Two siblings with acute necrotizing encephalopathy associated with variants of LARS1

Abstract

AbstractAcute necrotizing encephalopathy (ANE) is a rapidly progressive encephalopathy of unknown etiology. The underlying mechanisms are highly heterogeneous, often including genetic backgrounds. Variants of LARS1, encoding the leucyl‐tRNA synthetase 1, are responsible for infantile liver failure syndrome 1. We describe two siblings with ANE caused by compound heterozygous variants of LARS1. Patient 1 was a 17‐month‐old girl. She presented with generalized seizure and liver dysfunction due to influenza type A infection. Brain magnetic resonance imaging on day 4 of onset showed diffuse high‐intensity signals consistent with ANE. She died on day 10. Patient 2, a younger male sibling of patient 1, had mild to moderate developmental delay and growth failure at the age of 18 months. He showed a markedly elevated level of transaminases triggered by infection with human herpesvirus 6. On day 4 of onset, he had generalized seizures. Brain computed tomography showed a diffuse symmetrical hypodensity consistent with ANE. He died on day 7. Whole exome sequencing identified the compound heterozygous variants in LARS1 (NM_020117.11) as c.83_88delinsAATGGGATA, p.(Arg28_Phe30delinsLysTryAspIle) and c.1283C>T, p.(Pro428Leu) in both siblings. The severe neurologic phenotype, found in our patients, reflects the complicated pathogenesis of LARS1‐related disorder.