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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., Competing Interests: Declaration of competing interest None., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

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 β-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., (© 2022 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

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.

Acute liver failure (ALF) is a life-threatening condition in the absence of preexisting liver disease in children. The main clinical presentation comprises hepatic dysfunction, elevated liver biochemical values, and coagulopathy. The etiology of ALF remains unclear in most affected children; however, the recent identification of mutations in the neuroblastoma amplified sequence (NBAS) gene in autosomal recessively inherited ALF has shed light on the cause of a subgroup of fever-triggered pediatric ALF episodes. Previously, biallelic mutations in NBAS have been reported to be associated with a syndrome comprising short stature, optic atrophy, and Pelger-Huët anomaly (SOPH) specifically occurring in the Yakut population. No hepatic phenotype has been observed in individuals with this disorder who all carry the homozygous NBAS founder mutation c.5741G>A [p.(Arg1914His)]. We present the case of a 4-year-old girl with the cardinal features of SOPH syndrome: characteristic facial dysmorphism, postnatal growth retardation, delay of bone age, slender long bones, optic atrophy, and Pelger-Huët anomaly. During the first 2 years of her life, a series of infections with episodes of fever were accompanied by elevated liver enzyme levels, but hyperammonemia, hypoglycemia, coagulopathy, or encephalopathy suggestive of acute and severe liver disease were never observed. Whole exome sequencing in the patient revealed compound heterozygosity of the 2 NBAS variants, p.(Arg1914His) and p.(Glu943*). This case highlights the variability of clinical presentation associated with NBAS deficiency. Absence of severe liver problems in this case and SOPH-affected Yakut subjects suggests that individuals carrying the NBAS missense mutation p.(Arg1914His) are less susceptible to developing ALF., (Copyright © 2017 by the American Academy of Pediatrics.)