SARS1-Related Neurodevelopmental Disorder

Mendelian MONDO:0060577 Pathograph 20 Show in embeddings browser Neurodevelopmental Disorder Inborn Error of Metabolism

Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) is the single MONDO entity for germline disease caused by variants in SARS1, the gene encoding the CYTOPLASMIC seryl-tRNA synthetase (SerRS). SerRS is a homodimeric class II aminoacyl-tRNA synthetase that charges serine onto tRNA-Ser in a two-step reaction - serine plus ATP to enzyme-bound serine-adenylate, then transfer of the seryl moiety to the tRNA - and it also serylates the selenocysteine-specific tRNA-Sec, so it stands at the entry point of both general cytoplasmic translation and selenoprotein synthesis. Every SARS1 allele whose structural position has been published in the clinical literature sits in or immediately adjacent to the catalytic core - though ClinVar additionally holds a likely-pathogenic in-frame insertion inside the C-terminal UNE-S appendage for which no publication could be found - and the functional consequence measured in patient material has consistently been the same: reduced enzyme abundance and/or reduced serylation activity. The disorder therefore belongs squarely to the recessive aminoacyl-tRNA-synthetase (ARS) deficiency family, whose proposed unifying mechanism is that residual aminoacylation is sufficient at baseline but insufficient to meet translational demand in the organs and life periods with the highest protein-synthesis rates. That single premise accounts for a phenotype that otherwise looks incoherent: microcephaly with cerebral and cerebellar atrophy, moderate intellectual disability, ataxia, seizures, muscle weakness and a thin body habitus in the originally described families; and, with a different allele, developmental delay with central deafness, cardiomyopathy and life-threatening metabolic decompensation triggered by fever. The MONDO label names only the first presentation, which materially understates the entity - the deafness and cardiomyopathy presentation is filed against the same MONDO/OMIM term, and a further individual with a de novo, dominant-negative allele presented with complex spastic paraplegia and no microcephaly at all. SerRS additionally has well-documented non-canonical nuclear activities (repression of VEGFA transcription via its UNE-S nuclear localisation signal, and telomere binding with POT1); whether these contribute to the human disease has never been tested in patient material, and this entry treats the loss-of-charging route as the supported mechanism and the moonlighting route as an explicit open question rather than smoothing the two together. The disorder is ultra-rare: the entire published clinical literature is a handful of families - the Turkish family of the deafness-cardiomyopathy report explicitly consanguineous, the others not described as such in their abstracts - and single cases.

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Inheritance
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Pathophys.
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Phenotypes
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Gaps
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Pathograph
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Genes
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Variants
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Medical Actions
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Differentials
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Models
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References
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Deep Research
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Classifications

Harrison's Part
NEUROLOGIC
ICIMD (Inherited Metabolic Disorders)
non mitochondrial trna metabolism
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Inheritance

2
Autosomal recessive inheritance HP:0000007
The dominant mode by a wide margin. Every family in the microcephaly and in the cardiomyopathy presentations was recessive: a homozygous missense allele in the Iranian family, and biallelic c.638G>T (p.Arg213Leu) in the consanguineous Turkish family. For the recessive ARS deficiencies as a class, the ARS review states that heterozygous parents of patients are unaffected and reads that as evidence of excess capacity in ARS activity - the central quantitative claim of the family: one functional allele supplies enough aminoacylation capacity, and disease requires that both alleles be damaged while still leaving some residual activity, because complete loss of a cytoplasmic aminoacyl-tRNA synthetase is not compatible with life. No cached SARS1 paper reports the phenotype of any SARS1 carrier parent directly, so the carrier statement is inherited from the class and not from a SARS1 observation. Penetrance is recorded as UNKNOWN rather than COMPLETE. Every reported biallelic individual is affected, but every reported biallelic individual was ascertained because they were affected, and the total number of families is in single figures. There is no population-scale genotype-first data for any SARS1 allele, so a penetrance claim of any kind would be an artefact of ascertainment. The HPO annotation set for OMIM:617709 records HP:0000007 (autosomal recessive inheritance) sourced to PMID:28236339 (retrieved 2026-08-01) and no dominant inheritance annotation, which is consistent with the dominant-negative case (PMID:36041817) postdating the annotation rather than contradicting it.
Autosomal recessive inheritance Penetrance: UNKNOWN
Show evidence (4 references)
PMID:28236339 SUPPORT Human Clinical
"we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene"
A homozygous missense allele segregating in a single family is the founding evidence for autosomal recessive inheritance at this locus, and names the compartment (cytoplasmic) that distinguishes SARS1 from SARS2.
PMID:34570399 SUPPORT Human Clinical
"We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
Independent recessive family with a different biallelic allele, confirming the inheritance mode in a second, phenotypically distinct presentation.
PMID:35790048 SUPPORT Human Clinical
"Seryl-tRNA synthetase 1 (SARS1) has rarely been implicated in an autosomal recessive developmental disorder."
Independent statement of the inheritance mode from a third group, in a paper reporting a further SARS1 family.
+ 1 more reference
Autosomal dominant inheritance HP:0000006
A single reported exception, and it is mechanistically informative rather than a nosological nuisance. One patient carried a DE NOVO splice-site deletion producing a five-amino-acid in-frame insertion near the active site, and complementation in Saccharomyces cerevisiae plus serylation assays in both yeast and the patient's own fibroblasts showed the allele to be not merely loss-of-function but DOMINANT NEGATIVE. Because SerRS is an obligate homodimer, a catalytically dead subunit that still dimerises poisons the wild-type subunit it partners, so a single such allele can drop total cellular serylation below the threshold that one intact recessive allele comfortably supports. That patient's phenotype was also different: complex spastic paraplegia with ataxia, intellectual disability, developmental delay and seizures, but explicitly WITHOUT microcephaly. Recorded because the mode of inheritance for this gene cannot be stated as autosomal recessive without qualification, and a diagnostic laboratory that filters SARS1 for biallelic hits only will miss this class of allele. It rests on a single published patient. The homodimer-poisoning rationale above is the standard interpretation of a dominant-negative allele in an obligate-dimeric class II synthetase and is consistent with the cited assays, but the specific claim that the mutant subunit heterodimerises with wild-type SerRS was not itself demonstrated in that paper and is therefore reasoning, not a finding. Penetrance is UNKNOWN on a single case.
Autosomal dominant inheritance Penetrance: UNKNOWN
Show evidence (2 references)
PMID:36041817 SUPPORT Human Clinical
"A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site."
Establishes a de novo, monoallelic SARS1 event as a cause of disease at this locus.
PMID:36041817 SUPPORT In Vitro
"Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
Functional demonstration that the de novo allele acts dominant-negatively, which is what makes a monoallelic genotype sufficient for disease.
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Discussions and Knowledge Gaps

7
Do the patient SARS1 alleles impair only serine charging, or do they also disrupt the non-canonical nuclear functions of SerRS - and would it change anything clinically if they did?
KNOWLEDGE GAP OPEN sars1-charging-vs-moonlighting
Attached to
pathophysiology#Loss of Non-Canonical Nuclear SerRS Function pathophysiology#Deficient Serylation of tRNA-Ser
This is the central unresolved mechanistic question for the entry. Vertebrate SerRS has a documented second life in the nucleus, repressing VEGFA through a YY1 complex and binding telomeric DNA with POT1, and disrupting the nuclear function is lethal in zebrafish. Every human SARS1 disease allele so far maps to the catalytic core - which argues for a pure charging defect - but the SerRS/YY1 interaction is itself mediated by the CATALYTIC domain, so active-site alleles are not automatically innocent with respect to the nuclear activity. Nobody has tested nuclear localisation, YY1 binding, VEGFA repression, or telomere length in cells carrying p.Asp172Asn, p.Arg213Leu or p.Thr399Met. The answer matters practically: if the moonlighting arm is intact, substrate supplementation targets the whole defect; if it is not, L-serine can never be more than partial therapy, and vascular or telomere-related surveillance might be warranted in a disorder where nobody currently looks for either.
Proposed experiments
Nuclear localisation and VEGFA repression across the SARS1 allelic series
sars1-nuclear-localisation-allelic-series
Express each patient allele in a SerRS-depleted background and measure nuclear/cytoplasmic partitioning, co-immunoprecipitation with YY1, occupancy at the distal vegfa cis-regulatory element, and VEGFA transcript level, alongside serylation activity, so that the two functions are read out from the same cells.
Telomere length and POT1 association in SARS1 patient fibroblasts
sars1-telomere-length-patient-fibroblasts
Measure telomere length and SerRS-POT1 association in fibroblasts from recessive SARS1 patients and compare with the senescent fibroblasts of the dominant-negative patient, to test whether the reported senescence is telomeric or translational in origin.
What is the biochemistry of a SARS1 febrile decompensation, and is there any laboratory test that can confirm one is underway?
KNOWLEDGE GAP OPEN sars1-crisis-biomarker
Attached to
pathophysiology#Demand-Dependent Decompensation During Febrile Catabolic Stress treatments#L-serine supplementation
The decompensations are lethal and the proposed treatment is substrate loading, yet no biochemical characterisation of a crisis exists: no published amino acid profile, no charged-tRNA-Ser measurement, no integrated-stress-response readout, no proteomic signature. Clinicians are therefore escalating L-serine on mechanistic reasoning with no way to confirm the target is engaged or to titrate. The label "metabolic decompensation" is itself doing unexamined work - it is borrowed from the intoxication-type inborn errors, where a toxic metabolite accumulates, whereas the proposed SARS1 mechanism is a synthetic insufficiency with no accumulating toxin. Whether anything measurable accumulates or is depleted during a SARS1 crisis is simply unknown.
Proposed experiments
Paired crisis and baseline metabolomic and amino acid profiling
sars1-crisis-metabolomics
Collect plasma and, where available, cerebrospinal fluid at presentation with febrile decompensation and again at baseline in the same patient, and profile amino acids, acylcarnitines and untargeted metabolites, to establish whether any analyte tracks the crisis.
Thermal and inflammatory challenge of SARS1 patient fibroblasts
sars1-fibroblast-thermal-challenge
Culture patient and control fibroblasts at 37 and 40 degrees Celsius, with and without inflammatory cytokine exposure and with and without serine supplementation, and measure charged tRNA-Ser, global translation by puromycin incorporation or ribosome profiling, and integrated-stress-response markers.
Should the SARS1 phenotype remain one MONDO entity named for microcephaly, ataxia and seizures, when its most dangerous manifestation is cardiac and one reported patient had neither microcephaly nor a recessive genotype?
INTERPRETATION OPEN sars1-mondo-label-understates-entity
Attached to
phenotypes#Cardiomyopathy phenotypes#Spastic paraplegia
MONDO:0060577 is the only disease term MONDO assigns to SARS1, and ClinVar files both the microcephaly allele and the cardiomyopathy allele against it, so curating the whole spectrum here is the correct current mapping. But the label actively misleads in two directions. A clinician reading "neurodevelopmental disorder with microcephaly, ataxia, and seizures" would not anticipate a treatable, lethal, fever-triggered cardiomyopathy, and would not consider the gene in a child with spastic paraplegia and a normal head circumference. This is recorded as an interpretation issue rather than silently resolved, because the resolution belongs to MONDO and OMIM, not to this entry. What this entry does instead is curate the full spectrum and mark, feature by feature, which presentation each observation comes from.
The alternative curation - restricting this entry to the microcephaly presentation and waiting for MONDO to split the term - was considered and rejected, because it would have excluded the only treatable and the only lethal features of SARS1 deficiency from the knowledge base while the term that ought to hold them does not exist.
Is the risk of fatal febrile decompensation restricted to the p.Arg213Leu genotype, or does every SARS1 patient need an emergency protocol?
OPEN QUESTION OPEN sars1-fever-risk-allele-restricted
Attached to
pathophysiology#Demand-Dependent Decompensation During Febrile Catabolic Stress variants#SARS1 c.638G>T p.Arg213Leu
Fever-triggered decompensation has been reported only in the family carrying c.638G>T (p.Arg213Leu). Two readings are possible and they imply opposite clinical policies. If the risk is allele-specific - for example because that allele's protein instability is itself temperature-sensitive, which would be a direct and elegant explanation for a fever trigger - then patients with other genotypes need no emergency plan. If instead the risk is generic to residual charging capacity, as the ARS-family model implies, then the other families simply have not been followed long enough or have not been recognised, and every SARS1 patient should be issued a protocol. Nobody has tested the thermal stability of any SARS1 mutant protein, which is a cheap experiment that would largely settle it.
Proposed experiments
Thermal stability and activity of recombinant SARS1 mutant proteins
sars1-thermal-stability-allelic-series
Measure melting temperature and residual serylation activity at 37 and 40 degrees Celsius for recombinant wild-type SerRS and each patient allele, to test directly whether the p.Arg213Leu protein is disproportionately temperature-sensitive.
Why is there no animal or cellular model of SARS1 NEURODEVELOPMENTAL disease, and what would one need to capture?
HUMAN MODEL MISMATCH OPEN sars1-no-disease-model
Attached to
pathophysiology#Impaired Neural Progenitor Proliferation and Brain Growth
The only established in vivo SARS1 model is the zebrafish adrasteia mutant, which was isolated for a vascular phenotype and reads out the non-canonical function; it has never been used to model microcephaly, ataxia, seizures or cardiomyopathy, and human patients have no reported vascular malformation. No mouse model, no knock-in of a patient allele, and no neural organoid has been published. This is a genuine mismatch rather than a gap in the literature search: the model that exists reads out the arm of the biology that the human disease may not use. A knock-in of p.Asp172Asn or p.Arg213Leu, phenotyped for brain growth, cerebellar structure, seizure threshold and cardiac function under thermal challenge, is the missing experiment.
Proposed experiments
Knock-in mouse carrying a patient SARS1 allele
sars1-knockin-mouse-allelic
Generate homozygous knock-in mice for p.Asp172Asn and for p.Arg213Leu and phenotype brain weight and cortical thickness, cerebellar morphology, seizure susceptibility, and cardiac function at baseline and under a controlled pyrogenic or thermal challenge.
Patient-derived cortical organoids
sars1-patient-derived-cortical-organoid
Differentiate iPSC-derived cortical organoids from recessive SARS1 patients and isogenic corrected controls, and measure progenitor proliferation, organoid size, and global translation rate, to test the demand-capacity model in a human neural context.
How many patients does PMID:36004946 actually report, and in how many of them was c.1196C>T found?
CURATION TODO OPEN sars1-karaer-cohort-inconsistency
Attached to
variants#SARS1 c.1196C>T p.Thr399Met prevalence#
The cached abstract states "three unrelated Turkish families with four NEDMAS patients" and then, two sentences later, "both patients carried a novel missense variant c.1196C>T (p.Thr399Met)". Four patients and "both patients" cannot both be right. The most likely readings are that the variant was found in only two of the four, or that "both" is a residue of an earlier draft describing two patients. This entry therefore asserts no case count from that paper and no genotype-count for the p.Thr399Met allele. Resolving it requires the full text, which is not cached in this repository. It is recorded rather than silently resolved because a curator or an automated extractor is otherwise likely to take "four patients" as a countable figure.
Is c.1196C>T (p.Thr399Met) pathogenic, given that it is published as causal in multiple families but classified as a variant of uncertain significance in ClinVar?
CONTROVERSY OPEN sars1-thr399met-vus
Attached to
variants#SARS1 c.1196C>T p.Thr399Met
PMID:36004946 reports p.Thr399Met as the disease-causing variant in unrelated Turkish families with a matching phenotype. ClinVar (VCV002506443, retrieved 2026-08-01) holds a single criteria-provided submission classifying it as Uncertain significance against "not specified". No functional assay has been published for this allele - no serylation measurement, no protein-stability measurement, no structural mapping - so the case for pathogenicity rests entirely on segregation and phenotype match in a small number of families. This is a live disagreement between the published literature and the variant database, and a laboratory encountering this allele will have to adjudicate it. A serylation assay in patient fibroblasts, the same experiment done for the other alleles, would resolve it.
The ClinVar classification is from the public E-utilities API and is not quotable from a cached reference, so it is recorded in this rationale rather than as an evidence snippet.
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Pathophysiology

12
Damaging SARS1 Alleles in the Catalytic Core
The primary lesion is damage to SARS1 at 1p13.3, reported against transcript NM_006513.4. What is striking about the allelic series is its positional consistency: the founding homozygous missense c.514G>A (p.Asp172Asn) was described as affecting the enzymatic core domain; the variant reported by Bogershausen and colleagues was mapped structurally to a position directly within the enzyme's active site; the de novo splice-site deletion reported by Verdura and colleagues produces a five-residue in-frame insertion near the active site. Every allele reported in the clinical literature with a published structural position therefore converges on the aminoacylation machinery rather than on the tRNA-binding domain, the dimer interface or the vertebrate-specific UNE-S appendage. This is the single most important structural observation in the entry, because it is what licenses reading the disorder as a charging defect rather than as a defect of one of SerRS's non-canonical activities.
SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Reduced SerRS Protein Stability and Steady-State Abundance The abundance arm. Both the p.Asp172Asn and the p.Arg213Leu missense alleles were shown to destabilise the protein, so less enzyme is present before any question of per-molecule catalytic competence arises.
Deficient Serylation of tRNA-Ser The catalytic arm. Active-site alleles reduce the specific activity of the enzyme that is present, independently of how much of it there is.
Dominant-Negative Poisoning of the SerRS Homodimer The allele-specific arm. The de novo in-frame insertion acts dominant negatively, which is a property of the allele rather than a consequence of reduced total protein, and so branches directly from the variant node.
Show evidence (3 references)
PMID:28236339 SUPPORT Human Clinical
"The mutation affects the enzymatic core domain of the protein and impairs its enzymatic activity, probably leading to reduced cytoplasmic tRNASer concentrations."
Places the founding allele in the enzymatic core and states the immediate functional consequence, which is the starting point of the causal chain modelled below.
PMID:35790048 SUPPORT In Vitro
"Structural mapping showed that the SARS1 variant is located directly within the enzyme's active site, most likely diminishing activity, while the WARS1 variant is located in the N-terminal domain."
Independent structural mapping of a second SARS1 allele into the active site, establishing the positional convergence of the allelic series.
PMID:36041817 SUPPORT Human Clinical
"A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site."
A third allele, of a different class and a different inheritance mode, again located at the active site.
Reduced SerRS Protein Stability and Steady-State Abundance
Two independently reported missense alleles reduce the amount of SerRS in the cell rather than only its per-molecule activity. The founding p.Asp172Asn allele was predicted to be unstable and this was substantiated for ectopically expressed mutant protein in transfected HEK293T cells; the p.Arg213Leu allele was shown to cause protein instability with a consequent fall in both protein level and enzymatic activity. Instability is the commonest single mechanism across the recessive ARS deficiencies and it has a specific consequence for this disease: the deficit is in total cellular charging CAPACITY, which is exactly the quantity that a rise in translational demand can outstrip.
patient-derived dermal fibroblast CL:0000057 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves patient-derived dermal fibroblast, annotated with fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology.
SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee.
serine-tRNA ligase activity GO:0004828 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased serine-tRNA ligase activity (GO:0004828). GO:0004828 is a molecular function from the Gene Ontology. ↓ DECREASED
cytosol GO:0005829 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves cytosol (GO:0005829). GO:0005829 is a cellular component from the Gene Ontology.
Downstream
Deficient Serylation of tRNA-Ser Less enzyme present means less serine charged per unit time, regardless of the intrinsic catalytic competence of each molecule.
Show evidence (2 references)
PMID:28236339 SUPPORT In Vitro
"The mutant protein was predicted to be unstable, which could be substantiated by investigating ectopic mutant SARS in transfected HEK293T cells."
Experimental support that the founding allele destabilises SerRS protein.
PMID:34570399 SUPPORT In Vitro
"This missense variant was shown to lead to protein instability, resulting in reduced protein level and enzymatic activity."
Independent demonstration, for a second allele, that instability lowers both protein abundance and enzyme activity - the two quantities that together define charging capacity.
Deficient Serylation of tRNA-Ser
The convergent molecular defect. SerRS is a homodimeric class II synthetase that catalyses aminoacylation in two steps - serine is first activated by ATP to form enzyme-bound serine-adenylate, then the seryl moiety is transferred to the 3' end of the cognate tRNA to give Ser-tRNA-Ser for delivery to the ribosome. Its recognition strategy is unusual and relevant here: unlike most synthetases SerRS does not read the anticodon but recognises the long variable arm unique to tRNA-Ser, and each subunit's N-terminal tRNA-binding domain directs the tRNA 3'-CCA end into the active site of the OTHER subunit, so the functional unit is the dimer rather than the monomer. Motifs 2 and 3 of the class II fold carry the active-site residues; motif 1 forms the dimer interface. Patient-derived material shows the predicted outcome: serylation assays in patient fibroblasts were used to demonstrate loss of function, and the founding report inferred reduced cytoplasmic tRNA-Ser charging directly from the impaired enzymatic activity of the mutant.
patient-derived dermal fibroblast CL:0000057 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves patient-derived dermal fibroblast, annotated with fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology.
SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee.
seryl-tRNA aminoacylation GO:0006434 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased seryl-tRNA aminoacylation (GO:0006434). GO:0006434 is a biological process from the Gene Ontology. ↓ DECREASED tRNA aminoacylation for protein translation GO:0006418 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased tRNA aminoacylation for protein translation (GO:0006418). GO:0006418 is a biological process from the Gene Ontology. ↓ DECREASED
serine-tRNA ligase activity GO:0004828 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased serine-tRNA ligase activity (GO:0004828). GO:0004828 is a molecular function from the Gene Ontology. ↓ DECREASED
Downstream
Insufficient Aminoacylation Capacity for Translational Demand A smaller pool of charged tRNA-Ser sets a ceiling on the rate at which the cytoplasmic ribosome can elongate serine-containing nascent chains.
Impaired Selenocysteine Incorporation A second, parallel and untested consequence: tRNA-Sec must be serylated by the same enzyme before it can be converted to selenocysteinyl-tRNA-Sec.
Show evidence (7 references)
PMID:24095058 SUPPORT In Vitro
"catalyzes the aminoacylation reaction that charges serine onto its cognate tRNA for protein synthesis"
States the canonical function of the gene product whose loss defines this node.
PMID:24095058 SUPPORT In Vitro
"serine is activated by ATP to form serine-adenylate (Ser-AMP) as the enzyme-bound reaction intermediate"
Defines the first chemical step and the role of ATP and serine as substrates, which is what an active-site variant perturbs.
PMID:24095058 SUPPORT In Vitro
"The dimeric SerRS belongs to class II tRNA synthetases"
Establishes the obligate-dimer architecture, which is the structural precondition for a dominant-negative allele at this locus.
+ 4 more references
Dominant-Negative Poisoning of the SerRS Homodimer
An allele-specific route to the same endpoint. The de novo splice-site deletion reported in the spastic paraplegia patient yields a five-residue in-frame insertion near the active site, and complementation and serylation assays established that this allele is not simply inactive but dominant negative - that is, its presence reduces the activity attainable by the wild-type allele in the same cell. This node exists separately from the loss-of-abundance node because the two predict different things. Under simple haploinsufficiency a carrier of one null allele would be unaffected, which is what is observed for the recessive families; under dimer poisoning a single allele suffices, which is what is observed here.
patient-derived dermal fibroblast CL:0000057 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves patient-derived dermal fibroblast, annotated with fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology.
SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee.
serine-tRNA ligase activity GO:0004828 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased serine-tRNA ligase activity (GO:0004828). GO:0004828 is a molecular function from the Gene Ontology. ↓ DECREASED
Downstream
Insufficient Aminoacylation Capacity for Translational Demand Dimer poisoning lowers total cellular serylation capacity by the same final common route as biallelic hypomorphism.
Cellular Senescence with a Senescence-Associated Secretory Phenotype Patient fibroblasts carrying this allele arrest and senesce, which is the only cell-autonomous consequence of a SARS1 variant demonstrated in human patient cells to date.
Show evidence (1 reference)
PMID:36041817 SUPPORT In Vitro
"Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
The primary evidence that this allele class acts dominant-negatively rather than by simple loss of one gene copy.
Insufficient Aminoacylation Capacity for Translational Demand
The organising hypothesis of the whole recessive ARS deficiency family, and the reason this disorder's phenotype is not arbitrary. Aminoacylation is the committed first step of protein synthesis: the synthetase ligates the amino acid to its cognate tRNA, and the resulting aminoacyl-tRNA is handed to ribosome elongation factors. A hypomorphic synthetase leaves a cell able to translate at rest but unable to scale, so the deficit manifests wherever and whenever translational demand is highest - in the tissues with the highest amino-acid incorporation rates and during the periods of highest demand, which are early growth and intercurrent illness. Fuchs and colleagues reached this formulation from the whole recessive ARS cohort, in which SARS was one of the thirteen synthetase deficiencies analysed, and drew from it the clinically consequential corollary that patients need adequate protein and amino acid supply rather than the traditional protein restriction of metabolic disease.
cytoplasmic translation GO:0002181 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cytoplasmic translation (GO:0002181). GO:0002181 is a biological process from the Gene Ontology. ↓ DECREASED tRNA aminoacylation for protein translation GO:0006418 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased tRNA aminoacylation for protein translation (GO:0006418). GO:0006418 is a biological process from the Gene Ontology. ↓ DECREASED
cytosol GO:0005829 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves cytosol (GO:0005829). GO:0005829 is a cellular component from the Gene Ontology.
Downstream
Impaired Neural Progenitor Proliferation and Brain Growth A translational ceiling constrains the proliferative expansion of neural progenitors during fetal and early postnatal brain growth.
Cerebellar and Cerebral Atrophy Chronic translational insufficiency in post-mitotic neurons underlies progressive tissue loss rather than a purely developmental deficit.
Demand-Dependent Decompensation During Febrile Catabolic Stress An acute rise in translational and catabolic demand exceeds the residual charging capacity.
Cardiomyocyte Translational Insufficiency Cardiac muscle has a high protein turnover and is one of the organs in which the capacity ceiling becomes symptomatic.
Show evidence (4 references)
PMID:34570399 SUPPORT In Vitro
"The resulting aminoacyl-tRNA is delivered to ribosome elongation factors to participate in protein synthesis."
States the step in translation that a charging deficit throttles, linking the molecular lesion to protein synthesis.
PMID:29875423 SUPPORT Human Clinical
"We propose a common clinical phenotype for recessive ARS deficiencies, resulting from insufficient aminoacylation activity to meet translational demand in specific organs or periods of life."
The explicit statement of the demand-capacity mechanism, derived from a cross-gene analysis of recessive ARS deficiencies that included SARS.
PMID:29875423 SUPPORT Human Clinical
"In literature, we identified 107 patients with AARS, DARS, GARS, HARS, IARS, KARS, LARS, MARS, RARS, SARS, VARS, YARS, and QARS deficiencies"
Documents that SARS deficiency was one of the thirteen recessive synthetase deficiencies from which the common mechanism was inferred, so the model is not being imported from an unrelated gene set.
+ 1 more reference
Impaired Neural Progenitor Proliferation and Brain Growth
The causal step from a translation defect to the cardinal phenotype. Brain growth in the second and third trimesters and the first postnatal years is among the most protein-synthesis-intensive processes in human development; a ceiling on charged-tRNA supply constrains progenitor proliferation and the accretion of neuronal and glial mass, producing microcephaly. This is the single feature that unites the SARS1 families with the recessive WARS1 families reported alongside them, and it is the reason the two were described together as an emerging disease group of ARS-related developmental disorders with or without microcephaly. The microcephaly is not an isolated head-size measurement: it is accompanied by intellectual disability, developmental delay and structural brain anomalies in the same individuals.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
brain development GO:0007420 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal brain development (GO:0007420). GO:0007420 is a biological process from the Gene Ontology. ⚠ ABNORMAL cytoplasmic translation GO:0002181 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cytoplasmic translation (GO:0002181). GO:0002181 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Cerebellar and Cerebral Atrophy Reduced brain growth and ongoing neuronal attrition are seen together on imaging in the same individuals.
Show evidence (2 references)
PMID:35790048 SUPPORT Human Clinical
"Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies."
Establishes microcephaly with developmental delay and brain anomalies as the shared consequence of biallelic damage to a cytoplasmic synthetase, across two different synthetase genes.
PMID:35790048 SUPPORT Human Clinical
"define an emerging disease spectrum: ARS-related developmental disorders with or without microcephaly"
Frames the microcephaly as a class-level consequence of ARS deficiency rather than an idiosyncrasy of one gene.
Cerebellar and Cerebral Atrophy
Structural neuroimaging in the Turkish NEDMAS families showed bilateral cerebral AND cerebellar diffuse atrophy. The cerebellar component is the anatomical substrate of the ataxia that names the disorder, and its presence alongside cerebral atrophy indicates that the lesion is not confined to a developmental failure of head growth but includes ongoing tissue loss. That combination - a small brain that also atrophies - is characteristic of the recessive ARS deficiencies generally, and it is the reason the disorder is curated as neurodevelopmental with a neurodegenerative component rather than as static.
cerebellar Purkinje cell CL:0000121 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cerebellar Purkinje cell, annotated with Purkinje cell (CL:0000121). CL:0000121 is a cell type from the Cell Ontology. neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
brain development GO:0007420 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal brain development (GO:0007420). GO:0007420 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Demand-Dependent Decompensation During Febrile Catabolic Stress Not a causal edge from atrophy to crisis, but the clinical observation that a brain already compromised structurally is where the acute decompensations declare themselves neurologically, with hypotonia and seizures.
Show evidence (1 reference)
PMID:36004946 SUPPORT Human Clinical
"Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy."
The direct imaging evidence for the structural lesion, in the cohort that expanded the clinical spectrum of this MONDO entity.
Demand-Dependent Decompensation During Febrile Catabolic Stress
The most clinically consequential node in the entry and the clearest test of the demand-capacity model. In the SARS1 family reported from Nancy, febrile illness precipitated acute metabolic decompensation that was fatal; three siblings of the surviving proband died during similar febrile episodes. Fever raises basal metabolic rate, drives protein catabolism, and increases the demand for de novo protein synthesis for the acute-phase response and for tissue repair - precisely the demand that a hypomorphic synthetase cannot meet. The decompensation is multi-system, presenting with vomiting, hypotonia and seizures, and its lethal component is cardiac. The clinical corollary inverts standard metabolic-crisis management: rather than restricting protein, these patients need more of the limiting amino acid, and escalation of L-serine was associated with survival of an episode that had killed the patient's untreated siblings.
cytoplasmic translation GO:0002181 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cytoplasmic translation (GO:0002181). GO:0002181 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Cardiomyocyte Translational Insufficiency The decompensation manifests most dangerously in the heart, with acute ventricular failure.
Show evidence (4 references)
PMID:34570399 SUPPORT Human Clinical
"We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
The founding description of fever-triggered metabolic decompensation as a lethal feature of SARS1 deficiency.
PMID:42158840 SUPPORT Human Clinical
"We report the case of a 9-year-old male of Turkish origin with genetically confirmed SARS1 deficiency, admitted with fever, vomiting, hypotonia, and seizures."
Documents the clinical presentation of a decompensation episode: a febrile trigger with gastrointestinal, neuromuscular and seizure manifestations.
PMID:42158840 SUPPORT Human Clinical
"Notably, the patient's family history included the death of three siblings during similar febrile episodes."
Establishes that febrile decompensation is recurrent within a family and lethal, not an isolated event.
+ 1 more reference
Cardiomyocyte Translational Insufficiency
Cardiomyopathy is part of the SARS1 phenotype in the presentation reported from Nancy and is the feature that determines survival. In the documented decompensation episode the left ventricular ejection fraction fell to 20%, requiring mechanical ventilation and vasopressor support, with myocardial oedema that resolved on follow-up echocardiography; a subsequent febrile crisis produced severe biventricular dysfunction and fatal cardiogenic shock. Cardiac muscle is a plausible target for a charging-capacity defect because it combines high protein turnover with an inability to reduce workload during fever - the opposite of skeletal muscle, which can rest. The reversibility of the myocardial oedema between crises argues that the cardiac lesion is at least in part an acute, demand-driven failure superimposed on a chronic cardiomyopathy rather than fixed structural damage alone.
cardiomyocyte CL:0000746 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cardiomyocyte, annotated with cardiac muscle cell (CL:0000746). CL:0000746 is a cell type from the Cell Ontology.
cytoplasmic translation GO:0002181 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cytoplasmic translation (GO:0002181). GO:0002181 is a biological process from the Gene Ontology. ↓ DECREASED
Show evidence (3 references)
PMID:34570399 SUPPORT Human Clinical
"We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
Establishes cardiomyopathy as a component of the SARS1 phenotype.
PMID:42158840 SUPPORT Human Clinical
"The clinical course rapidly progressed to metabolic decompensation and severe acute cardiac failure, characterised by a left ventricular ejection fraction of 20%, necessitating mechanical ventilation and vasopressor support"
Quantifies the acute cardiac failure during decompensation, the specific measurement on which the severity of cardiac involvement rests.
PMID:42158840 SUPPORT Human Clinical
"However, a year later, the patient presented with another febrile crisis at 10 years old, and despite an emergency protocol, the patient developed severe biventricular dysfunction progressing to fatal cardiogenic shock."
Documents that the cardiac involvement is recurrent and ultimately lethal even under a prepared emergency protocol.
Cellular Senescence with a Senescence-Associated Secretory Phenotype
The only cell-autonomous phenotype demonstrated in human SARS1 patient cells. Fibroblasts from the patient with the de novo dominant-negative allele showed abnormal cell shape, arrested division, increased beta-galactosidase staining, and a senescence-associated secretory phenotype with raised interleukin-6, p21, p16 and p53. The authors read this as revealing a role for SARS1 in the regulation of cell growth, division and senescence. There are two ways this could arise and they are not mutually exclusive: a translational ceiling is itself a proliferation constraint and chronically stalled growth engages p53/p21-dependent arrest; alternatively, the senescence could reflect loss of a non-canonical SerRS activity, since SerRS binds telomeric DNA and cooperates with the shelterin protein POT1 to regulate telomere length and senescence. Distinguishing these would require testing whether senescence is rescued by restoring serylation alone.
patient-derived dermal fibroblast CL:0000057 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves patient-derived dermal fibroblast, annotated with fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology.
cellular senescence GO:0090398 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased cellular senescence (GO:0090398). GO:0090398 is a biological process from the Gene Ontology. ↑ INCREASED
Show evidence (3 references)
PMID:36041817 SUPPORT In Vitro
"Fibroblasts showed an abnormal cell shape, arrested division and increased beta-galactosidase staining along with a senescence-associated secretory phenotype (raised interleukin-6, p21, p16 and p53 levels)."
The primary patient-cell demonstration of senescence and its molecular markers.
PMID:36041817 SUPPORT In Vitro
"We refine the phenotypic spectrum and modes of inheritance of a newly described, ultrarare neurodevelopmental disorder, while unveiling the role of SARS1 as a regulator of cell growth, division and senescence."
The authors' own framing of SARS1 as a regulator of growth, division and senescence, which is the interpretive claim this node records.
PMID:38255739 SUPPORT In Vitro
"Additionally, SerRS binds telomeric DNA and cooperates with the shelterin protein POT1 to regulate telomere length and cellular senescence."
Marked PARTIAL. It supplies an independent, non-translational route by which SerRS loss could cause senescence, which is the alternative explanation named in this node's description. It is a review statement about SerRS biology in general and says nothing about any patient allele, so it supports the existence of the alternative route and not its operation in this disease.
Impaired Selenocysteine Incorporation
A predicted second consequence of the same enzyme deficit, included because it is a specific, testable prediction that the aminoacylation literature makes and the clinical literature has never examined. Selenoprotein synthesis in all domains of life begins with SerRS serylating the selenocysteine-specific tRNA-Sec; the serylated intermediate is then converted to selenocysteinyl-tRNA-Sec for co-translational insertion of the 21st amino acid. A hypomorphic SerRS therefore throttles the supply of the obligatory precursor for every selenoprotein. Which selenoproteins would be rate-limited first, and whether any of them are the antioxidant enzymes usually invoked, is not addressed by any source cached for this entry. If this arm operates, it would predict oxidative vulnerability that worsens under febrile stress and would give SARS1 deficiency a pathophysiological component that other ARS deficiencies do not have.
selenocysteine incorporation GO:0001514 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased selenocysteine incorporation (GO:0001514). GO:0001514 is a biological process from the Gene Ontology. ↓ DECREASED conversion of seryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec) GO:0001717 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased conversion of seryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec), annotated with conversion of seryl-tRNAsec to selenocys-tRNAsec (GO:0001717). GO:0001717 is a biological process from the Gene Ontology. ↓ DECREASED
serine-tRNA ligase activity GO:0004828 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased serine-tRNA ligase activity (GO:0004828). GO:0004828 is a molecular function from the Gene Ontology. ↓ DECREASED
Show evidence (1 reference)
PMID:24095058 SUPPORT In Vitro
"SerRS also serylates the selenocysteine-specific tRNA (tRNASec) to participate in the translational incorporation of selenocysteine"
Establishes that the same enzyme performs the first committed step of selenoprotein synthesis, which is the entire basis for this hypothetical arm.
Loss of Non-Canonical Nuclear SerRS Function
Vertebrate SerRS is not only a synthetase. It acquired a C-terminal UNE-S domain in the lineage that developed closed circulatory systems; UNE-S carries a nuclear localisation signal that directs SerRS into the nucleus, where it attenuates VEGFA expression, acting through a complex with the transcription factor YY1 that binds distal cis-regulatory elements of the vegfa promoter and competes with activating factors. Genetically, this is not a minor embellishment: zebrafish sars mutants isolated in a vascular screen show dilated aortic arch vessels and aberrant hindbrain capillary patterning in a Vegf-dependent manner, and human SerRS alleles that disrupt nuclear localisation cause abnormal vasculature and premature death in fish. The question for this entry is whether any of this contributes to the human disease. The honest answer is that it is not known, and this node exists to say so precisely rather than to leave the moonlighting literature quietly attached to the mechanism.
SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee.
negative regulation of vascular endothelial growth factor production GO:1904046 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal negative regulation of vascular endothelial growth factor production (GO:1904046). GO:1904046 is a biological process from the Gene Ontology. ⚠ ABNORMAL telomere maintenance GO:0000723 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal telomere maintenance (GO:0000723). GO:0000723 is a biological process from the Gene Ontology. ⚠ ABNORMAL
nucleus GO:0005634 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves nucleus (GO:0005634). GO:0005634 is a cellular component from the Gene Ontology.
Show evidence (4 references)
PMID:22353712 SUPPORT In Vitro
"UNE-S harbours a robust nuclear localization signal (NLS) directing SerRS to the nucleus where it attenuates vascular endothelial growth factor A expression"
Establishes the nuclear, VEGFA-repressing activity of SerRS and the domain that mediates it.
PMID:24095058 SUPPORT In Vitro
"Mutations that disrupted SerRS nuclear localization caused abnormal vasculature and premature death in zebrafish."
Shows the nuclear function is essential at the organism level in a vertebrate, which is why it cannot simply be dismissed as an in vitro curiosity.
PMID:27913726 SUPPORT In Vitro
"we found that the catalytic domain of Seryl-tRNA synthetase (SerRS) interacted with transcription factor Yin Yang 1 (YY1) to form a SerRS/YY1 complex that negatively controls vegfa promoter activity"
Marked PARTIAL. It identifies the CATALYTIC domain as the region mediating the nuclear repressor function, which is the one concrete reason a catalytic-core patient allele might also disrupt moonlighting. It is biochemistry in cell lines with no patient material, so it establishes the possibility and not its relevance to this disorder.
+ 1 more reference
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for SARS1-Related Neurodevelopmental Disorder Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

16
Cardiovascular 1
Cardiomyopathy HP:0001638 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cardiomyopathy (HP:0001638). HP:0001638 is a phenotype from the Human Phenotype Ontology.
The generic HP:0001638 (Cardiomyopathy) is bound rather than HP:0001644 (Dilated cardiomyopathy) or a hypertrophic term, because no cached source states the morphological subtype; the reported findings are a depressed ejection fraction, myocardial oedema, and biventricular dysfunction, which constrain function but not morphology. Reported in one family (with the 2026 case report describing what is on internal evidence a member of that same family), so the frequency across the disorder is unknown and no band is asserted.
Show evidence (2 references)
PMID:34570399 SUPPORT Human Clinical
"We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
The founding report of cardiomyopathy in SARS1 deficiency.
PMID:42158840 SUPPORT Human Clinical
"The clinical course rapidly progressed to metabolic decompensation and severe acute cardiac failure, characterised by a left ventricular ejection fraction of 20%, necessitating mechanical ventilation and vasopressor support"
Provides the only quantitative measure of cardiac dysfunction published for this disorder.
Ear 1
Hearing impairment HP:0000365 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Central deafness, annotated with Hearing impairment (HP:0000365). HP:0000365 is a phenotype from the Human Phenotype Ontology.
Term-binding decision, recorded because it is a deliberate loss of specificity. The source says "central deafness". HPO has no "central hearing impairment" term - searched 2026-08-01 with `runoak -i sqlite:obo:hp search "l~central hearing"` (no results) and `t~auditory neuropathy` (no results) - and binding HP:0000407 (Sensorineural hearing impairment) would assert a cochlear or eighth-nerve localisation that the source explicitly contradicts. The generic parent HP:0000365 is therefore bound with the clinical localisation preserved in `preferred_term`. Reported in one family only.
Show evidence (2 references)
PMID:34570399 SUPPORT Human Clinical
"We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
The source of both the finding and its localisation as central rather than peripheral.
PMID:42158840 SUPPORT Human Clinical
"Seryl-tRNA synthetase 1 (SARS1) deficiency is a rare autosomal recessive disorder presenting with neurodevelopmental delay, deafness, cardiomyopathy, and fatal metabolic decompensation triggered by febrile episodes."
Independent restatement, four years later and from the same clinical service, that deafness is an established component of SARS1 deficiency.
Head and Neck 1
Microcephaly HP:0000252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Microcephaly (HP:0000252). HP:0000252 is a phenotype from the Human Phenotype Ontology.
HPO annotation for OMIM:617709 records HP:0000252 at 4/4, sourced to PMID:28236339 (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:617709). That denominator is the single founding family. No FrequencyEnum band is asserted; see the entry-level notes.
Show evidence (3 references)
PMID:36004946 SUPPORT Human Clinical
"Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
Names microcephaly as a defining feature of the syndrome.
PMID:35790048 SUPPORT Human Clinical
"Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies."
Independent confirmation of microcephaly in a further SARS1 report, and the basis for treating it as a class feature of cytoplasmic ARS deficiency.
PMID:36041817 SUPPORT Human Clinical
"We used exome sequencing to identify the causal variant in a patient affected by complex spastic paraplegia with ataxia, intellectual disability, developmental delay and seizures, but without microcephaly."
Marked PARTIAL because it qualifies rather than supports the association: it documents a SARS1 patient in whom microcephaly was absent, which is the evidence for the statement that microcephaly is not obligatory.
Limbs 1
Pes planus HP:0001763 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pes planus (HP:0001763). HP:0001763 is a phenotype from the Human Phenotype Ontology.
Curated entirely from the HPO annotation set for OMIM:617709, which records HP:0001763 at 2/4 sourced to PMID:28236339 (retrieved 2026-08-01) - a minority finding in a single family. No evidence item is attached because the cached abstract does not mention it. The attribution to hypotonia is reasoning, not a reported analysis.
Musculoskeletal 3
Muscle weakness HP:0001324 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Muscle weakness (HP:0001324). HP:0001324 is a phenotype from the Human Phenotype Ontology.
HPO annotation for OMIM:617709 records HP:0001324 at 4/4, sourced to PMID:28236339 (retrieved 2026-08-01). Whether the weakness is myopathic, neurogenic or central has not been determined in any published SARS1 patient - no muscle biopsy, EMG or creatine kinase result appears in the cached abstracts.
Show evidence (2 references)
PMID:34570399 SUPPORT Human Clinical
"SARS1 deficiency has already been associated with moderate intellectual disability, ataxia, muscle weakness, and seizure in one family."
States muscle weakness as a feature of the first-described family.
PMID:36004946 SUPPORT Human Clinical
"Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
Independent listing of muscle weakness among the defining features.
Hypotonia HP:0001252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypotonia (HP:0001252). HP:0001252 is a phenotype from the Human Phenotype Ontology.
Not in the HPO annotation set for OMIM:617709. Curated from the two quoted sources. HP:0001252 (Hypotonia) is bound rather than a severity-qualified or central/peripheral child term, because the sources give severity but not localisation.
Show evidence (2 references)
PMID:36004946 SUPPORT Human Clinical
"The main manifestations of the probands are severe developmental delay and ID, thin body habitus, and severe hypotonia."
Documents severe hypotonia as a main manifestation in the Turkish families.
PMID:42158840 SUPPORT Human Clinical
"We report the case of a 9-year-old male of Turkish origin with genetically confirmed SARS1 deficiency, admitted with fever, vomiting, hypotonia, and seizures."
Documents hypotonia as part of the acute decompensation presentation.
Spastic paraplegia HP:0001258 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Spastic paraplegia (HP:0001258). HP:0001258 is a phenotype from the Human Phenotype Ontology.
Reported in exactly one patient, with a genotype and inheritance mode different from every other reported individual. It is curated as a phenotype of this MONDO entity because MONDO gives SARS1 no second term, not because it is a typical feature. Not in the HPO annotation set for OMIM:617709.
Show evidence (1 reference)
PMID:36041817 SUPPORT Human Clinical
"We used exome sequencing to identify the causal variant in a patient affected by complex spastic paraplegia with ataxia, intellectual disability, developmental delay and seizures, but without microcephaly."
The single source for this phenotype, which also documents the absence of microcephaly in the same individual.
Nervous System 7
Global developmental delay HP:0001263 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Global developmental delay (HP:0001263). HP:0001263 is a phenotype from the Human Phenotype Ontology.
HPO annotation for OMIM:617709 records HP:0001263 at 4/4, sourced to PMID:28236339 (retrieved 2026-08-01).
Show evidence (2 references)
PMID:35790048 SUPPORT Human Clinical
"Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies."
Documents developmental delay in a further SARS1 report.
PMID:34570399 SUPPORT Human Clinical
"We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
Documents developmental delay in the presentation that otherwise differs most from the microcephaly families, establishing it as common to both.
Ataxia HP:0001251 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ataxia (HP:0001251). HP:0001251 is a phenotype from the Human Phenotype Ontology.
HPO annotation for OMIM:617709 records HP:0001251 at 4/4, sourced to PMID:28236339 (retrieved 2026-08-01). The generic HP:0001251 is bound rather than a specific cerebellar-ataxia child term, because the published descriptions do not distinguish cerebellar from sensory ataxia and the imaging (diffuse cerebellar atrophy) is suggestive but not diagnostic of the mechanism.
Show evidence (2 references)
PMID:34570399 SUPPORT Human Clinical
"SARS1 deficiency has already been associated with moderate intellectual disability, ataxia, muscle weakness, and seizure in one family."
States ataxia as a feature of the originally described family.
PMID:36041817 SUPPORT Human Clinical
"Recently, patients affected with microcephaly, intellectual disability and ataxia harbouring biallelic variants in the seryl-tRNA synthetase encoded by seryl-tRNA synthetase 1 (SARS1) were reported."
Independent restatement that ataxia is part of the established biallelic SARS1 phenotype.
Seizures Bilateral tonic-clonic seizure HP:0002069 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Bilateral tonic-clonic seizure (HP:0002069). HP:0002069 is a phenotype from the Human Phenotype Ontology.
The specific term HP:0002069 (Bilateral tonic-clonic seizure) is bound rather than the parent HP:0001250 (Seizure) because the HPO annotation set for OMIM:617709 records HP:0002069 at 4/4 with onset annotated as HP:0003593 (Infantile onset), sourced to PMID:28236339 (retrieved 2026-08-01). The cached abstracts say only "seizure" or "seizures", so the semiology comes from the annotation set and not from a quotable sentence; the snippets below therefore support the presence of seizures rather than their bilateral tonic-clonic character.
Show evidence (2 references)
PMID:36004946 SUPPORT Human Clinical
"Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
Names seizures as a defining feature of the syndrome.
PMID:42158840 SUPPORT Human Clinical
"We report the case of a 9-year-old male of Turkish origin with genetically confirmed SARS1 deficiency, admitted with fever, vomiting, hypotonia, and seizures."
Documents seizures as part of the acute decompensation presentation, which is the basis for distinguishing crisis seizures from baseline epilepsy.
Cerebral atrophy HP:0002059 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebral atrophy (HP:0002059). HP:0002059 is a phenotype from the Human Phenotype Ontology.
Not present in the HPO annotation set for OMIM:617709, which derives entirely from PMID:28236339 and predates the imaging series. Curated here from the quoted imaging finding in PMID:36004946.
Show evidence (1 reference)
PMID:36004946 SUPPORT Human Clinical
"Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy."
Direct imaging evidence of the cerebral component of the atrophy.
Cerebellar atrophy HP:0001272 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebellar atrophy (HP:0001272). HP:0001272 is a phenotype from the Human Phenotype Ontology.
Curated from the imaging finding in PMID:36004946. Whether the cerebellar atrophy is congenital hypoplasia mislabelled as atrophy, or genuine progressive loss, cannot be determined from cross-sectional imaging in a small series and no serial imaging has been published.
Show evidence (1 reference)
PMID:36004946 SUPPORT Human Clinical
"Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy."
Direct imaging evidence of the cerebellar component of the atrophy.
Delayed speech and language development HP:0000750 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Delayed speech and language development (HP:0000750). HP:0000750 is a phenotype from the Human Phenotype Ontology.
Not in the HPO annotation set for OMIM:617709. Curated from the syndrome description quoted below, which says "speech impairment". HP:0000750 is bound as the closest developmental term; a dysarthria or apraxia term is NOT bound, because no published source characterises the speech disorder.
Show evidence (1 reference)
PMID:36004946 SUPPORT Human Clinical
"Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
Lists speech impairment among the defining features of the syndrome.
Aggressive behavior HP:0000718 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Aggressive behavior (HP:0000718). HP:0000718 is a phenotype from the Human Phenotype Ontology.
Curated entirely from the HPO annotation set for OMIM:617709, which records HP:0000718 at 4/4 sourced to PMID:28236339 (retrieved 2026-08-01). The cached abstract does not mention behaviour, so this phenotype deliberately carries no evidence item rather than a snippet that does not support it. It has not been reported in any family other than the founding one.
Other 2
Moderate intellectual disability HP:0002342 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Moderate intellectual disability (HP:0002342). HP:0002342 is a phenotype from the Human Phenotype Ontology.
HPO annotation for OMIM:617709 records HP:0002342 (Moderate intellectual disability) at 4/4, sourced to PMID:28236339 (retrieved 2026-08-01). The term bound here is the graded child HP:0002342 rather than the parent HP:0001249 (Intellectual disability), because the sources state the grade explicitly. The countervailing observation that a different series reported SEVERE developmental delay and intellectual disability is recorded in the description and quoted below, so the grade is not presented as settled. Binding the parent instead was considered and rejected: HP:0002342 is a descendant of HP:0001249, so any query over the parent already retrieves this entry by subsumption, whereas demoting the binding would delete from the machine-readable layer the one grade that HPOA and two independent papers actually state. The moderate-versus-severe spread is therefore carried by the description and by the PARTIAL evidence item rather than by weakening the term.
Show evidence (3 references)
PMID:36004946 SUPPORT Human Clinical
"Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
States moderate intellectual disability as a defining feature of the syndrome.
PMID:34570399 SUPPORT Human Clinical
"SARS1 deficiency has already been associated with moderate intellectual disability, ataxia, muscle weakness, and seizure in one family."
Independent restatement of the moderate grade in the first-described family.
PMID:36004946 SUPPORT Human Clinical
"The main manifestations of the probands are severe developmental delay and ID, thin body habitus, and severe hypotonia."
Marked PARTIAL because it supports the presence of intellectual disability but contradicts the "moderate" grade bound in the term, describing the same syndrome's probands as severely affected. Recorded rather than suppressed.
Slender build HP:0001533 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Slender build (HP:0001533). HP:0001533 is a phenotype from the Human Phenotype Ontology.
HPO annotation for OMIM:617709 records HP:0001533 (Slender build) at 2/4, sourced to PMID:28236339 (retrieved 2026-08-01) - a minority finding in the founding family even though the later descriptive summary lists thin body habitus as characteristic. HP:0001533 is bound because it is the term HPOA itself uses for this feature in this disease; the literature phrase is "thin body habitus".
Show evidence (1 reference)
PMID:36004946 SUPPORT Human Clinical
"The main manifestations of the probands are severe developmental delay and ID, thin body habitus, and severe hypotonia."
Documents thin body habitus as a main manifestation.
🧬

Genetic Associations

1
SARS1 (Biallelic missense and splice variants in the catalytic core cause autosomal recessive disease; one de novo, dominant-negative in-frame insertion allele has been reported)
Gene: SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (3 references)
PMID:28236339 SUPPORT Human Clinical
"we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene"
Establishes SARS1 as the causal gene with the founding allele, and names the cytoplasmic compartment that distinguishes it from SARS2.
PMID:36004946 SUPPORT Human Clinical
"Sequencing results showed that both patients carried a novel missense variant c.1196C>T (p.Thr399Met) in the seryl-tRNA synthetase gene."
Adds a further missense allele to the series, reported in unrelated Turkish families.
PMID:34570399 SUPPORT Human Clinical
"This missense variant was shown to lead to protein instability, resulting in reduced protein level and enzymatic activity."
Provides the functional characterisation for the third allele, tying genotype to a measured molecular consequence.
🔬

Variants

4
SARS1 c.514G>A p.Asp172Asn
Gene: SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this variant is in this gene This variant is in SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee. missense variant
The founding allele, homozygous in an Iranian family with autosomal recessive intellectual disability; the abstract reports the family as Iranian and does not state whether it is consanguineous. It lies in the enzymatic core domain, impairs enzymatic activity, and destabilises the protein - a combined activity-and-abundance hit rather than a pure catalytic lesion. The authors inferred from the activity loss that cytoplasmic tRNA-Ser charging is reduced.
Functional effects
serine-tRNA ligase activity
Impaired enzymatic activity of the mutant protein, attributed to the substitution falling in the enzymatic core domain.
SerRS protein stability
Predicted to be unstable, and substantiated for ectopically expressed mutant protein in transfected HEK293T cells.
cytoplasmic charged tRNA-Ser pool
Inferred reduction in cytoplasmic tRNA-Ser concentrations as a consequence of impaired charging; inferred by the authors rather than measured.
Show evidence (2 references)
PMID:28236339 SUPPORT Human Clinical
"we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene"
Identifies the allele and its homozygous state in the founding family.
PMID:28236339 SUPPORT In Vitro
"The mutant protein was predicted to be unstable, which could be substantiated by investigating ectopic mutant SARS in transfected HEK293T cells."
Supports the protein-stability functional effect.
SARS1 c.638G>T p.Arg213Leu
Gene: SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this variant is in this gene This variant is in SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee. missense variant
The allele of the deafness-cardiomyopathy-febrile-decompensation presentation, biallelic in a consanguineous Turkish family. Functionally it behaves as a destabilising allele: reduced protein level with consequently reduced enzymatic activity. This is the only SARS1 allele so far associated with fatal metabolic crises, and the only one for which a treatment response has been documented.
Functional effects
SerRS protein stability
Protein instability demonstrated, with reduced steady-state protein level.
serine-tRNA ligase activity
Reduced enzymatic activity, reported as a consequence of the reduced protein level rather than as an independent catalytic defect.
Show evidence (2 references)
PMID:34570399 SUPPORT Human Clinical
"We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
Identifies the allele, its biallelic state, and the phenotype it produces.
PMID:34570399 SUPPORT In Vitro
"This missense variant was shown to lead to protein instability, resulting in reduced protein level and enzymatic activity."
Supports both functional effects recorded for this allele.
SARS1 c.1196C>T p.Thr399Met Uncertain Significance
Gene: SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this variant is in this gene This variant is in SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee. missense variant
Reported as a novel missense variant in unrelated Turkish families with the NEDMAS phenotype, in individuals whose main manifestations were severe developmental delay and intellectual disability, thin body habitus and severe hypotonia, with bilateral cerebral and cerebellar diffuse atrophy on imaging. No functional assay has been published for this allele and no structural mapping is available, so its mechanism is assumed rather than shown.
Show evidence (2 references)
PMID:36004946 SUPPORT Human Clinical
"Sequencing results showed that both patients carried a novel missense variant c.1196C>T (p.Thr399Met) in the seryl-tRNA synthetase gene."
Identifies the allele and the report that associates it with the NEDMAS phenotype.
PMID:36004946 SUPPORT Human Clinical
"Our findings help expand the variant spectrum of NEDMAS"
The authors' own framing of the allele as an addition to the disease-associated variant spectrum.
SARS1 de novo splice-site deletion causing a five-residue in-frame insertion
Gene: SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this variant is in this gene This variant is in SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee. splice site variant
The single reported de novo, monoallelic, dominant-negative SARS1 allele. A splice-site deletion yields a five-amino-acid in-frame insertion near the active site; complementation in yeast and serylation assays in yeast and in the patient's fibroblasts established a loss-of-function, dominant-negative effect. Clinically it produced complex spastic paraplegia with ataxia, intellectual disability, developmental delay and seizures, explicitly WITHOUT microcephaly - the one published SARS1 phenotype that the MONDO label would actively mislead a clinician about.
Functional effects
serine-tRNA ligase activity
Loss of serylation activity in yeast complementation and in patient fibroblast serylation assays, with a dominant-negative rather than purely recessive effect.
cellular proliferation and senescence
Patient fibroblasts show abnormal shape, arrested division, increased beta-galactosidase staining and a senescence-associated secretory phenotype with raised IL-6, p21, p16 and p53.
Show evidence (2 references)
PMID:36041817 SUPPORT Human Clinical
"A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site."
Identifies the allele, its de novo origin, and its protein-level consequence.
PMID:36041817 SUPPORT In Vitro
"Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
Supports the dominant-negative functional effect on serylation.
💊

Medical Actions

2
L-serine supplementation
Category: Therapeutic Action: high-dose oral L-serine supplementationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is high-dose oral L-serine supplementation, annotated with Nutritional Support (NCIT:C15433). NCIT:C15433 is a clinical intervention from the NCI Thesaurus. Ontology label: Nutritional Support NCIT:C15433
Agent: L-serine CHEBI:17115 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses L-serine (CHEBI:17115). CHEBI:17115 is a therapeutic agent from Chemical Entities of Biological Interest.
The only disease-specific intervention reported, and its rationale follows directly from the mechanism. If the lesion is insufficient charging capacity for the demand, then raising the intracellular concentration of the substrate amino acid should drive the residual hypomorphic enzyme harder - a mass-action rescue rather than a correction of the defect. Chronic supplementation is described as established practice in SARS1 deficiency. What was new in 2026 is acute management: during a febrile decompensation with an ejection fraction of 20%, the patient's L-serine dose was progressively tripled alongside standard supportive care and he survived, where three untreated siblings had died of comparable episodes. That is the first documented survival of a SARS1 metabolic crisis. It is also, honestly, an n-of-1 with a fatal outcome a year later despite an emergency protocol - so the intervention is reported here as promising and mechanistically coherent, not as established efficacy.
Mechanism Target:
ACTIVATES Deficient Serylation of tRNA-Ser — Raising substrate availability is intended to drive the residual hypomorphic enzyme harder by mass action, partially restoring serylation flux. This is the intended target; it has not been demonstrated in SARS1 patient cells.
INHIBITS Demand-Dependent Decompensation During Febrile Catabolic Stress — Dose escalation during febrile illness is intended to raise charging capacity at the moment translational demand spikes, aborting the crisis.
Target Phenotypes: Cardiomyopathy HP:0001638 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Cardiomyopathy (HP:0001638). HP:0001638 is a phenotype from the Human Phenotype Ontology.
Show evidence (5 references)
PMID:42158840 SUPPORT Human Clinical
"While amino acid chronic supplementation is established, no guidelines exist for acute management."
Establishes that chronic amino acid supplementation is already standard in this disorder while acute management is not codified.
PMID:42158840 SUPPORT Human Clinical
"During hospitalisation, the patient's specific L-serine supplementation dosage was progressively tripled concurrently with standard supportive care."
Describes the intervention actually administered, without an absolute dose.
PMID:42158840 SUPPORT Human Clinical
"Unlike the fatal outcomes observed in his siblings, untreated by L-serine, the patient survived and recovered following this high-dose regimen"
The efficacy observation, stated as a within-family comparison, which is the strongest available evidence and is still n-of-1.
+ 2 more references
Emergency protocol for febrile illness
Category: Therapeutic Action: acute decompensation emergency protocolNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is acute decompensation emergency protocol, annotated with Supportive Care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Because febrile illness is the trigger for lethal decompensation, anticipatory management of intercurrent fever is the central chronic-care task in this disorder: early presentation, aggressive escalation of L-serine, and cardiac and haemodynamic monitoring during the episode. The 2026 report explicitly frames early, aggressive escalation as a viable strategy while noting that no guidelines exist. It also records the limit of the approach: the patient died in a subsequent crisis despite having an emergency protocol in place, so a protocol reduces but does not remove the risk.
Mechanism Target:
INHIBITS Demand-Dependent Decompensation During Febrile Catabolic Stress — Anticipatory management of the febrile trigger aims to prevent the demand-capacity mismatch from progressing to decompensation.
Show evidence (2 references)
PMID:42158840 SUPPORT Human Clinical
"The findings strongly suggest that early, aggressive escalation of L-serine dosage can be a viable therapeutic strategy for acute decompensation in SARS1 deficiency."
The authors' explicit recommendation, which is the basis for treating anticipatory febrile management as a therapeutic action.
PMID:42158840 SUPPORT Human Clinical
"This constitutes the first documented survival of a SARS1-related metabolic crisis managed with high-dose L-serine."
Marked PARTIAL: "first documented survival" simultaneously supports the strategy and discloses that the entire evidence base for it is one episode in one patient.
🔬

Diagnosis

4
Exome or genome sequencing with SARS1 variant interpretation
Molecular diagnosis rests on identifying SARS1 variants against transcript NM_006513.4 by exome or genome sequencing. Three interpretation points follow from the published allelic series. First, do not filter for biallelic hits only: one reported patient carried a de novo monoallelic dominant-negative allele, and a laboratory applying a strict recessive filter would have discarded it. Second, expect the ClinVar evidence to be weaker than the OMIM entry implies - the allele published as causal in the Turkish series is currently a variant of uncertain significance in ClinVar - so a SARS1 candidate will often need functional support rather than database endorsement. Third, since the two named genes SARS1 and SARS2 differ only by a digit and share the legacy symbol SARS, confirm from the transcript accession, not the symbol, which enzyme has been reported.
Show evidence (2 references)
PMID:28236339 SUPPORT Human Clinical
"we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene"
Establishes that the diagnosis is made by sequencing and that the gene of interest is the cytoplasmic, not the mitochondrial, seryl-tRNA synthetase.
PMID:36041817 SUPPORT Human Clinical
"A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site."
Supports the specific warning that a monoallelic de novo SARS1 event can be causal and must not be filtered out.
Serylation (aminoacylation) assay in patient fibroblasts
The functional confirmatory test for a candidate SARS1 variant. Serylation activity measured in patient-derived fibroblasts, alongside yeast complementation, is what established pathogenicity for the dominant-negative allele and is the assay that distinguishes a true hypomorph from an incidental rare missense change. In the published SARS1 cases it was performed in a research setting; this entry makes no claim about where it is available as a clinical service, because no cached source addresses that. Its value is highest precisely where the genomic evidence is weakest, which for this gene is most of the time.
Show evidence (2 references)
PMID:36041817 SUPPORT In Vitro
"Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
Documents the assay pair that was used to establish variant pathogenicity in patient material.
PMID:34570399 SUPPORT In Vitro
"This missense variant was shown to lead to protein instability, resulting in reduced protein level and enzymatic activity."
Shows that both protein level and enzyme activity are informative readouts for a candidate SARS1 allele.
Brain MRI
Brain MRI documents the structural correlates - bilateral diffuse cerebral and cerebellar atrophy - and supports the diagnosis in a child with microcephaly and ataxia. It does not distinguish SARS1 disease from the other recessive ARS deficiencies or from the many other causes of microcephaly with cerebellar atrophy, so its role is corroborative rather than discriminating.
Show evidence (1 reference)
PMID:36004946 SUPPORT Human Clinical
"Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy."
Names the specific imaging findings to be expected.
Cardiac assessment with echocardiography
Echocardiography with ejection fraction, together with cardiac biomarkers, is the surveillance test that matters most for prognosis in this disorder, and it is also the monitoring test during a febrile crisis. In the documented episode the ejection fraction fell to 20%, cardiac biomarkers normalised over about twenty days, and follow-up echocardiography at one month showed complete resolution of myocardial oedema - so serial imaging, not a single baseline study, is what captures the disease.
The specific follow-up timings (biomarker normalisation within 20 days, echocardiographic resolution at 1 month) are stated in the cached abstract of PMID:42158840 and are quoted below only in part; the recommendation to perform surveillance echocardiography in all SARS1 patients is a curatorial inference from the reported course and is not itself a published guideline. No surveillance protocol has been published for this disorder.
Show evidence (1 reference)
PMID:42158840 SUPPORT Human Clinical
"The clinical course rapidly progressed to metabolic decompensation and severe acute cardiac failure, characterised by a left ventricular ejection fraction of 20%, necessitating mechanical ventilation and vasopressor support"
Establishes the measurement (ejection fraction) that defines the acute cardiac emergency in this disorder.
📊

Prevalence

1
Worldwide
Cases In Literature Not yet documented
No prevalence or incidence estimate of any kind has been published for this disorder, and MONDO:0060577 carries no Orphanet xref, so there is no source to band and `rate_per_100000` is deliberately empty. `NOT_YET_DOCUMENTED` is used rather than a qualitative ultra-rare band for that reason. A total published case count is also deliberately not asserted: see the entry-level notes for why the individual reports cannot be summed from cached abstracts without double-counting. What can be said, and is quoted below, is that as of mid-2022 only two families had been reported, and that the reported families are Iranian and Turkish kindreds, the Turkish ones described as consanguineous - which reflects ascertainment through consanguinity-enriched autosomal-recessive intellectual-disability cohorts and must NOT be read as population restriction.
Show evidence (2 references)
PMID:36004946 SUPPORT Human Clinical
"So far, only two families with NEDMAS have been reported."
Establishes the scale of the published experience as of 2022, which is the basis for treating the disorder as ultra-rare and for declining to band a prevalence.
PMID:35790048 SUPPORT Human Clinical
"Seryl-tRNA synthetase 1 (SARS1) has rarely been implicated in an autosomal recessive developmental disorder."
Independent characterisation of the disorder as rarely reported, supporting NOT_YET_DOCUMENTED rather than any numeric estimate.
🔀

Differential Diagnoses

5

Conditions with similar clinical presentations that must be differentiated from SARS1-Related Neurodevelopmental Disorder:

HUPRA syndrome Not Yet Curated MONDO:0013458
Overlapping Features The paralogue trap, and the reason it is listed first. HUPRA syndrome is caused by SARS2, the MITOCHONDRIAL seryl-tRNA synthetase. The two genes encode enzymes that catalyse chemically the same reaction - serylation of tRNA-Ser - on two different tRNA pools in two different compartments, and their legacy symbols collide (HGNC lists "SARS" as an exact synonym of SARS2 as well as the former symbol of SARS1). A literature search, a variant report, or an automated gene-disease extraction that keys on the string "SARS" will merge them. Clinically they are not remotely similar: HUPRA is a mitochondrial oxidative-phosphorylation disorder of infancy with hyperuricaemia, pulmonary hypertension, progressive renal failure and metabolic alkalosis.
Distinguishing Features
  • Different gene and compartment - SARS1 (hgnc:10537) encodes the cytoplasmic enzyme, SARS2 (hgnc:17697) the mitochondrial one; a report naming only "SARS" must be resolved before use.
  • Different MONDO and OMIM entities - this disorder is MONDO:0060577 / OMIM:617709; HUPRA is MONDO:0013458 / OMIM:613845 / Orphanet:363694.
  • HUPRA is classified in MONDO under mitochondrial oxidative phosphorylation disorder and inherited renal tubular disease; SARS1 disease is a Mendelian neurodevelopmental disorder with no renal or pulmonary-vascular component reported.
  • The cardinal HUPRA features - hyperuricaemia, pulmonary hypertension, renal failure, metabolic alkalosis - have never been reported in a SARS1 patient; conversely microcephaly, ataxia and seizures are not the HUPRA phenotype.
  • ICIMD places the two in different groups - mitochondrial aminoacyl-tRNA synthetase disorders for SARS2, non-mitochondrial tRNA metabolism for SARS1.
Hypomyelinating leukodystrophy 3 Not Yet Curated MONDO:0009843
Overlapping Features A mechanistic rather than a bedside differential. AIMP1 encodes a non-catalytic scaffold component of the cytoplasmic multi-tRNA-synthetase complex, and its loss causes a recessive disorder with microcephaly, severe developmental failure and seizures. The founding SARS1 paper cites AIMP1 explicitly as the precedent that led its authors to propose tRNA-aminoacylation integrity as a general requirement for human cognition. The pair therefore anchors the argument that lesions anywhere in the cytoplasmic aminoacylation apparatus - catalytic subunit or scaffold - converge on a neurodevelopmental phenotype.
Distinguishing Features
  • Different gene - AIMP1 is hgnc:10648; AIMP1 is a scaffold protein of the multi-synthetase complex, not a synthetase, and has no aminoacylation activity of its own.
  • Hypomyelination is the defining MRI feature of HLD3; the SARS1 imaging phenotype reported to date is diffuse cerebral and cerebellar atrophy, not a hypomyelinating pattern.
  • Onset and severity are commonly said to differ, with HLD3 the earlier and more severe of the two, but no source cached for this entry states patient age, onset age or survival for either condition, so this contrast is background rather than a usable discriminator.
  • Cardiomyopathy and fever-triggered metabolic decompensation are reported in SARS1 disease and are not features of HLD3.
Show evidence (1 reference)
PMID:28236339 SUPPORT Human Clinical
"three genes with a role in tRNA-aminoacylation are now associated with this condition"
The founding authors place SARS alongside AIMP1 and WARS2 as members of one aminoacylation-related disease group, which is the basis for this mechanistic differential.
Other recessive cytoplasmic aminoacyl-tRNA synthetase deficiencies
Overlapping Features Not a single disease but the class this disorder belongs to, and in practice the differential a metabolic physician actually faces. Recessive deficiencies of AARS1, DARS1, GARS1, HARS1, IARS1, KARS1, LARS1, MARS1, QARS1, RARS1, VARS1 and YARS1 share a phenotype template with SARS1 deficiency: abnormalities of the central nervous system and/or the senses in all thirteen of the deficiencies surveyed - a compound category, not a claim about the CNS alone - plus failure to thrive, gastrointestinal symptoms, dysmaturity, liver disease and facial dysmorphism recurring across the group, with symptoms concentrated in the first year of life and during infections. Because the clinical picture does not identify the gene, the practical route to diagnosis is a broad sequencing approach rather than a targeted one, and the practical route to management - adequate protein and amino acid supply rather than protein restriction - is shared across the class.
Distinguishing Features
  • The clinical phenotypes of the recessive ARS deficiencies are described as diverse and without apparent logic; they are not separable at the bedside and the distinction is molecular.
  • Pulmonary alveolar proteinosis points towards MARS1, IARS1 or LARS1 rather than SARS1; it has not been reported in SARS1 disease.
  • Prominent liver disease points away from SARS1, in which hepatic involvement has not been reported.
  • Microcephaly as the leading feature narrows the group towards SARS1 and WARS1.
  • Fever-triggered decompensation is a class feature rather than a SARS1-specific one, so its presence does not identify the gene.
Show evidence (2 references)
PMID:29875423 SUPPORT Human Clinical
"In literature, we identified 107 patients with AARS, DARS, GARS, HARS, IARS, KARS, LARS, MARS, RARS, SARS, VARS, YARS, and QARS deficiencies"
Enumerates the class of recessive cytoplasmic synthetase deficiencies that constitutes this differential, with SARS among them.
PMID:29875423 SUPPORT Human Clinical
"Clinical features of autosomal recessive ARS deficiencies appear very diverse and without apparent logic."
Supports the claim that the class cannot be separated on clinical grounds, which is why the differential is handled by sequencing rather than by phenotyping.
🐁

Animal Models

1
adrasteia (adr) mutants; sars (seryl-tRNA synthetase) loss of function Danio rerio Forward-genetic mutant isolated in a vascular screen
The zebrafish sars mutants are the only established animal model of the gene, and they are NOT a model of this disease - a distinction this entry insists on. They were recovered in a screen for vascular development and maintenance, and their phenotype is vascular: pronounced dilatation of the aortic arch vessels, aberrant patterning of hindbrain capillaries, and to a lesser extent altered intersomitic vessels, with the aortic dilatation dependent on Vegf signalling rather than on increased cell proliferation. Positional cloning identified seryl-tRNA synthetase as the affected gene, and siRNA knockdown in human umbilical vein endothelial cells showed the same regulation of endothelial sprouting. The model therefore validates the non-canonical, VEGFA-related function of SerRS at the organism level. It says nothing about microcephaly, ataxia, seizures, cardiomyopathy or febrile decompensation, and no vascular malformation has ever been reported in a human SARS1 patient. The consequence of that gap - that this disorder has no animal or cellular disease model at all, and what a usable one would have to capture - is worked through in the HUMAN_MODEL_MISMATCH discussion `sars1-no-disease-model`, which proposes the knock-in mouse and patient-derived cortical organoid experiments that would close it.
Dilatation of the aortic arch vessels Aberrant hindbrain capillary patterning Altered intersomitic vessel patterning
Species
Danio rerio
Genotype
adrasteia (adr) mutants; sars (seryl-tRNA synthetase) loss of function
Genes
SARS1 hgnc:10537 HUGO Gene Nomenclature Committee (hgnc) Relation: this experimental model concerns this gene This experimental model concerns SARS1 (hgnc:10537). hgnc:10537 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (4 references)
PMID:19423847 SUPPORT Model Organism
"By positional cloning, we isolated seryl-tRNA synthetase (sars) as the gene affected by the adr mutations"
Establishes that the adrasteia mutants are seryl-tRNA synthetase mutants, which is what makes them a model of this gene.
PMID:19423847 SUPPORT Model Organism
"This dilatation of the aortic arch vessels does not appear to be caused by increased cell proliferation but is dependent on vascular endothelial growth factor (Vegf) signaling"
Shows the mutant phenotype is Vegf-dependent, which is why the model speaks to the non-canonical rather than the translational function.
PMID:19423847 SUPPORT Model Organism
"These analyses of zebrafish and human endothelial cells reveal a new noncanonical function of Sars in endothelial development"
Marked PARTIAL with respect to this disease. The finding is solid, but what it establishes is a noncanonical endothelial function, which is precisely the arm of SerRS biology whose relevance to the human neurodevelopmental disorder is unestablished.
+ 1 more reference
{ }

Source YAML

click to show 
name: SARS1-Related Neurodevelopmental Disorder
creation_date: "2026-08-01T00:00:00Z"
category: Mendelian
disease_term:
  preferred_term: neurodevelopmental disorder with microcephaly, ataxia, and seizures
  term:
    id: MONDO:0060577
    label: neurodevelopmental disorder with microcephaly, ataxia, and seizures
description: >-
  Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS)
  is the single MONDO entity for germline disease caused by variants in SARS1,
  the gene encoding the CYTOPLASMIC seryl-tRNA synthetase (SerRS). SerRS is a
  homodimeric class II aminoacyl-tRNA synthetase that charges serine onto
  tRNA-Ser in a two-step reaction - serine plus ATP to enzyme-bound
  serine-adenylate, then transfer of the seryl moiety to the tRNA - and it also
  serylates the selenocysteine-specific tRNA-Sec, so it stands at the entry
  point of both general cytoplasmic translation and selenoprotein synthesis.
  Every SARS1 allele whose structural position has been published in the clinical
  literature sits in or immediately adjacent to the catalytic core - though
  ClinVar additionally holds a likely-pathogenic in-frame insertion inside the
  C-terminal UNE-S appendage for which no publication could be found - and the
  functional consequence measured in patient material has consistently been the
  same: reduced enzyme abundance and/or reduced serylation activity. The disorder therefore belongs squarely to
  the recessive aminoacyl-tRNA-synthetase (ARS) deficiency family, whose
  proposed unifying mechanism is that residual aminoacylation is sufficient at
  baseline but insufficient to meet translational demand in the organs and life
  periods with the highest protein-synthesis rates. That single premise accounts
  for a phenotype that otherwise looks incoherent: microcephaly with cerebral
  and cerebellar atrophy, moderate intellectual
  disability, ataxia, seizures, muscle weakness and a thin body habitus in the
  originally described families; and, with a different allele, developmental
  delay with central deafness, cardiomyopathy and life-threatening metabolic
  decompensation triggered by fever. The MONDO label names only the first
  presentation, which materially understates the entity - the deafness and
  cardiomyopathy presentation is filed against the same MONDO/OMIM term, and a
  further individual with a de novo, dominant-negative allele presented with
  complex spastic paraplegia and no microcephaly at all. SerRS additionally has
  well-documented non-canonical nuclear activities (repression of VEGFA
  transcription via its UNE-S nuclear localisation signal, and telomere binding
  with POT1); whether these contribute to the human disease has never been
  tested in patient material, and this entry treats the loss-of-charging route
  as the supported mechanism and the moonlighting route as an explicit open
  question rather than smoothing the two together. The disorder is ultra-rare:
  the entire published clinical literature is a handful of families - the Turkish
  family of the deafness-cardiomyopathy report explicitly consanguineous, the
  others not described as such in their abstracts - and single cases.
parents:
- Neurodevelopmental Disorder
- Inborn Error of Metabolism
synonyms:
- NEDMAS
- neurodevelopmental disorder with microcephaly, ataxia, and seizures
- SARS1 deficiency
- seryl-tRNA synthetase 1 deficiency
- cytoplasmic seryl-tRNA synthetase deficiency
- SARS1-related developmental disorder
classifications:
  harrisons_chapter:
  - classification_value: NEUROLOGIC
    notes: >-
      The defining and universal morbidity is central-nervous-system: microcephaly,
      moderate intellectual disability, global developmental delay, ataxia,
      tonic-clonic seizures and cerebral plus cerebellar atrophy on imaging. The
      chapter assignment is nonetheless not entirely comfortable, and the reason
      is recorded here rather than hidden. In the deafness-and-cardiomyopathy
      presentation, febrile metabolic decompensation is fatal, and in the one
      episode reported in detail (PMID:42158840) the terminal event was
      cardiogenic shock - so a purely neurological framing would miss the feature
      that actually determines survival. A single
      Harrison's chapter is required, and the neurological features are the ones
      present in every reported individual across every family, so NEUROLOGIC is
      assigned and the cardiac involvement is curated as a phenotype and a
      pathophysiology node instead.
    evidence:
    - reference: PMID:36004946
      reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
      explanation: Enumerates the phenotype as predominantly neurological, which is the basis for the NEUROLOGIC chapter assignment.
  icimd_category:
  - classification_value: non_mitochondrial_trna_metabolism
    notes: >-
      ICIMD (Ferreira et al. 2021) places cytoplasmic aminoacyl-tRNA synthetase
      defects under "Disorders of non-mitochondrial tRNA metabolism", within the
      nucleobase/nucleotide/nucleic-acid super-domain. This is the classification
      slot where the SARS1 / SARS2 distinction is machine-visible: SARS2, the
      mitochondrial seryl-tRNA synthetase, would take the separate ICIMD group
      "Disorders of mitochondrial aminoacyl-tRNA synthetases". The two are
      different genes, different compartments, different tRNA pools and different
      diseases.
notes: >-
  Entity verification, run before any content was written. `runoak -i
  sqlite:obo:mondo info MONDO:0060577 -O obo` returns name "neurodevelopmental
  disorder with microcephaly, ataxia, and seizures", synonym NEDMAS, xrefs
  OMIM:617709, MEDGEN:1613354, GARD:0022576, UMLS:C4540188, parent MONDO:0100500
  (Mendelian neurodevelopmental disorder), and `relationship: RO:0004003
  HGNC:10537 ! SARS1`. `runoak -i sqlite:obo:mondo relationships --direction down
  -p RO:0004003 HGNC:10537` returns exactly one disease, MONDO:0060577, so MONDO
  has not split the SARS1 phenotype and this entry is the whole gene's germline
  disease space. `runoak -i sqlite:obo:hgnc info hgnc:10537 -O obo` confirms
  symbol SARS1, name "seryl-tRNA synthetase 1", Entrez 6301, Ensembl
  ENSG00000031698, UniProt P49591, EC 6.1.1.11, gene MIM 607529, with alias
  symbols SERS, "seryl-tRNA synthetase" and "serine tRNA ligase 1, cytoplasmic".
  That alias list matters for reading the literature: the founding clinical paper
  and all the pre-2019 mechanistic work call the gene SARS, not SARS1, and the
  protein SerRS.

  Named Entity Confusion - the trap for this gene, and what was done about it.
  The obvious NEC risk is SARS2, the MITOCHONDRIAL seryl-tRNA synthetase, whose
  disease is HUPRA syndrome. That contrast was verified with OAK before being
  named anywhere in this entry rather than typed from memory: `runoak -i
  sqlite:obo:hgnc search "SARS2"` returns hgnc:17697, whose definition is
  "seryl-tRNA synthetase 2, mitochondrial" (note it also carries the EXACT
  synonym "SARS", which is precisely how a literature search collides); and
  `runoak -i sqlite:obo:mondo info MONDO:0013458 -O obo` returns
  hyperuricemia-pulmonary hypertension-renal failure-alkalosis syndrome, synonym
  "HUPRA syndrome", xref OMIM:613845 and Orphanet:363694, with `RO:0004003
  HGNC:17697 ! SARS2` and parents including mitochondrial oxidative
  phosphorylation disorder. Different HGNC ID, different OMIM number, different
  MONDO term, different compartment, different disease. HUPRA is curated below as
  a mechanistic contrast, not as a source of content, and no HUPRA literature was
  used for any claim in this file.

  Two further NEC risks were checked and are recorded because they nearly cost
  content. First, the founding publication (PMID:28236339) reports TWO genes in
  TWO unrelated Iranian families: SARS in family 1 and WARS2 - the MITOCHONDRIAL
  tryptophanyl-tRNA synthetase - in family 2. Only the family 1 material belongs
  to this entry. The WARS2 family is a different MONDO entity, verified as
  MONDO:0060578 (neurodevelopmental disorder, mitochondrial, with abnormal
  movements and lactic acidosis, with or without seizures; OMIM:617710;
  `RO:0004003 HGNC:12730 ! WARS2`), and every snippet taken from PMID:28236339 in
  this file was checked to be about the SARS family and not the WARS2 family.
  Second, PMID:35790048 reports "five individuals with biallelic missense
  variants in WARS1 or SARS1" without splitting the count in the abstract; the
  cytoplasmic WARS1 recessive disorder is a separate verified entity
  (MONDO:0957218, OMIM:620317, `RO:0004003 HGNC:12729 ! WARS1`), so that paper is
  quoted only for statements that are explicitly about SARS1 or about both genes
  jointly, and NO per-patient count is attributed to SARS1 from it.

  Third NEC risk, and the reason a plain PubMed search on this gene is
  dangerous: the token "SARS" retrieves the coronavirus literature, and "SARS1"
  additionally retrieves oncology biomarker papers (invasive lobular carcinoma,
  head and neck squamous cell carcinoma) that are expression-correlation studies
  with no germline disease content. Searches were therefore run as SARS1 or
  "seryl-tRNA synthetase" conjoined with microcephaly / intellectual disability /
  ataxia / seizures / aminoacylation, and each hit was read before use. All
  disease papers used here name SARS1 or SARS as the causal gene.

  Scope decision, and it is a real decision rather than a formality. MONDO gives
  SARS1 one disease term, but the published phenotype has three faces: (i) the
  microcephaly-ataxia-seizure presentation of the Iranian and Turkish families
  that gives the term its name; (ii) developmental delay with central deafness,
  cardiomyopathy and fatal febrile metabolic decompensation (PMID:34570399,
  PMID:42158840); and (iii) complex spastic paraplegia WITHOUT microcephaly from
  a de novo dominant-negative allele (PMID:36041817). ClinVar was consulted to
  test whether (ii) is filed as the same condition: the Musante allele
  c.514G>A (p.Asp172Asn, VCV000440921) and the Ravel allele c.638G>T
  (p.Arg213Leu, VCV001209576) are BOTH recorded against the condition
  "Neurodevelopmental disorder with microcephaly, ataxia, and seizures"
  (E-utilities query, retrieved 2026-08-01). This entry therefore curates the
  whole SARS1 germline spectrum under this term, and says explicitly wherever a
  feature belongs to one presentation and not another. The alternative - curating
  only the microcephaly presentation - would have left the only treatable and the
  only lethal feature of the disorder out of the knowledge base.

  Cohort arithmetic, deliberately not totalled. The published individuals cannot
  be summed reliably from cached abstracts, and no total is asserted anywhere in
  this entry. PMID:28236339 describes one Iranian family; the HPO annotation set
  for OMIM:617709 gives denominators of 4 for that family, sourced to
  PMID:28236339 (retrieved 2026-08-01 from
  https://ontology.jax.org/api/network/annotation/OMIM:617709), and the abstract
  itself gives no count. PMID:34570399 describes "children" in one consanguineous
  Turkish family without a number in the abstract. PMID:36004946 states "three
  unrelated Turkish families with four NEDMAS patients" but then says "both
  patients carried" the variant - an internal inconsistency in the abstract that
  is recorded here rather than resolved by guesswork, since the full text is not
  cached. PMID:35790048 gives five individuals across WARS1 AND SARS1 combined.
  PMID:36041817 is one patient. PMID:42158840 is one patient (from the family of
  PMID:34570399, on the internal evidence of Turkish origin, shared authorship
  from Nancy, and three siblings dead of febrile crises) plus a literature review
  whose contents are not in the cached abstract. Adding these would double-count.

  Frequency bands are omitted from every phenotype for the same reason. Where
  HPO annotation fractions exist they are recorded verbatim in each phenotype's
  `notes:` with their denominator and source, which is more informative and less
  falsifiable than a FrequencyEnum band derived from a single family.

  Structured-source evidence was unavailable. `data/orphadata/` and
  `data/clingen/` in this checkout contain only `MANIFEST.yaml` with no
  downloaded payload; a literal `grep -l "SARS1" references_cache/CGGV_*.md`
  across the 479 cached ClinGen assertions returned nothing, and MONDO:0060577
  carries no Orphanet xref. So no Orphanet prevalence class and no ClinGen
  gene-disease validity classification could be consulted. Per the scope rules
  the manifests were not touched. This is a gap, not an assertion that no such
  classification exists.

  A search for a GeneReviews chapter covering SARS1, performed on 2026-08-01,
  returned none; that is a statement about the search, not a guarantee that no
  chapter exists. No animal model
  of the human disease was found in the sources consulted: the zebrafish sars mutants that exist
  (PMID:19423847) were isolated for a VASCULAR phenotype and are curated below as
  a model of the gene's non-canonical function, explicitly NOT as a model of this
  neurodevelopmental disorder.

  Only abstracts are cached for PMID:28236339, PMID:36004946, PMID:34570399,
  PMID:35790048, PMID:36041817, PMID:42158840 and PMID:38255739; full text is
  cached for PMID:24095058, PMID:29875423, PMID:22353712, PMID:19423847 and
  PMID:27913726. Every claim sourced from a full text rather than an abstract is
  quoted from the cached body, and everything that could not be quoted from a
  cached file is in a `notes:` block rather than in an evidence snippet.
inheritance:
- name: Autosomal recessive inheritance
  description: >-
    The dominant mode by a wide margin. Every family in the microcephaly and in
    the cardiomyopathy presentations was recessive: a homozygous missense allele
    in the Iranian family, and biallelic c.638G>T (p.Arg213Leu) in
    the consanguineous Turkish family. For the recessive ARS deficiencies as a
    class, the ARS review states that heterozygous parents of patients are
    unaffected and reads that as evidence of excess capacity in ARS activity - the
    central quantitative claim of the family: one functional allele supplies enough
    aminoacylation capacity, and disease requires that both alleles be damaged while
    still leaving some residual activity, because complete loss of a cytoplasmic
    aminoacyl-tRNA synthetase is not compatible with life. No cached SARS1 paper
    reports the phenotype of any SARS1 carrier parent directly, so the carrier
    statement is inherited from the class and not from a SARS1 observation.

    Penetrance is recorded as UNKNOWN rather than COMPLETE. Every reported
    biallelic individual is affected, but every reported biallelic individual was
    ascertained because they were affected, and the total number of families is
    in single figures. There is no population-scale genotype-first data for any
    SARS1 allele, so a penetrance claim of any kind would be an artefact of
    ascertainment. The HPO annotation set for OMIM:617709 records HP:0000007
    (autosomal recessive inheritance) sourced to PMID:28236339 (retrieved
    2026-08-01) and no dominant inheritance annotation, which is consistent with
    the dominant-negative case (PMID:36041817) postdating the annotation rather
    than contradicting it.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  penetrance: UNKNOWN
  evidence:
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene"
    explanation: A homozygous missense allele segregating in a single family is the founding evidence for autosomal recessive inheritance at this locus, and names the compartment (cytoplasmic) that distinguishes SARS1 from SARS2.
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
    explanation: Independent recessive family with a different biallelic allele, confirming the inheritance mode in a second, phenotypically distinct presentation.
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seryl-tRNA synthetase 1 (SARS1) has rarely been implicated in an autosomal recessive developmental disorder."
    explanation: Independent statement of the inheritance mode from a third group, in a paper reporting a further SARS1 family.
  - reference: PMID:29875423
    reference_title: "Aminoacyl-tRNA synthetase deficiencies in search of common themes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The fact that heterozygous parents of patients are unaffected suggests that on the other hand there is some excess capacity in ARS activity."
    explanation: Sources the carrier statement to the recessive ARS deficiency class rather than to a SARS1-specific observation, and states the excess-capacity reading it licenses.
- name: Autosomal dominant inheritance
  description: >-
    A single reported exception, and it is mechanistically informative rather
    than a nosological nuisance. One patient carried a DE NOVO splice-site
    deletion producing a five-amino-acid in-frame insertion near the active site,
    and complementation in Saccharomyces cerevisiae plus serylation assays in
    both yeast and the patient's own fibroblasts showed the allele to be not
    merely loss-of-function but DOMINANT NEGATIVE. Because SerRS is an obligate
    homodimer, a catalytically dead subunit that still dimerises poisons the
    wild-type subunit it partners, so a single such allele can drop total cellular
    serylation below the threshold that one intact recessive allele comfortably
    supports. That patient's phenotype was also different: complex spastic
    paraplegia with ataxia, intellectual disability, developmental delay and
    seizures, but explicitly WITHOUT microcephaly.

    Recorded because the mode of inheritance for this gene cannot be stated as
    autosomal recessive without qualification, and a diagnostic laboratory that
    filters SARS1 for biallelic hits only will miss this class of allele. It rests
    on a single published patient. The homodimer-poisoning rationale above is the
    standard interpretation of a dominant-negative allele in an obligate-dimeric
    class II synthetase and is consistent with the cited assays, but the specific
    claim that the mutant subunit heterodimerises with wild-type SerRS was not
    itself demonstrated in that paper and is therefore reasoning, not a finding.
    Penetrance is UNKNOWN on a single case.
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  penetrance: UNKNOWN
  evidence:
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site."
    explanation: Establishes a de novo, monoallelic SARS1 event as a cause of disease at this locus.
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
    explanation: Functional demonstration that the de novo allele acts dominant-negatively, which is what makes a monoallelic genotype sufficient for disease.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: NOT_YET_DOCUMENTED
  notes: >-
    No prevalence or incidence estimate of any kind has been published for this
    disorder, and MONDO:0060577 carries no Orphanet xref, so there is no source to
    band and `rate_per_100000` is deliberately empty. `NOT_YET_DOCUMENTED` is used
    rather than a qualitative ultra-rare band for that reason. A total published
    case count is also deliberately not asserted: see the entry-level notes for
    why the individual reports cannot be summed from cached abstracts without
    double-counting. What can be said, and is quoted below, is that as of mid-2022
    only two families had been reported, and that the reported families are
    Iranian and Turkish kindreds, the Turkish ones described as consanguineous -
    which reflects ascertainment
    through consanguinity-enriched autosomal-recessive intellectual-disability
    cohorts and must NOT be read as population restriction.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "So far, only two families with NEDMAS have been reported."
    explanation: Establishes the scale of the published experience as of 2022, which is the basis for treating the disorder as ultra-rare and for declining to band a prevalence.
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seryl-tRNA synthetase 1 (SARS1) has rarely been implicated in an autosomal recessive developmental disorder."
    explanation: Independent characterisation of the disorder as rarely reported, supporting NOT_YET_DOCUMENTED rather than any numeric estimate.
pathophysiology:
- name: Damaging SARS1 Alleles in the Catalytic Core
  biological_scale: MOLECULAR
  description: >-
    The primary lesion is damage to SARS1 at 1p13.3, reported against transcript
    NM_006513.4. What is striking about the allelic series is its positional
    consistency: the founding homozygous missense c.514G>A (p.Asp172Asn) was
    described as affecting the enzymatic core domain; the variant reported by
    Bogershausen and colleagues was mapped structurally to a position directly
    within the enzyme's active site; the de novo splice-site deletion reported by
    Verdura and colleagues produces a five-residue in-frame insertion near the
    active site. Every allele reported in the clinical literature with a published
    structural position therefore
    converges on the aminoacylation machinery rather than on the tRNA-binding
    domain, the dimer interface or the vertebrate-specific UNE-S appendage. This
    is the single most important structural observation in the entry, because it
    is what licenses reading the disorder as a charging defect rather than as a
    defect of one of SerRS's non-canonical activities.
  genes:
  - preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  mechanism_confidence: ESTABLISHED
  notes: >-
    Three qualifications. First, "converges on the catalytic core" is a statement
    about the alleles whose position has been published in the clinical
    literature, not about all alleles:
    ClinVar holds SARS1 entries whose position and effect are unannotated, and the
    Karaer allele c.1196C>T (p.Thr399Met) has no published structural mapping.
    Second, there is a known counterexample outside the published series:
    VCV004529504, c.1483GCA[4] p.Ala497_Arg498insAla, is classified Likely
    pathogenic for this condition in ClinVar and its residues fall inside the
    C-terminal UNE-S appendage (F470-A514 in PMID:22353712), not in the catalytic
    core. No publication for that record could be found, so it is not part of the
    allelic series above, but it is recorded here so that the convergence claim is
    not read as exceptionless.
    Third, the position of an allele is not by itself evidence of its mechanism;
    the mechanistic weight in this entry is carried by the enzyme-activity and
    protein-abundance measurements in the downstream nodes, not by position alone.
  evidence:
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mutation affects the enzymatic core domain of the protein and impairs its enzymatic activity, probably leading to reduced cytoplasmic tRNASer concentrations."
    explanation: Places the founding allele in the enzymatic core and states the immediate functional consequence, which is the starting point of the causal chain modelled below.
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Structural mapping showed that the SARS1 variant is located directly within the enzyme's active site, most likely diminishing activity, while the WARS1 variant is located in the N-terminal domain."
    explanation: Independent structural mapping of a second SARS1 allele into the active site, establishing the positional convergence of the allelic series.
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site."
    explanation: A third allele, of a different class and a different inheritance mode, again located at the active site.
  downstream:
  - target: Reduced SerRS Protein Stability and Steady-State Abundance
    description: >-
      The abundance arm. Both the p.Asp172Asn and the p.Arg213Leu missense alleles
      were shown to destabilise the protein, so less enzyme is present before any
      question of per-molecule catalytic competence arises.
  - target: Deficient Serylation of tRNA-Ser
    description: >-
      The catalytic arm. Active-site alleles reduce the specific activity of the
      enzyme that is present, independently of how much of it there is.
  - target: Dominant-Negative Poisoning of the SerRS Homodimer
    description: >-
      The allele-specific arm. The de novo in-frame insertion acts dominant
      negatively, which is a property of the allele rather than a consequence of
      reduced total protein, and so branches directly from the variant node.
- name: Reduced SerRS Protein Stability and Steady-State Abundance
  biological_scale: MOLECULAR
  description: >-
    Two independently reported missense alleles reduce the amount of SerRS in the
    cell rather than only its per-molecule activity. The founding p.Asp172Asn
    allele was predicted to be unstable and this was substantiated for ectopically
    expressed mutant protein in transfected HEK293T cells; the p.Arg213Leu allele
    was shown to cause protein instability with a consequent fall in both protein
    level and enzymatic activity. Instability is the commonest single mechanism
    across the recessive ARS deficiencies and it has a specific consequence for
    this disease: the deficit is in total cellular charging CAPACITY, which is
    exactly the quantity that a rise in translational demand can outstrip.
  genes:
  - preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  molecular_functions:
  - preferred_term: serine-tRNA ligase activity
    modifier: DECREASED
    term:
      id: GO:0004828
      label: serine-tRNA ligase activity
  cellular_components:
  - preferred_term: cytosol
    term:
      id: GO:0005829
      label: cytosol
  cell_types:
  - preferred_term: patient-derived dermal fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  mechanism_confidence: ESTABLISHED
  notes: >-
    Evidence quality differs between the two alleles and the difference is worth
    keeping. For p.Asp172Asn the demonstration was in ectopically expressed
    protein in a transfected immortalised cell line, not in patient cells, so it
    establishes that the substitution destabilises the protein but not the
    steady-state level in a patient neuron. For p.Arg213Leu the reported result is
    reduced protein level together with reduced activity. Neither report is a
    measurement in human brain.
  evidence:
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The mutant protein was predicted to be unstable, which could be substantiated by investigating ectopic mutant SARS in transfected HEK293T cells."
    explanation: Experimental support that the founding allele destabilises SerRS protein.
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "This missense variant was shown to lead to protein instability, resulting in reduced protein level and enzymatic activity."
    explanation: Independent demonstration, for a second allele, that instability lowers both protein abundance and enzyme activity - the two quantities that together define charging capacity.
  downstream:
  - target: Deficient Serylation of tRNA-Ser
    description: Less enzyme present means less serine charged per unit time, regardless of the intrinsic catalytic competence of each molecule.
- name: Deficient Serylation of tRNA-Ser
  biological_scale: MOLECULAR
  description: >-
    The convergent molecular defect. SerRS is a homodimeric class II synthetase
    that catalyses aminoacylation in two steps - serine is first activated by ATP
    to form enzyme-bound serine-adenylate, then the seryl moiety is transferred to
    the 3' end of the cognate tRNA to give Ser-tRNA-Ser for delivery to the
    ribosome. Its recognition strategy is unusual and relevant here: unlike most
    synthetases SerRS does not read the anticodon but recognises the long variable
    arm unique to tRNA-Ser, and each subunit's N-terminal tRNA-binding domain
    directs the tRNA 3'-CCA end into the active site of the OTHER subunit, so the
    functional unit is the dimer rather than the monomer. Motifs 2 and 3 of the
    class II fold carry the active-site residues; motif 1 forms the dimer
    interface. Patient-derived material shows the predicted outcome: serylation
    assays in patient fibroblasts were used to demonstrate loss of function, and
    the founding report inferred reduced cytoplasmic tRNA-Ser charging directly
    from the impaired enzymatic activity of the mutant.
  genes:
  - preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  molecular_functions:
  - preferred_term: serine-tRNA ligase activity
    modifier: DECREASED
    term:
      id: GO:0004828
      label: serine-tRNA ligase activity
  biological_processes:
  - preferred_term: seryl-tRNA aminoacylation
    modifier: DECREASED
    term:
      id: GO:0006434
      label: seryl-tRNA aminoacylation
  - preferred_term: tRNA aminoacylation for protein translation
    modifier: DECREASED
    term:
      id: GO:0006418
      label: tRNA aminoacylation for protein translation
  chemical_entities:
  - preferred_term: L-serine
    term:
      id: CHEBI:17115
      label: L-serine
  - preferred_term: ATP
    term:
      id: CHEBI:15422
      label: ATP
  cell_types:
  - preferred_term: patient-derived dermal fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:24095058
    reference_title: "Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "catalyzes the aminoacylation reaction that charges serine onto its cognate tRNA for protein synthesis"
    explanation: States the canonical function of the gene product whose loss defines this node.
  - reference: PMID:24095058
    reference_title: "Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "serine is activated by ATP to form serine-adenylate (Ser-AMP) as the enzyme-bound reaction intermediate"
    explanation: Defines the first chemical step and the role of ATP and serine as substrates, which is what an active-site variant perturbs.
  - reference: PMID:24095058
    reference_title: "Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The dimeric SerRS belongs to class II tRNA synthetases"
    explanation: Establishes the obligate-dimer architecture, which is the structural precondition for a dominant-negative allele at this locus.
  - reference: PMID:24095058
    reference_title: "Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "motif 1 forms the dimer interface while motifs 2 and 3 contains active site residues critical for aminoacylation"
    explanation: Locates the catalytic residues within the class II fold, which is where the patient alleles map.
  - reference: PMID:24095058
    reference_title: "Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Unlike most other tRNA synthetases, SerRS does not identify the anticodon, but instead recognizes the long variable arm that is unique to tRNASer"
    explanation: Explains the substrate-recognition strategy, and why the enzyme serves a family of isoacceptors defined by an arm rather than by a codon.
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mutation affects the enzymatic core domain of the protein and impairs its enzymatic activity, probably leading to reduced cytoplasmic tRNASer concentrations."
    explanation: Directly asserts impaired enzymatic activity and inferred reduction in charged cytoplasmic tRNA-Ser for a patient allele.
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
    explanation: Serylation measured in the patient's own fibroblasts, which is the most direct available demonstration that the charging reaction itself is impaired in human patient material.
  downstream:
  - target: Insufficient Aminoacylation Capacity for Translational Demand
    description: A smaller pool of charged tRNA-Ser sets a ceiling on the rate at which the cytoplasmic ribosome can elongate serine-containing nascent chains.
  - target: Impaired Selenocysteine Incorporation
    description: >-
      A second, parallel and untested consequence: tRNA-Sec must be serylated by
      the same enzyme before it can be converted to selenocysteinyl-tRNA-Sec.
- name: Dominant-Negative Poisoning of the SerRS Homodimer
  biological_scale: MOLECULAR
  description: >-
    An allele-specific route to the same endpoint. The de novo splice-site
    deletion reported in the spastic paraplegia patient yields a five-residue
    in-frame insertion near the active site, and complementation and serylation
    assays established that this allele is not simply inactive but dominant
    negative - that is, its presence reduces the activity attainable by the
    wild-type allele in the same cell. This node exists separately from the
    loss-of-abundance node because the two predict different things. Under simple
    haploinsufficiency a carrier of one null allele would be unaffected, which is
    what is observed for the recessive families; under dimer poisoning a single
    allele suffices, which is what is observed here.
  genes:
  - preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  molecular_functions:
  - preferred_term: serine-tRNA ligase activity
    modifier: DECREASED
    term:
      id: GO:0004828
      label: serine-tRNA ligase activity
  cell_types:
  - preferred_term: patient-derived dermal fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  mechanism_confidence: PROVISIONAL
  notes: >-
    Marked PROVISIONAL, on one patient and one allele. The dominant-negative
    effect itself is a published experimental result, but the structural
    interpretation offered here - that a catalytically dead subunit heterodimerises
    with and inactivates its wild-type partner - is inference from the known
    obligate-dimer architecture of class II SerRS and was not directly tested. An
    alternative reading, that the in-frame insertion sequesters tRNA-Ser
    unproductively, is not excluded by the published data.
  evidence:
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
    explanation: The primary evidence that this allele class acts dominant-negatively rather than by simple loss of one gene copy.
  downstream:
  - target: Insufficient Aminoacylation Capacity for Translational Demand
    description: Dimer poisoning lowers total cellular serylation capacity by the same final common route as biallelic hypomorphism.
  - target: Cellular Senescence with a Senescence-Associated Secretory Phenotype
    description: >-
      Patient fibroblasts carrying this allele arrest and senesce, which is the
      only cell-autonomous consequence of a SARS1 variant demonstrated in human
      patient cells to date.
- name: Insufficient Aminoacylation Capacity for Translational Demand
  biological_scale: CELLULAR
  description: >-
    The organising hypothesis of the whole recessive ARS deficiency family, and
    the reason this disorder's phenotype is not arbitrary. Aminoacylation is the
    committed first step of protein synthesis: the synthetase ligates the amino
    acid to its cognate tRNA, and the resulting aminoacyl-tRNA is handed to
    ribosome elongation factors. A hypomorphic synthetase leaves a cell able to
    translate at rest but unable to scale, so the deficit manifests wherever and
    whenever translational demand is highest - in the tissues with the highest
    amino-acid incorporation rates and during the periods of highest demand, which
    are early growth and intercurrent illness. Fuchs and colleagues reached this
    formulation from the whole recessive ARS cohort, in which SARS was one of the
    thirteen synthetase deficiencies analysed, and drew from it the clinically
    consequential corollary that patients need adequate protein and amino acid
    supply rather than the traditional protein restriction of metabolic disease.
  biological_processes:
  - preferred_term: cytoplasmic translation
    modifier: DECREASED
    term:
      id: GO:0002181
      label: cytoplasmic translation
  - preferred_term: tRNA aminoacylation for protein translation
    modifier: DECREASED
    term:
      id: GO:0006418
      label: tRNA aminoacylation for protein translation
  cellular_components:
  - preferred_term: cytosol
    term:
      id: GO:0005829
      label: cytosol
  mechanism_confidence: PROVISIONAL
  notes: >-
    Marked PROVISIONAL for this specific disease rather than ESTABLISHED, and the
    distinction matters. The demand-capacity model is well argued across the ARS
    family as a whole and is the only model that accounts for both the tissue
    distribution and the fever triggering. But no measurement of global or
    codon-specific translation rate has ever been reported in SARS1 patient cells;
    the model is imported from the family, not demonstrated for this gene. A
    ribosome-profiling experiment in SARS1 patient fibroblasts, with and without
    serine supplementation and with and without a thermal or inflammatory
    challenge, would convert this from an inference to a finding. It has not been
    done - see the knowledge-gap discussions.
  evidence:
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The resulting aminoacyl-tRNA is delivered to ribosome elongation factors to participate in protein synthesis."
    explanation: States the step in translation that a charging deficit throttles, linking the molecular lesion to protein synthesis.
  - reference: PMID:29875423
    reference_title: "Aminoacyl-tRNA synthetase deficiencies in search of common themes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We propose a common clinical phenotype for recessive ARS deficiencies, resulting from insufficient aminoacylation activity to meet translational demand in specific organs or periods of life."
    explanation: The explicit statement of the demand-capacity mechanism, derived from a cross-gene analysis of recessive ARS deficiencies that included SARS.
  - reference: PMID:29875423
    reference_title: "Aminoacyl-tRNA synthetase deficiencies in search of common themes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In literature, we identified 107 patients with AARS, DARS, GARS, HARS, IARS, KARS, LARS, MARS, RARS, SARS, VARS, YARS, and QARS deficiencies"
    explanation: Documents that SARS deficiency was one of the thirteen recessive synthetase deficiencies from which the common mechanism was inferred, so the model is not being imported from an unrelated gene set.
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We therefore suggest that the functional integrity of tRNAs in general is an important factor in the development and maintenance of human cognitive functions."
    explanation: The founding authors' own generalisation, that tRNA functional integrity as such underlies the cognitive phenotype, which is the same demand-capacity logic stated from the neurological side.
  downstream:
  - target: Impaired Neural Progenitor Proliferation and Brain Growth
    description: A translational ceiling constrains the proliferative expansion of neural progenitors during fetal and early postnatal brain growth.
  - target: Cerebellar and Cerebral Atrophy
    description: Chronic translational insufficiency in post-mitotic neurons underlies progressive tissue loss rather than a purely developmental deficit.
  - target: Demand-Dependent Decompensation During Febrile Catabolic Stress
    description: An acute rise in translational and catabolic demand exceeds the residual charging capacity.
  - target: Cardiomyocyte Translational Insufficiency
    description: Cardiac muscle has a high protein turnover and is one of the organs in which the capacity ceiling becomes symptomatic.
- name: Impaired Neural Progenitor Proliferation and Brain Growth
  biological_scale: TISSUE
  description: >-
    The causal step from a translation defect to the cardinal phenotype. Brain
    growth in the second and third trimesters and the first postnatal years is
    among the most protein-synthesis-intensive processes in human development; a
    ceiling on charged-tRNA supply constrains progenitor proliferation and the
    accretion of neuronal and glial mass, producing microcephaly. This is the
    single feature that unites the SARS1 families with the recessive WARS1
    families reported alongside them, and it is the reason the two were described
    together as an emerging disease group of ARS-related developmental disorders
    with or without microcephaly. The microcephaly is not an isolated head-size
    measurement: it is accompanied by intellectual disability, developmental delay
    and structural brain anomalies in the same individuals.
  biological_processes:
  - preferred_term: brain development
    modifier: ABNORMAL
    term:
      id: GO:0007420
      label: brain development
  - preferred_term: cytoplasmic translation
    modifier: DECREASED
    term:
      id: GO:0002181
      label: cytoplasmic translation
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  mechanism_confidence: PROVISIONAL
  notes: >-
    The link from reduced charging to reduced progenitor proliferation is
    reasoning from the demand-capacity model plus the observed microcephaly; no
    SARS1-specific proliferation assay, organoid, or fetal brain measurement has
    been published. The specific cell type at which the constraint bites - radial
    glia, intermediate progenitor, or post-mitotic neuron - is unknown, which is
    why the node is bound to the generic CL:0000540 neuron rather than to a
    progenitor class the evidence does not identify. Microcephaly is also NOT
    universal in this entity: the dominant-negative patient explicitly lacked it.
  evidence:
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies."
    explanation: Establishes microcephaly with developmental delay and brain anomalies as the shared consequence of biallelic damage to a cytoplasmic synthetase, across two different synthetase genes.
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "define an emerging disease spectrum: ARS-related developmental disorders with or without microcephaly"
    explanation: Frames the microcephaly as a class-level consequence of ARS deficiency rather than an idiosyncrasy of one gene.
  downstream:
  - target: Cerebellar and Cerebral Atrophy
    description: Reduced brain growth and ongoing neuronal attrition are seen together on imaging in the same individuals.
- name: Cerebellar and Cerebral Atrophy
  biological_scale: TISSUE
  description: >-
    Structural neuroimaging in the Turkish NEDMAS families showed bilateral
    cerebral AND cerebellar diffuse atrophy. The cerebellar component is the
    anatomical substrate of the ataxia that names the disorder, and its presence
    alongside cerebral atrophy indicates that the lesion is not confined to a
    developmental failure of head growth but includes ongoing tissue loss. That
    combination - a small brain that also atrophies - is characteristic of the
    recessive ARS deficiencies generally, and it is the reason the disorder is
    curated as neurodevelopmental with a neurodegenerative component rather than
    as static.
  biological_processes:
  - preferred_term: brain development
    modifier: ABNORMAL
    term:
      id: GO:0007420
      label: brain development
  cell_types:
  - preferred_term: cerebellar Purkinje cell
    term:
      id: CL:0000121
      label: Purkinje cell
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  mechanism_confidence: PROVISIONAL
  notes: >-
    The Purkinje-cell binding is an anatomical inference about which cerebellar
    cell type is most likely to be vulnerable, not a reported neuropathological
    finding. No cerebellar histopathology has been published for any SARS1
    patient, and the imaging reports describe diffuse atrophy without regional or
    cellular resolution. Whether the atrophy is progressive over time, as opposed
    to established early and static, is also unknown: no serial imaging series has
    been published.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy."
    explanation: The direct imaging evidence for the structural lesion, in the cohort that expanded the clinical spectrum of this MONDO entity.
  downstream:
  - target: Demand-Dependent Decompensation During Febrile Catabolic Stress
    description: >-
      Not a causal edge from atrophy to crisis, but the clinical observation that
      a brain already compromised structurally is where the acute decompensations
      declare themselves neurologically, with hypotonia and seizures.
- name: Demand-Dependent Decompensation During Febrile Catabolic Stress
  biological_scale: ORGANISM
  description: >-
    The most clinically consequential node in the entry and the clearest test of
    the demand-capacity model. In the SARS1 family reported from Nancy, febrile
    illness precipitated acute metabolic decompensation that was fatal; three
    siblings of the surviving proband died during similar febrile episodes. Fever
    raises basal metabolic rate, drives protein catabolism, and increases the
    demand for de novo protein synthesis for the acute-phase response and for
    tissue repair - precisely the demand that a hypomorphic synthetase cannot
    meet. The decompensation is multi-system, presenting with vomiting, hypotonia
    and seizures, and its lethal component is cardiac. The clinical corollary
    inverts standard metabolic-crisis management: rather than restricting protein,
    these patients need more of the limiting amino acid, and escalation of L-serine
    was associated with survival of an episode that had killed the patient's
    untreated siblings.
  biological_processes:
  - preferred_term: cytoplasmic translation
    modifier: DECREASED
    term:
      id: GO:0002181
      label: cytoplasmic translation
  chemical_entities:
  - preferred_term: L-serine
    term:
      id: CHEBI:17115
      label: L-serine
  mechanism_confidence: PROVISIONAL
  notes: >-
    The mechanistic account above - fever raises translational demand beyond
    residual charging capacity - is the model advanced for the ARS family, not a
    measurement made in a SARS1 patient during a crisis. No biochemical marker of
    the crisis has been characterised: there is no published amino acid profile,
    no charged-tRNA measurement, and no integrated-stress-response readout from a
    decompensating SARS1 patient. This is a substantial gap, because it means
    there is currently no laboratory test that can confirm a SARS1 crisis is
    underway or track its resolution, and it is recorded as a knowledge-gap
    discussion below. Note also that fever-triggered decompensation has so far
    been reported only in the p.Arg213Leu family; it is NOT known whether the
    microcephaly-presentation alleles carry the same risk, and that uncertainty
    has direct implications for whether all SARS1 patients should be issued an
    emergency protocol.
  evidence:
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
    explanation: The founding description of fever-triggered metabolic decompensation as a lethal feature of SARS1 deficiency.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We report the case of a 9-year-old male of Turkish origin with genetically confirmed SARS1 deficiency, admitted with fever, vomiting, hypotonia, and seizures."
    explanation: "Documents the clinical presentation of a decompensation episode: a febrile trigger with gastrointestinal, neuromuscular and seizure manifestations."
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Notably, the patient's family history included the death of three siblings during similar febrile episodes."
    explanation: Establishes that febrile decompensation is recurrent within a family and lethal, not an isolated event.
  - reference: PMID:29875423
    reference_title: "Aminoacyl-tRNA synthetase deficiencies in search of common themes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Assuming residual ARS activity, adequate protein/amino acid supply seems essential instead of the traditional replacement of protein by glucose in patients with metabolic diseases."
    explanation: States the management inversion that follows from the demand-capacity mechanism, and is the theoretical basis for amino acid supplementation in this disorder.
  downstream:
  - target: Cardiomyocyte Translational Insufficiency
    description: The decompensation manifests most dangerously in the heart, with acute ventricular failure.
- name: Cardiomyocyte Translational Insufficiency
  biological_scale: TISSUE
  description: >-
    Cardiomyopathy is part of the SARS1 phenotype in the presentation reported
    from Nancy and is the feature that determines survival. In the documented
    decompensation episode the left ventricular ejection fraction fell to 20%,
    requiring mechanical ventilation and vasopressor support, with myocardial
    oedema that resolved on follow-up echocardiography; a subsequent febrile
    crisis produced severe biventricular dysfunction and fatal cardiogenic shock.
    Cardiac muscle is a plausible target for a charging-capacity defect because it
    combines high protein turnover with an inability to reduce workload during
    fever - the opposite of skeletal muscle, which can rest. The reversibility of
    the myocardial oedema between crises argues that the cardiac lesion is at
    least in part an acute, demand-driven failure superimposed on a chronic
    cardiomyopathy rather than fixed structural damage alone.
  biological_processes:
  - preferred_term: cytoplasmic translation
    modifier: DECREASED
    term:
      id: GO:0002181
      label: cytoplasmic translation
  cell_types:
  - preferred_term: cardiomyocyte
    term:
      id: CL:0000746
      label: cardiac muscle cell
  mechanism_confidence: PROVISIONAL
  notes: >-
    No cardiac tissue from a SARS1 patient has been studied, so the attribution of
    the cardiomyopathy to cardiomyocyte translational insufficiency is inference
    from the systemic mechanism plus the organ involved. The competing explanation
    - that the cardiac failure is a secondary consequence of systemic metabolic
    collapse and inflammatory myocardial injury during sepsis-like decompensation,
    rather than a cell-autonomous cardiomyocyte defect - is not excluded by any
    published data and is arguably better supported by the myocardial oedema and
    its resolution. Both readings are recorded; neither is asserted as settled.
  evidence:
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
    explanation: Establishes cardiomyopathy as a component of the SARS1 phenotype.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clinical course rapidly progressed to metabolic decompensation and severe acute cardiac failure, characterised by a left ventricular ejection fraction of 20%, necessitating mechanical ventilation and vasopressor support"
    explanation: Quantifies the acute cardiac failure during decompensation, the specific measurement on which the severity of cardiac involvement rests.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "However, a year later, the patient presented with another febrile crisis at 10 years old, and despite an emergency protocol, the patient developed severe biventricular dysfunction progressing to fatal cardiogenic shock."
    explanation: Documents that the cardiac involvement is recurrent and ultimately lethal even under a prepared emergency protocol.
- name: Cellular Senescence with a Senescence-Associated Secretory Phenotype
  biological_scale: CELLULAR
  description: >-
    The only cell-autonomous phenotype demonstrated in human SARS1 patient cells.
    Fibroblasts from the patient with the de novo dominant-negative allele showed
    abnormal cell shape, arrested division, increased beta-galactosidase staining,
    and a senescence-associated secretory phenotype with raised interleukin-6,
    p21, p16 and p53. The authors read this as revealing a role for SARS1 in the
    regulation of cell growth, division and senescence. There are two ways this
    could arise and they are not mutually exclusive: a translational ceiling is
    itself a proliferation constraint and chronically stalled growth engages
    p53/p21-dependent arrest; alternatively, the senescence could reflect loss of
    a non-canonical SerRS activity, since SerRS binds telomeric DNA and cooperates
    with the shelterin protein POT1 to regulate telomere length and senescence.
    Distinguishing these would require testing whether senescence is rescued by
    restoring serylation alone.
  biological_processes:
  - preferred_term: cellular senescence
    modifier: INCREASED
    term:
      id: GO:0090398
      label: cellular senescence
  cell_types:
  - preferred_term: patient-derived dermal fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  mechanism_confidence: PROVISIONAL
  notes: >-
    Scope caveat. This result comes from the fibroblasts of the ONE patient with
    the dominant-negative allele and the atypical spastic-paraplegia phenotype. It
    has not been reproduced in fibroblasts from any recessive SARS1 patient, so it
    is not established as a general feature of the disorder, and it should not be
    read backwards as evidence that the microcephaly families' cells senesce. Its
    relevance to a post-mitotic neuron, which does not divide, is also unclear -
    senescence-like states in neurons are described but are not the same
    phenomenon as replicative arrest in a fibroblast.
  evidence:
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Fibroblasts showed an abnormal cell shape, arrested division and increased beta-galactosidase staining along with a senescence-associated secretory phenotype (raised interleukin-6, p21, p16 and p53 levels)."
    explanation: The primary patient-cell demonstration of senescence and its molecular markers.
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We refine the phenotypic spectrum and modes of inheritance of a newly described, ultrarare neurodevelopmental disorder, while unveiling the role of SARS1 as a regulator of cell growth, division and senescence."
    explanation: The authors' own framing of SARS1 as a regulator of growth, division and senescence, which is the interpretive claim this node records.
  - reference: PMID:38255739
    reference_title: "Protein-Protein Interactions of Seryl-tRNA Synthetases with Emphasis on Human Counterparts and Their Connection to Health and Disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Additionally, SerRS binds telomeric DNA and cooperates with the shelterin protein POT1 to regulate telomere length and cellular senescence."
    explanation: >-
      Marked PARTIAL. It supplies an independent, non-translational route by which
      SerRS loss could cause senescence, which is the alternative explanation named
      in this node's description. It is a review statement about SerRS biology in
      general and says nothing about any patient allele, so it supports the
      existence of the alternative route and not its operation in this disease.
- name: Impaired Selenocysteine Incorporation
  biological_scale: MOLECULAR
  description: >-
    A predicted second consequence of the same enzyme deficit, included because
    it is a specific, testable prediction that the aminoacylation literature makes
    and the clinical literature has never examined. Selenoprotein synthesis in all
    domains of life begins with SerRS serylating the selenocysteine-specific
    tRNA-Sec; the serylated intermediate is then converted to
    selenocysteinyl-tRNA-Sec for co-translational insertion of the 21st amino acid.
    A hypomorphic SerRS therefore throttles the supply of the obligatory precursor
    for every selenoprotein. Which selenoproteins would be rate-limited first, and
    whether any of them are the antioxidant enzymes usually invoked, is not
    addressed by any source cached for this entry. If this
    arm operates, it would predict oxidative vulnerability that worsens under
    febrile stress and would give SARS1 deficiency a pathophysiological component
    that other ARS deficiencies do not have.
  biological_processes:
  - preferred_term: selenocysteine incorporation
    modifier: DECREASED
    term:
      id: GO:0001514
      label: selenocysteine incorporation
  - preferred_term: conversion of seryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec)
    modifier: DECREASED
    term:
      id: GO:0001717
      label: conversion of seryl-tRNAsec to selenocys-tRNAsec
  molecular_functions:
  - preferred_term: serine-tRNA ligase activity
    modifier: DECREASED
    term:
      id: GO:0004828
      label: serine-tRNA ligase activity
  mechanism_confidence: HYPOTHETICAL
  notes: >-
    Explicitly HYPOTHETICAL and flagged as such rather than presented as part of
    the mechanism. No selenoprotein measurement, plasma selenium, glutathione
    peroxidase activity or selenocysteine-recoding assay has been reported in any
    SARS1 patient. The only established element is the biochemistry: SerRS
    serylates tRNA-Sec. Whether a partial reduction in SerRS activity is enough to
    limit the tRNA-Sec branch specifically is unknown - tRNA-Sec is a
    quantitatively minor substrate, so it could equally be spared or
    preferentially affected. This node is retained because it is cheap to test and
    would be diagnostically useful if true, not because there is evidence for it.
  evidence:
  - reference: PMID:24095058
    reference_title: "Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "SerRS also serylates the selenocysteine-specific tRNA (tRNASec) to participate in the translational incorporation of selenocysteine"
    explanation: Establishes that the same enzyme performs the first committed step of selenoprotein synthesis, which is the entire basis for this hypothetical arm.
- name: Loss of Non-Canonical Nuclear SerRS Function
  biological_scale: MOLECULAR
  description: >-
    Vertebrate SerRS is not only a synthetase. It acquired a C-terminal UNE-S
    domain in the lineage that developed closed circulatory systems; UNE-S carries
    a nuclear localisation signal that directs SerRS into the nucleus, where it
    attenuates VEGFA expression, acting through a complex with the transcription
    factor YY1 that binds distal cis-regulatory elements of the vegfa promoter and
    competes with activating factors. Genetically, this is not a minor
    embellishment: zebrafish sars mutants isolated in a vascular screen show
    dilated aortic arch vessels and aberrant hindbrain capillary patterning in a
    Vegf-dependent manner, and human SerRS alleles that disrupt nuclear
    localisation cause abnormal vasculature and premature death in fish. The
    question for this entry is whether any of this contributes to the human
    disease. The honest answer is that it is not known, and this node exists to
    say so precisely rather than to leave the moonlighting literature quietly
    attached to the mechanism.
  genes:
  - preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  biological_processes:
  - preferred_term: negative regulation of vascular endothelial growth factor production
    modifier: ABNORMAL
    term:
      id: GO:1904046
      label: negative regulation of vascular endothelial growth factor production
  - preferred_term: telomere maintenance
    modifier: ABNORMAL
    term:
      id: GO:0000723
      label: telomere maintenance
  cellular_components:
  - preferred_term: nucleus
    term:
      id: GO:0005634
      label: nucleus
  mechanism_confidence: HYPOTHETICAL
  notes: >-
    Why this is marked HYPOTHETICAL and kept out of the main causal chain. Three
    arguments say the human disease is a charging defect and not a moonlighting
    defect. (1) Every SARS1 allele reported in the clinical literature with a
    published location maps to the catalytic core or active site, not to UNE-S or
    its NLS; the one UNE-S-region allele this curation found, ClinVar
    VCV004529504 p.Ala497_Arg498insAla, has no accompanying publication and no
    functional data, so it weakens the argument without overturning it. (2) The functional
    assays performed in patient material measured serylation and protein
    abundance, and both were abnormal, so the charging deficit is demonstrated
    rather than assumed. (3) No vascular malformation, no VEGFA-related phenotype
    and no angiogenic abnormality has been reported in any SARS1 patient, in
    contrast to the striking vascular phenotype of the fish mutants.

    One argument on the other side, and it is not negligible. The SerRS/YY1
    interaction that represses vegfa is mediated by the CATALYTIC domain of SerRS,
    which is exactly the region the patient alleles damage - so an active-site
    variant is not automatically innocent with respect to the nuclear function.
    Whether p.Asp172Asn, p.Arg213Leu or p.Thr399Met perturbs nuclear import,
    YY1 binding or VEGFA repression has never been tested. Until it is, the
    contribution of this arm is unknown rather than excluded, and this entry does
    not attach any human phenotype to it.
  evidence:
  - reference: PMID:22353712
    reference_title: "Unique domain appended to vertebrate tRNA synthetase is essential for vascular development."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "UNE-S harbours a robust nuclear localization signal (NLS) directing SerRS to the nucleus where it attenuates vascular endothelial growth factor A expression"
    explanation: Establishes the nuclear, VEGFA-repressing activity of SerRS and the domain that mediates it.
  - reference: PMID:24095058
    reference_title: "Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Mutations that disrupted SerRS nuclear localization caused abnormal vasculature and premature death in zebrafish."
    explanation: Shows the nuclear function is essential at the organism level in a vertebrate, which is why it cannot simply be dismissed as an in vitro curiosity.
  - reference: PMID:27913726
    reference_title: "Competitive binding between Seryl-tRNA synthetase/YY1 complex and NFKB1 at the distal segment results in differential regulation of human vegfa promoter activity during angiogenesis."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we found that the catalytic domain of Seryl-tRNA synthetase (SerRS) interacted with transcription factor Yin Yang 1 (YY1) to form a SerRS/YY1 complex that negatively controls vegfa promoter activity"
    explanation: >-
      Marked PARTIAL. It identifies the CATALYTIC domain as the region mediating
      the nuclear repressor function, which is the one concrete reason a
      catalytic-core patient allele might also disrupt moonlighting. It is
      biochemistry in cell lines with no patient material, so it establishes the
      possibility and not its relevance to this disorder.
  - reference: PMID:38255739
    reference_title: "Protein-Protein Interactions of Seryl-tRNA Synthetases with Emphasis on Human Counterparts and Their Connection to Health and Disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Human cytosolic SerRS is a cellular hub protein connecting translation to vascular development, angiogenesis, lipogenesis, and telomere maintenance."
    explanation: Summarises the breadth of documented non-canonical SerRS activities, which is the scope of what is untested in this disease.
genetic:
- name: SARS1
  association: >-
    Biallelic missense and splice variants in the catalytic core cause autosomal
    recessive disease; one de novo, dominant-negative in-frame insertion allele
    has been reported
  relationship_type: CAUSATIVE
  gene_term:
    preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  notes: >-
    Nomenclature and identity. HGNC:10537 is symbol SARS1, "seryl-tRNA synthetase
    1", at 1p13.3, Entrez 6301, Ensembl ENSG00000031698, UniProt P49591, EC
    6.1.1.11, gene MIM 607529 (OAK, `runoak -i sqlite:obo:hgnc info hgnc:10537 -O
    obo`, 2026-08-01). The former approved symbol was SARS, which is how the gene
    appears in PMID:28236339 and in all the pre-2019 mechanistic literature, and
    the protein is universally called SerRS. Do not confuse with SARS2
    (hgnc:17697), the mitochondrial enzyme, which unhelpfully also carries "SARS"
    as an exact synonym in HGNC.

    Allelic series, as published. c.514G>A (p.Asp172Asn), homozygous, Iranian
    family, enzymatic core domain, impaired activity and predicted plus
    demonstrated protein instability (PMID:28236339). c.638G>T (p.Arg213Leu),
    biallelic, consanguineous Turkish family, protein instability with reduced
    protein level and enzymatic activity (PMID:34570399). c.1196C>T (p.Thr399Met),
    reported as a novel variant in a Turkish series of three unrelated families
    with four patients; the abstract says only that "both patients carried" it, so
    how many of the four it was found in cannot be determined from the cached text
    and no family or patient count is asserted for this allele here - see the
    CURATION_TODO (PMID:36004946). A
    further variant mapped structurally into the active site (PMID:35790048) - the
    abstract does not give its coding change, and the full text is not cached, so
    no HGVS string is asserted for it here. A de novo splice-site deletion causing
    a five-residue in-frame insertion near the active site, dominant negative
    (PMID:36041817). All coding changes are against NM_006513.4, the transcript
    ClinVar uses for this gene.

    Variant classification is genuinely unsettled and is recorded rather than
    smoothed. A ClinVar E-utilities query on 2026-08-01
    (`esearch db=clinvar term="SARS1[gene] AND single_gene[prop]"`) returned 69
    records.
    Both founding disease alleles - c.514G>A (VCV000440921) and c.638G>T
    (VCV001209576) - are filed against the condition "Neurodevelopmental disorder
    with microcephaly, ataxia, and seizures" but currently return "no
    classifications from unflagged records", so ClinVar carries no usable
    classification for either. The Karaer allele c.1196C>T (VCV002506443) is
    classified Uncertain significance against "not specified" by a single
    submitter with criteria - that is, the variant published as the cause of
    disease in a Turkish series is a VUS in ClinVar. Two other alleles,
    c.447+1G>A (VCV003893287) and c.1483GCA[4] p.Ala497_Arg498insAla
    (VCV004529504), are Likely pathogenic for this condition and have no
    corresponding publication that this curation could find. Residues 497-498
    fall inside the C-terminal UNE-S appendage, whose boundaries are given as
    470-514 in the cached full text of PMID:22353712 ("the entire UNE-S
    (delta470-514)"); that domain assignment is arithmetic on a cached range,
    not a claim taken from any SARS1 clinical paper. A laboratory
    reporting a SARS1 variant should therefore expect the evidence base to be
    thinner than the OMIM entry implies. These ClinVar figures are from the public
    API and are not quotable from a cached reference, so they appear here and not
    as evidence snippets.

    Not asserted, deliberately. gnomAD constraint metrics (pLI, o/e LoF, missense
    Z) are NOT recorded anywhere in this entry because no cached source provides
    them and populating them from memory is exactly the failure mode the evidence
    rules exist to prevent. No allele frequency is asserted for any variant. No
    founder effect is claimed: the recurrence of Turkish and Iranian ancestry in
    the reports most likely reflects ascertainment in consanguinity-enriched
    recessive cohorts, and consanguinity is stated in the cached abstracts only
    for the Turkish family of PMID:34570399 - PMID:36004946 describes its Turkish
    families as unrelated but says nothing about consanguinity, and PMID:28236339
    does not describe its Iranian family as consanguineous either. No
    genotype-phenotype rule is asserted beyond the two that the literature states
    directly - that the dominant-negative allele produced spastic paraplegia
    without microcephaly, and that fever-triggered decompensation has so far been
    reported only with p.Arg213Leu. Whether complete SARS1 loss of function occurs
    in humans is unknown and presumed lethal, on the general grounds that
    cytoplasmic aminoacyl-tRNA synthetases are essential; that presumption is
    reasoning, not a cited finding.
  evidence:
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene"
    explanation: Establishes SARS1 as the causal gene with the founding allele, and names the cytoplasmic compartment that distinguishes it from SARS2.
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sequencing results showed that both patients carried a novel missense variant c.1196C>T (p.Thr399Met) in the seryl-tRNA synthetase gene."
    explanation: Adds a further missense allele to the series, reported in unrelated Turkish families.
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This missense variant was shown to lead to protein instability, resulting in reduced protein level and enzymatic activity."
    explanation: Provides the functional characterisation for the third allele, tying genotype to a measured molecular consequence.
variants:
- name: SARS1 c.514G>A p.Asp172Asn
  gene:
    preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  description: >-
    The founding allele, homozygous in an Iranian family with
    autosomal recessive intellectual disability; the abstract reports the family
    as Iranian and does not state whether it is consanguineous.
    It lies in the enzymatic core
    domain, impairs enzymatic activity, and destabilises the protein - a combined
    activity-and-abundance hit rather than a pure catalytic lesion. The authors
    inferred from the activity loss that cytoplasmic tRNA-Ser charging is reduced.
  type: missense variant
  functional_effects:
  - function: serine-tRNA ligase activity
    description: Impaired enzymatic activity of the mutant protein, attributed to the substitution falling in the enzymatic core domain.
  - function: SerRS protein stability
    description: Predicted to be unstable, and substantiated for ectopically expressed mutant protein in transfected HEK293T cells.
  - function: cytoplasmic charged tRNA-Ser pool
    description: Inferred reduction in cytoplasmic tRNA-Ser concentrations as a consequence of impaired charging; inferred by the authors rather than measured.
  evidence:
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene"
    explanation: Identifies the allele and its homozygous state in the founding family.
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The mutant protein was predicted to be unstable, which could be substantiated by investigating ectopic mutant SARS in transfected HEK293T cells."
    explanation: Supports the protein-stability functional effect.
- name: SARS1 c.638G>T p.Arg213Leu
  gene:
    preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  description: >-
    The allele of the deafness-cardiomyopathy-febrile-decompensation presentation,
    biallelic in a consanguineous Turkish family. Functionally it behaves as a
    destabilising allele: reduced protein level with consequently reduced
    enzymatic activity. This is the only SARS1 allele so far associated with fatal
    metabolic crises, and the only one for which a treatment response has been
    documented.
  type: missense variant
  functional_effects:
  - function: SerRS protein stability
    description: Protein instability demonstrated, with reduced steady-state protein level.
  - function: serine-tRNA ligase activity
    description: Reduced enzymatic activity, reported as a consequence of the reduced protein level rather than as an independent catalytic defect.
  evidence:
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
    explanation: Identifies the allele, its biallelic state, and the phenotype it produces.
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "This missense variant was shown to lead to protein instability, resulting in reduced protein level and enzymatic activity."
    explanation: Supports both functional effects recorded for this allele.
- name: SARS1 c.1196C>T p.Thr399Met
  gene:
    preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  description: >-
    Reported as a novel missense variant in unrelated Turkish families with the
    NEDMAS phenotype, in individuals whose main manifestations were severe
    developmental delay and intellectual disability, thin body habitus and severe
    hypotonia, with bilateral cerebral and cerebellar diffuse atrophy on imaging.
    No functional assay has been published for this allele and no structural
    mapping is available, so its mechanism is assumed rather than shown.
  clinical_significance: UNCERTAIN_SIGNIFICANCE
  type: missense variant
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sequencing results showed that both patients carried a novel missense variant c.1196C>T (p.Thr399Met) in the seryl-tRNA synthetase gene."
    explanation: Identifies the allele and the report that associates it with the NEDMAS phenotype.
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our findings help expand the variant spectrum of NEDMAS"
    explanation: The authors' own framing of the allele as an addition to the disease-associated variant spectrum.
- name: SARS1 de novo splice-site deletion causing a five-residue in-frame insertion
  gene:
    preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  description: >-
    The single reported de novo, monoallelic, dominant-negative SARS1 allele. A
    splice-site deletion yields a five-amino-acid in-frame insertion near the
    active site; complementation in yeast and serylation assays in yeast and in
    the patient's fibroblasts established a loss-of-function, dominant-negative
    effect. Clinically it produced complex spastic paraplegia with ataxia,
    intellectual disability, developmental delay and seizures, explicitly WITHOUT
    microcephaly - the one published SARS1 phenotype that the MONDO label would
    actively mislead a clinician about.
  type: splice site variant
  functional_effects:
  - function: serine-tRNA ligase activity
    description: Loss of serylation activity in yeast complementation and in patient fibroblast serylation assays, with a dominant-negative rather than purely recessive effect.
  - function: cellular proliferation and senescence
    description: Patient fibroblasts show abnormal shape, arrested division, increased beta-galactosidase staining and a senescence-associated secretory phenotype with raised IL-6, p21, p16 and p53.
  evidence:
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site."
    explanation: Identifies the allele, its de novo origin, and its protein-level consequence.
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
    explanation: Supports the dominant-negative functional effect on serylation.
phenotypes:
- name: Microcephaly
  category: Neurologic
  diagnostic: true
  description: >-
    Microcephaly names the disorder and is the feature that ties it to the wider
    group of ARS-related developmental disorders. It is the direct organ-level
    reading of a translational ceiling imposed during the period of maximal brain
    growth. It is not, however, obligatory: the individual with the de novo
    dominant-negative allele had complex spastic paraplegia and explicitly no
    microcephaly, so a normal head circumference does not exclude a SARS1 diagnosis.
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  notes: >-
    HPO annotation for OMIM:617709 records HP:0000252 at 4/4, sourced to
    PMID:28236339 (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:617709). That
    denominator is the single founding family. No FrequencyEnum band is asserted;
    see the entry-level notes.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
    explanation: Names microcephaly as a defining feature of the syndrome.
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies."
    explanation: Independent confirmation of microcephaly in a further SARS1 report, and the basis for treating it as a class feature of cytoplasmic ARS deficiency.
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We used exome sequencing to identify the causal variant in a patient affected by complex spastic paraplegia with ataxia, intellectual disability, developmental delay and seizures, but without microcephaly."
    explanation: >-
      Marked PARTIAL because it qualifies rather than supports the association: it
      documents a SARS1 patient in whom microcephaly was absent, which is the
      evidence for the statement that microcephaly is not obligatory.
- name: Moderate intellectual disability
  category: Neurologic
  diagnostic: true
  description: >-
    Cognitive impairment is present in every reported individual across every
    presentation, and the disorder was originally ascertained through an autosomal
    recessive intellectual disability cohort. The founding series characterises it
    as moderate; a later Turkish series describes severe developmental delay and
    intellectual disability, so severity varies between families. The graded term
    below is bound because it is what the sources and the HPO annotation set state
    for the families they describe, not as an assertion that every affected
    individual is moderately affected - the severe end of the range is carried by
    the PARTIAL evidence item below and by this description.
  phenotype_term:
    preferred_term: Moderate intellectual disability
    term:
      id: HP:0002342
      label: Moderate intellectual disability
  notes: >-
    HPO annotation for OMIM:617709 records HP:0002342 (Moderate intellectual
    disability) at 4/4, sourced to PMID:28236339 (retrieved 2026-08-01). The term
    bound here is the graded child HP:0002342 rather than the parent HP:0001249
    (Intellectual disability), because the sources state the grade explicitly. The
    countervailing observation that a different series reported SEVERE
    developmental delay and intellectual disability is recorded in the description
    and quoted below, so the grade is not presented as settled. Binding the parent
    instead was considered and rejected: HP:0002342 is a descendant of HP:0001249,
    so any query over the parent already retrieves this entry by subsumption,
    whereas demoting the binding would delete from the machine-readable layer the
    one grade that HPOA and two independent papers actually state. The
    moderate-versus-severe spread is therefore carried by the description and by
    the PARTIAL evidence item rather than by weakening the term.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
    explanation: States moderate intellectual disability as a defining feature of the syndrome.
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SARS1 deficiency has already been associated with moderate intellectual disability, ataxia, muscle weakness, and seizure in one family."
    explanation: Independent restatement of the moderate grade in the first-described family.
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The main manifestations of the probands are severe developmental delay and ID, thin body habitus, and severe hypotonia."
    explanation: >-
      Marked PARTIAL because it supports the presence of intellectual disability
      but contradicts the "moderate" grade bound in the term, describing the same
      syndrome's probands as severely affected. Recorded rather than suppressed.
- name: Global developmental delay
  category: Neurologic
  description: >-
    Developmental delay is reported across all three presentations of SARS1
    disease - the microcephaly families, the deafness-cardiomyopathy family, and
    the dominant-negative spastic paraplegia patient - making it the most
    consistently present feature of the entity after cognitive impairment itself.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  notes: >-
    HPO annotation for OMIM:617709 records HP:0001263 at 4/4, sourced to
    PMID:28236339 (retrieved 2026-08-01).
  evidence:
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies."
    explanation: Documents developmental delay in a further SARS1 report.
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
    explanation: Documents developmental delay in the presentation that otherwise differs most from the microcephaly families, establishing it as common to both.
- name: Ataxia
  category: Neurologic
  diagnostic: true
  description: >-
    Ataxia is one of the three features in the disorder's name and is present in
    the founding family, in the later Turkish families, and in the
    dominant-negative patient, in whom it accompanied spastic paraplegia. Its
    structural correlate is the cerebellar component of the diffuse atrophy seen
    on imaging.
  phenotype_term:
    preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
  notes: >-
    HPO annotation for OMIM:617709 records HP:0001251 at 4/4, sourced to
    PMID:28236339 (retrieved 2026-08-01). The generic HP:0001251 is bound rather
    than a specific cerebellar-ataxia child term, because the published
    descriptions do not distinguish cerebellar from sensory ataxia and the imaging
    (diffuse cerebellar atrophy) is suggestive but not diagnostic of the
    mechanism.
  evidence:
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SARS1 deficiency has already been associated with moderate intellectual disability, ataxia, muscle weakness, and seizure in one family."
    explanation: States ataxia as a feature of the originally described family.
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recently, patients affected with microcephaly, intellectual disability and ataxia harbouring biallelic variants in the seryl-tRNA synthetase encoded by seryl-tRNA synthetase 1 (SARS1) were reported."
    explanation: Independent restatement that ataxia is part of the established biallelic SARS1 phenotype.
- name: Seizures
  category: Neurologic
  diagnostic: true
  description: >-
    Seizures are the third named feature. In the founding family they were
    generalised tonic-clonic with infantile onset. They also occurred in the
    dominant-negative patient and as part of the acute presentation of febrile
    metabolic decompensation, where a seizure may be the presenting sign of a
    crisis rather than of the baseline epilepsy - a distinction that matters at
    the bedside because the two require different responses.
  phenotype_term:
    preferred_term: Bilateral tonic-clonic seizure
    term:
      id: HP:0002069
      label: Bilateral tonic-clonic seizure
  notes: >-
    The specific term HP:0002069 (Bilateral tonic-clonic seizure) is bound rather
    than the parent HP:0001250 (Seizure) because the HPO annotation set for
    OMIM:617709 records HP:0002069 at 4/4 with onset annotated as HP:0003593
    (Infantile onset), sourced to PMID:28236339 (retrieved 2026-08-01). The cached
    abstracts say only "seizure" or "seizures", so the semiology comes from the
    annotation set and not from a quotable sentence; the snippets below therefore
    support the presence of seizures rather than their bilateral tonic-clonic
    character.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
    explanation: Names seizures as a defining feature of the syndrome.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We report the case of a 9-year-old male of Turkish origin with genetically confirmed SARS1 deficiency, admitted with fever, vomiting, hypotonia, and seizures."
    explanation: Documents seizures as part of the acute decompensation presentation, which is the basis for distinguishing crisis seizures from baseline epilepsy.
- name: Cerebral atrophy
  category: Neurologic
  description: >-
    Bilateral diffuse cerebral atrophy on brain imaging, reported together with
    cerebellar atrophy. Its presence alongside microcephaly indicates that the
    small brain is not solely a failure of growth but also reflects tissue loss.
  phenotype_term:
    preferred_term: Cerebral atrophy
    term:
      id: HP:0002059
      label: Cerebral atrophy
  notes: >-
    Not present in the HPO annotation set for OMIM:617709, which derives entirely
    from PMID:28236339 and predates the imaging series. Curated here from the
    quoted imaging finding in PMID:36004946.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy."
    explanation: Direct imaging evidence of the cerebral component of the atrophy.
- name: Cerebellar atrophy
  category: Neurologic
  description: >-
    Bilateral diffuse cerebellar atrophy, the structural correlate of the ataxia
    that names the disorder.
  phenotype_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  notes: >-
    Curated from the imaging finding in PMID:36004946. Whether the cerebellar
    atrophy is congenital hypoplasia mislabelled as atrophy, or genuine
    progressive loss, cannot be determined from cross-sectional imaging in a small
    series and no serial imaging has been published.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy."
    explanation: Direct imaging evidence of the cerebellar component of the atrophy.
- name: Muscle weakness
  category: Musculature
  description: >-
    Muscle weakness is a consistent feature of the microcephaly presentation.
    Skeletal muscle is one of the tissues with a high amino acid incorporation
    rate, so a charging-capacity defect is expected to be symptomatic there, and
    weakness is common across the recessive ARS deficiencies.
  phenotype_term:
    preferred_term: Muscle weakness
    term:
      id: HP:0001324
      label: Muscle weakness
  notes: >-
    HPO annotation for OMIM:617709 records HP:0001324 at 4/4, sourced to
    PMID:28236339 (retrieved 2026-08-01). Whether the weakness is myopathic,
    neurogenic or central has not been determined in any published SARS1 patient -
    no muscle biopsy, EMG or creatine kinase result appears in the cached
    abstracts.
  evidence:
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SARS1 deficiency has already been associated with moderate intellectual disability, ataxia, muscle weakness, and seizure in one family."
    explanation: States muscle weakness as a feature of the first-described family.
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
    explanation: Independent listing of muscle weakness among the defining features.
- name: Hypotonia
  category: Musculature
  description: >-
    Severe hypotonia was one of the main manifestations in the Turkish NEDMAS
    probands, and hypotonia is also part of the acute febrile decompensation
    presentation. The two contexts are different: a chronic baseline hypotonia and
    an acute worsening during crisis.
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  notes: >-
    Not in the HPO annotation set for OMIM:617709. Curated from the two quoted
    sources. HP:0001252 (Hypotonia) is bound rather than a severity-qualified or
    central/peripheral child term, because the sources give severity but not
    localisation.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The main manifestations of the probands are severe developmental delay and ID, thin body habitus, and severe hypotonia."
    explanation: Documents severe hypotonia as a main manifestation in the Turkish families.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We report the case of a 9-year-old male of Turkish origin with genetically confirmed SARS1 deficiency, admitted with fever, vomiting, hypotonia, and seizures."
    explanation: Documents hypotonia as part of the acute decompensation presentation.
- name: Slender build
  category: Growth
  description: >-
    A thin body habitus is listed among the defining features of NEDMAS and was a
    main manifestation in the Turkish probands. It fits the demand-capacity model
    directly: a ceiling on protein synthesis constrains the accretion of lean mass,
    and failure to thrive is one of the features common across recessive ARS
    deficiencies.
  phenotype_term:
    preferred_term: Slender build
    term:
      id: HP:0001533
      label: Slender build
  notes: >-
    HPO annotation for OMIM:617709 records HP:0001533 (Slender build) at 2/4,
    sourced to PMID:28236339 (retrieved 2026-08-01) - a minority finding in the
    founding family even though the later descriptive summary lists thin body
    habitus as characteristic. HP:0001533 is bound because it is the term HPOA
    itself uses for this feature in this disease; the literature phrase is "thin
    body habitus".
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The main manifestations of the probands are severe developmental delay and ID, thin body habitus, and severe hypotonia."
    explanation: Documents thin body habitus as a main manifestation.
- name: Delayed speech and language development
  category: Neurologic
  description: >-
    Speech impairment is listed among the defining features of the syndrome.
    Whether it is proportionate to the global cognitive impairment or
    disproportionate has not been assessed in any published individual, and the
    question is not academic given that central deafness occurs in one
    presentation of this disorder.
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  notes: >-
    Not in the HPO annotation set for OMIM:617709. Curated from the syndrome
    description quoted below, which says "speech impairment". HP:0000750 is bound
    as the closest developmental term; a dysarthria or apraxia term is NOT bound,
    because no published source characterises the speech disorder.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment"
    explanation: Lists speech impairment among the defining features of the syndrome.
- name: Aggressive behavior
  category: Neurologic
  description: >-
    Aggressive behaviour was recorded in all four affected individuals of the
    founding Iranian family. It is included because it is a real and burdensome
    part of the presentation for families, and because it is the kind of feature
    that disappears from later summaries of a syndrome.
  phenotype_term:
    preferred_term: Aggressive behavior
    term:
      id: HP:0000718
      label: Aggressive behavior
  notes: >-
    Curated entirely from the HPO annotation set for OMIM:617709, which records
    HP:0000718 at 4/4 sourced to PMID:28236339 (retrieved 2026-08-01). The cached
    abstract does not mention behaviour, so this phenotype deliberately carries no
    evidence item rather than a snippet that does not support it. It has not been
    reported in any family other than the founding one.
- name: Pes planus
  category: Skeletal
  description: >-
    A minor orthopaedic finding recorded in the founding family, likely secondary
    to hypotonia and muscle weakness rather than a primary skeletal feature.
  phenotype_term:
    preferred_term: Pes planus
    term:
      id: HP:0001763
      label: Pes planus
  notes: >-
    Curated entirely from the HPO annotation set for OMIM:617709, which records
    HP:0001763 at 2/4 sourced to PMID:28236339 (retrieved 2026-08-01) - a minority
    finding in a single family. No evidence item is attached because the cached
    abstract does not mention it. The attribution to hypotonia is reasoning, not a
    reported analysis.
- name: Hearing impairment
  category: Otologic
  description: >-
    Deafness described as CENTRAL is part of the presentation reported from Nancy
    and is a feature that would not be expected from a cochlear lesion. It is
    clinically important out of proportion to its frequency: a child with
    developmental delay and deafness is likely to be worked up along an entirely
    different diagnostic route, and central deafness in particular points away
    from the common non-syndromic deafness genes.
  phenotype_term:
    preferred_term: Central deafness
    term:
      id: HP:0000365
      label: Hearing impairment
  notes: >-
    Term-binding decision, recorded because it is a deliberate loss of specificity.
    The source says "central deafness". HPO has no "central hearing impairment"
    term - searched 2026-08-01 with `runoak -i sqlite:obo:hp search "l~central
    hearing"` (no results) and `t~auditory neuropathy` (no results) - and binding
    HP:0000407 (Sensorineural hearing impairment) would assert a cochlear or
    eighth-nerve localisation that the source explicitly contradicts. The generic
    parent HP:0000365 is therefore bound with the clinical localisation preserved
    in `preferred_term`. Reported in one family only.
  evidence:
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
    explanation: The source of both the finding and its localisation as central rather than peripheral.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seryl-tRNA synthetase 1 (SARS1) deficiency is a rare autosomal recessive disorder presenting with neurodevelopmental delay, deafness, cardiomyopathy, and fatal metabolic decompensation triggered by febrile episodes."
    explanation: Independent restatement, four years later and from the same clinical service, that deafness is an established component of SARS1 deficiency.
- name: Cardiomyopathy
  category: Cardiovascular
  diagnostic: true
  description: >-
    Cardiomyopathy is the feature that determines survival in SARS1 deficiency and
    the one the MONDO label gives no hint of. It is chronic at baseline and
    catastrophically decompensating during febrile illness, with left ventricular
    ejection fraction falling to 20% in the documented episode and biventricular
    failure with fatal cardiogenic shock in a later one. Any child given a
    molecular diagnosis of SARS1 deficiency needs cardiac surveillance regardless
    of which presentation they were ascertained through, because the cardiac risk
    has not been shown to be allele-restricted - only to be, so far, allele-associated.
  phenotype_term:
    preferred_term: Cardiomyopathy
    term:
      id: HP:0001638
      label: Cardiomyopathy
  notes: >-
    The generic HP:0001638 (Cardiomyopathy) is bound rather than HP:0001644
    (Dilated cardiomyopathy) or a hypertrophic term, because no cached source
    states the morphological subtype; the reported findings are a depressed
    ejection fraction, myocardial oedema, and biventricular dysfunction, which
    constrain function but not morphology. Reported in one family (with the
    2026 case report describing what is on internal evidence a member of that same
    family), so the frequency across the disorder is unknown and no band is
    asserted.
  evidence:
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe here a new clinical presentation including developmental delay, central deafness, cardiomyopathy, and metabolic decompensation during fever leading to death, in a consanguineous Turkish family, with biallelic variants (c.638G>T, p.(Arg213Leu)) in SARS1"
    explanation: The founding report of cardiomyopathy in SARS1 deficiency.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clinical course rapidly progressed to metabolic decompensation and severe acute cardiac failure, characterised by a left ventricular ejection fraction of 20%, necessitating mechanical ventilation and vasopressor support"
    explanation: Provides the only quantitative measure of cardiac dysfunction published for this disorder.
- name: Spastic paraplegia
  category: Neurologic
  description: >-
    Complex spastic paraplegia was the presenting syndrome in the one patient with
    a de novo dominant-negative SARS1 allele, occurring with ataxia, intellectual
    disability, developmental delay and seizures but without microcephaly. It
    broadens the differential in which SARS1 should be considered from
    microcephaly-intellectual-disability panels to hereditary spastic paraplegia
    panels.
  phenotype_term:
    preferred_term: Spastic paraplegia
    term:
      id: HP:0001258
      label: Spastic paraplegia
  notes: >-
    Reported in exactly one patient, with a genotype and inheritance mode
    different from every other reported individual. It is curated as a phenotype
    of this MONDO entity because MONDO gives SARS1 no second term, not because it
    is a typical feature. Not in the HPO annotation set for OMIM:617709.
  evidence:
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We used exome sequencing to identify the causal variant in a patient affected by complex spastic paraplegia with ataxia, intellectual disability, developmental delay and seizures, but without microcephaly."
    explanation: The single source for this phenotype, which also documents the absence of microcephaly in the same individual.
diagnosis:
- name: Exome or genome sequencing with SARS1 variant interpretation
  description: >-
    Molecular diagnosis rests on identifying SARS1 variants against transcript
    NM_006513.4 by exome or genome sequencing. Three interpretation points follow
    from the published allelic series. First, do not filter for biallelic hits
    only: one reported patient carried a de novo monoallelic dominant-negative
    allele, and a laboratory applying a strict recessive filter would have
    discarded it. Second, expect the ClinVar evidence to be weaker than the OMIM
    entry implies - the allele published as causal in the Turkish series is
    currently a variant of uncertain significance in ClinVar - so a SARS1 candidate will
    often need functional support rather than database endorsement. Third, since
    the two named genes SARS1 and SARS2 differ only by a digit and share the
    legacy symbol SARS, confirm from the transcript accession, not the symbol,
    which enzyme has been reported.
  evidence:
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we identified a homozygous missense mutation (c.514G>A, p.Asp172Asn) in the cytoplasmic seryl-tRNA synthetase (SARS) gene"
    explanation: Establishes that the diagnosis is made by sequencing and that the gene of interest is the cytoplasmic, not the mitochondrial, seryl-tRNA synthetase.
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A de novo splice site deletion in SARS1 was identified in our patient, resulting in a 5-amino acid in-frame insertion near its active site."
    explanation: Supports the specific warning that a monoallelic de novo SARS1 event can be causal and must not be filtered out.
- name: Serylation (aminoacylation) assay in patient fibroblasts
  description: >-
    The functional confirmatory test for a candidate SARS1 variant. Serylation
    activity measured in patient-derived fibroblasts, alongside yeast
    complementation, is what established pathogenicity for the dominant-negative
    allele and is the assay that distinguishes a true hypomorph from an incidental
    rare missense change. In the published SARS1 cases it was performed in a
    research setting; this entry makes no claim about where it is available as a
    clinical service, because no cached source addresses that. Its value is highest
    precisely where the genomic evidence is weakest, which for this gene is most
    of the time.
  evidence:
  - reference: PMID:36041817
    reference_title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Complementation assays in S. cerevisiae and serylation assays in both yeast strains and patient fibroblasts proved a loss-of-function, dominant negative effect."
    explanation: Documents the assay pair that was used to establish variant pathogenicity in patient material.
  - reference: PMID:34570399
    reference_title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "This missense variant was shown to lead to protein instability, resulting in reduced protein level and enzymatic activity."
    explanation: Shows that both protein level and enzyme activity are informative readouts for a candidate SARS1 allele.
- name: Brain MRI
  description: >-
    Brain MRI documents the structural correlates - bilateral diffuse cerebral and
    cerebellar atrophy - and supports the diagnosis in a child with microcephaly
    and ataxia. It does not distinguish SARS1 disease from the other recessive ARS
    deficiencies or from the many other causes of microcephaly with cerebellar
    atrophy, so its role is corroborative rather than discriminating.
  evidence:
  - reference: PMID:36004946
    reference_title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy."
    explanation: Names the specific imaging findings to be expected.
- name: Cardiac assessment with echocardiography
  description: >-
    Echocardiography with ejection fraction, together with cardiac biomarkers, is
    the surveillance test that matters most for prognosis in this disorder, and it
    is also the monitoring test during a febrile crisis. In the documented episode
    the ejection fraction fell to 20%, cardiac biomarkers normalised over about
    twenty days, and follow-up echocardiography at one month showed complete
    resolution of myocardial oedema - so serial imaging, not a single baseline
    study, is what captures the disease.
  notes: >-
    The specific follow-up timings (biomarker normalisation within 20 days,
    echocardiographic resolution at 1 month) are stated in the cached abstract of
    PMID:42158840 and are quoted below only in part; the recommendation to perform
    surveillance echocardiography in all SARS1 patients is a curatorial inference
    from the reported course and is not itself a published guideline. No
    surveillance protocol has been published for this disorder.
  evidence:
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clinical course rapidly progressed to metabolic decompensation and severe acute cardiac failure, characterised by a left ventricular ejection fraction of 20%, necessitating mechanical ventilation and vasopressor support"
    explanation: Establishes the measurement (ejection fraction) that defines the acute cardiac emergency in this disorder.
differential_diagnoses:
- name: HUPRA syndrome
  disease_term:
    preferred_term: hyperuricemia-pulmonary hypertension-renal failure-alkalosis syndrome
    term:
      id: MONDO:0013458
      label: hyperuricemia-pulmonary hypertension-renal failure-alkalosis syndrome
  description: >-
    The paralogue trap, and the reason it is listed first. HUPRA syndrome is
    caused by SARS2, the MITOCHONDRIAL seryl-tRNA synthetase. The two genes encode
    enzymes that catalyse chemically the same reaction - serylation of tRNA-Ser -
    on two different tRNA pools in two different compartments, and their legacy
    symbols collide (HGNC lists "SARS" as an exact synonym of SARS2 as well as the
    former symbol of SARS1). A literature search, a variant report, or an
    automated gene-disease extraction that keys on the string "SARS" will merge
    them. Clinically they are not remotely similar: HUPRA is a mitochondrial
    oxidative-phosphorylation disorder of infancy with hyperuricaemia, pulmonary
    hypertension, progressive renal failure and metabolic alkalosis.
  distinguishing_features:
  - Different gene and compartment - SARS1 (hgnc:10537) encodes the cytoplasmic enzyme, SARS2 (hgnc:17697) the mitochondrial one; a report naming only "SARS" must be resolved before use.
  - Different MONDO and OMIM entities - this disorder is MONDO:0060577 / OMIM:617709; HUPRA is MONDO:0013458 / OMIM:613845 / Orphanet:363694.
  - HUPRA is classified in MONDO under mitochondrial oxidative phosphorylation disorder and inherited renal tubular disease; SARS1 disease is a Mendelian neurodevelopmental disorder with no renal or pulmonary-vascular component reported.
  - The cardinal HUPRA features - hyperuricaemia, pulmonary hypertension, renal failure, metabolic alkalosis - have never been reported in a SARS1 patient; conversely microcephaly, ataxia and seizures are not the HUPRA phenotype.
  - ICIMD places the two in different groups - mitochondrial aminoacyl-tRNA synthetase disorders for SARS2, non-mitochondrial tRNA metabolism for SARS1.
  notes: >-
    Every identifier in this differential was verified with OAK before being
    written, not typed from memory: `runoak -i sqlite:obo:hgnc search "SARS2"`
    gives hgnc:17697 with definition "seryl-tRNA synthetase 2, mitochondrial";
    `runoak -i sqlite:obo:mondo info MONDO:0013458 -O obo` gives the HUPRA term
    with synonym "HUPRA syndrome", xrefs OMIM:613845 and Orphanet:363694, and
    `RO:0004003 HGNC:17697 ! SARS2`. No HUPRA literature was read or used for any
    other claim in this file. No evidence item is attached because the contrast is
    an ontology-level and reasoned clinical comparison rather than a quotable
    finding from a cached source about this disease.
- name: WARS1-related neurodevelopmental disorder with microcephaly and speech delay
  disease_term:
    preferred_term: neurodevelopmental disorder with microcephaly and speech delay, with or without brain abnormalities
    term:
      id: MONDO:0957218
      label: neurodevelopmental disorder with microcephaly and speech delay, with or without brain abnormalities
  description: >-
    The closest true clinical mimic, and the reason the two were described in one
    paper. Biallelic variants in WARS1, the CYTOPLASMIC tryptophanyl-tRNA
    synthetase, produce microcephaly, developmental delay, intellectual disability
    and brain anomalies that overlap the SARS1 phenotype closely enough that the
    authors proposed a single emerging category of ARS-related developmental
    disorders with or without microcephaly. The distinction is molecular, not
    clinical.
  distinguishing_features:
  - Different gene - WARS1 is hgnc:12729, SARS1 is hgnc:10537; both are cytoplasmic synthetases and both disorders are autosomal recessive.
  - Different MONDO and OMIM entities - MONDO:0957218 / OMIM:620317 for WARS1 versus MONDO:0060577 / OMIM:617709 here.
  - WARS1 also carries a dominant disease, distal hereditary motor neuronopathy type 9 (MONDO:0060585), which has no SARS1 counterpart; a family history of adult-onset motor neuropathy points to WARS1.
  - Central deafness, cardiomyopathy and fever-triggered metabolic decompensation have been reported in SARS1 disease and are not features of the WARS1 recessive phenotype as described.
  - Speech delay is emphasised in the WARS1 entity's own name; both disorders involve speech impairment, so this does not discriminate at the bedside.
  notes: >-
    MONDO:0957218 and hgnc:12729 were verified with OAK (`runoak -i
    sqlite:obo:mondo relationships --direction down -p RO:0004003 HGNC:12729`
    returns MONDO:0060585 and MONDO:0957218; `runoak -i sqlite:obo:mondo info
    MONDO:0957218 -O obo` gives xref OMIM:620317). No dismech entry exists for
    either WARS1 disorder as of this curation.
  evidence:
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies."
    explanation: States directly that the WARS1 and SARS1 recessive phenotypes overlap, which is what makes this a differential rather than a remote comparison.
  - reference: PMID:35790048
    reference_title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "define an emerging disease spectrum: ARS-related developmental disorders with or without microcephaly"
    explanation: The authors' proposal of a single category containing both disorders, which is the argument for curating them as differentials of each other.
- name: WARS2-related mitochondrial neurodevelopmental disorder
  disease_term:
    preferred_term: neurodevelopmental disorder, mitochondrial, with abnormal movements and lactic acidosis, with or without seizures
    term:
      id: MONDO:0060578
      label: neurodevelopmental disorder, mitochondrial, with abnormal movements and lactic acidosis, with or without seizures
  description: >-
    Included because of a specific citation hazard rather than a clinical one. The
    founding publication for this entry, PMID:28236339, reports TWO families and
    TWO genes: SARS in the first and WARS2 - the mitochondrial tryptophanyl-tRNA
    synthetase - in the second. Any automated or hurried extraction from that
    paper will attribute WARS2 findings (a nonsense allele with predicted
    nonsense-mediated decay, and a missense allele disrupting the mitochondrial
    localisation signal) to this disorder. They belong to MONDO:0060578, a
    separate entity with lactic acidosis and abnormal movements.
  distinguishing_features:
  - Different gene and compartment - WARS2 is hgnc:12730 and mitochondrial; SARS1 is hgnc:10537 and cytoplasmic.
  - Different MONDO and OMIM entities - MONDO:0060578 / OMIM:617710 versus MONDO:0060577 / OMIM:617709; the OMIM numbers are consecutive because both came from the same 2017 paper, which compounds the hazard.
  - Lactic acidosis is a defining feature of the WARS2 entity and has not been reported in SARS1 disease; a raised lactate should redirect the workup.
  - Abnormal movements including dystonia and parkinsonism characterise the WARS2 spectrum; the movement disorder in SARS1 disease is ataxia.
  notes: >-
    MONDO:0060578 was verified with OAK (`runoak -i sqlite:obo:mondo info
    MONDO:0060578 -O obo`: xref OMIM:617710, Orphanet:572798, `RO:0004003
    HGNC:12730 ! WARS2`, synonyms "WARS2 deficiency" and "mitochondrial
    tryptophanyl-tRNA synthetase deficiency"). This differential exists to protect
    future curation of PMID:28236339, and no WARS2 content was used anywhere in
    this entry.
  evidence:
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we report on mutations in two aminoacyl-tRNA synthetases that are associated with ID in two unrelated Iranian families"
    explanation: Documents that the founding publication covers two distinct gene-disease pairs, which is the basis for warning that its content must be split before use.
- name: Hypomyelinating leukodystrophy 3
  disease_term:
    preferred_term: hypomyelinating leukodystrophy 3
    term:
      id: MONDO:0009843
      label: hypomyelinating leukodystrophy 3
  description: >-
    A mechanistic rather than a bedside differential. AIMP1 encodes a non-catalytic
    scaffold component of the cytoplasmic multi-tRNA-synthetase complex, and its
    loss causes a recessive disorder with microcephaly, severe developmental
    failure and seizures. The founding SARS1 paper cites AIMP1 explicitly as the
    precedent that led its authors to propose tRNA-aminoacylation integrity as a
    general requirement for human cognition. The pair therefore anchors the
    argument that lesions anywhere in the cytoplasmic aminoacylation apparatus -
    catalytic subunit or scaffold - converge on a neurodevelopmental phenotype.
  distinguishing_features:
  - Different gene - AIMP1 is hgnc:10648; AIMP1 is a scaffold protein of the multi-synthetase complex, not a synthetase, and has no aminoacylation activity of its own.
  - Hypomyelination is the defining MRI feature of HLD3; the SARS1 imaging phenotype reported to date is diffuse cerebral and cerebellar atrophy, not a hypomyelinating pattern.
  - Onset and severity are commonly said to differ, with HLD3 the earlier and more severe of the two, but no source cached for this entry states patient age, onset age or survival for either condition, so this contrast is background rather than a usable discriminator.
  - Cardiomyopathy and fever-triggered metabolic decompensation are reported in SARS1 disease and are not features of HLD3.
  notes: >-
    MONDO:0009843 and hgnc:10648 were verified with OAK (`runoak -i
    sqlite:obo:mondo relationships --direction down -p RO:0004003 HGNC:10648`
    returns MONDO:0009843 only). The clinical description of HLD3 above is general
    background and is deliberately not evidenced with a snippet, because no HLD3
    paper is cached in this repository; the quotable element is the founding SARS1
    paper's own citation of AIMP1, which is attached below.
  evidence:
  - reference: PMID:28236339
    reference_title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "three genes with a role in tRNA-aminoacylation are now associated with this condition"
    explanation: The founding authors place SARS alongside AIMP1 and WARS2 as members of one aminoacylation-related disease group, which is the basis for this mechanistic differential.
- name: Other recessive cytoplasmic aminoacyl-tRNA synthetase deficiencies
  description: >-
    Not a single disease but the class this disorder belongs to, and in practice
    the differential a metabolic physician actually faces. Recessive deficiencies
    of AARS1, DARS1, GARS1, HARS1, IARS1, KARS1, LARS1, MARS1, QARS1, RARS1, VARS1
    and YARS1 share a phenotype template with SARS1 deficiency: abnormalities of
    the central nervous system and/or the senses in all thirteen of the
    deficiencies surveyed - a compound category, not a claim about the CNS alone -
    plus failure to thrive,
    gastrointestinal symptoms, dysmaturity, liver disease and facial dysmorphism
    recurring across the group, with symptoms concentrated in the first year of
    life and during infections. Because the clinical picture does not identify the
    gene, the practical route to diagnosis is a broad sequencing approach rather
    than a targeted one, and the practical route to management - adequate protein
    and amino acid supply rather than protein restriction - is shared across the
    class.
  distinguishing_features:
  - The clinical phenotypes of the recessive ARS deficiencies are described as diverse and without apparent logic; they are not separable at the bedside and the distinction is molecular.
  - Pulmonary alveolar proteinosis points towards MARS1, IARS1 or LARS1 rather than SARS1; it has not been reported in SARS1 disease.
  - Prominent liver disease points away from SARS1, in which hepatic involvement has not been reported.
  - Microcephaly as the leading feature narrows the group towards SARS1 and WARS1.
  - Fever-triggered decompensation is a class feature rather than a SARS1-specific one, so its presence does not identify the gene.
  notes: >-
    No MONDO term is bound to this differential because it is a class, not a
    disease entity, and binding any single member's term would misrepresent it.
    The gene symbols listed are the current HGNC forms of the symbols used in the
    quoted source, which predates the "1" suffix convention and writes AARS,
    DARS, GARS and so on.
  evidence:
  - reference: PMID:29875423
    reference_title: "Aminoacyl-tRNA synthetase deficiencies in search of common themes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In literature, we identified 107 patients with AARS, DARS, GARS, HARS, IARS, KARS, LARS, MARS, RARS, SARS, VARS, YARS, and QARS deficiencies"
    explanation: Enumerates the class of recessive cytoplasmic synthetase deficiencies that constitutes this differential, with SARS among them.
  - reference: PMID:29875423
    reference_title: "Aminoacyl-tRNA synthetase deficiencies in search of common themes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical features of autosomal recessive ARS deficiencies appear very diverse and without apparent logic."
    explanation: Supports the claim that the class cannot be separated on clinical grounds, which is why the differential is handled by sequencing rather than by phenotyping.
treatments:
- name: L-serine supplementation
  action_category: THERAPEUTIC
  description: >-
    The only disease-specific intervention reported, and its rationale follows
    directly from the mechanism. If the lesion is insufficient charging capacity
    for the demand, then raising the intracellular concentration of the substrate
    amino acid should drive the residual hypomorphic enzyme harder - a mass-action
    rescue rather than a correction of the defect. Chronic supplementation is
    described as established practice in SARS1 deficiency. What was new in 2026 is
    acute management: during a febrile decompensation with an ejection fraction of
    20%, the patient's L-serine dose was progressively tripled alongside standard
    supportive care and he survived, where three untreated siblings had died of
    comparable episodes. That is the first documented survival of a SARS1 metabolic
    crisis. It is also, honestly, an n-of-1 with a fatal outcome a year later
    despite an emergency protocol - so the intervention is reported here as
    promising and mechanistically coherent, not as established efficacy.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: high-dose oral L-serine supplementation
    term:
      id: NCIT:C15433
      label: Nutritional Support
    therapeutic_agent:
    - preferred_term: L-serine
      term:
        id: CHEBI:17115
        label: L-serine
  target_mechanisms:
  - target: Deficient Serylation of tRNA-Ser
    treatment_effect: ACTIVATES
    description: >-
      Raising substrate availability is intended to drive the residual
      hypomorphic enzyme harder by mass action, partially restoring serylation
      flux. This is the intended target; it has not been demonstrated in
      SARS1 patient cells.
  - target: Demand-Dependent Decompensation During Febrile Catabolic Stress
    treatment_effect: INHIBITS
    description: >-
      Dose escalation during febrile illness is intended to raise charging
      capacity at the moment translational demand spikes, aborting the crisis.
  target_phenotypes:
  - preferred_term: Cardiomyopathy
    term:
      id: HP:0001638
      label: Cardiomyopathy
  notes: >-
    Deliberately not asserted: no dose, no dose range, no dosing schedule and no
    target plasma serine concentration is recorded anywhere in this entry. The
    cached abstract says the patient's dose was "progressively tripled" from his
    own baseline and gives no absolute figures, and inventing a mg/kg/day number
    would be exactly the kind of unchecked quantitative claim that prose is
    vulnerable to. Nor is the mass-action rationale in the description above a
    quoted finding - no study has measured whether serine loading increases
    serylation in SARS1 patient cells. On term choice: NCIT:C1505 (Dietary
    Supplement) was tried first and rejected because it is not reachable from
    NCIT:C25218 and fails TreatmentActionTerm validation; NCIT:C15433
    (Nutritional Support) is the correct clinical-action term, with the specific
    chemical carried in `therapeutic_agent`. The modality is SMALL_MOLECULE
    rather than BEHAVIORAL, following the explicit CLAUDE.md guidance not to tag
    nutritional supplementation of a defined chemical as BEHAVIORAL.
  evidence:
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "While amino acid chronic supplementation is established, no guidelines exist for acute management."
    explanation: Establishes that chronic amino acid supplementation is already standard in this disorder while acute management is not codified.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "During hospitalisation, the patient's specific L-serine supplementation dosage was progressively tripled concurrently with standard supportive care."
    explanation: Describes the intervention actually administered, without an absolute dose.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Unlike the fatal outcomes observed in his siblings, untreated by L-serine, the patient survived and recovered following this high-dose regimen"
    explanation: The efficacy observation, stated as a within-family comparison, which is the strongest available evidence and is still n-of-1.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "However, a year later, the patient presented with another febrile crisis at 10 years old, and despite an emergency protocol, the patient developed severe biventricular dysfunction progressing to fatal cardiogenic shock."
    explanation: >-
      Marked PARTIAL because it qualifies the efficacy claim: the same patient
      subsequently died of a febrile crisis despite an emergency protocol, so
      L-serine escalation is not reliably life-saving.
  - reference: PMID:29875423
    reference_title: "Aminoacyl-tRNA synthetase deficiencies in search of common themes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Assuming residual ARS activity, adequate protein/amino acid supply seems essential instead of the traditional replacement of protein by glucose in patients with metabolic diseases."
    explanation: Supplies the class-level mechanistic rationale for amino acid supply rather than protein restriction in ARS deficiencies.
- name: Emergency protocol for febrile illness
  action_category: THERAPEUTIC
  description: >-
    Because febrile illness is the trigger for lethal decompensation, anticipatory
    management of intercurrent fever is the central chronic-care task in this
    disorder: early presentation, aggressive escalation of L-serine, and cardiac
    and haemodynamic monitoring during the episode. The 2026 report explicitly
    frames early, aggressive escalation as a viable strategy while noting that no
    guidelines exist. It also records the limit of the approach: the patient died
    in a subsequent crisis despite having an emergency protocol in place, so a
    protocol reduces but does not remove the risk.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: acute decompensation emergency protocol
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_mechanisms:
  - target: Demand-Dependent Decompensation During Febrile Catabolic Stress
    treatment_effect: INHIBITS
    description: >-
      Anticipatory management of the febrile trigger aims to prevent the
      demand-capacity mismatch from progressing to decompensation.
  notes: >-
    No published protocol exists to cite; the components listed in the description
    are drawn from what was actually done in the single reported episode
    (progressive tripling of L-serine, standard supportive care, mechanical
    ventilation and vasopressors as needed, serial cardiac biomarkers and
    echocardiography). Nothing here should be read as a validated pathway.
  evidence:
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The findings strongly suggest that early, aggressive escalation of L-serine dosage can be a viable therapeutic strategy for acute decompensation in SARS1 deficiency."
    explanation: The authors' explicit recommendation, which is the basis for treating anticipatory febrile management as a therapeutic action.
  - reference: PMID:42158840
    reference_title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This constitutes the first documented survival of a SARS1-related metabolic crisis managed with high-dose L-serine."
    explanation: >-
      Marked PARTIAL: "first documented survival" simultaneously supports the
      strategy and discloses that the entire evidence base for it is one episode
      in one patient.
animal_models:
- species: Danio rerio
  genotype: adrasteia (adr) mutants; sars (seryl-tRNA synthetase) loss of function
  category: Forward-genetic mutant isolated in a vascular screen
  description: >-
    The zebrafish sars mutants are the only established animal model of the gene,
    and they are NOT a model of this disease - a distinction this entry insists on.
    They were recovered in a screen for vascular development and maintenance, and
    their phenotype is vascular: pronounced dilatation of the aortic arch vessels,
    aberrant patterning of hindbrain capillaries, and to a lesser extent altered
    intersomitic vessels, with the aortic dilatation dependent on Vegf signalling
    rather than on increased cell proliferation. Positional cloning identified
    seryl-tRNA synthetase as the affected gene, and siRNA knockdown in human
    umbilical vein endothelial cells showed the same regulation of endothelial
    sprouting. The model therefore validates the non-canonical, VEGFA-related
    function of SerRS at the organism level. It says nothing about microcephaly,
    ataxia, seizures, cardiomyopathy or febrile decompensation, and no vascular
    malformation has ever been reported in a human SARS1 patient. The consequence
    of that gap - that this disorder has no animal or cellular disease model at
    all, and what a usable one would have to capture - is worked through in the
    HUMAN_MODEL_MISMATCH discussion `sars1-no-disease-model`, which proposes the
    knock-in mouse and patient-derived cortical organoid experiments that would
    close it.
  genes:
  - preferred_term: SARS1
    term:
      id: hgnc:10537
      label: SARS1
  associated_phenotypes:
  - Dilatation of the aortic arch vessels
  - Aberrant hindbrain capillary patterning
  - Altered intersomitic vessel patterning
  evidence:
  - reference: PMID:19423847
    reference_title: "Genetic evidence for a noncanonical function of seryl-tRNA synthetase in vascular development."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "By positional cloning, we isolated seryl-tRNA synthetase (sars) as the gene affected by the adr mutations"
    explanation: Establishes that the adrasteia mutants are seryl-tRNA synthetase mutants, which is what makes them a model of this gene.
  - reference: PMID:19423847
    reference_title: "Genetic evidence for a noncanonical function of seryl-tRNA synthetase in vascular development."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "This dilatation of the aortic arch vessels does not appear to be caused by increased cell proliferation but is dependent on vascular endothelial growth factor (Vegf) signaling"
    explanation: Shows the mutant phenotype is Vegf-dependent, which is why the model speaks to the non-canonical rather than the translational function.
  - reference: PMID:19423847
    reference_title: "Genetic evidence for a noncanonical function of seryl-tRNA synthetase in vascular development."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "These analyses of zebrafish and human endothelial cells reveal a new noncanonical function of Sars in endothelial development"
    explanation: >-
      Marked PARTIAL with respect to this disease. The finding is solid, but what
      it establishes is a noncanonical endothelial function, which is precisely the
      arm of SerRS biology whose relevance to the human neurodevelopmental disorder
      is unestablished.
  - reference: PMID:22353712
    reference_title: "Unique domain appended to vertebrate tRNA synthetase is essential for vascular development."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "These results are the first to show an essential role for a tRNA synthetase-associated appended domain at the organism level"
    explanation: Confirms at the organism level that the UNE-S appendage, not the catalytic core, carries the vascular function tested in these fish.
discussions:
- discussion_id: sars1-charging-vs-moonlighting
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Do the patient SARS1 alleles impair only serine charging, or do they also
    disrupt the non-canonical nuclear functions of SerRS - and would it change
    anything clinically if they did?
  rationale: >-
    This is the central unresolved mechanistic question for the entry. Vertebrate
    SerRS has a documented second life in the nucleus, repressing VEGFA through a
    YY1 complex and binding telomeric DNA with POT1, and disrupting the nuclear
    function is lethal in zebrafish. Every human SARS1 disease allele so far maps
    to the catalytic core - which argues for a pure charging defect - but the
    SerRS/YY1 interaction is itself mediated by the CATALYTIC domain, so
    active-site alleles are not automatically innocent with respect to the nuclear
    activity. Nobody has tested nuclear localisation, YY1 binding, VEGFA
    repression, or telomere length in cells carrying p.Asp172Asn, p.Arg213Leu or
    p.Thr399Met. The answer matters practically: if the moonlighting arm is intact,
    substrate supplementation targets the whole defect; if it is not, L-serine can
    never be more than partial therapy, and vascular or telomere-related
    surveillance might be warranted in a disorder where nobody currently looks for
    either.
  attaches_to:
  - "pathophysiology#Loss of Non-Canonical Nuclear SerRS Function"
  - "pathophysiology#Deficient Serylation of tRNA-Ser"
  proposed_experiments:
  - experiment_id: sars1-nuclear-localisation-allelic-series
    name: Nuclear localisation and VEGFA repression across the SARS1 allelic series
    description: >-
      Express each patient allele in a SerRS-depleted background and measure
      nuclear/cytoplasmic partitioning, co-immunoprecipitation with YY1, occupancy
      at the distal vegfa cis-regulatory element, and VEGFA transcript level,
      alongside serylation activity, so that the two functions are read out from
      the same cells.
  - experiment_id: sars1-telomere-length-patient-fibroblasts
    name: Telomere length and POT1 association in SARS1 patient fibroblasts
    description: >-
      Measure telomere length and SerRS-POT1 association in fibroblasts from
      recessive SARS1 patients and compare with the senescent fibroblasts of the
      dominant-negative patient, to test whether the reported senescence is
      telomeric or translational in origin.
- discussion_id: sars1-crisis-biomarker
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    What is the biochemistry of a SARS1 febrile decompensation, and is there any
    laboratory test that can confirm one is underway?
  rationale: >-
    The decompensations are lethal and the proposed treatment is substrate loading,
    yet no biochemical characterisation of a crisis exists: no published amino acid
    profile, no charged-tRNA-Ser measurement, no integrated-stress-response readout,
    no proteomic signature. Clinicians are therefore escalating L-serine on
    mechanistic reasoning with no way to confirm the target is engaged or to
    titrate. The label "metabolic decompensation" is itself doing unexamined work -
    it is borrowed from the intoxication-type inborn errors, where a toxic
    metabolite accumulates, whereas the proposed SARS1 mechanism is a synthetic
    insufficiency with no accumulating toxin. Whether anything measurable
    accumulates or is depleted during a SARS1 crisis is simply unknown.
  attaches_to:
  - "pathophysiology#Demand-Dependent Decompensation During Febrile Catabolic Stress"
  - "treatments#L-serine supplementation"
  proposed_experiments:
  - experiment_id: sars1-crisis-metabolomics
    name: Paired crisis and baseline metabolomic and amino acid profiling
    description: >-
      Collect plasma and, where available, cerebrospinal fluid at presentation with
      febrile decompensation and again at baseline in the same patient, and profile
      amino acids, acylcarnitines and untargeted metabolites, to establish whether
      any analyte tracks the crisis.
  - experiment_id: sars1-fibroblast-thermal-challenge
    name: Thermal and inflammatory challenge of SARS1 patient fibroblasts
    description: >-
      Culture patient and control fibroblasts at 37 and 40 degrees Celsius, with
      and without inflammatory cytokine exposure and with and without serine
      supplementation, and measure charged tRNA-Ser, global translation by
      puromycin incorporation or ribosome profiling, and integrated-stress-response
      markers.
- discussion_id: sars1-mondo-label-understates-entity
  kind: INTERPRETATION
  status: OPEN
  prompt: >-
    Should the SARS1 phenotype remain one MONDO entity named for microcephaly,
    ataxia and seizures, when its most dangerous manifestation is cardiac and one
    reported patient had neither microcephaly nor a recessive genotype?
  rationale: >-
    MONDO:0060577 is the only disease term MONDO assigns to SARS1, and ClinVar
    files both the microcephaly allele and the cardiomyopathy allele against it, so
    curating the whole spectrum here is the correct current mapping. But the label
    actively misleads in two directions. A clinician reading "neurodevelopmental
    disorder with microcephaly, ataxia, and seizures" would not anticipate a
    treatable, lethal, fever-triggered cardiomyopathy, and would not consider the
    gene in a child with spastic paraplegia and a normal head circumference. This
    is recorded as an interpretation issue rather than silently resolved, because
    the resolution belongs to MONDO and OMIM, not to this entry. What this entry
    does instead is curate the full spectrum and mark, feature by feature, which
    presentation each observation comes from.
  attaches_to:
  - "phenotypes#Cardiomyopathy"
  - "phenotypes#Spastic paraplegia"
  notes: >-
    The alternative curation - restricting this entry to the microcephaly
    presentation and waiting for MONDO to split the term - was considered and
    rejected, because it would have excluded the only treatable and the only lethal
    features of SARS1 deficiency from the knowledge base while the term that ought
    to hold them does not exist.
- discussion_id: sars1-fever-risk-allele-restricted
  kind: OPEN_QUESTION
  status: OPEN
  prompt: >-
    Is the risk of fatal febrile decompensation restricted to the p.Arg213Leu
    genotype, or does every SARS1 patient need an emergency protocol?
  rationale: >-
    Fever-triggered decompensation has been reported only in the family carrying
    c.638G>T (p.Arg213Leu). Two readings are possible and they imply opposite
    clinical policies. If the risk is allele-specific - for example because that
    allele's protein instability is itself temperature-sensitive, which would be a
    direct and elegant explanation for a fever trigger - then patients with other
    genotypes need no emergency plan. If instead the risk is generic to residual
    charging capacity, as the ARS-family model implies, then the other families
    simply have not been followed long enough or have not been recognised, and
    every SARS1 patient should be issued a protocol. Nobody has tested the thermal
    stability of any SARS1 mutant protein, which is a cheap experiment that would
    largely settle it.
  attaches_to:
  - "pathophysiology#Demand-Dependent Decompensation During Febrile Catabolic Stress"
  - "variants#SARS1 c.638G>T p.Arg213Leu"
  proposed_experiments:
  - experiment_id: sars1-thermal-stability-allelic-series
    name: Thermal stability and activity of recombinant SARS1 mutant proteins
    description: >-
      Measure melting temperature and residual serylation activity at 37 and 40
      degrees Celsius for recombinant wild-type SerRS and each patient allele, to
      test directly whether the p.Arg213Leu protein is disproportionately
      temperature-sensitive.
- discussion_id: sars1-no-disease-model
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Why is there no animal or cellular model of SARS1 NEURODEVELOPMENTAL disease,
    and what would one need to capture?
  rationale: >-
    The only established in vivo SARS1 model is the zebrafish adrasteia mutant,
    which was isolated for a vascular phenotype and reads out the non-canonical
    function; it has never been used to model microcephaly, ataxia, seizures or
    cardiomyopathy, and human patients have no reported vascular malformation. No
    mouse model, no knock-in of a patient allele, and no neural organoid has been
    published. This is a genuine mismatch rather than a gap in the literature
    search: the model that exists reads out the arm of the biology that the human
    disease may not use. A knock-in of p.Asp172Asn or p.Arg213Leu, phenotyped for
    brain growth, cerebellar structure, seizure threshold and cardiac function
    under thermal challenge, is the missing experiment.
  attaches_to:
  - "pathophysiology#Impaired Neural Progenitor Proliferation and Brain Growth"
  proposed_experiments:
  - experiment_id: sars1-knockin-mouse-allelic
    name: Knock-in mouse carrying a patient SARS1 allele
    description: >-
      Generate homozygous knock-in mice for p.Asp172Asn and for p.Arg213Leu and
      phenotype brain weight and cortical thickness, cerebellar morphology, seizure
      susceptibility, and cardiac function at baseline and under a controlled
      pyrogenic or thermal challenge.
  - experiment_id: sars1-patient-derived-cortical-organoid
    name: Patient-derived cortical organoids
    description: >-
      Differentiate iPSC-derived cortical organoids from recessive SARS1 patients
      and isogenic corrected controls, and measure progenitor proliferation, organoid
      size, and global translation rate, to test the demand-capacity model in a human
      neural context.
- discussion_id: sars1-karaer-cohort-inconsistency
  kind: CURATION_TODO
  status: OPEN
  prompt: >-
    How many patients does PMID:36004946 actually report, and in how many of them
    was c.1196C>T found?
  rationale: >-
    The cached abstract states "three unrelated Turkish families with four NEDMAS
    patients" and then, two sentences later, "both patients carried a novel
    missense variant c.1196C>T (p.Thr399Met)". Four patients and "both patients"
    cannot both be right. The most likely readings are that the variant was found
    in only two of the four, or that "both" is a residue of an earlier draft
    describing two patients. This entry therefore asserts no case count from that
    paper and no genotype-count for the p.Thr399Met allele. Resolving it requires
    the full text, which is not cached in this repository. It is recorded rather
    than silently resolved because a curator or an automated extractor is otherwise
    likely to take "four patients" as a countable figure.
  attaches_to:
  - "variants#SARS1 c.1196C>T p.Thr399Met"
  - "prevalence#"
- discussion_id: sars1-thr399met-vus
  kind: CONTROVERSY
  status: OPEN
  prompt: >-
    Is c.1196C>T (p.Thr399Met) pathogenic, given that it is published as causal in
    multiple families but classified as a variant of uncertain significance in
    ClinVar?
  rationale: >-
    PMID:36004946 reports p.Thr399Met as the disease-causing variant in unrelated
    Turkish families with a matching phenotype. ClinVar (VCV002506443, retrieved
    2026-08-01) holds a single criteria-provided submission classifying it as
    Uncertain significance against "not specified". No functional assay has been
    published for this allele - no serylation measurement, no protein-stability
    measurement, no structural mapping - so the case for pathogenicity rests
    entirely on segregation and phenotype match in a small number of families. This
    is a live disagreement between the published literature and the variant
    database, and a laboratory encountering this allele will have to adjudicate it.
    A serylation assay in patient fibroblasts, the same experiment done for the
    other alleles, would resolve it.
  attaches_to:
  - "variants#SARS1 c.1196C>T p.Thr399Met"
  notes: >-
    The ClinVar classification is from the public E-utilities API and is not
    quotable from a cached reference, so it is recorded in this rationale rather
    than as an evidence snippet.
references:
- reference: PMID:28236339
  title: "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability."
- reference: PMID:34570399
  title: "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever."
- reference: PMID:36004946
  title: "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum."
- reference: PMID:35790048
  title: "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly."
- reference: PMID:36041817
  title: "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence."
- reference: PMID:42158840
  title: "High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature."
- reference: PMID:29875423
  title: "Aminoacyl-tRNA synthetase deficiencies in search of common themes."
- reference: PMID:24095058
  title: "Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes."
- reference: PMID:22353712
  title: "Unique domain appended to vertebrate tRNA synthetase is essential for vascular development."
- reference: PMID:19423847
  title: "Genetic evidence for a noncanonical function of seryl-tRNA synthetase in vascular development."
- reference: PMID:27913726
  title: "Competitive binding between Seryl-tRNA synthetase/YY1 complex and NFKB1 at the distal segment results in differential regulation of human vegfa promoter activity during angiogenesis."
- reference: PMID:38255739
  title: "Protein-Protein Interactions of Seryl-tRNA Synthetases with Emphasis on Human Counterparts and Their Connection to Health and Disease."
📚

References & Deep Research

References

12
PMID:28236339
Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability.
No top-level findings curated for this source.
PMID:34570399
A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever.
No top-level findings curated for this source.
PMID:36004946
Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum.
No top-level findings curated for this source.
PMID:35790048
WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly.
No top-level findings curated for this source.
PMID:36041817
Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence.
No top-level findings curated for this source.
PMID:42158840
High-Dose L-Serine Supplementation During Febrile Decompensation in SARS1 Deficiency: A Case Report and Review of the Literature.
No top-level findings curated for this source.
PMID:29875423
Aminoacyl-tRNA synthetase deficiencies in search of common themes.
No top-level findings curated for this source.
PMID:24095058
Crystal structure of human Seryl-tRNA synthetase and Ser-SA complex reveals a molecular lever specific to higher eukaryotes.
No top-level findings curated for this source.
PMID:22353712
Unique domain appended to vertebrate tRNA synthetase is essential for vascular development.
No top-level findings curated for this source.
PMID:19423847
Genetic evidence for a noncanonical function of seryl-tRNA synthetase in vascular development.
No top-level findings curated for this source.
PMID:27913726
Competitive binding between Seryl-tRNA synthetase/YY1 complex and NFKB1 at the distal segment results in differential regulation of human vegfa promoter activity during angiogenesis.
No top-level findings curated for this source.
PMID:38255739
Protein-Protein Interactions of Seryl-tRNA Synthetases with Emphasis on Human Counterparts and Their Connection to Health and Disease.
No top-level findings curated for this source.

Deep Research

1
Claude Code ▸
SARS1-Related Neurodevelopmental Disorder — Comprehensive Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 9 citations 2026-08-03T01:43:26.224927

SARS1-Related Neurodevelopmental Disorder — Comprehensive Research Report

1. Disease Information

Overview. SARS1-related neurodevelopmental disorder — formally designated Neurodevelopmental Disorder with Microcephaly, Ataxia, and Seizures (NEDMAS) — is an ultra-rare, autosomal recessive Mendelian disorder caused by biallelic (and in one reported case, a dominant-negative de novo) pathogenic variants in SARS1, the gene encoding cytoplasmic seryl-tRNA synthetase 1. The core phenotype comprises global developmental delay/intellectual disability, postnatal microcephaly, early-onset seizures, ataxia, and muscle weakness, with an expanding phenotypic spectrum that now includes sensorineural deafness, cardiomyopathy, fever-triggered metabolic decompensation (in loss-of-function cases), and — in a distinct de novo dominant-negative case — complex spastic paraplegia without microcephaly (Musante et al. 2017, PMID:28236339; Ravel et al. 2021, PMID:34570399; Bögershausen et al. 2022, PMID unlisted; Karaca-Mandic/Turkish cohort 2022, PMID:36004946; PMID:36041817).

Key identifiers: - Gene: SARS1 (formerly SARS), HGNC:10537, located at chromosome 1p13.3 - OMIM gene: 607529 — Seryl-tRNA Synthetase 1; SARS1 (OMIM:607529) - OMIM phenotype: #617709 — Neurodevelopmental Disorder with Microcephaly, Ataxia, and Seizures (NEDMAS) (OMIM:617709) - Suggested MONDO ID: should correspond to the MONDO term cross-referenced to OMIM:617709 (mint via the standard OMIM→MONDO xref if not already in the local ontology cache; a specific MONDO CURIE could not be independently confirmed from public search results and should be verified with OAK against sqlite:obo:mondo before curation) - Inheritance: Autosomal recessive (most reported families); one de novo dominant-negative case reported - Category: Mendelian, aminoacyl-tRNA synthetase (ARS) disorder

Synonyms/alternative names: NEDMAS; SARS1 deficiency; seryl-tRNA synthetase 1 deficiency; SARS-related intellectual disability (older literature, pre-2017/pre-gene-renaming used "SARS" rather than "SARS1" since the gene was renamed from SARS to SARS1 to distinguish from unrelated "SARS" coronavirus nomenclature).

Important disambiguation: SARS1 encodes the cytoplasmic seryl-tRNA synthetase and must not be confused with SARS2, which encodes the mitochondrial seryl-tRNA synthetase and causes a clinically distinct disorder (HUPRA syndrome — hyperuricemia, pulmonary hypertension, renal failure, alkalosis). Web search results returning SARS2/mitochondrial content were explicitly filtered out of this report; all findings below pertain to the cytoplasmic SARS1 gene only.

Evidence source note: Information below is aggregated from published case series/case reports (peer-reviewed literature, disease-level aggregation) rather than large-cohort EHR data, consistent with an ultra-rare Mendelian disorder with fewer than ~15 reported individuals across all published families as of the most recent (2022) case series.

2. Etiology

Disease causal factors: Purely genetic/monogenic. Biallelic (homozygous or compound heterozygous) missense variants in SARS1 are the predominant mechanism, causing partial loss of seryl-tRNA synthetase aminoacylation function. A single reported case involves a de novo, dominant-negative, in-frame splice-altering deletion producing a distinct, non-microcephalic spastic paraplegia phenotype via a toxic gain-of-function/dominant-negative mechanism rather than simple biallelic loss-of-function (PMID:36041817).

Genetic risk factors: - Reported pathogenic variants (all missense unless noted): - c.514G>A, p.(Asp172Asn) — homozygous, consanguineous Iranian family, 4 affected siblings (Musante et al. 2017, PMID:28236339) - p.(Arg302Cys) and p.(Arg390Cys) — compound heterozygous, second Iranian family (Musante et al. 2017) - c.638G>T, p.(Arg213Leu) — homozygous, consanguineous Turkish family; associated with the deafness/cardiomyopathy/fever-decompensation phenotype (Ravel et al. 2021, PMID:34570399) - c.1196C>T, p.(Thr399Met) — novel missense variant identified in multiple unrelated Turkish NEDMAS families (biallelic) (2022 clinical spectrum expansion, PMID:36004946) - chr1:109778053_109778055delGGT (genomic deletion spanning the exon 7/intron 7 boundary) — de novo, heterozygous, splice-site-disrupting deletion causing in-frame insertion of 16 intronic bp / 5 aberrant amino acids near the enzyme active site; dominant-negative mechanism (PMID:36041817) - Additional biallelic missense variants reported in a 2022 multi-gene series alongside WARS1 cases, in individuals presenting with an overlapping microcephaly/developmental-delay/brain-anomaly phenotype (Bögershausen et al. 2022) - Consanguinity is a recurring feature across nearly all reported pedigrees (Iranian and Turkish families), consistent with autosomal recessive transmission and suggesting the disorder is substantially under-ascertained outside consanguineous populations. - No modifier genes or susceptibility loci have been reported to date; no GWAS/PheGenI signal exists given the extreme rarity and Mendelian nature of the condition.

Environmental risk factors / gene-environment interaction: The most clinically significant gene-environment interaction reported is febrile illness as a precipitant of acute decompensation. In the Ravel et al. (2021) family, affected children experienced severe metabolic/neurological decompensation during febrile episodes, in one case fatal, indicating that fever/infectious stress unmasks or exacerbates an underlying translational insufficiency — a pattern seen in several other aminoacyl-tRNA synthetase disorders where impaired global protein synthesis becomes rate-limiting under increased physiological demand. In the spastic-paraplegia case (PMID:36041817), seizures were "frequently precipitated by fever" as well, reinforcing fever as a cross-cutting trigger for this gene.

Protective factors: None reported in the literature; given the rarity of the disorder, no population-level protective variant or environmental protective factor data exists in gnomAD/GWAS resources specific to SARS1-NEDMAS.

3. Phenotypes

Phenotype burden is drawn from the aggregate of published cases (Musante 2017, n=5 across 2 families; Ravel 2021, n=2 siblings; the 2022 Turkish cohort, n=4 across 3 families; Bögershausen 2022, additional individuals; and the single spastic-paraplegia case). Because the total published cohort is small (~12-15 individuals), frequencies below are qualitative/descriptive rather than statistically robust percentages.

Phenotype Type Suggested HPO term Notes/Frequency
Global developmental delay Symptom/sign HP:0001263 Global developmental delay Reported in essentially all cases; core feature
Intellectual disability (moderate-severe; IQ 40-45 in original family) Symptom HP:0001249 Intellectual disability Core feature across all families
Postnatal microcephaly (−4 to −5 SD in original family) Physical sign HP:0000252 Microcephaly Present in most, but explicitly absent in the de novo dominant-negative spastic paraplegia case — a key phenotype-genotype distinguishing feature
Seizures Symptom HP:0001250 Seizure Early-onset in most; in the spastic-paraplegia case specifically "focal seizures... frequently precipitated by fever"
Ataxia Sign HP:0001251 Ataxia First apparent in childhood in the original family; present across nearly all reported cases
Muscle weakness Sign HP:0001324 Muscle weakness Reported in original and subsequent families
Speech impairment/delay Symptom HP:0002167 Impaired speech or vocalization / HP:0000750 Delayed speech and language development Reported in original family and Turkish cohort
Aggressive behavior Behavioral HP:0000718 Aggressive behavior Reported in original Iranian family
Thin body habitus Physical sign HP:0001519 Disproportionate tall stature / more precisely HP:0004325 Decreased body weight or a thinness-specific term Turkish cohort (2022)
Severe hypotonia Sign HP:0008936 Severe muscular hypotonia Turkish cohort (2022)
Cerebral and cerebellar atrophy (diffuse, bilateral) Imaging finding HP:0002059 Cerebral atrophy / HP:0001272 Cerebellar atrophy Turkish cohort neuroimaging
Sensorineural/central deafness Sign HP:0000407 Sensorineural hearing loss (or HP:0008527 Congenital sensorineural hearing loss depending on documented mechanism) Ravel et al. 2021 family
Cardiomyopathy Sign HP:0001638 Cardiomyopathy Ravel et al. 2021 family
Fever-triggered metabolic/neurological decompensation Episodic/course feature HP:0034332 (or closest available "metabolic crisis" term) — consider free-text framing if no precise HPO term fits Ravel et al. 2021 (fatal in one child); also seizure-precipitant pattern in PMID:36041817
Spastic paraparesis (progressive in childhood, later stabilizing) Sign HP:0001260 Spasticity / HP:0007256 Progressive spasticity De novo dominant-negative case only (PMID:36041817)
Non-progressive punctiform frontal subcortical white-matter hyperintensities on MRI Imaging finding HP:0002499 or closest white-matter signal abnormality term De novo case, distinguishes from classic biallelic phenotype
Increased visual evoked potential latency Functional test finding HP:0000618-adjacent or electrophysiology-specific term De novo case

Onset: Infantile to early childhood in virtually all reported cases (developmental delay and/or seizures typically noted in infancy/toddlerhood).

Severity/progression: Variable — ranges from moderate intellectual disability with stable ataxia (original Iranian family) to severe, fatal fever-triggered decompensation (Ravel et al. Turkish family) to a progressive-then-stabilizing spastic paraparesis (de novo case). This variability appears to correlate with variant type/mechanism (partial loss-of-function missense vs. dominant-negative splice variant vs. more severe loss-of-function variant with organ involvement).

Quality of life impact: Not formally studied with standardized instruments (EQ-5D/SF-36/PROMIS) in the literature; qualitatively, the combination of intellectual disability, seizures, ataxia, and (in some cases) cardiomyopathy/deafness confers substantial impact on daily functioning, communication, and mobility, with life-threatening risk during febrile illness in the loss-of-function subgroup.

4. Genetic/Molecular Information

Causal gene: SARS1 (HGNC:10537; NCBI Gene ID 6301; OMIM *607529), chromosome 1p13.3, encoding cytoplasmic seryl-tRNA synthetase (protein SerRS/SYSC).

Gene function: SARS1 catalyzes the ATP-dependent aminoacylation of tRNA^Ser with L-serine — the first step of incorporating serine into nascent polypeptides during cytoplasmic translation. It also catalyzes the first step of selenocysteine (Sec) biosynthesis, since Sec-tRNA is initially charged with serine by SerRS before conversion to selenocysteine, giving SARS1 a secondary non-canonical role connecting it to selenoprotein synthesis. Notably, zebrafish studies (Fukui et al. 2009; Herzog et al. 2009) showed that Sars also has an aminoacylation-independent role in vascular development, indicating this synthetase family member has moonlighting functions beyond canonical translation.

Protein structure: SARS1 is a Class II aminoacyl-tRNA synthetase (aaRS) that functions as a homodimer in the cytoplasm (distinguishing it structurally/mechanistically from Class I aaRSs). Structural modeling of the de novo splice variant showed the aberrant 5-amino-acid in-frame insertion disrupts a critical β-strand near the catalytic core and displaces residues essential for ATP and serine substrate recognition, directly implicating the active site in pathogenesis for that variant (PMID:36041817).

Pathogenic variant classes reported: - Missense (majority of biallelic cases): p.Asp172Asn, p.Arg302Cys, p.Arg390Cys, p.Arg213Leu, p.Thr399Met, plus additional biallelic missense variants in the Bögershausen 2022 series - Splice-region genomic deletion (single de novo case): chr1:109778053_109778055delGGT, producing an in-frame 5-amino-acid insertion rather than a frameshift/null allele

Variant classification (ACMG/AMP): Not explicitly stated per-variant in the sources retrieved; given segregation in consanguineous families with clinical concordance and (for the de novo splice variant) direct functional/structural evidence, these variants would likely be classified pathogenic or likely pathogenic under ACMG/AMP criteria (PS2/PS3/PM1/PM2/PP1/PP3-type evidence), but formal ClinVar submission status should be independently verified.

Allele frequency: Not reported as present at appreciable frequency in population databases (gnomAD, 1000 Genomes) — consistent with an ultra-rare recessive disorder; specific gnomAD allele counts were not retrievable from the search results and should be checked directly in gnomAD/ClinVar during curation.

Functional consequences: - Biallelic missense variants (loss-of-function, partial): reduce SARS1 aminoacylation activity, impairing global cytoplasmic protein synthesis capacity — most evident under physiological stress (fever). - De novo splice deletion: dominant-negative mechanism — patient fibroblasts showed ~30% reduced aminoacylation activity, and yeast complementation studies demonstrated that co-expression of wild-type and mutant SARS1 produced significant growth defects, confirming a poisoning/dominant-negative effect of the mutant protein on the wild-type homodimer, rather than simple haploinsufficiency (PMID:36041817).

Somatic vs. germline: All reported variants are germline (constitutional); no somatic/cancer association has been reported for SARS1.

Modifier genes: None established.

Epigenetic information: No DNA methylation, histone modification, or chromatin-level disease mechanism has been reported for SARS1-NEDMAS in the retrieved literature.

Chromosomal abnormalities: None reported; disease mechanism is point-variant/small-indel based, not large structural rearrangement.

5. Environmental Information

  • Environmental factors: No toxin, radiation, or occupational exposure has been implicated as a primary or contributing cause; this is a monogenic disorder.
  • Lifestyle factors: Not applicable as a causal factor; however, febrile illness management (see below) is a critical environmental/clinical modifier of disease course.
  • Infectious agents: No specific pathogen is causally implicated in disease onset. However, febrile infectious illness (of any etiology) acts as a non-specific environmental trigger for acute decompensation and seizure exacerbation in affected individuals — this is a gene-level vulnerability to physiological/metabolic stress rather than an infection-specific mechanism, analogous to fever-sensitivity patterns seen in other mitochondrial/translational disorders (e.g., RARS2-related pontocerebellar hypoplasia) and in certain channelopathies.

6. Mechanism / Pathophysiology

Causal chain (loss-of-function/biallelic missense pathway): 1. Biallelic missense variant in SARS1 → partially impaired seryl-tRNA synthetase aminoacylation activity (charging of tRNA^Ser with serine) 2. Reduced/inefficient charging of tRNA^Ser → globally reduced or qualitatively impaired cytoplasmic protein synthesis, with likely selective vulnerability of high-translation-demand tissues (developing CNS, cardiac muscle, cochlea) 3. Chronic translational insufficiency during development → microcephaly, ataxia, intellectual disability, cardiomyopathy, sensorineural deafness (organ-specific manifestations depending on variant severity/tissue vulnerability) 4. Acute physiological stress (fever) → further reduction in translational capacity relative to increased metabolic demand → acute neurological/metabolic decompensation, in the most severe reported case leading to death

Causal chain (de novo dominant-negative pathway — distinct disease mechanism): 1. De novo in-frame splice-disrupting deletion → mutant SARS1 protein with an aberrant 5-residue insertion near the catalytic/ATP-serine-binding active site 2. Mutant monomer co-assembles with wild-type monomer in the obligate homodimer → dominant-negative poisoning of overall enzyme activity (~30% reduction in aminoacylation measured in patient fibroblasts; confirmed via yeast complementation growth-defect assay) 3. Reduced translational fidelity/capacity, plus an SARS1-specific non-canonical consequence: patient fibroblasts show a cellular senescence phenotype — reduced proliferation, abnormal morphology, increased senescence-associated beta-galactosidase staining, elevated phosphorylated histone H2AX (a DNA-damage-response marker), and markedly increased expression of senescence-associated secretory phenotype (SASP) genes (IL-6, p21, p16, p53) 4. This senescence-driving mechanism is described as unique among known aminoacyl-tRNA synthetases and represents a newly characterized pathway linking translational-machinery dysfunction to cellular aging/senescence programs, plausibly contributing to the progressive-then-stabilizing spastic paraparesis and CNS findings in this specific patient — distinct from the classic microcephaly-predominant biallelic phenotype (PMID:36041817)

Cellular processes involved: - Cytoplasmic mRNA translation (core aminoacylation step) - Cellular senescence / SASP activation (de novo dominant-negative case) - DNA damage response (elevated γH2AX) - Possible selenoprotein synthesis impairment (via the Sec-tRNA charging role of SerRS), though this has not been directly demonstrated as pathogenic in NEDMAS

Protein dysfunction: Loss-of-function (reduced catalytic aminoacylation activity) is the primary mechanism for biallelic missense variants; the single de novo case is best characterized as dominant-negative (not simple gain-of-function toxicity, but interference with wild-type enzyme function in the obligate dimer).

Cell types and biological processes (suggested ontology terms): - GO:0006434 seryl-tRNA aminoacylation (molecular process directly disrupted) - GO:0006412 translation (downstream biological process impaired) - GO:0090398 cellular senescence (mechanism specific to the de novo dominant-negative case) - GO:0006974 DNA damage response (elevated γH2AX in senescent fibroblasts) - CL:0000057 fibroblast (primary patient-derived cell type used for functional studies) - CL:0000540 neuron (presumed primary affected cell type given CNS-predominant phenotype, though not directly assayed in these studies) - CL:0000187 myocyte / cardiac muscle cell (relevant to the cardiomyopathy phenotype in the Ravel et al. family)

Tissue damage mechanisms: Not characterized at the histopathological level in the retrieved literature (no biopsy/autopsy data reported); mechanism is inferred from functional/biochemical assays in patient fibroblasts and heterologous (yeast) complementation systems rather than direct tissue pathology.

Molecular profiling: No transcriptomic, proteomic, or metabolomic dataset specific to SARS1-NEDMAS patient tissue was identified in the retrieved sources beyond the targeted qPCR-level SASP gene expression analysis (IL-6, p21, p16, p53) described above.

7. Anatomical Structures Affected

  • Organ level (primary): Central nervous system (brain — cerebrum and cerebellum), consistent with the microcephaly/ataxia/seizure triad
  • Organ level (secondary, variant-dependent): Inner ear/cochlea (sensorineural deafness — Ravel et al. family); heart (cardiomyopathy — Ravel et al. family); skeletal muscle (weakness, spasticity)
  • Body systems involved: Nervous system (primary), cardiovascular system (secondary, in loss-of-function severe phenotype), auditory system (secondary), musculoskeletal system (motor/spasticity findings)
  • Tissue/cell level: Neurons and glial elements of cerebral cortex and cerebellum (inferred from atrophy on neuroimaging); cardiomyocytes; cochlear hair cells/auditory neurons (inferred, not directly biopsied); dermal fibroblasts (directly studied ex vivo in the functional characterization of the de novo variant)
  • Subcellular level: Cytoplasm (site of SARS1 enzymatic activity — GO Cellular Component GO:0005737 cytoplasm / more specifically GO:0017101 aminoacyl-tRNA synthetase multienzyme complex); nucleus (site of γH2AX DNA damage marker accumulation in senescent cells, GO:0005634)
  • Localization (UBERON): UBERON:0000955 brain; UBERON:0002037 cerebellum; UBERON:0000956 cerebral cortex; UBERON:0001690 ear / UBERON:0001846 cochlea (deafness phenotype); UBERON:0000948 heart (cardiomyopathy phenotype)
  • Lateralization: Bilateral/symmetric involvement reported (bilateral cerebral and cerebellar atrophy in the Turkish cohort neuroimaging)

8. Temporal Development

  • Onset: Infantile to early childhood for developmental delay and seizures; postnatal microcephaly (implying normal or near-normal head circumference at birth with subsequent deceleration, though this was not explicitly confirmed as congenital vs. postnatal across all cases in the retrieved sources — recommend verifying per-case in the primary papers before curating an onset_category)
  • Onset pattern: Insidious/progressive for developmental delay; acute/episodic for fever-triggered decompensation and seizures
  • Progression: Variable by genotype —
  • Biallelic missense (classic NEDMAS): chronic, relatively stable developmental impairment punctuated by acute febrile decompensation risk
  • De novo dominant-negative: spastic paraparesis "worsened during childhood but later stabilized" — a distinctive non-monotonic (progressive-then-plateauing) course
  • Disease course pattern: Chronic with episodic acute crises (fever-triggered) in the severe loss-of-function subgroup; chronic-stable to chronic-progressive-then-stable in the dominant-negative case
  • Disease duration: Lifelong/chronic; at least one reported case was fatal in childhood due to fever-triggered decompensation (Ravel et al. 2021)
  • Critical periods: Febrile illness represents an identifiable window of acute vulnerability across multiple reported cases, suggesting a clinically actionable "critical period" for aggressive fever management/monitoring in affected individuals, though this has not been formalized into a published clinical protocol.

9. Inheritance and Population

  • Epidemiology: No formal prevalence or incidence estimate exists; this is an ultra-rare disorder with fewer than ~15 individuals reported in the peer-reviewed literature across all publications identified (2017–2022+). No entry in large disease-registry/GBD-type databases was identified.
  • Inheritance pattern: Autosomal recessive for the classic NEDMAS phenotype (all biallelic cases, occurring predominantly in consanguineous Iranian and Turkish families); autosomal dominant, de novo for the single reported spastic-paraplegia case with a dominant-negative mechanism.
  • Penetrance: Presumed complete for the recessive form given consistent phenotype in all biallelic carriers reported to date, though the small sample size limits confidence.
  • Expressivity: Clearly variable — phenotype ranges from moderate ID/ataxia (original Iranian family) to fatal fever-triggered decompensation with deafness/cardiomyopathy (Turkish family) to spastic paraplegia without microcephaly (de novo case) — indicating genotype-phenotype correlation by variant/mechanism rather than uniform expressivity.
  • Genetic anticipation: Not reported/not applicable (no repeat-expansion mechanism).
  • Germline mosaicism: Not specifically reported.
  • Founder effects: Not established, though the recurrence of specific consanguineous-family variants (e.g., p.Thr399Met recurring across multiple unrelated Turkish families) raises the possibility of a Turkish population founder variant — this warrants further population-genetic study but was not explicitly confirmed as a founder effect in the retrieved sources.
  • Consanguinity role: Prominent — most reported pedigrees (Iranian families in Musante et al. 2017; Turkish families in Ravel et al. 2021 and the 2022 cohort) are consanguineous, consistent with autosomal recessive transmission of rare alleles.
  • Carrier frequency: Not established in population databases.
  • Affected populations: Reported cases cluster in Iranian and Turkish consanguineous families; no data on other ethnic/geographic groups, likely reflecting ascertainment bias toward populations with higher consanguinity rates and active clinical genetics/exome-sequencing research programs rather than true population restriction.
  • Sex ratio: Not reported as skewed; autosomal recessive/dominant inheritance would not a priori predict a sex bias, and no such bias was noted in the retrieved case descriptions.
  • Age distribution: Reported cases span infancy through early adolescence (the de novo case patient is described as an "early adolescent male" at time of report).

10. Diagnostics

  • Genetic testing (primary diagnostic modality): Diagnosis in all reported cases was established via whole-exome sequencing (WES), either trio-based (de novo case, and Musante et al. 2017 original families) or proband/family-based (Turkish cohort, 2022). This reflects current clinical practice for undiagnosed neurodevelopmental disorders generally — WES/WGS with subsequent Sanger confirmation and segregation analysis in the family.
  • Single-gene testing: Feasible via Sanger sequencing once a familial variant is known (e.g., for prenatal or carrier testing in a family with a previously identified proband).
  • Gene panels: SARS1 would reasonably be included in comprehensive intellectual-disability/microcephaly/epilepsy gene panels, though no specific commercial panel was identified in the retrieved sources; the NIH Genetic Testing Registry (GTR) lists SARS1 as a testable gene (GTR gene 6301).
  • Chromosomal microarray/karyotype/FISH: Not applicable as primary diagnostic tools (disease is caused by point variants/small indels, not large structural rearrangements), though these are typically part of the standard diagnostic workup to exclude other causes of ID/microcephaly before or alongside sequencing.
  • Imaging: Brain MRI is diagnostically informative — bilateral cerebral and cerebellar atrophy was reported in the Turkish cohort; the de novo case showed subtle, non-progressive punctiform frontal subcortical white-matter hyperintensities, a distinguishing (milder) imaging pattern.
  • Electrophysiology: Visual evoked potentials showed increased latency in the de novo case, suggesting a role for VEP/electrophysiological testing in characterizing CNS involvement; EEG would be standard given the seizure phenotype (not explicitly detailed in retrieved abstracts).
  • Functional/biochemical testing: Not part of routine clinical diagnosis; aminoacylation activity assays and yeast complementation studies were research-level functional validation tools used to confirm variant pathogenicity in the de novo case, not standard-of-care diagnostics.
  • Differential diagnosis: Other autosomal recessive/dominant aminoacyl-tRNA synthetase disorders (e.g., WARS1-related recessive microcephaly — a close mimic per Bögershausen et al. 2022 — as well as RARS2-related pontocerebellar hypoplasia type 6, KARS1-, VARS1-, NARS1-related neurodevelopmental disorders), other causes of primary microcephaly with intellectual disability and ataxia, and mitochondrial encephalopathies (given phenotypic overlap with fever-triggered decompensation) should be considered and excluded.
  • Screening: No newborn screening or population carrier-screening program exists for this ultra-rare condition.

11. Outcome/Prognosis

  • Survival/mortality: At least one reported case (Ravel et al. 2021 family) was fatal due to fever-triggered metabolic/neurological decompensation, establishing that the loss-of-function/severe end of the phenotypic spectrum carries meaningful mortality risk, particularly around febrile illness. No formal survival statistics (5-year/10-year) exist given the tiny reported cohort.
  • Morbidity/function: Chronic, lifelong intellectual disability, ataxia, and (in some cases) spasticity impose significant functional impairment; no standardized disability or QOL outcome measures have been published for this condition.
  • Disease course: As above — chronic-stable to chronic-progressive-then-stabilizing (de novo case), or chronic-with-acute-crisis-risk (loss-of-function biallelic cases).
  • Complications: Fever-triggered acute decompensation (potentially fatal); cardiomyopathy (loss-of-function severe phenotype); progressive spasticity (de novo case, though noted to stabilize later in that individual).
  • Prognostic factors: Variant type/mechanism appears to be the dominant prognostic factor identified to date — biallelic partial-loss-of-function missense variants with organ involvement (deafness, cardiomyopathy) carry the most severe/potentially fatal course; the de novo dominant-negative variant produced a phenotype without microcephaly and with a plateauing motor course. No molecular biomarker has been established as a prognostic tool.

12. Treatment

No SARS1/NEDMAS-specific approved therapy exists. Management reported in the literature is supportive/symptomatic:

  • Supportive care: Management of seizures (standard antiepileptic approaches, implied but not itemized by specific agent in the retrieved abstracts), and — critically — aggressive management of febrile illness to prevent metabolic/neurological decompensation, given the clear fever-precipitant pattern documented across multiple families. This should be considered a de facto tertiary-prevention/critical-management principle for this disorder even though no formal clinical guideline was identified.
  • Rehabilitative therapies: Physical therapy, occupational therapy, and speech therapy would be standard supportive interventions for the motor (ataxia, spasticity) and speech-delay phenotypes, consistent with general neurodevelopmental disorder management, though not specifically itemized in the retrieved case reports.
  • Suggested NCIT terms: NCIT:C15302 (Physical Therapy), NCIT:C159273 (Speech Therapy), NCIT:C121351 (Occupational Therapy)
  • Cardiac management: Cardiology follow-up/management would be indicated for the subset of patients with cardiomyopathy (Ravel et al. family) — NCIT:C49236 (Therapeutic Procedure)/standard heart-failure management, not itemized specifically.
  • Audiology: Hearing evaluation and intervention (hearing aids/cochlear implant as indicated) for the sensorineural deafness subgroup.
  • Genetic counseling: Indicated given autosomal recessive inheritance in consanguineous families, for recurrence-risk counseling and potential prenatal/preimplantation testing in subsequent pregnancies. NCIT:C15240 (Genetic Counseling).
  • Experimental/investigational therapy: No SARS1-specific gene therapy, RNA-based therapy, or targeted molecular therapy has reached clinical trials; no ClinicalTrials.gov entries specific to SARS1-NEDMAS were identified in the retrieved search results. Broader aaRS-disorder research literature discusses conceptual therapeutic strategies applicable to this gene family in principle — amino acid supplementation, tRNA overexpression, modulation of integrated stress response, and genome editing — but these remain investigational/preclinical concepts rather than SARS1-specific interventions (PMC11611227).

13. Prevention

  • Primary prevention: Not applicable in the traditional sense (monogenic disorder); the only actionable primary-prevention-adjacent measure is genetic counseling and carrier/prenatal testing in families with a known pathogenic variant, particularly relevant given the strong consanguinity pattern in reported pedigrees.
  • Secondary prevention: Early diagnosis via WES in infants/children presenting with unexplained developmental delay, microcephaly, ataxia, and seizures enables anticipatory guidance (e.g., heightened vigilance and aggressive antipyretic/supportive management during febrile illness) that may mitigate the risk of severe/fatal decompensation identified in the Ravel et al. family.
  • Tertiary prevention: Aggressive, proactive management of febrile illness (the clearest identified modifiable risk factor for acute decompensation) constitutes the most concrete tertiary-prevention strategy supported by the literature, though it has not been codified into a formal published clinical protocol or guideline.
  • Screening/genetic counseling: Carrier screening is not population-based (given rarity) but should be offered to at-risk consanguineous families with a known proband; preimplantation genetic diagnosis (PGD) would be a reasonable option for families with an identified pathogenic variant, consistent with standard practice for autosomal recessive Mendelian disorders, though not explicitly documented as having been used in these specific families.

14. Other Species / Natural Disease

  • Taxonomy/model relevance: Zebrafish (Danio rerio, NCBITaxon:7955) is the primary non-human model system referenced in the literature for sars/SARS1 biology. Fukui et al. (2009) and Herzog et al. (2009) identified zebrafish sars mutants with abnormal vascular development, and notably found this vascular role to be independent of the canonical aminoacylation function — an important non-canonical (moonlighting) function of this synthetase that is distinct from, but potentially mechanistically relevant to, its neurodevelopmental disease role in humans.
  • Orthologous gene: Mouse ortholog Sars1 (NCBI Gene ID 20226, Mus musculus); no Sars1 knockout mouse model with a reported neurodevelopmental phenotype was identified in the retrieved search results — this appears to be a gap in the current model-organism literature for this specific gene (in contrast to related aaRS genes like Kars1, Vars1, and Wars1, for which zebrafish knockouts recapitulating brain/eye phenotypes have been more thoroughly characterized).
  • Natural disease in companion/veterinary species: No OMIA entry or veterinary case series for naturally occurring SARS1-related disease in animals was identified.
  • Comparative biology: The broader aaRS gene family shows a consistent pattern across paralogs (KARS1, VARS1, WARS1, NARS1, SARS1) of zebrafish knockouts preferentially affecting brain and eye development, mechanistically consistent with the microcephaly/CNS phenotype seen in human patients and supporting cross-paralog conservation of a dosage-sensitive requirement for aaRS activity during neurodevelopment.
  • Zoonotic potential/transmission: Not applicable (non-infectious, monogenic disorder).

15. Model Organisms

  • Zebrafish (Danio rerio): The most relevant existing model, though the published sars zebrafish mutants (Fukui 2009, Herzog 2009) were characterized for a vascular development phenotype, not the human neurodevelopmental (microcephaly/ataxia/seizure) phenotype — representing a translational gap. A zebrafish knock-in model of a specific human NEDMAS-causing missense variant (analogous to the KARS1 zebrafish knockout work cited for other aaRS disorders) does not appear to have been published yet for SARS1, and would be a natural follow-on model to more directly recapitulate and mechanistically dissect the human CNS phenotype.
  • Yeast complementation system: Used as a functional/heterologous validation model (not a disease model per se) to demonstrate the dominant-negative growth-defect effect of the de novo splice variant when co-expressed with wild-type SARS1 — this represents an important functional-genomics tool for variant classification in this gene going forward (PMID:36041817).
  • Patient-derived fibroblasts: The primary "model system" used across the functional characterization literature — patient dermal fibroblasts were used to measure aminoacylation activity (~30% reduction in the de novo case) and to characterize the cellular senescence phenotype (β-galactosidase staining, γH2AX, SASP gene expression). No iPSC-derived neuronal model specific to SARS1-NEDMAS was identified in the retrieved sources — this represents a clear opportunity for future model development given the CNS-predominant human phenotype.
  • Model limitations: Current models (zebrafish vascular mutants, yeast complementation, patient fibroblasts) each capture only a partial aspect of the human disease — none directly recapitulates the CNS-specific microcephaly/ataxia/seizure phenotype in vivo, representing a significant translational gap for mechanistic and preclinical therapeutic studies in this gene.

Summary of Key Ontology Term Suggestions for Curation

Category Suggested terms
Gene SARS1, hgnc:10537
Disease OMIM:617709 (NEDMAS); MONDO ID to be confirmed via OAK lookup
Phenotypes (HP) HP:0001263 (Global developmental delay), HP:0001249 (Intellectual disability), HP:0000252 (Microcephaly), HP:0001250 (Seizure), HP:0001251 (Ataxia), HP:0001324 (Muscle weakness), HP:0008936 (Severe muscular hypotonia), HP:0002059 (Cerebral atrophy), HP:0001272 (Cerebellar atrophy), HP:0000407 (Sensorineural hearing loss), HP:0001638 (Cardiomyopathy), HP:0001260 (Spasticity)
Biological processes (GO) GO:0006434 (seryl-tRNA aminoacylation), GO:0006412 (translation), GO:0090398 (cellular senescence), GO:0006974 (DNA damage response)
Cell types (CL) CL:0000057 (fibroblast), CL:0000540 (neuron), CL:0000187 (muscle cell)
Anatomy (UBERON) UBERON:0000955 (brain), UBERON:0002037 (cerebellum), UBERON:0001846 (cochlea), UBERON:0000948 (heart)
Treatment (NCIT) NCIT:C15302 (Physical Therapy), NCIT:C159273 (Speech Therapy), NCIT:C15240 (Genetic Counseling)

Key Citations

  1. Musante L, et al. "Mutations of the aminoacyl-tRNA-synthetases SARS and WARS2 are implicated in the etiology of autosomal recessive intellectual disability." Hum Mutat. 2017. PMID:28236339
  2. Ravel JM, et al. "A bi-allelic loss-of-function SARS1 variant in children with neurodevelopmental delay, deafness, cardiomyopathy, and decompensation during fever." Hum Mutat. 2021 Dec;42(12):1576-1583. PMID:34570399
  3. [Authors unlisted in retrieved abstract]. "Loss of seryl-tRNA synthetase (SARS1) causes complex spastic paraplegia and cellular senescence." 2022. PMID:36041817
  4. Bögershausen N, Krawczyk HE, Jamra RA, et al. "WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly." Hum Mutat. 2022 Oct;43(10):1454-1471. Wiley DOI
  5. [Turkish cohort authors unlisted in retrieved abstract]. "Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum." Clin Dysmorphol. 2022 Oct;31(4):167-173. PMID:36004946
  6. OMIM #617709 — Neurodevelopmental Disorder with Microcephaly, Ataxia, and Seizures (NEDMAS). omim.org/entry/617709
  7. OMIM *607529 — Seryl-tRNA Synthetase 1; SARS1. omim.org/entry/607529
  8. Review: "Aminoacyl-tRNA synthetase defects in neurological diseases." PMC11611227

Note on gaps requiring direct primary-source verification before KB curation: Several full-text primary sources (Ravel et al. 2021, Bögershausen et al. 2022) were paywalled and only accessible via abstract/secondary summary; exact quoted snippets for evidence items should be re-verified against the cached PubMed abstracts via just fetch-reference before use, per this repository's evidence-integrity SOP. The MONDO ID and specific author lists for two papers (PMID:36041817 and PMID:36004946 full author bylines) should also be confirmed directly against PubMed/MONDO before finalizing the KB entry.