@article {935, title = {Genotypic diversity and phenotypic spectrum of infantile liver failure syndrome type 1 due to variants in LARS1.}, journal = {Genet Med}, volume = {22}, year = {2020}, month = {2020 11}, pages = {1863-1873}, abstract = {

PURPOSE: Biallelic variants in LARS1, coding for the cytosolic leucyl-tRNA synthetase, cause infantile liver failure syndrome 1 (ILFS1). Since its description in 2012, there has been no systematic analysis of the clinical spectrum and genetic findings.

METHODS: Individuals with biallelic variants in LARS1 were included through an international, multicenter collaboration including novel and previously published patients. Clinical variables were analyzed and functional studies were performed in patient-derived fibroblasts.

RESULTS: Twenty-five individuals from 15 families were ascertained including 12 novel patients with eight previously unreported variants. The most prominent clinical findings are recurrent elevation of liver transaminases up to liver failure and encephalopathic episodes, both triggered by febrile illness. Magnetic resonance image (MRI) changes during an encephalopathic episode can be consistent with metabolic stroke. Furthermore, growth retardation, microcytic anemia, neurodevelopmental delay, muscular hypotonia, and infection-related seizures are prevalent. Aminoacylation activity is significantly decreased in all patient cells studied upon temperature elevation in vitro.

CONCLUSION: ILFS1 is characterized by recurrent elevation of liver transaminases up to liver failure in conjunction with abnormalities of growth, blood, nervous system, and musculature. Encephalopathic episodes with seizures can occur independently from liver crises and may present with metabolic stroke.

}, keywords = {Humans, Liver Failure, Muscle Hypotonia, Mutation, Seizures}, issn = {1530-0366}, doi = {10.1038/s41436-020-0904-4}, author = {Lenz, Dominic and Smith, Desir{\'e}e E C and Crushell, Ellen and Husain, Ralf A and Salomons, Gajja S and Alhaddad, Bader and Bernstein, Jonathan A and Bianzano, Alyssa and Biskup, Saskia and Brennenstuhl, Heiko and Caldari, Dominique and Dikow, Nicola and Haack, Tobias B and Hanson-Kahn, Andrea and Harting, Inga and Horn, Denise and Hughes, Joanne and Huijberts, Maya and Isidor, Bertrand and Kathemann, Simone and Kopajtich, Robert and Kotzaeridou, Urania and K{\"u}ry, S{\'e}bastien and Lainka, Elke and Laugwitz, Lucia and Lupski, James R and Posey, Jennifer E and Reynolds, Claire and Rosenfeld, Jill A and Schr{\"o}ter, Julian and Vansenne, Fleur and Wagner, Matias and Wei{\ss}, Claudia and Wolffenbuttel, Bruce H R and Wortmann, Saskia B and K{\"o}lker, Stefan and Hoffmann, Georg F and Prokisch, Holger and Mendes, Marisa I and Staufner, Christian} } @article {804, title = {Loss of NARS1 impairs progenitor proliferation in cortical brain organoids and leads to microcephaly.}, journal = {Nat Commun}, volume = {11}, year = {2020}, month = {2020 08 12}, pages = {4038}, abstract = {

Asparaginyl-tRNA synthetase1 (NARS1) is a member of the ubiquitously expressed cytoplasmic Class IIa family of tRNA synthetases required for protein translation. Here, we identify biallelic missense and frameshift mutations in NARS1 in seven patients from three unrelated families with microcephaly and neurodevelopmental delay. Patient cells show reduced NARS1 protein, impaired NARS1 activity and impaired global protein synthesis. Cortical brain organoid modeling shows reduced proliferation of radial glial cells (RGCs), leading to smaller organoids characteristic of microcephaly. Single-cell analysis reveals altered constituents of both astrocytic and RGC lineages, suggesting a requirement for NARS1 in RGC proliferation. Our findings demonstrate that NARS1 is required to meet protein synthetic needs and to support RGC proliferation in human brain development.

}, keywords = {Adolescent, Adult, Aspartate-tRNA Ligase, Base Sequence, Cell Differentiation, Cell Proliferation, Cell Size, Cell Survival, Cerebral Cortex, Child, Family, Female, Fibroblasts, HEK293 Cells, Humans, Induced Pluripotent Stem Cells, Ki-67 Antigen, Male, Microcephaly, Mutation, Neural Stem Cells, Neuroglia, Organoids, Pedigree, RNA, Transfer, Amino Acyl, Young Adult}, issn = {2041-1723}, doi = {10.1038/s41467-020-17454-4}, author = {Wang, Lu and Li, Zhen and Sievert, David and Smith, Desir{\'e}e E C and Mendes, Marisa I and Chen, Dillon Y and Stanley, Valentina and Ghosh, Shereen and Wang, Yulu and Kara, Majdi and Aslanger, Ayca Dilruba and Rosti, Rasim O and Houlden, Henry and Salomons, Gajja S and Gleeson, Joseph G} }