemokine receptors expression after in vitro expansion results in a poor homing capacity of MSCs. METHODS: By evaluating the chemokine expression profile in the liver of ALF patients and ALF mice, we found that CCL2 expression was highly upregulated in damaged livers, while the corresponding receptor, CCR2, was lacking in cultured MSCs. Thus, we genetically modified MSCs to overexpress CCR2 and investigated the targeted homing capacity and treatment efficacy of MSCCCR2 compared to those of the MSCvector control. RESULTS: In vivo and ex vivo near-infrared fluorescence imaging showed that MSCCCR2 rapidly migrated and localized to injured livers in remarkably greater numbers following systemic infusion, and these cells were retained in liver lesions for a longer time than MSCvector. Furthermore, MSCCCR2 exhibited significantly enhanced efficacy in the treatment of ALF in mice, which was indicated by a dramatically improved survival rate, the alleviation of liver injury with reduced inflammatory infiltration and hepatic apoptosis, and the promotion of liver regeneration. CONCLUSIONS: Altogether, these results indicate that CCR2 overexpression enhances the targeted migration of MSCs to damaged livers, improves their treatment effect, and may provide a novel strategy for improving the efficacy of cell therapy for ALF.

Efficient intracellular delivery of proteins by a multifunctional chimaeric peptide in vitro and in vivo.

Protein delivery with cell-penetrating peptide is opening up the possibility of using targets inside cells for therapeutic or biological applications; however, cell-penetrating peptide-mediated protein delivery commonly suffers from ineffective endosomal escape and low tolerance in serum, thereby limiting in vivo efficacy. Here, we present an intracellular protein delivery system consisting of four modules in series: cell-penetrating peptide, pH-dependent membrane active peptide, endosome-specific protease sites and a leucine zipper. This system exhibits enhanced delivery efficiency and serum tolerance, depending on proteolytic cleavage-facilitated endosomal escape and leucine zipper-based dimerisation. Intravenous injection of protein phosphatase 1B fused with this system successfully suppresses the tumour necrosis factor-α-induced systemic inflammatory response and acetaminophen-induced acute liver failure in a mouse model. We believe that the strategy of using multifunctional chimaeric peptides is valuable for the development of cell-penetrating peptide-based protein delivery systems, and facilitate the development of biological macromolecular drugs for use against intracellular targets.

NBAS deficiency due to biallelic c.2809C > G variant presenting with recurrent acute liver failure with severe hyperammonemia, acquired microcephaly and progressive brain atrophy.

Biallelic pathogenic variants in the neuroblastoma amplified sequence (NBAS) gene were firstly (2015) identified as a cause of fever-triggered recurrent acute liver failure (RALF). Since then, some patients with NBAS deficiency presenting with neurologic features, including a motor delay, intellectual disability, muscular hypotonia and a mild brain atrophy, have been reported. Here, we describe a case of pediatric patient diagnosed with NBAS deficiency due to a homozygous c.2809C > G, p.(Pro937Ala) variant presenting with RALF with severe hyperammonemia, acquired microcephaly and progressive brain atrophy. Not reported in the literature findings include severe hyperammonemia during ALF episode, and neurologic features in the form of acquired progressive microcephaly with brain atrophy. The latter raises the hypothesis about a primary neurologic phenotype in NBAS deficiency.

Resolution of recurrent pediatric acute liver failure with liver transplantation in a patient with NBAS mutation.

BACKGROUND: Pediatric acute liver failure (PALF) remains an enigmatic process of rapid end-organ dysfunction associated with a variety of pathologic conditions though the predominant cause is indeterminate. A growing body of research has identified mutations in the NBAS gene to be associated with recurrent acute liver failure and multi-systemic disease including short stature, skeletal dysplasia, facial dysmorphism, immunologic abnormalities, and Pelger-Huët anomaly. METHODS AND RESULTS: Here, we describe a 4-year-old girl who presented with dehydration in the setting of acute gastroenteritis and fever but went on to develop PALF on day 2 of hospitalization. She clinically recovered with supportive measures, but after discharge, had at least 2 additional episodes of PALF. Ultimately, she underwent liver transplant and her recurrent episodes of PALF did not recur throughout a 6-year follow-up period. Whole-exome sequencing post-liver transplant initially revealed two variants of uncertain significance in the NBAS gene. Parental studies confirmed the c.1549C > T(p.R517C; now likely pathogenic) variant from her mother and a novel c.4646T > C(p.L1549P) variant from her father. In silico analyses predicted these variants to have a deleterious effect on protein function. Consistent with previously characterized NBAS mutation-associated disease (NMAD), our patient demonstrated the following features: progeroid facial features, hypoplasia of the 12th ribs, Pelger-Huët anomaly on peripheral blood smear, and abnormal B and NK cell function. CONCLUSION: Altogether, we describe a novel pathogenic variant in the NBAS gene of a patient with NMAD and report the resolution of recurrent PALF secondary to NMAD following liver transplantation.

AIRE Gene Mutation Presenting at Age 2 Years With Autoimmune Retinopathy and Steroid-Responsive Acute Liver Failure: A Case Report and Literature Review.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare monogenic autosomal recessive disorder caused by mutation in the autoimmune regulator (AIRE) gene. Patients usually are diagnosed at ages between 5 and 15 years when they show 3 or more manifestations, most typically mucocutaneous candidiasis, Addison's disease, and hypoparathyroidism. APECED-associated hepatitis (APAH) develops in only 10% to 40% of patients, with severity varying from subclinical chronic active hepatitis to potentially fatal acute liver failure (ALF). Ocular abnormalities are fairly common, most often keratopathy but sometimes retinopathy. Here we report a 2-year-old Japanese girl with an AIRE gene mutation who developed APAH with ALF, preceded by autoimmune retinopathy associated with anti-recoverin antibody before major symptoms suggested a diagnosis of APECED. Intravenous pulse methylprednisolone therapy followed by a corticosteroid combined with azathioprine treatment resolved ALF and achieved control of APAH. To our knowledge, our patient is the youngest reported to have ALF resulting from an AIRE gene mutation. Pulse methylprednisolone induction therapy followed by treatment with corticosteroid plus azathioprine may well be effective in other children with APAH and AIRE gene mutations.