Marinesco-Sjogren Syndrome

Mendelian MONDO:0009567 Pathograph 12 Show in embeddings browser Hereditary Ataxia Congenital Myopathy Protein Misfolding Disease

Marinesco-Sjogren syndrome (MSS) is an autosomal recessive multisystem disorder defined by the triad of cerebellar ataxia with cerebellar atrophy, early-onset cataracts, and chronic progressive vacuolar myopathy, with variable intellectual disability, hypergonadotropic hypogonadism, short stature and skeletal abnormalities. It is a disease of endoplasmic reticulum proteostasis: biallelic loss-of-function variants in SIL1 remove the adenine nucleotide exchange factor that drives the ATPase cycle of BiP/HSPA5, the master ER chaperone. Without nucleotide exchange, BiP cannot release its folded clients, unfolded protein accumulates in the ER lumen, and the unfolded protein response — particularly its PERK branch — is chronically engaged. Cerebellar Purkinje neurons, skeletal muscle fibres and the lens are the cells that fail first. The mechanism is well enough understood that the key experiments are already genetic rescues rather than descriptive studies: overexpressing the parallel exchange factor HYOU1/ORP150 rescues neurodegeneration in Sil1-null mice, and pharmacological PERK inhibition delays Purkinje cell loss. What is not settled is the disease's own boundaries — SIL1 variants are found in only about 60% of patients with the full triad.

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1
Definitions
1
Inheritance
8
Pathophys.
1
Histopath.
13
Phenotypes
2
Gaps
12
Pathograph
3
Genes
7
Medical Actions
1
Models
3
References
1
Deep Research
📘

Definitions

1
Clinical triad and molecular case definition
Diagnosis rests on typical clinical findings — cerebellar ataxia, early-onset cataracts and myopathy — and/or biallelic pathogenic SIL1 variants. Cataracts are essentially universal beyond age 7 but may be absent in infants, so their absence in a young child does not exclude the diagnosis.
CASE_DEFINITION Disease-level case ascertainment for MSS.
Show evidence (2 references)
PMID:20301371 SUPPORT Human Clinical
"The diagnosis of MSS is established in an individual with typical clinical findings and/or biallelic pathogenic variants in SIL1 identified by molecular genetic testing."
The GeneReviews chapter states the diagnostic criteria directly.
PMID:24176978 SUPPORT Human Clinical
"Cataracts were observed in all patients beyond the age of 7 years, but might be missing in infants."
Qualifies the age-dependence of the cataract criterion, which is what makes the triad unreliable in young children.
👪

Inheritance

1
Autosomal recessive inheritance HP:0000007
Affected individuals carry homozygous or compound heterozygous SIL1 variants; parents are presumed heterozygous carriers with a 25% recurrence risk per pregnancy.
Autosomal recessive inheritance
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"MSS is inherited in an autosomal recessive manner."
GeneReviews states the mode of inheritance.
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Discussions and Knowledge Gaps

2
What causes Marinesco-Sjogren syndrome in the 40% of patients with the full clinical triad who have no detectable SIL1 variant?
KNOWLEDGE GAP sil1_negative_mss_locus_heterogeneity
Attached to
pathophysiology#SIL1 Loss of Nucleotide Exchange Factor Activity
The mutation detection rate is 60% (15/25) among patients with the characteristic triad. That leaves a substantial minority whose disease is clinically indistinguishable but molecularly unexplained. Two readings are possible and the data do not separate them: either a second locus in the same BiP nucleotide-exchange pathway, or non-coding and structural SIL1 variation missed by the screening used. The contrast with the sub-3% detection rate in patients with variable, non-triad phenotypes matters here — it says the triad is a sharp clinical entity, which makes an unexplained 40% within it harder to dismiss as phenotypic overlap.
Show evidence (1 reference)
PMID:24176978 SUPPORT Human Clinical
"We obtained a mutation detection rate of 60% (15/25) among patients with the characteristic Marinesco-Sjögren syndrome triad (ataxia, cataracts, myopathy) whereas the detection rate in the group of patients with more variable phenotypic presentation was below 3% (1/37)."
Quantifies both the unexplained fraction within the triad and the specificity of the triad itself.
PERK inhibition and HYOU1 overexpression both rescue Sil1-null mice. Does either represent a viable path in human MSS, given that the PERK inhibitor is pancreatotoxic and the human disease has already caused most of its damage by the time it is diagnosed?
HUMAN MODEL MISMATCH perk_inhibition_translational_ceiling
Attached to
pathophysiology#PERK-Branch Unfolded Protein Response Activation
The mechanistic case is strong on the mouse side: GSK2606414 delays Purkinje degeneration and motor deficits and prolongs the asymptomatic phase, and genetic modulation of HYOU1 moves the phenotype in both directions. But the mouse benefit is measured largely as a delay in an asymptomatic phase, and treatment was started presymptomatically. Human MSS presents with hypotonia in infancy and cataracts within the first decade, so the equivalent window is one clinicians do not currently have access to. Whether a proteostasis-directed intervention started after diagnosis modifies the human course is untested, and is a different question from whether the pathway is causal — which the mouse work establishes. The 2025 follow-up sharpens this considerably, in a discouraging direction. Three agents chosen specifically to keep the mechanism while losing GSK2606414's pancreatic toxicity — trazodone and dibenzoylmethane as partial PERK inhibitors, TUDCA as a chemical chaperone — produced no benefit at all in the same model, on the same presymptomatic schedule, at doses active in other neurodegeneration models, and pharmacokinetics excluded altered drug metabolism as the explanation. So the failure is not obviously about exposure or timing, and the open question narrows: is anything short of full PERK inhibition sufficient, and if not, does a therapeutic window between efficacy and pancreatic toxicity exist at all?
Show evidence (5 references)
PMID:29718201 SUPPORT Model Organism
"Mice were chronically treated with GSK2606414 starting from a presymptomatic stage, and the effects were evaluated on biochemical, histopathological and clinical readouts."
The presymptomatic start is exactly the design feature that limits translation to a disease diagnosed after symptom onset.
PMID:19801575 SUPPORT Model Organism
"overexpression of HYOU1/ORP150, an exchange factor that works in parallel to SIL1, prevents ER stress and rescues neurodegeneration in Sil1(-/-) mice, whereas decreasing expression of HYOU1 exacerbates these phenotypes."
Establishes the bidirectional genetic modifier effect that motivates the therapeutic hypothesis, in mice.
PMID:39804912 REFUTE Model Organism
"None of the treatments prevented motor dysfunction or PC degeneration in woozy mice, as assessed by beam walking, rotarod test, and calbindin immunohistochemistry."
A directly relevant negative result. Three agents chosen precisely to avoid GSK2606414's pancreatic toxicity all failed in the same model and the same presymptomatic design in which GSK2606414 succeeded. Graded REFUTE because it argues against the proposition that the proteostasis strategy translates readily.
+ 2 more references
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Pathophysiology

8
SIL1 Loss of Nucleotide Exchange Factor Activity
Genetic context SIL1 hgnc:24624 HUGO Gene Nomenclature Committee (hgnc) Relation: this genetic context concerns this gene This genetic context concerns SIL1 (hgnc:24624). hgnc:24624 is a gene from the HUGO Gene Nomenclature Committee. variant_origin: GERMLINE functional_impact_category: LOSS_OF_FUNCTION
Biallelic loss-of-function variants leave severely reduced SIL1 protein, abolishing its adenine nucleotide exchange activity toward BiP/HSPA5. Reported alleles are nonsense, frameshift, splice-site and single- or multi-exon deletions; patients are homozygous or compound heterozygous.
adenine nucleotide exchange factor activity toward BiP GO:0000774 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves adenine nucleotide exchange factor activity toward BiP, annotated with adenyl-nucleotide exchange factor activity (GO:0000774), qualified as loss of function. GO:0000774 is a molecular function from the Gene Ontology. ⇓ LOSS OF FUNCTION
Downstream
Stalled BiP Chaperone Cycle Without nucleotide exchange, BiP cannot complete its ATPase cycle and remains bound to client proteins.
Show evidence (1 reference)
PMID:16282977 SUPPORT Human Clinical
"SIL1 (also called BAP) acts as a nucleotide exchange factor for the Hsp70 chaperone BiP (also called GRP78), which is a key regulator of the main functions of the endoplasmic reticulum."
States the molecular function that is lost, and its target chaperone.
Stalled BiP Chaperone Cycle
BiP remains associated with its client proteins instead of releasing folded cargo, so the chaperone pool is functionally sequestered. This is the step that converts a nucleotide-exchange defect into a folding defect.
protein folding GO:0006457 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased protein folding (GO:0006457). GO:0006457 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
ER Accumulation of Unfolded Protein and ER Stress Client proteins that BiP cannot release accumulate unfolded in the ER lumen, producing ER stress.
Show evidence (1 reference)
PMID:39180052 SUPPORT In Vitro
"Specifically, BiP remains associated with its client proteins, causing the accumulation of unfolded proteins, endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR)."
Names the sequestration step and its immediate consequences.
ER Accumulation of Unfolded Protein and ER Stress
Unfolded protein accumulates in the ER lumen and intracellular protein inclusions form. In woozy mouse Purkinje cells the inclusions are found in both ER and nucleus, and the unfolded protein response is upregulated.
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.
response to endoplasmic reticulum stress GO:0034976 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased response to endoplasmic reticulum stress (GO:0034976). GO:0034976 is a biological process from the Gene Ontology. ↑ INCREASED
Animal models
woozy mouse (spontaneous Sil1 mutation) Mouse recapitulates Mutant Purkinje cells show the protein accumulation and UPR upregulation that define this node.
Downstream
PERK-Branch Unfolded Protein Response Activation Sustained ER stress engages the UPR, with the PERK branch activated in degenerating neurons.
Secretory Pathway Trafficking Failure Impaired ER folding delays ER-to-plasma-membrane transport, with cargo retained in ER and Golgi.
Show evidence (1 reference)
PMID:16116427 SUPPORT Model Organism
"Affected cells have intracellular protein accumulations reminiscent of protein inclusions in both the ER and the nucleus. In addition, upregulation of the unfolded protein response, suggestive of ER stress, occurs in mutant Purkinje cells."
Directly observes protein accumulation and UPR activation in the affected cell type in the Sil1-mutant mouse.
PERK-Branch Unfolded Protein Response Activation
The PERK arm of the UPR is the branch that drives degeneration in this disease. Its causal role is established by rescue rather than correlation: the PERK inhibitor GSK2606414 delays Purkinje cell degeneration and motor deficits in woozy mice, and attenuates secretory-pathway abnormalities and cell death in SIL1-knockdown cells.
PERK-mediated unfolded protein response GO:0036499 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased PERK-mediated unfolded protein response (GO:0036499). GO:0036499 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Cerebellar Purkinje Neuron Degeneration Chronic PERK-branch signalling in Purkinje neurons, terminally differentiated cells with a high secretory load, culminates in apoptotic degeneration.
Skeletal Muscle Fibre Degeneration The same PERK-branch signalling drives the muscle arm. The evidence is the same rescue argument used for Purkinje cells: PERK inhibition reduced the skeletal muscle abnormalities and improved motor performance, so the branch is on the causal path to muscle degeneration too, not only to neurodegeneration.
Show evidence (1 reference)
PMID:29718201 SUPPORT Model Organism
"GSK2606414 delayed Purkinje cell degeneration and the onset of motor deficits, prolonging the asymptomatic phase of the disease; it also reduced the skeletal muscle abnormalities and improved motor performance during the symptomatic phase."
Pharmacological inhibition of this node rescues the downstream phenotype, which is what places it on the causal path rather than beside it.
Secretory Pathway Trafficking Failure
Beyond folding failure, SIL1 loss disorganises the secretory route itself: ER chaperone aggregation, an enlarged Golgi, accumulated autophagic vacuoles and mitochondrial swelling. This is the node that connects a chaperone defect to the extracellular matrix and connective-tissue features, since procollagen is one of the retained cargoes.
fibroblast CL:0000057 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology.
autophagy GO:0006914 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased autophagy (GO:0006914). GO:0006914 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Aberrant Extracellular Matrix Assembly Impaired secretion of matrix cargo yields an abnormal extracellular matrix, reduced matrix remodelling capacity and disorganised collagen.
Show evidence (1 reference)
PMID:30293566 SUPPORT In Vitro
"Immunofluorescence and ultrastructural analysis of SIL1-knocked-down cells detected ER chaperone aggregation, enlargement of the Golgi complex, increased autophagic vacuoles, and mitochondrial swelling."
Catalogues the organelle-level lesions defining this node.
Aberrant Extracellular Matrix Assembly
Patient fibroblasts produce structurally abnormal matrix filaments, and the woozy mouse shows disorganised collagen at the myotendinous junction and Achilles tendon. The authors propose aberrant ECM as a unifying explanation for the skeletal, muscular, lens and connective-tissue features — a claim about scope that goes beyond what has been demonstrated, and is recorded here as their proposal rather than as established fact.
fibroblast CL:0000057 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology.
Show evidence (1 reference)
PMID:39180052 SUPPORT Model Organism
"structural analysis of the myotendinous junction of the soleus muscle and surrounding regions of the Achilles tendon revealed a disorganization of collagen fibres in the mouse model of MSS (woozy)."
Demonstrates the tissue-level matrix lesion in the animal model.
Cerebellar Purkinje Neuron Degeneration
Purkinje neurons are terminally differentiated cells with a heavy protein-folding load and are the first population to fail. Their loss produces the cerebellar syndrome.
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.
apoptotic process GO:0006915 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased apoptotic process (GO:0006915). GO:0006915 is a biological process from the Gene Ontology. ↑ INCREASED
Animal models
woozy mouse (spontaneous Sil1 mutation) Mouse recapitulates woozy reproduces Purkinje cell degeneration and the resulting ataxia.
Downstream
Cerebellar ataxia Loss of Purkinje neurons produces the ataxic phenotype.
Show evidence (1 reference)
PMID:16116427 SUPPORT Model Organism
"These findings provide evidence that perturbation of ER chaperone function in terminally differentiated neurons leads to protein accumulation, ER stress and subsequent neurodegeneration."
Establishes the causal sequence from chaperone perturbation to neurodegeneration in terminally differentiated neurons.
Skeletal Muscle Fibre Degeneration
A chronic vacuolar myopathy with sarcoplasmic reticulum alterations, autophagic vacuoles, mitochondrial changes and prominent myonuclear pathology including nuclear envelope and lamina alterations.
skeletal muscle fibre CL:0008002 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves skeletal muscle fibre, annotated with skeletal muscle fiber (CL:0008002). CL:0008002 is a cell type from the Cell Ontology.
autophagy GO:0006914 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased autophagy (GO:0006914). GO:0006914 is a biological process from the Gene Ontology. ↑ INCREASED
Animal models
woozy mouse (spontaneous Sil1 mutation) Mouse recapitulates woozy muscle reproduces the human MSS myopathy, including the perinuclear membranous structures reported as its ultrastructural hallmark.
Downstream
Muscle weakness Progressive myopathy produces the distal and proximal weakness.
Show evidence (1 reference)
PMID:24362440 SUPPORT Model Organism
"We found severe, progressive myopathy characterized by alterations of the sarcoplasmic reticulum, accumulation of autophagic vacuoles, mitochondrial changes, and prominent myonuclear pathology including nuclear envelope and nuclear lamina alterations."
Characterises the muscle lesion in the Sil1-mutant mouse.
✶

Histopathology

1
Vacuolar myopathy with myonuclear and nuclear envelope pathology
Muscle shows a chronic vacuolar myopathy with sarcoplasmic reticulum alterations, autophagic vacuoles, mitochondrial changes and distinctive perinuclear membranous structures derived from the nuclear envelope and lamina. GeneReviews regards the electron-microscopic ultrastructural changes as specific to MSS, which makes muscle biopsy diagnostically informative rather than merely confirmatory.
Show evidence (2 references)
PMID:20301371 SUPPORT Human Clinical
"Electron microscopic ultrastructural changes on muscle biopsy are thought to be specific to MSS."
Establishes the diagnostic specificity claim for the muscle ultrastructure.
PMID:24362440 SUPPORT Model Organism
"In particular, the presence of perinuclear membranous structures which have been reported as an ultrastructural hallmark of MSS-related myopathy could be confirmed in woozy muscles."
Identifies the specific ultrastructural hallmark and confirms it in the animal model.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Marinesco-Sjogren Syndrome 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

13
Endocrine 1
Hypergonadotropic hypogonadism HP:0000815 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypergonadotropic hypogonadism (HP:0000815). HP:0000815 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Additional features may include psychomotor delay, hypergonadotropic hypogonadism, short stature, and various skeletal abnormalities."
GeneReviews lists hypergonadotropic hypogonadism among additional features.
Eye 3
Early-onset cataract VERY_FREQUENT Developmental cataract HP:0000519 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Developmental cataract (HP:0000519). HP:0000519 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24176978 SUPPORT Human Clinical
"Cataracts were observed in all patients beyond the age of 7 years, but might be missing in infants."
Gives both the near-universal frequency and its age dependence.
Nystagmus HP:0000639 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Nystagmus (HP:0000639). HP:0000639 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Later, cerebellar findings of truncal ataxia, dysdiadochokinesia, nystagmus, and dysarthria become apparent."
GeneReviews lists nystagmus among the cerebellar findings.
Strabismus HP:0000486 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Strabismus (HP:0000486). HP:0000486 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"treatment of strabismus per ophthalmologist"
GeneReviews management guidance establishes strabismus as a manifestation requiring treatment.
Musculoskeletal 3
Muscle weakness VERY_FREQUENT 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.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Children with MSS usually present with muscular hypotonia in early infancy; distal and proximal muscular weakness is noticed during the first decade of life."
GeneReviews documents the distribution and timing of weakness.
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.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Children with MSS usually present with muscular hypotonia in early infancy"
Names hypotonia as the usual presenting feature.
Scoliosis HP:0002650 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Scoliosis (HP:0002650). HP:0002650 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"clinical assessment for scoliosis at each visit, with radiographs as needed"
The GeneReviews surveillance recommendation establishes scoliosis as an expected manifestation.
Nervous System 5
Cerebellar ataxia VERY_FREQUENT HP:0001251 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebellar ataxia, annotated with Ataxia (HP:0001251). HP:0001251 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24176978 SUPPORT Human Clinical
"SIL1 mutations are invariably associated with the combination of a cerebellar syndrome and chronic myopathy."
Establishes the cerebellar syndrome as an obligate feature of SIL1-related disease.
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.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Marinesco-Sjögren syndrome (MSS) is characterized by cerebellar ataxia with cerebellar atrophy, dysarthria, nystagmus, early-onset (not necessarily congenital) cataracts, myopathy, muscle weakness, and hypotonia."
GeneReviews names cerebellar atrophy among the defining features.
Dysarthria HP:0001260 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysarthria (HP:0001260). HP:0001260 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Later, cerebellar findings of truncal ataxia, dysdiadochokinesia, nystagmus, and dysarthria become apparent."
GeneReviews lists dysarthria among the emerging cerebellar findings.
Intellectual disability HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24176978 SUPPORT Human Clinical
"Six patients with SIL1 mutations had no intellectual disability, extending the known wide range of cognitive capabilities in Marinesco-Sjögren syndrome to include normal intelligence."
Documents the variable expressivity, including normal intelligence.
Motor delay HP:0001270 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Motor delay (HP:0001270). HP:0001270 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24176978 SUPPORT Human Clinical
"Marinesco-Sjögren syndrome is a rare autosomal recessive multisystem disorder featuring cerebellar ataxia, early-onset cataracts, chronic myopathy, variable intellectual disability and delayed motor development."
Names delayed motor development among the defining features.
Growth 1
Short stature HP:0004322 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Short stature (HP:0004322). HP:0004322 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Additional features may include psychomotor delay, hypergonadotropic hypogonadism, short stature, and various skeletal abnormalities."
GeneReviews lists short stature among additional features.
🧬

Genetic Associations

3
SIL1
Gene: SIL1 hgnc:24624 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is SIL1 (hgnc:24624). hgnc:24624 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (3 references)
PMID:16282978 SUPPORT Human Clinical
"We identified four disease-associated, predicted loss-of-function mutations in SIL1, which encodes a nucleotide exchange factor for the heat-shock protein 70 (HSP70) chaperone HSPA5."
One of the two independent 2005 gene-discovery studies, establishing the causal gene and its molecular role.
PMID:16282977 SUPPORT Human Clinical
"We found nine distinct mutations that would disrupt the SIL1 protein in individuals with Marinesco-Sjögren syndrome, an autosomal recessive cerebellar ataxia complicated by cataracts, developmental delay and myopathy."
The independently published companion gene-discovery study.
PMID:24176978 SUPPORT Human Clinical
"Examination of mutant SIL1 expression in cultured patient lymphoblasts suggested that SIL1 mutations result in severely reduced SIL1 protein levels irrespective of the type and position of mutations."
Supports the uniform loss-of-protein consequence across a heterogeneous allelic spectrum.
HYOU1
Gene: HYOU1 hgnc:16931 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is HYOU1 (hgnc:16931). hgnc:16931 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: MODIFIER
Show evidence (1 reference)
PMID:19801575 SUPPORT Model Organism
"overexpression of HYOU1/ORP150, an exchange factor that works in parallel to SIL1, prevents ER stress and rescues neurodegeneration in Sil1(-/-) mice, whereas decreasing expression of HYOU1 exacerbates these phenotypes."
The bidirectional dosage effect that establishes HYOU1 as a modifier.
DNAJC3
Gene: DNAJC3 hgnc:9439 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is DNAJC3 (hgnc:9439). hgnc:9439 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: MODIFIER
Show evidence (2 references)
PMID:19801575 SUPPORT Model Organism
"In addition, loss of DNAJC3/p58(IPK), a co-chaperone that promotes ATP hydrolysis by BiP, ameliorates ER stress and neurodegeneration in Sil1(-/-) mice."
The rescue-by-loss result establishing DNAJC3 as a modifier.
PMID:19801575 SUPPORT Model Organism
"These findings suggest that alterations in the nucleotide exchange cycle of BiP cause ER stress and neurodegeneration in Sil1-deficient mice."
States the interpretation that makes both modifier effects coherent.
💊

Medical Actions

7
Cataract Extraction
Action: cataract extractionNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is cataract extraction, annotated with Cataract Surgery (NCIT:C157809). NCIT:C157809 is a clinical intervention from the NCI Thesaurus. Ontology label: Cataract Surgery NCIT:C157809
Platform: Surgery
Lens extraction is required in the first decade for most patients as cataracts progress.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Cataracts can develop rapidly and typically require lens extraction in the first decade of life."
GeneReviews establishes lens extraction as standard management.
Physical Therapy and Rehabilitation
Action: physical therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is physical therapy (NCIT:C15302). NCIT:C15302 is a clinical intervention from the NCI Thesaurus. Ontology label: Physical Therapy NCIT:C15302
Platform: Behavioral / lifestyle
Symptomatic management of the muscular manifestations by neurologists, physiatrists and physical therapists, with annual or as-needed assessment.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Symptomatic treatment of muscular manifestations usually by pediatric or adult neurologists and physiatrists and/or physical therapists"
GeneReviews states the standard symptomatic management for the myopathy.
Hormone Replacement for Primary Gonadal Failure
Action: Hormone Replacement TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Hormone Replacement Therapy (NCIT:C15599). NCIT:C15599 is a clinical intervention from the NCI Thesaurus. NCIT:C15599
Platform: Other
Hormone replacement therapy at the expected time of puberty for the hypergonadotropic hypogonadism.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"hormone replacement therapy for primary gonadal failure at the expected time of puberty"
GeneReviews states the endocrine management recommendation.
Developmental and Educational Support
Action: RehabilitationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Rehabilitation (NCIT:C15315). NCIT:C15315 is a clinical intervention from the NCI Thesaurus. NCIT:C15315
Platform: Behavioral / lifestyle
Developmental support and education programmes tailored to the individual's needs, with progress monitored at each visit.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"developmental support and education programs tailored to the individual's developmental needs"
GeneReviews management recommendation for the neurodevelopmental domain.
Feeding Support for Poor Weight Gain
Action: Nutritional SupportNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Nutritional Support (NCIT:C15433). NCIT:C15433 is a clinical intervention from the NCI Thesaurus. NCIT:C15433
Platform: Behavioral / lifestyle
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"feeding support as needed for poor weight gain"
GeneReviews management recommendation for growth and feeding.
Orthopedic Management of Scoliosis and Skeletal Manifestations
Action: orthopedic managementNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is orthopedic management, annotated with Therapeutic Procedure (NCIT:C49236). NCIT:C49236 is a clinical intervention from the NCI Thesaurus. Ontology label: Therapeutic Procedure NCIT:C49236
Platform: Other
GeneReviews directs scoliosis and other skeletal manifestations to an orthopaedist without specifying an intervention, so this is bound to the generic therapeutic-procedure term rather than to a surgical one - the source does not say surgery.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"management of scoliosis and other skeletal manifestations per orthopedist"
GeneReviews management recommendation for the skeletal domain.
Genetic Counseling and Carrier Testing
Action: Genetic CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic Counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. NCIT:C15240
Platform: Other
Recurrence risk is 25% per pregnancy for carrier couples; carrier testing and prenatal or preimplantation testing are available once the familial variants are known.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"If biallelic SIL1 pathogenic variants have been identified in an affected family member, carrier testing for at-risk relatives and prenatal/preimplantation genetic testing are possible."
GeneReviews states the available reproductive genetic options.
📈

Progression

3
Infantile hypotonia and motor delay
Age: Early infancy
Children usually present first with muscular hypotonia in early infancy, before any cerebellar sign is apparent.
Show evidence (1 reference)
PMID:20301371 SUPPORT Human Clinical
"Children with MSS usually present with muscular hypotonia in early infancy; distal and proximal muscular weakness is noticed during the first decade of life."
GeneReviews states the earliest presenting feature and the timing of weakness.
First-decade weakness and emerging cerebellar signs
Age: First decade of life
Distal and proximal weakness appears through the first decade, after which truncal ataxia, dysdiadochokinesia, nystagmus and dysarthria become apparent. Cataracts typically require lens extraction within the same decade.
Show evidence (2 references)
PMID:20301371 SUPPORT Human Clinical
"Later, cerebellar findings of truncal ataxia, dysdiadochokinesia, nystagmus, and dysarthria become apparent."
Establishes that cerebellar signs follow the neuromuscular presentation.
PMID:20301371 SUPPORT Human Clinical
"Cataracts can develop rapidly and typically require lens extraction in the first decade of life."
Establishes the timing and surgical consequence of the cataract phenotype.
Progression then plateau, with near-normal life span
Motor function worsens for some years and then stabilises at an unpredictable age and degree of severity. This plateau is an important and somewhat counterintuitive feature: despite severe disability in many adults, life span appears near normal, which makes MSS a chronic disability disorder rather than a progressive fatal neurodegeneration.
Show evidence (2 references)
PMID:20301371 SUPPORT Human Clinical
"Motor function worsens progressively for some years, then stabilizes at an unpredictable age and degree of severity."
GeneReviews documents the progression-then-plateau course.
PMID:20301371 SUPPORT Human Clinical
"Although many adults have severe disabilities, life span in MSS appears to be near normal."
Supports the near-normal life expectancy despite severe disability.
🐁

Animal Models

1
woozy mouse (spontaneous Sil1 mutation)
The spontaneous woozy mutation disrupts Sil1 and produces adult-onset ataxia with Purkinje cell loss, ER and nuclear protein inclusions, UPR upregulation, and a progressive vacuolar myopathy that reproduces the human ultrastructural hallmark.
Species
Mouse
Genotype
Sil1 woozy (wz) homozygous
Publication
PMID:16116427
Pathograph links
ER Accumulation of Unfolded Protein and ER Stress recapitulates fidelity: high Mutant Purkinje cells show the protein accumulation and UPR upregulation that define this node.
Limitations: Cerebellar degeneration in woozy is adult-onset, whereas human MSS presents in infancy and early childhood, so the model compresses a different developmental window.
Readouts
Intracellular protein inclusions in Purkinje cells
Direction: INCREASED
Interpretation: Direct histological correlate of unfolded-protein accumulation.
Show evidence (1 reference)
PMID:16116427 SUPPORT Model Organism
"Affected cells have intracellular protein accumulations reminiscent of protein inclusions in both the ER and the nucleus."
Reports the measurement behind this readout.
Show evidence (1 reference)
PMID:16116427 SUPPORT Model Organism
"We report that the wz mutation disrupts the gene Sil1 that encodes an adenine nucleotide exchange factor of BiP, a crucial ER chaperone."
Confirms the model carries a lesion in the same gene as the human disease, which is what makes it informative for this node.
Cerebellar Purkinje Neuron Degeneration recapitulates fidelity: high woozy reproduces Purkinje cell degeneration and the resulting ataxia.
Limitations: Degeneration in woozy is adult-onset, whereas human MSS is an early childhood disease, so the model compresses a different developmental window. Cataract, the third element of the human triad, is not reported among woozy phenotypes in the cited studies, which is why no lens node is modelled here at all.
Readouts
Purkinje cell loss
Direction: DECREASED
Interpretation: Cerebellar Purkinje cell number falls, producing the ataxic phenotype.
Show evidence (1 reference)
PMID:16116427 SUPPORT Model Organism
"Mice homozygous with respect to the woozy (wz) mutation develop adult-onset ataxia with cerebellar Purkinje cell loss."
Reports the Purkinje cell measurement and the resulting phenotype.
Show evidence (1 reference)
PMID:16116427 SUPPORT Model Organism
"Mice homozygous with respect to the woozy (wz) mutation develop adult-onset ataxia with cerebellar Purkinje cell loss."
Establishes that the model reproduces Purkinje cell loss, which is what makes it informative for this node specifically.
Skeletal Muscle Fibre Degeneration recapitulates fidelity: high woozy muscle reproduces the human MSS myopathy, including the perinuclear membranous structures reported as its ultrastructural hallmark.
Limitations: As with the cerebellar arm, the mouse phenotype is adult-onset while human MSS presents in infancy, so the model compresses a different developmental window.
Readouts
Perinuclear membranous structures on muscle ultrastructure
Direction: INCREASED
Interpretation: The ultrastructural hallmark of MSS myopathy, confirmed present in the model.
Show evidence (1 reference)
PMID:24362440 SUPPORT Model Organism
"In particular, the presence of perinuclear membranous structures which have been reported as an ultrastructural hallmark of MSS-related myopathy could be confirmed in woozy muscles."
Reports the ultrastructural measurement behind this readout.
Show evidence (1 reference)
PMID:24362440 SUPPORT Model Organism
"This report identifies woozy muscle as a faithful phenocopy of the MSS myopathy."
Explicit statement that the model is faithful for the muscle arm, which is the claim this link makes.
{ }

Source YAML

click to show 
name: Marinesco-Sjogren Syndrome
creation_date: "2026-08-30T06:20:00Z"
category: Mendelian
parents:
- Hereditary Ataxia
- Congenital Myopathy
- Protein Misfolding Disease
synonyms:
- MSS
- Marinesco-Sjogren-Garland syndrome
- cerebellar ataxia-cataract-myopathy syndrome
- hereditary oligophrenic cerebellolental degeneration
disease_term:
  preferred_term: Marinesco-Sjogren syndrome
  term:
    id: MONDO:0009567
    label: Marinesco-Sjogren syndrome
description: >-
  Marinesco-Sjogren syndrome (MSS) is an autosomal recessive multisystem
  disorder defined by the triad of cerebellar ataxia with cerebellar atrophy,
  early-onset cataracts, and chronic progressive vacuolar myopathy, with
  variable intellectual disability, hypergonadotropic hypogonadism, short
  stature and skeletal abnormalities. It is a disease of endoplasmic reticulum
  proteostasis: biallelic loss-of-function variants in SIL1 remove the adenine
  nucleotide exchange factor that drives the ATPase cycle of BiP/HSPA5, the
  master ER chaperone. Without nucleotide exchange, BiP cannot release its
  folded clients, unfolded protein accumulates in the ER lumen, and the
  unfolded protein response — particularly its PERK branch — is chronically
  engaged. Cerebellar Purkinje neurons, skeletal muscle fibres and the lens are
  the cells that fail first. The mechanism is well enough understood that the
  key experiments are already genetic rescues rather than descriptive studies:
  overexpressing the parallel exchange factor HYOU1/ORP150 rescues
  neurodegeneration in Sil1-null mice, and pharmacological PERK inhibition
  delays Purkinje cell loss. What is not settled is the disease's own
  boundaries — SIL1 variants are found in only about 60% of patients with the
  full triad.
definitions:
- name: Clinical triad and molecular case definition
  definition_type: CASE_DEFINITION
  description: >-
    Diagnosis rests on typical clinical findings — cerebellar ataxia,
    early-onset cataracts and myopathy — and/or biallelic pathogenic SIL1
    variants. Cataracts are essentially universal beyond age 7 but may be
    absent in infants, so their absence in a young child does not exclude the
    diagnosis.
  scope: Disease-level case ascertainment for MSS.
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The diagnosis of MSS is established in an individual with typical clinical
      findings and/or biallelic pathogenic variants in SIL1 identified by
      molecular genetic testing.
    explanation: >-
      The GeneReviews chapter states the diagnostic criteria directly.
  - reference: PMID:24176978
    reference_title: SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cataracts were observed in all patients beyond the age of 7 years, but
      might be missing in infants.
    explanation: >-
      Qualifies the age-dependence of the cataract criterion, which is what makes
      the triad unreliable in young children.
progression:
- phase: Infantile hypotonia and motor delay
  age_range: Early infancy
  notes: >-
    Children usually present first with muscular hypotonia in early infancy,
    before any cerebellar sign is apparent.
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Children with MSS usually present with muscular hypotonia in early
      infancy; distal and proximal muscular weakness is noticed during the first
      decade of life.
    explanation: >-
      GeneReviews states the earliest presenting feature and the timing of
      weakness.
- phase: First-decade weakness and emerging cerebellar signs
  age_range: First decade of life
  notes: >-
    Distal and proximal weakness appears through the first decade, after which
    truncal ataxia, dysdiadochokinesia, nystagmus and dysarthria become
    apparent. Cataracts typically require lens extraction within the same
    decade.
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Later, cerebellar findings of truncal ataxia, dysdiadochokinesia,
      nystagmus, and dysarthria become apparent.
    explanation: >-
      Establishes that cerebellar signs follow the neuromuscular presentation.
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cataracts can develop rapidly and typically require lens extraction in the
      first decade of life.
    explanation: >-
      Establishes the timing and surgical consequence of the cataract phenotype.
- phase: Progression then plateau, with near-normal life span
  notes: >-
    Motor function worsens for some years and then stabilises at an
    unpredictable age and degree of severity. This plateau is an important and
    somewhat counterintuitive feature: despite severe disability in many adults,
    life span appears near normal, which makes MSS a chronic disability disorder
    rather than a progressive fatal neurodegeneration.
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Motor function worsens progressively for some years, then stabilizes at an
      unpredictable age and degree of severity.
    explanation: >-
      GeneReviews documents the progression-then-plateau course.
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Although many adults have severe disabilities, life span in MSS appears to
      be near normal.
    explanation: >-
      Supports the near-normal life expectancy despite severe disability.
inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    Affected individuals carry homozygous or compound heterozygous SIL1
    variants; parents are presumed heterozygous carriers with a 25% recurrence
    risk per pregnancy.
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MSS is inherited in an autosomal recessive manner.
    explanation: >-
      GeneReviews states the mode of inheritance.
genetic:
- name: SIL1
  relationship_type: CAUSATIVE
  gene_term:
    preferred_term: SIL1
    term:
      id: hgnc:24624
      label: SIL1
  notes: >-
    SIL1 encodes an adenine nucleotide exchange factor for the ER chaperone
    HSPA5/BiP. Pathogenic variants are predominantly loss-of-function —
    nonsense, frameshift, splice-site, and single- or multi-exon deletions —
    and, notably, produce severely reduced SIL1 protein regardless of variant
    type or position. That uniform effect on protein level is the proposed
    explanation for why an allelically heterogeneous disease has a relatively
    homogeneous phenotype.
  evidence:
  - reference: PMID:16282978
    reference_title: The gene disrupted in Marinesco-Sjögren syndrome encodes SIL1, an HSPA5 cochaperone.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We identified four disease-associated, predicted loss-of-function
      mutations in SIL1, which encodes a nucleotide exchange factor for the
      heat-shock protein 70 (HSP70) chaperone HSPA5.
    explanation: >-
      One of the two independent 2005 gene-discovery studies, establishing the
      causal gene and its molecular role.
  - reference: PMID:16282977
    reference_title: Mutations in SIL1 cause Marinesco-Sjögren syndrome, a cerebellar ataxia with cataract and myopathy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We found nine distinct mutations that would disrupt the SIL1 protein in
      individuals with Marinesco-Sjögren syndrome, an autosomal recessive
      cerebellar ataxia complicated by cataracts, developmental delay and
      myopathy.
    explanation: >-
      The independently published companion gene-discovery study.
  - reference: PMID:24176978
    reference_title: SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Examination of mutant SIL1 expression in cultured patient lymphoblasts
      suggested that SIL1 mutations result in severely reduced SIL1 protein
      levels irrespective of the type and position of mutations.
    explanation: >-
      Supports the uniform loss-of-protein consequence across a heterogeneous
      allelic spectrum.
- name: HYOU1
  relationship_type: MODIFIER
  gene_term:
    preferred_term: HYOU1
    term:
      id: hgnc:16931
      label: HYOU1
  notes: >-
    HYOU1/ORP150 is a nucleotide exchange factor that works in parallel to SIL1.
    Its dosage modifies the phenotype bidirectionally in Sil1-null mice, which
    is what makes it a modifier rather than an incidental correlate:
    overexpression prevents ER stress and rescues neurodegeneration, and
    reduced expression makes it worse. Established in mouse; no human modifier
    effect has been demonstrated.
  evidence:
  - reference: PMID:19801575
    reference_title: Alteration of the unfolded protein response modifies neurodegeneration in a mouse model of Marinesco-Sjögren syndrome.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      overexpression of HYOU1/ORP150, an exchange factor that works in parallel
      to SIL1, prevents ER stress and rescues neurodegeneration in Sil1(-/-)
      mice, whereas decreasing expression of HYOU1 exacerbates these phenotypes.
    explanation: >-
      The bidirectional dosage effect that establishes HYOU1 as a modifier.
- name: DNAJC3
  relationship_type: MODIFIER
  gene_term:
    preferred_term: DNAJC3
    term:
      id: hgnc:9439
      label: DNAJC3
  notes: >-
    DNAJC3/p58IPK is an ER co-chaperone that promotes ATP hydrolysis by BiP.
    Its loss ameliorates ER stress and neurodegeneration in Sil1-null mice.
    Note the direction: losing a second chaperone component improves the
    phenotype, which is what points to the nucleotide-exchange cycle itself
    rather than chaperone capacity as the thing that is broken. Established in
    mouse only.
  evidence:
  - reference: PMID:19801575
    reference_title: Alteration of the unfolded protein response modifies neurodegeneration in a mouse model of Marinesco-Sjögren syndrome.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      In addition, loss of DNAJC3/p58(IPK), a co-chaperone that promotes ATP
      hydrolysis by BiP, ameliorates ER stress and neurodegeneration in
      Sil1(-/-) mice.
    explanation: >-
      The rescue-by-loss result establishing DNAJC3 as a modifier.
  - reference: PMID:19801575
    reference_title: Alteration of the unfolded protein response modifies neurodegeneration in a mouse model of Marinesco-Sjögren syndrome.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      These findings suggest that alterations in the nucleotide exchange cycle
      of BiP cause ER stress and neurodegeneration in Sil1-deficient mice.
    explanation: >-
      States the interpretation that makes both modifier effects coherent.
pathophysiology:
- name: SIL1 Loss of Nucleotide Exchange Factor Activity
  biological_scale: MOLECULAR
  genetic_context:
    gene:
      preferred_term: SIL1
      term:
        id: hgnc:24624
        label: SIL1
    variant_origin: GERMLINE
    functional_impact_category: LOSS_OF_FUNCTION
    description: >-
      Biallelic loss-of-function variants leave severely reduced SIL1 protein,
      abolishing its adenine nucleotide exchange activity toward BiP/HSPA5.
      Reported alleles are nonsense, frameshift, splice-site and single- or
      multi-exon deletions; patients are homozygous or compound heterozygous.
  molecular_functions:
  - preferred_term: adenine nucleotide exchange factor activity toward BiP
    modifier: LOSS_OF_FUNCTION
    term:
      id: GO:0000774
      label: adenyl-nucleotide exchange factor activity
  evidence:
  - reference: PMID:16282977
    reference_title: Mutations in SIL1 cause Marinesco-Sjögren syndrome, a cerebellar ataxia with cataract and myopathy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      SIL1 (also called BAP) acts as a nucleotide exchange factor for the Hsp70
      chaperone BiP (also called GRP78), which is a key regulator of the main
      functions of the endoplasmic reticulum.
    explanation: >-
      States the molecular function that is lost, and its target chaperone.
  downstream:
  - target: Stalled BiP Chaperone Cycle
    causal_link_type: DIRECT
    description: >-
      Without nucleotide exchange, BiP cannot complete its ATPase cycle and
      remains bound to client proteins.
    evidence:
    - reference: PMID:39180052
      reference_title: Sil1-deficient fibroblasts generate an aberrant extracellular matrix leading to tendon disorganisation in Marinesco-Sjögren syndrome.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        The folding of newly synthesised proteins involves the ATPase cycle of
        BiP, therefore the loss of Sil1 impairs both the BiP cycle and protein
        folding
      explanation: >-
        States the direct mechanistic consequence of SIL1 loss for the BiP
        cycle.
- name: Stalled BiP Chaperone Cycle
  biological_scale: MOLECULAR
  description: >-
    BiP remains associated with its client proteins instead of releasing folded
    cargo, so the chaperone pool is functionally sequestered. This is the step
    that converts a nucleotide-exchange defect into a folding defect.
  biological_processes:
  - preferred_term: protein folding
    modifier: DECREASED
    term:
      id: GO:0006457
      label: protein folding
  evidence:
  - reference: PMID:39180052
    reference_title: Sil1-deficient fibroblasts generate an aberrant extracellular matrix leading to tendon disorganisation in Marinesco-Sjögren syndrome.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Specifically, BiP remains associated with its client proteins, causing the
      accumulation of unfolded proteins, endoplasmic reticulum (ER) stress and
      activation of the unfolded protein response (UPR).
    explanation: >-
      Names the sequestration step and its immediate consequences.
  downstream:
  - target: ER Accumulation of Unfolded Protein and ER Stress
    causal_link_type: DIRECT
    description: >-
      Client proteins that BiP cannot release accumulate unfolded in the ER
      lumen, producing ER stress.
    evidence:
    - reference: PMID:16282978
      reference_title: The gene disrupted in Marinesco-Sjögren syndrome encodes SIL1, an HSPA5 cochaperone.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        These data, together with the similar spatial and temporal patterns of
        tissue expression of Sil1 and Hspa5, suggest that disturbed SIL1-HSPA5
        interaction and protein folding is the primary pathology in
        Marinesco-Sjögren syndrome.
      explanation: >-
        The gene-discovery paper identifies disturbed folding as the primary
        pathology.
- name: ER Accumulation of Unfolded Protein and ER Stress
  biological_scale: CELLULAR
  description: >-
    Unfolded protein accumulates in the ER lumen and intracellular protein
    inclusions form. In woozy mouse Purkinje cells the inclusions are found in
    both ER and nucleus, and the unfolded protein response is upregulated.
  biological_processes:
  - preferred_term: response to endoplasmic reticulum stress
    modifier: INCREASED
    term:
      id: GO:0034976
      label: response to endoplasmic reticulum stress
  cell_types:
  - preferred_term: cerebellar Purkinje cell
    term:
      id: CL:0000121
      label: Purkinje cell
  evidence:
  - reference: PMID:16116427
    reference_title: Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Affected cells have intracellular protein accumulations reminiscent of
      protein inclusions in both the ER and the nucleus. In addition,
      upregulation of the unfolded protein response, suggestive of ER stress,
      occurs in mutant Purkinje cells.
    explanation: >-
      Directly observes protein accumulation and UPR activation in the affected
      cell type in the Sil1-mutant mouse.
  downstream:
  - target: PERK-Branch Unfolded Protein Response Activation
    causal_link_type: DIRECT
    description: >-
      Sustained ER stress engages the UPR, with the PERK branch activated in
      degenerating neurons.
    evidence:
    - reference: PMID:29718201
      reference_title: PERK inhibition delays neurodegeneration and improves motor function in a mouse model of Marinesco-Sjögren syndrome.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Because the PERK branch of the unfolded protein response is activated in
        degenerating neurons of woozy mice
      explanation: >-
        States that the PERK branch specifically is activated in the degenerating
        cells.
  - target: Secretory Pathway Trafficking Failure
    causal_link_type: DIRECT
    description: >-
      Impaired ER folding delays ER-to-plasma-membrane transport, with cargo
      retained in ER and Golgi.
    evidence:
    - reference: PMID:30293566
      reference_title: PERK inhibition attenuates the abnormalities of the secretory pathway and the increased apoptotic rate induced by SIL1 knockdown in HeLa cells.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        SIL1-interefered cells also had delayed ER-to-plasma membrane transport
        with retention of Na+/K+-ATPase and procollagen-I in the ER and Golgi,
        and increased apoptosis.
      explanation: >-
        Directly measures the trafficking defect and names the retained cargoes.
- name: PERK-Branch Unfolded Protein Response Activation
  biological_scale: CELLULAR
  description: >-
    The PERK arm of the UPR is the branch that drives degeneration in this
    disease. Its causal role is established by rescue rather than correlation:
    the PERK inhibitor GSK2606414 delays Purkinje cell degeneration and motor
    deficits in woozy mice, and attenuates secretory-pathway abnormalities and
    cell death in SIL1-knockdown cells.
  biological_processes:
  - preferred_term: PERK-mediated unfolded protein response
    modifier: INCREASED
    term:
      id: GO:0036499
      label: PERK-mediated unfolded protein response
  evidence:
  - reference: PMID:29718201
    reference_title: PERK inhibition delays neurodegeneration and improves motor function in a mouse model of Marinesco-Sjögren syndrome.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      GSK2606414 delayed Purkinje cell degeneration and the onset of motor
      deficits, prolonging the asymptomatic phase of the disease; it also reduced
      the skeletal muscle abnormalities and improved motor performance during the
      symptomatic phase.
    explanation: >-
      Pharmacological inhibition of this node rescues the downstream phenotype,
      which is what places it on the causal path rather than beside it.
  downstream:
  - target: Cerebellar Purkinje Neuron Degeneration
    causal_link_type: DIRECT
    description: >-
      Chronic PERK-branch signalling in Purkinje neurons, terminally
      differentiated cells with a high secretory load, culminates in apoptotic
      degeneration.
    evidence:
    - reference: PMID:30293566
      reference_title: PERK inhibition attenuates the abnormalities of the secretory pathway and the increased apoptotic rate induced by SIL1 knockdown in HeLa cells.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        The PERK pathway of the unfolded protein response was activated in
        SIL1-interfered cells, and the PERK inhibitor GSK2606414 attenuated the
        morphological and functional alterations of the secretory pathway, and
        significantly reduced cell death.
      directness: INDIRECT
      explanation: >-
        Inhibiting PERK reduces cell death in a SIL1-deficient cell model, which
        supports PERK signalling as the route from ER stress to cell loss. The
        model is HeLa rather than a vulnerable MSS cell type.
  - target: Skeletal Muscle Fibre Degeneration
    causal_link_type: DIRECT
    description: >-
      The same PERK-branch signalling drives the muscle arm. The evidence is the
      same rescue argument used for Purkinje cells: PERK inhibition reduced the
      skeletal muscle abnormalities and improved motor performance, so the
      branch is on the causal path to muscle degeneration too, not only to
      neurodegeneration.
    evidence:
    - reference: PMID:29718201
      reference_title: PERK inhibition delays neurodegeneration and improves motor function in a mouse model of Marinesco-Sjögren syndrome.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        it also reduced the skeletal muscle abnormalities and improved motor
        performance during the symptomatic phase
      explanation: >-
        A rescue result covering the muscle arm specifically, which is what
        places PERK upstream of this node rather than only of the Purkinje one.
- name: Secretory Pathway Trafficking Failure
  biological_scale: CELLULAR
  description: >-
    Beyond folding failure, SIL1 loss disorganises the secretory route itself:
    ER chaperone aggregation, an enlarged Golgi, accumulated autophagic vacuoles
    and mitochondrial swelling. This is the node that connects a chaperone
    defect to the extracellular matrix and connective-tissue features, since
    procollagen is one of the retained cargoes.
  biological_processes:
  - preferred_term: autophagy
    modifier: INCREASED
    term:
      id: GO:0006914
      label: autophagy
  cell_types:
  - preferred_term: fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  evidence:
  - reference: PMID:30293566
    reference_title: PERK inhibition attenuates the abnormalities of the secretory pathway and the increased apoptotic rate induced by SIL1 knockdown in HeLa cells.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Immunofluorescence and ultrastructural analysis of SIL1-knocked-down cells
      detected ER chaperone aggregation, enlargement of the Golgi complex,
      increased autophagic vacuoles, and mitochondrial swelling.
    explanation: >-
      Catalogues the organelle-level lesions defining this node.
  downstream:
  - target: Aberrant Extracellular Matrix Assembly
    causal_link_type: DIRECT
    description: >-
      Impaired secretion of matrix cargo yields an abnormal extracellular
      matrix, reduced matrix remodelling capacity and disorganised collagen.
    evidence:
    - reference: PMID:39180052
      reference_title: Sil1-deficient fibroblasts generate an aberrant extracellular matrix leading to tendon disorganisation in Marinesco-Sjögren syndrome.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Functional assays showed that patient fibroblasts have a reduced capacity
        of ECM remodelling, reduced motility, and slower spreading during
        adhesion to Petri dishes.
      explanation: >-
        Measures the matrix consequence in patient-derived cells.
- name: Aberrant Extracellular Matrix Assembly
  biological_scale: TISSUE
  description: >-
    Patient fibroblasts produce structurally abnormal matrix filaments, and the
    woozy mouse shows disorganised collagen at the myotendinous junction and
    Achilles tendon. The authors propose aberrant ECM as a unifying explanation
    for the skeletal, muscular, lens and connective-tissue features — a claim
    about scope that goes beyond what has been demonstrated, and is recorded
    here as their proposal rather than as established fact.
  cell_types:
  - preferred_term: fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  evidence:
  - reference: PMID:39180052
    reference_title: Sil1-deficient fibroblasts generate an aberrant extracellular matrix leading to tendon disorganisation in Marinesco-Sjögren syndrome.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      structural analysis of the myotendinous junction of the soleus muscle and
      surrounding regions of the Achilles tendon revealed a disorganization of
      collagen fibres in the mouse model of MSS (woozy).
    explanation: >-
      Demonstrates the tissue-level matrix lesion in the animal model.
- name: Cerebellar Purkinje Neuron Degeneration
  biological_scale: TISSUE
  description: >-
    Purkinje neurons are terminally differentiated cells with a heavy
    protein-folding load and are the first population to fail. Their loss
    produces the cerebellar syndrome.
  cell_types:
  - preferred_term: cerebellar Purkinje cell
    term:
      id: CL:0000121
      label: Purkinje cell
  biological_processes:
  - preferred_term: apoptotic process
    modifier: INCREASED
    term:
      id: GO:0006915
      label: apoptotic process
  evidence:
  - reference: PMID:16116427
    reference_title: Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      These findings provide evidence that perturbation of ER chaperone function
      in terminally differentiated neurons leads to protein accumulation, ER
      stress and subsequent neurodegeneration.
    explanation: >-
      Establishes the causal sequence from chaperone perturbation to
      neurodegeneration in terminally differentiated neurons.
  downstream:
  - target: Cerebellar ataxia
    causal_link_type: DIRECT
    description: >-
      Loss of Purkinje neurons produces the ataxic phenotype.
    evidence:
    - reference: PMID:16116427
      reference_title: Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Mice homozygous with respect to the woozy (wz) mutation develop
        adult-onset ataxia with cerebellar Purkinje cell loss.
      directness: INDIRECT
      explanation: >-
        Couples Purkinje cell loss to ataxia in the model organism; the human
        cerebellar syndrome is evidenced on the phenotype itself.
- name: Skeletal Muscle Fibre Degeneration
  biological_scale: TISSUE
  description: >-
    A chronic vacuolar myopathy with sarcoplasmic reticulum alterations,
    autophagic vacuoles, mitochondrial changes and prominent myonuclear
    pathology including nuclear envelope and lamina alterations.
  cell_types:
  - preferred_term: skeletal muscle fibre
    term:
      id: CL:0008002
      label: skeletal muscle fiber
  biological_processes:
  - preferred_term: autophagy
    modifier: INCREASED
    term:
      id: GO:0006914
      label: autophagy
  evidence:
  - reference: PMID:24362440
    reference_title: Myopathy in Marinesco-Sjögren syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      We found severe, progressive myopathy characterized by alterations of the
      sarcoplasmic reticulum, accumulation of autophagic vacuoles,
      mitochondrial changes, and prominent myonuclear pathology including
      nuclear envelope and nuclear lamina alterations.
    explanation: >-
      Characterises the muscle lesion in the Sil1-mutant mouse.
  downstream:
  - target: Muscle weakness
    causal_link_type: DIRECT
    description: >-
      Progressive myopathy produces the distal and proximal weakness.
    evidence:
    - reference: PMID:24362440
      reference_title: Myopathy in Marinesco-Sjögren syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Marinesco-Sjögren syndrome (MSS) features cerebellar ataxia, mental
        retardation, cataracts, and progressive vacuolar myopathy with peculiar
        myonuclear alterations.
      directness: INDIRECT
      explanation: >-
        Couples the progressive vacuolar myopathy this node describes to the
        clinical syndrome in which weakness is the presenting muscle feature.
phenotypes:
- category: Neurologic
  name: Cerebellar ataxia
  description: >-
    Truncal ataxia with dysdiadochokinesia is an obligate feature; SIL1 variants
    are invariably associated with a cerebellar syndrome combined with chronic
    myopathy.
  phenotype_term:
    preferred_term: Cerebellar ataxia
    term:
      id: HP:0001251
      label: Ataxia
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:24176978
    reference_title: SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      SIL1 mutations are invariably associated with the combination of a
      cerebellar syndrome and chronic myopathy.
    explanation: >-
      Establishes the cerebellar syndrome as an obligate feature of SIL1-related
      disease.
- category: Neurologic
  name: Cerebellar atrophy
  description: >-
    Structural cerebellar atrophy accompanies the clinical ataxia.
  phenotype_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Marinesco-Sjögren syndrome (MSS) is characterized by cerebellar ataxia with
      cerebellar atrophy, dysarthria, nystagmus, early-onset (not necessarily
      congenital) cataracts, myopathy, muscle weakness, and hypotonia.
    explanation: >-
      GeneReviews names cerebellar atrophy among the defining features.
- category: Ophthalmologic
  name: Early-onset cataract
  description: >-
    Bilateral cataracts, present in all patients beyond age 7 but potentially
    absent in infancy, typically requiring lens extraction in the first decade.
    Bound to Developmental cataract rather than plain Cataract because the
    lesion is an early-onset developmental one.
  phenotype_term:
    preferred_term: Developmental cataract
    term:
      id: HP:0000519
      label: Developmental cataract
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:24176978
    reference_title: SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cataracts were observed in all patients beyond the age of 7 years, but
      might be missing in infants.
    explanation: >-
      Gives both the near-universal frequency and its age dependence.
- category: Neuromuscular
  name: Muscle weakness
  description: >-
    Distal and proximal muscular weakness from chronic vacuolar myopathy,
    noticed during the first decade.
  phenotype_term:
    preferred_term: Muscle weakness
    term:
      id: HP:0001324
      label: Muscle weakness
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Children with MSS usually present with muscular hypotonia in early
      infancy; distal and proximal muscular weakness is noticed during the first
      decade of life.
    explanation: >-
      GeneReviews documents the distribution and timing of weakness.
- category: Neuromuscular
  name: Hypotonia
  description: >-
    Muscular hypotonia in early infancy is typically the presenting feature.
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Children with MSS usually present with muscular hypotonia in early
      infancy
    explanation: >-
      Names hypotonia as the usual presenting feature.
- category: Neurologic
  name: Dysarthria
  phenotype_term:
    preferred_term: Dysarthria
    term:
      id: HP:0001260
      label: Dysarthria
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Later, cerebellar findings of truncal ataxia, dysdiadochokinesia,
      nystagmus, and dysarthria become apparent.
    explanation: >-
      GeneReviews lists dysarthria among the emerging cerebellar findings.
- category: Ophthalmologic
  name: Nystagmus
  phenotype_term:
    preferred_term: Nystagmus
    term:
      id: HP:0000639
      label: Nystagmus
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Later, cerebellar findings of truncal ataxia, dysdiadochokinesia,
      nystagmus, and dysarthria become apparent.
    explanation: >-
      GeneReviews lists nystagmus among the cerebellar findings.
- category: Neurodevelopmental
  name: Intellectual disability
  description: >-
    Cognitive impairment is variable and, importantly, not obligatory: six
    patients with confirmed SIL1 variants had no intellectual disability. A
    normal IQ therefore does not exclude MSS, and testing should not be withheld
    on that basis.
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:24176978
    reference_title: SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Six patients with SIL1 mutations had no intellectual disability, extending
      the known wide range of cognitive capabilities in Marinesco-Sjögren
      syndrome to include normal intelligence.
    explanation: >-
      Documents the variable expressivity, including normal intelligence.
- category: Neurodevelopmental
  name: Motor delay
  phenotype_term:
    preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  evidence:
  - reference: PMID:24176978
    reference_title: SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Marinesco-Sjögren syndrome is a rare autosomal recessive multisystem
      disorder featuring cerebellar ataxia, early-onset cataracts, chronic
      myopathy, variable intellectual disability and delayed motor development.
    explanation: >-
      Names delayed motor development among the defining features.
- category: Endocrine
  name: Hypergonadotropic hypogonadism
  description: >-
    Primary gonadal failure requiring hormone replacement at the expected time
    of puberty.
  phenotype_term:
    preferred_term: Hypergonadotropic hypogonadism
    term:
      id: HP:0000815
      label: Hypergonadotropic hypogonadism
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Additional features may include psychomotor delay, hypergonadotropic
      hypogonadism, short stature, and various skeletal abnormalities.
    explanation: >-
      GeneReviews lists hypergonadotropic hypogonadism among additional
      features.
- category: Growth
  name: Short stature
  phenotype_term:
    preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Additional features may include psychomotor delay, hypergonadotropic
      hypogonadism, short stature, and various skeletal abnormalities.
    explanation: >-
      GeneReviews lists short stature among additional features.
- category: Musculoskeletal
  name: Scoliosis
  description: >-
    One of the skeletal abnormalities requiring orthopaedic management and
    clinical surveillance at each visit.
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      clinical assessment for scoliosis at each visit, with radiographs as
      needed
    explanation: >-
      The GeneReviews surveillance recommendation establishes scoliosis as an
      expected manifestation.
- category: Ophthalmologic
  name: Strabismus
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      treatment of strabismus per ophthalmologist
    explanation: >-
      GeneReviews management guidance establishes strabismus as a manifestation
      requiring treatment.
histopathology:
- name: Vacuolar myopathy with myonuclear and nuclear envelope pathology
  description: >-
    Muscle shows a chronic vacuolar myopathy with sarcoplasmic reticulum
    alterations, autophagic vacuoles, mitochondrial changes and distinctive
    perinuclear membranous structures derived from the nuclear envelope and
    lamina. GeneReviews regards the electron-microscopic ultrastructural changes
    as specific to MSS, which makes muscle biopsy diagnostically informative
    rather than merely confirmatory.
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Electron microscopic ultrastructural changes on muscle biopsy are thought
      to be specific to MSS.
    explanation: >-
      Establishes the diagnostic specificity claim for the muscle ultrastructure.
  - reference: PMID:24362440
    reference_title: Myopathy in Marinesco-Sjögren syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      In particular, the presence of perinuclear membranous structures which
      have been reported as an ultrastructural hallmark of MSS-related myopathy
      could be confirmed in woozy muscles.
    explanation: >-
      Identifies the specific ultrastructural hallmark and confirms it in the
      animal model.
treatments:
- name: Cataract Extraction
  description: >-
    Lens extraction is required in the first decade for most patients as
    cataracts progress.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: cataract extraction
    term:
      id: NCIT:C157809
      label: Cataract Surgery
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cataracts can develop rapidly and typically require lens extraction in the
      first decade of life.
    explanation: >-
      GeneReviews establishes lens extraction as standard management.
- name: Physical Therapy and Rehabilitation
  description: >-
    Symptomatic management of the muscular manifestations by neurologists,
    physiatrists and physical therapists, with annual or as-needed assessment.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: physical therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Symptomatic treatment of muscular manifestations usually by pediatric or
      adult neurologists and physiatrists and/or physical therapists
    explanation: >-
      GeneReviews states the standard symptomatic management for the myopathy.
- name: Hormone Replacement for Primary Gonadal Failure
  description: >-
    Hormone replacement therapy at the expected time of puberty for the
    hypergonadotropic hypogonadism.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Hormone Replacement Therapy
    term:
      id: NCIT:C15599
      label: Hormone Replacement Therapy
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      hormone replacement therapy for primary gonadal failure at the expected
      time of puberty
    explanation: >-
      GeneReviews states the endocrine management recommendation.
- name: Developmental and Educational Support
  description: >-
    Developmental support and education programmes tailored to the individual's
    needs, with progress monitored at each visit.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Rehabilitation
    term:
      id: NCIT:C15315
      label: Rehabilitation
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      developmental support and education programs tailored to the individual's
      developmental needs
    explanation: >-
      GeneReviews management recommendation for the neurodevelopmental domain.
- name: Feeding Support for Poor Weight Gain
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Nutritional Support
    term:
      id: NCIT:C15433
      label: Nutritional Support
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      feeding support as needed for poor weight gain
    explanation: >-
      GeneReviews management recommendation for growth and feeding.
- name: Orthopedic Management of Scoliosis and Skeletal Manifestations
  description: >-
    GeneReviews directs scoliosis and other skeletal manifestations to an
    orthopaedist without specifying an intervention, so this is bound to the
    generic therapeutic-procedure term rather than to a surgical one - the
    source does not say surgery.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: orthopedic management
    term:
      id: NCIT:C49236
      label: Therapeutic Procedure
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      management of scoliosis and other skeletal manifestations per orthopedist
    explanation: >-
      GeneReviews management recommendation for the skeletal domain.
- name: Genetic Counseling and Carrier Testing
  description: >-
    Recurrence risk is 25% per pregnancy for carrier couples; carrier testing
    and prenatal or preimplantation testing are available once the familial
    variants are known.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:20301371
    reference_title: Marinesco-Sjögren Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      If biallelic SIL1 pathogenic variants have been identified in an affected
      family member, carrier testing for at-risk relatives and
      prenatal/preimplantation genetic testing are possible.
    explanation: >-
      GeneReviews states the available reproductive genetic options.
animal_models:
- name: woozy mouse (spontaneous Sil1 mutation)
  species: Mouse
  genotype: Sil1 woozy (wz) homozygous
  publication: PMID:16116427
  description: >-
    The spontaneous woozy mutation disrupts Sil1 and produces adult-onset ataxia
    with Purkinje cell loss, ER and nuclear protein inclusions, UPR upregulation,
    and a progressive vacuolar myopathy that reproduces the human ultrastructural
    hallmark.
  modeled_mechanisms:
  - target: ER Accumulation of Unfolded Protein and ER Stress
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Mutant Purkinje cells show the protein accumulation and UPR upregulation
      that define this node.
    limitations: >-
      Cerebellar degeneration in woozy is adult-onset, whereas human MSS
      presents in infancy and early childhood, so the model compresses a
      different developmental window.
    readouts:
    - name: Intracellular protein inclusions in Purkinje cells
      target: ER Accumulation of Unfolded Protein and ER Stress
      direction: INCREASED
      interpretation: >-
        Direct histological correlate of unfolded-protein accumulation.
      evidence:
      - reference: PMID:16116427
        reference_title: Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Affected cells have intracellular protein accumulations reminiscent of
          protein inclusions in both the ER and the nucleus.
        explanation: >-
          Reports the measurement behind this readout.
    evidence:
    - reference: PMID:16116427
      reference_title: Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        We report that the wz mutation disrupts the gene Sil1 that encodes an
        adenine nucleotide exchange factor of BiP, a crucial ER chaperone.
      explanation: >-
        Confirms the model carries a lesion in the same gene as the human
        disease, which is what makes it informative for this node.
  - target: Cerebellar Purkinje Neuron Degeneration
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      woozy reproduces Purkinje cell degeneration and the resulting ataxia.
    limitations: >-
      Degeneration in woozy is adult-onset, whereas human MSS is an early
      childhood disease, so the model compresses a different developmental
      window. Cataract, the third element of the human triad, is not reported
      among woozy phenotypes in the cited studies, which is why no lens node is
      modelled here at all.
    readouts:
    - name: Purkinje cell loss
      target: Cerebellar Purkinje Neuron Degeneration
      direction: DECREASED
      interpretation: >-
        Cerebellar Purkinje cell number falls, producing the ataxic phenotype.
      evidence:
      - reference: PMID:16116427
        reference_title: Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Mice homozygous with respect to the woozy (wz) mutation develop
          adult-onset ataxia with cerebellar Purkinje cell loss.
        explanation: >-
          Reports the Purkinje cell measurement and the resulting phenotype.
    evidence:
    - reference: PMID:16116427
      reference_title: Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Mice homozygous with respect to the woozy (wz) mutation develop
        adult-onset ataxia with cerebellar Purkinje cell loss.
      explanation: >-
        Establishes that the model reproduces Purkinje cell loss, which is what
        makes it informative for this node specifically.
  - target: Skeletal Muscle Fibre Degeneration
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      woozy muscle reproduces the human MSS myopathy, including the perinuclear
      membranous structures reported as its ultrastructural hallmark.
    limitations: >-
      As with the cerebellar arm, the mouse phenotype is adult-onset while human
      MSS presents in infancy, so the model compresses a different developmental
      window.
    readouts:
    - name: Perinuclear membranous structures on muscle ultrastructure
      target: Skeletal Muscle Fibre Degeneration
      direction: INCREASED
      interpretation: >-
        The ultrastructural hallmark of MSS myopathy, confirmed present in the
        model.
      evidence:
      - reference: PMID:24362440
        reference_title: Myopathy in Marinesco-Sjögren syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          In particular, the presence of perinuclear membranous structures which
          have been reported as an ultrastructural hallmark of MSS-related
          myopathy could be confirmed in woozy muscles.
        explanation: >-
          Reports the ultrastructural measurement behind this readout.
    evidence:
    - reference: PMID:24362440
      reference_title: Myopathy in Marinesco-Sjögren syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        This report identifies woozy muscle as a faithful phenocopy of the MSS
        myopathy.
      explanation: >-
        Explicit statement that the model is faithful for the muscle arm, which
        is the claim this link makes.
discussions:
- discussion_id: sil1_negative_mss_locus_heterogeneity
  kind: KNOWLEDGE_GAP
  prompt: >-
    What causes Marinesco-Sjogren syndrome in the 40% of patients with the full
    clinical triad who have no detectable SIL1 variant?
  attaches_to:
  - pathophysiology#SIL1 Loss of Nucleotide Exchange Factor Activity
  rationale: >-
    The mutation detection rate is 60% (15/25) among patients with the
    characteristic triad. That leaves a substantial minority whose disease is
    clinically indistinguishable but molecularly unexplained. Two readings are
    possible and the data do not separate them: either a second locus in the
    same BiP nucleotide-exchange pathway, or non-coding and structural SIL1
    variation missed by the screening used. The contrast with the sub-3%
    detection rate in patients with variable, non-triad phenotypes matters here
    — it says the triad is a sharp clinical entity, which makes an unexplained
    40% within it harder to dismiss as phenotypic overlap.
  evidence:
  - reference: PMID:24176978
    reference_title: SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We obtained a mutation detection rate of 60% (15/25) among patients with
      the characteristic Marinesco-Sjögren syndrome triad (ataxia, cataracts,
      myopathy) whereas the detection rate in the group of patients with more
      variable phenotypic presentation was below 3% (1/37).
    explanation: >-
      Quantifies both the unexplained fraction within the triad and the
      specificity of the triad itself.
- discussion_id: perk_inhibition_translational_ceiling
  kind: HUMAN_MODEL_MISMATCH
  prompt: >-
    PERK inhibition and HYOU1 overexpression both rescue Sil1-null mice. Does
    either represent a viable path in human MSS, given that the PERK inhibitor
    is pancreatotoxic and the human disease has already caused most of its
    damage by the time it is diagnosed?
  attaches_to:
  - pathophysiology#PERK-Branch Unfolded Protein Response Activation
  rationale: >-
    The mechanistic case is strong on the mouse side: GSK2606414 delays Purkinje
    degeneration and motor deficits and prolongs the asymptomatic phase, and
    genetic modulation of HYOU1 moves the phenotype in both directions. But the
    mouse benefit is measured largely as a delay in an asymptomatic phase, and
    treatment was started presymptomatically. Human MSS presents with hypotonia
    in infancy and cataracts within the first decade, so the equivalent window
    is one clinicians do not currently have access to. Whether a
    proteostasis-directed intervention started after diagnosis modifies the
    human course is untested, and is a different question from whether the
    pathway is causal — which the mouse work establishes.

    The 2025 follow-up sharpens this considerably, in a discouraging direction.
    Three agents chosen specifically to keep the mechanism while losing
    GSK2606414's pancreatic toxicity — trazodone and dibenzoylmethane as partial
    PERK inhibitors, TUDCA as a chemical chaperone — produced no benefit at all
    in the same model, on the same presymptomatic schedule, at doses active in
    other neurodegeneration models, and pharmacokinetics excluded altered drug
    metabolism as the explanation. So the failure is not obviously about
    exposure or timing, and the open question narrows: is anything short of full
    PERK inhibition sufficient, and if not, does a therapeutic window between
    efficacy and pancreatic toxicity exist at all?
  evidence:
  - reference: PMID:29718201
    reference_title: PERK inhibition delays neurodegeneration and improves motor function in a mouse model of Marinesco-Sjögren syndrome.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Mice were chronically treated with GSK2606414 starting from a
      presymptomatic stage, and the effects were evaluated on biochemical,
      histopathological and clinical readouts.
    explanation: >-
      The presymptomatic start is exactly the design feature that limits
      translation to a disease diagnosed after symptom onset.
  - reference: PMID:19801575
    reference_title: Alteration of the unfolded protein response modifies neurodegeneration in a mouse model of Marinesco-Sjögren syndrome.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      overexpression of HYOU1/ORP150, an exchange factor that works in parallel
      to SIL1, prevents ER stress and rescues neurodegeneration in Sil1(-/-)
      mice, whereas decreasing expression of HYOU1 exacerbates these phenotypes.
    explanation: >-
      Establishes the bidirectional genetic modifier effect that motivates the
      therapeutic hypothesis, in mice.
  - reference: PMID:39804912
    reference_title: "Trazodone, dibenzoylmethane and tauroursodeoxycholic acid do not prevent motor dysfunction and neurodegeneration in Marinesco-Sjögren syndrome mice."
    supports: REFUTE
    evidence_source: MODEL_ORGANISM
    snippet: >-
      None of the treatments prevented motor dysfunction or PC degeneration in
      woozy mice, as assessed by beam walking, rotarod test, and calbindin
      immunohistochemistry.
    explanation: >-
      A directly relevant negative result. Three agents chosen precisely to
      avoid GSK2606414's pancreatic toxicity all failed in the same model and
      the same presymptomatic design in which GSK2606414 succeeded. Graded
      REFUTE because it argues against the proposition that the proteostasis
      strategy translates readily.
  - reference: PMID:39804912
    reference_title: "Trazodone, dibenzoylmethane and tauroursodeoxycholic acid do not prevent motor dysfunction and neurodegeneration in Marinesco-Sjögren syndrome mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Pharmacokinetic studies excluded that the lack of effect was due to
      altered drug metabolism in woozy mice.
    explanation: >-
      Rules out the obvious confound, which is what makes the negative result
      informative rather than uninterpretable.
  - reference: PMID:39804912
    reference_title: "Trazodone, dibenzoylmethane and tauroursodeoxycholic acid do not prevent motor dysfunction and neurodegeneration in Marinesco-Sjögren syndrome mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      This underscores the difficulty of translating neuroprotective strategies
      from other conditions to MSS, highlighting the need for more targeted
      therapeutic approaches.
    explanation: >-
      The authors' own reading, which is the substance of this discussion.
references:
- reference: PMID:20301371
  title: Marinesco-Sjögren Syndrome.
  tags:
  - GeneReviews
- reference: PMID:24176978
  title: SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
- reference: PMID:16116427
  title: Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
notes: >-
  Named Entity Confusion notes, two of which are load-bearing.

  First, the MONDO stub for this disease carries "Marshall Smith Syndrome" as a
  synonym. That is a different disorder (NFIX-related) and it is not used
  anywhere in this entry; it was also kept out of literature searches. The
  synonyms recorded here are the ones that genuinely name MSS.

  Second, kb/disorders/Autosomal_Recessive_Cerebellar_Ataxia_With_Late_Onset_Spasticity.yaml
  curates a GBA2-related "Marinesco-Sjogren-LIKE syndrome". That is a
  phenocopy with a different gene and a different mechanism, not this disease,
  and no evidence was taken from it or cited into this entry.

  Deep research. One OpenScientist report was generated for this entry
  (research/Marinesco-Sjogren_Syndrome-deep-research-openscientist.md). Its
  reference validation was clean (16/16 verified), but its term validation set
  needs_review: true, and two of the flagged bindings were real errors that
  would have propagated into this entry had they been copied:

  - The report gives MONDO:0008541 as the MONDO ID for MSS. That CURIE resolves
    to "spermatic cord torsion". The correct term, MONDO:0009567, is the one
    used here and is the one the curation stub carries.
  - The report binds cerebellar/vermian atrophy to HP:0002151, which is
    "Increased circulating lactate concentration". Cerebellar atrophy is bound
    here to HP:0001272 instead.
  - The report also names GO:0036498 as PERK-mediated UPR; that CURIE is
    IRE1-mediated UPR. GO:0036499 is the PERK term and is what this entry uses.

  Review round 2 fixed two defects the round-1 node split had itself created:
  the muscle node was left without an incoming edge (it is now downstream of
  the PERK node, on the same rescue evidence that places PERK upstream of the
  Purkinje node), and the woozy model's muscle-phenocopy evidence was still
  attached to the Purkinje-only link, describing an arm that node no longer
  had. That evidence now supports its own RECAPITULATES link on the muscle
  node, with the perinuclear-membranous-structure readout. Splitting a bundled
  node is not finished when the node is split; every edge and every piece of
  evidence that pointed at the old node has to be re-aimed.

  Review round 1 (PR #10142) additionally corrected: one reference_title that
  belonged to a different paper; a folded scalar that split
  prenatal/preimplantation across a line break, which check-folded-hyphens does
  not catch because the break is at a slash rather than a hyphen; a
  pathophysiology node that bundled Purkinje, muscle and lens degeneration into
  one, whose lens arm had no evidence at all (it is now three nodes, and no lens
  node is modelled since nothing supports one); the absence of any edge from the
  pathograph into the phenotype layer; two treatment terms bound more generically
  than NCIT supports; and the HYOU1/DNAJC3 modifiers, which were prose in a notes
  field and are now genetic entries with relationship_type: MODIFIER.

  Most of the report's other "mislabelled" flags were an artefact of its
  phenotype table, whose "Type" column (Clinical sign, Lab abnormality) was
  parsed as the term label. Those CURIEs themselves resolve correctly and were
  used after checking each against the committed term cache.

  Prevalence is still omitted, and the reason has changed. The reviewer
  correctly pointed out that ORPHA is a structured source, so the route is
  `just structured-rebuild-orphanet --id 559` rather than `just
  fetch-reference`. That was tried. It needs data/orphadata/en_product1.xml,
  which is gitignored, and `just refresh-orphadata` fails with a checksum
  mismatch against the pinned MANIFEST — Orphadata has republished the file
  since the pin. Filed separately. So the prevalence is unobtainable in this
  environment rather than unattempted, and no record is invented in its place.

  Other deliberate omissions. Serum creatine kinase elevation: universally described but not stated
  in any abstract cached for this entry, so no biochemical record. Peripheral
  neuropathy and pyramidal signs: named in the deep-research phenotype table but
  not in a cached quotable source at the frequency asserted.

  Frequency bands are given only for ataxia, cataract and weakness, where the
  cited text supports "invariably associated" or "all patients beyond the age of
  7". Everything else is left unbanded rather than guessed.
📚

References & Deep Research

References

3
PMID:20301371
Marinesco-Sjögren Syndrome.
No top-level findings curated for this source.
PMID:24176978
SIL1 mutations and clinical spectrum in patients with Marinesco-Sjogren syndrome.
No top-level findings curated for this source.
PMID:16116427
Protein accumulation and neurodegeneration in the woozy mutant mouse is caused by disruption of SIL1, a cochaperone of BiP.
No top-level findings curated for this source.

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (2)

Record notes

Named Entity Confusion notes, two of which are load-bearing. First, the MONDO stub for this disease carries "Marshall Smith Syndrome" as a synonym. That is a different disorder (NFIX-related) and it is not used anywhere in this entry; it was also kept out of literature searches. The synonyms recorded here are the ones that genuinely name MSS. Second, kb/disorders/Autosomal_Recessive_Cerebellar_Ataxia_With_Late_Onset_Spasticity.yaml curates a GBA2-related "Marinesco-Sjogren-LIKE syndrome". That is a phenocopy with a different gene and a different mechanism, not this disease, and no evidence was taken from it or cited into this entry. Deep research. One OpenScientist report was generated for this entry (research/Marinesco-Sjogren_Syndrome-deep-research-openscientist.md). Its reference validation was clean (16/16 verified), but its term validation set needs_review: true, and two of the flagged bindings were real errors that would have propagated into this entry had they been copied: - The report gives MONDO:0008541 as the MONDO ID for MSS. That CURIE resolves to "spermatic cord torsion". The correct term, MONDO:0009567, is the one used here and is the one the curation stub carries. - The report binds cerebellar/vermian atrophy to HP:0002151, which is "Increased circulating lactate concentration". Cerebellar atrophy is bound here to HP:0001272 instead. - The report also names GO:0036498 as PERK-mediated UPR; that CURIE is IRE1-mediated UPR. GO:0036499 is the PERK term and is what this entry uses. Review round 2 fixed two defects the round-1 node split had itself created: the muscle node was left without an incoming edge (it is now downstream of the PERK node, on the same rescue evidence that places PERK upstream of the Purkinje node), and the woozy model's muscle-phenocopy evidence was still attached to the Purkinje-only link, describing an arm that node no longer had. That evidence now supports its own RECAPITULATES link on the muscle node, with the perinuclear-membranous-structure readout. Splitting a bundled node is not finished when the node is split; every edge and every piece of evidence that pointed at the old node has to be re-aimed. Review round 1 (PR #10142) additionally corrected: one reference_title that belonged to a different paper; a folded scalar that split prenatal/preimplantation across a line break, which check-folded-hyphens does not catch because the break is at a slash rather than a hyphen; a pathophysiology node that bundled Purkinje, muscle and lens degeneration into one, whose lens arm had no evidence at all (it is now three nodes, and no lens node is modelled since nothing supports one); the absence of any edge from the pathograph into the phenotype layer; two treatment terms bound more generically than NCIT supports; and the HYOU1/DNAJC3 modifiers, which were prose in a notes field and are now genetic entries with relationship_type: MODIFIER. Most of the report's other "mislabelled" flags were an artefact of its phenotype table, whose "Type" column (Clinical sign, Lab abnormality) was parsed as the term label. Those CURIEs themselves resolve correctly and were used after checking each against the committed term cache. Prevalence is still omitted, and the reason has changed. The reviewer correctly pointed out that ORPHA is a structured source, so the route is `just structured-rebuild-orphanet --id 559` rather than `just fetch-reference`. That was tried. It needs data/orphadata/en_product1.xml, which is gitignored, and `just refresh-orphadata` fails with a checksum mismatch against the pinned MANIFEST — Orphadata has republished the file since the pin. Filed separately. So the prevalence is unobtainable in this environment rather than unattempted, and no record is invented in its place. Other deliberate omissions. Serum creatine kinase elevation: universally described but not stated in any abstract cached for this entry, so no biochemical record. Peripheral neuropathy and pyramidal signs: named in the deep-research phenotype table but not in a cached quotable source at the frequency asserted. Frequency bands are given only for ataxia, cataract and weakness, where the cited text supports "invariably associated" or "all patients beyond the age of 7". Everything else is left unbanded rather than guessed.

Create: Marinesco-Sjogren Syndrome · 2026-08-30T06:33:58Z · View source

De novo curation of Marinesco-Sjogren syndrome (MONDO:0009567, SIL1), using GeneReviews PMID:20301371 as the phenotype baseline plus primary literature. One OpenScientist deep-research report was generated and read. Its reference validation was clean (16/16 verified) but its term validation set needs_review; three of its bindings were wrong and were NOT used: MONDO:0008541 (which resolves to spermatic cord torsion) as the disease term, HP:0002151 (Increased circulating lactate concentration) for cerebellar atrophy, and GO:0036498 (IRE1-mediated UPR) for the PERK branch. This entry uses MONDO:0009567, HP:0001272 and GO:0036499 instead. Named Entity Confusion checks: the stub synonym Marshall Smith Syndrome, a different NFIX disorder, was excluded from the entry and from literature searches; the GBA2 Marinesco-Sjogren-like phenocopy already curated in kb/disorders/Autosomal_Recessive_Cerebellar_Ataxia_With_Late_Onset_Spasticity.yaml was kept separate and nothing was cited across. Validated with just validate (51/51 snippets verified against cached references), check-entity-refs, check-duplicate-keys, check-snippet-length, check-title-snippets, check-snippet-grading and check-folded-hyphens.

OpenScientist ▸
Marinesco-Sjögren Syndrome: A Comprehensive Disease Characteristics Report
openscientist-autonomous 14 citations 2026-08-30T06:21:42.876945

Marinesco-Sjögren Syndrome: A Comprehensive Disease Characteristics Report

Category: Mendelian (monogenic, autosomal recessive) Evidence sources: Human clinical cohorts/case reports, mouse models (woozy, Sil1⁻/⁻), in vitro/cellular models, and aggregated disease-level resources (OMIM, Orphanet). Citations are PubMed PMIDs.

Summary

Marinesco-Sjögren syndrome (MSS) is a rare, autosomal recessive, multisystem neurodegenerative disorder classically defined by the triad of cerebellar ataxia, early-onset (congenital/childhood) bilateral cataracts, and chronic progressive vacuolar myopathy, frequently accompanied by variable intellectual disability, hypergonadotropic hypogonadism, short stature, and skeletal abnormalities such as scoliosis. It is an ultra-rare disorder (prevalence <1/1,000,000; Orphanet ORPHA:559) with a few hundred cases reported worldwide, enriched in consanguineous and genetically isolated populations, affecting both sexes roughly equally. Onset is congenital-to-early-childhood and insidious, and the disease follows a chronic, slowly progressive, lifelong course.

The principal molecular cause is biallelic loss-of-function mutation in SIL1 (chromosome 5q31.2), identified independently in 2005 by two groups. SIL1 encodes a nucleotide-exchange factor (NEF) for the master endoplasmic reticulum (ER) chaperone BiP/HSPA5 (GRP78). Loss of SIL1 impairs the BiP chaperone cycle (ADP release/nucleotide exchange), causing accumulation of unfolded/misfolded proteins, ER stress, and activation of the unfolded protein response (UPR)—particularly the PERK branch. This drives apoptotic degeneration in the cells most vulnerable to protein-folding stress: cerebellar Purkinje neurons, skeletal muscle fibers, and the lens. SIL1 detection rate is ~60% among patients with the classic triad, indicating additional locus heterogeneity for the remaining ~40%.

There is no disease-modifying therapy; management is entirely supportive and symptomatic (cataract extraction, physiotherapy/occupational therapy, orthopedic management, endocrine hormone replacement, educational support). The best-characterized preclinical model is the woozy mouse (spontaneous Sil1 mutation), which recapitulates cerebellar Purkinje-cell degeneration and progressive myopathy. Pharmacologic PERK inhibition (GSK2606414) is neuroprotective in this model but is pancreatotoxic, and other candidate agents (trazodone, dibenzoylmethane, TUDCA) failed. Genetic modifiers—HYOU1/ORP150 and DNAJC3/p58IPK—modulate neurodegeneration severity, offering rational therapeutic targets. Prevention is currently limited to genetic counseling and prenatal/carrier testing.

1. Disease Information

Overview. Marinesco-Sjögren syndrome (MSS) is a rare autosomal recessive multisystem disease of infancy characterized by cerebellar and skeletal-muscle degeneration together with early-onset cataracts. It is a Mendelian protein-misfolding disorder driven by dysfunction of ER protein homeostasis. As stated by Roos et al., "Loss of SIL1's function is the leading cause of Marinesco-Sjögren syndrome (MSS), an autosomal recessive, multisystem disorder" (PMID: 33557244).

Key identifiers.

Resource Identifier
OMIM (phenotype) #248800 (Marinesco-Sjögren syndrome)
OMIM (gene) SIL1 608005
Orphanet ORPHA:559
MONDO MONDO:0008541
ICD-10 G11.1 (early-onset cerebellar ataxia)
ICD-11 LD90.0 / hereditary ataxia range
MeSH D008426 (Marinesco-Sjogren Disease)
Gene locus SIL1, chromosome 5q31.2
HGNC SIL1

Note: OMIM, ICD, and MeSH mappings above reflect standard database entries; the MONDO ID for MSS is MONDO:0008541. These should be reconciled against live database entries during knowledge-base population.

Synonyms / alternative names. Marinesco-Sjögren syndrome; Marinesco-Sjögren-Garland syndrome; cerebellar ataxia–cataract–myopathy syndrome; hereditary oligophrenic cerebellolental degeneration; MSS.

Data source type. Information here is derived from aggregated disease-level resources (OMIM, Orphanet, HPO) and primary literature (case series, gene-discovery studies, animal-model experiments)—not from individual electronic health records. The largest genotype–phenotype series is Krieger et al. 2013 (PMID: 24176978).

2. Etiology

Disease causal factors. MSS is a monogenic (Mendelian) disorder. The primary cause is biallelic loss-of-function mutation in SIL1. There is no established infectious, toxic, or environmental cause. As Amodei et al. describe, "Sil1 is an endoplasmic reticulum (ER) protein required for the release of ADP from the master chaperone Bip, which in turn will release the folded proteins" (PMID: 39180052).

Genetic risk factors. - Causal variants: Homozygous or compound-heterozygous loss-of-function SIL1 variants (nonsense, frameshift, splice-site, single- and multi-exon deletions). - Modifier genes: HYOU1/ORP150 (GRP170) and DNAJC3/p58IPK modify neurodegeneration severity (see §4 and §6). - Locus heterogeneity: ~40% of triad-positive patients lack detectable SIL1 mutations, implying additional, as-yet-unidentified loci (PMID: 24176978).

Environmental risk factors. None established. Age, sex, occupational or toxic exposures are not causal. Consanguinity and membership in a genetically isolated population increase the probability of biallelic inheritance (population structure, not an environmental exposure per se).

Protective factors. No environmental or dietary protective factors are established. Genetically, higher endogenous expression of the parallel NEF HYOU1/ORP150 is protective against ER stress and neurodegeneration in the mouse model, and reduced DNAJC3/p58IPK activity is likewise ameliorating (PMID: 19801575).

Gene–environment interactions. No documented gene–environment interactions. MSS is essentially fully penetrant for biallelic LoF genotypes; phenotypic variability appears driven by genetic modifiers rather than environmental exposures.

3. Phenotypes

MSS is a multisystem disorder. The obligate combination is cerebellar syndrome + chronic myopathy; cataracts are essentially universal beyond age 7 but may be absent in infancy. As Krieger et al. report: "SIL1 mutations are invariably associated with the combination of a cerebellar syndrome and chronic myopathy. Cataracts were observed in all patients beyond the age of 7 years, but might be missing in infants" (PMID: 24176978).

Core triad and associated phenotypes

Phenotype Type HPO term Onset Severity/Progression Frequency
Cerebellar ataxia Clinical sign HP:0001251 Early childhood Progressive, moderate–severe Obligate (~100%)
Cerebellar/vermian atrophy (MRI) Imaging/structural HP:0002151 Childhood Progressive Very frequent
Bilateral cataracts Physical manifestation HP:0000519 Congenital–early childhood Progressive; universal >7 y ~100% >7 y
Chronic vacuolar myopathy / muscle weakness Clinical sign HP:0003198 / HP:0003701 Early childhood Chronic progressive Obligate (~100%)
Elevated creatine kinase Lab abnormality HP:0003236 Childhood Mild–moderate elevation Frequent
Intellectual disability Behavioral/cognitive HP:0001249 Congenital/childhood Stable, variable Variable (some normal IQ)
Delayed motor development Developmental HP:0001270 Infancy — Frequent
Muscular hypotonia Clinical sign HP:0001252 Infancy — Frequent
Hypergonadotropic hypogonadism Lab/endocrine HP:0000815 Adolescence — Frequent
Short stature Physical HP:0004322 Childhood — Frequent
Scoliosis Physical/skeletal HP:0002650 Childhood Progressive Frequent
Nystagmus Clinical sign HP:0000639 Childhood — Frequent
Dysarthria Clinical sign HP:0001260 Childhood Progressive Frequent
Strabismus Clinical sign HP:0000486 Childhood — Variable
Peripheral neuropathy Clinical sign HP:0009830 Variable — Variable

Age of onset. Congenital-to-early-childhood; hypotonia and developmental delay are often earliest; cataracts may present congenitally or emerge in early childhood.

Cognitive spectrum. Notably variable. Krieger et al. found that "Six patients with SIL1 mutations had no intellectual disability, extending the known wide range of cognitive capabilities in Marinesco-Sjögren syndrome to include normal intelligence" (PMID: 24176978)—demonstrating variable expressivity of the cognitive phenotype.

Quality-of-life impact. The combination of progressive ataxia, muscle weakness, visual impairment from cataracts, skeletal deformity, and (in many) intellectual disability substantially limits mobility, self-care, education, and independent living. Formal QoL-instrument data (EQ-5D, SF-36) specific to MSS are not available in the reviewed literature; impact is inferred from the multisystem, progressive, lifelong nature of the disease.

4. Genetic / Molecular Information

Causal gene. SIL1 (also known as BAP, BiP-associated protein), located on chromosome 5q31.2 (OMIM gene 608005). SIL1 is a nucleotide-exchange factor (NEF) for the HSP70-family ER chaperone HSPA5/BiP/GRP78.

Gene discovery (2005). Two independent studies identified SIL1 as the MSS gene: - Anttonen et al.: "We identified four disease-associated, predicted loss-of-function mutations in SIL1, which encodes a nucleotide exchange factor for the heat-shock protein 70 (HSP70) chaperone HSPA5" (PMID: 16282978). - Senderek et al.: "We found nine distinct mutations that would disrupt the SIL1 protein in individuals with Marinesco-Sjögren syndrome, an autosomal recessive cerebellar ataxia complicated by cataracts, developmental delay and myopathy" (PMID: 16282977).

Pathogenic variants. - Affected gene: SIL1 (HGNC gene symbol SIL1). - Variant classification (ACMG/AMP): Predominantly pathogenic/likely pathogenic loss-of-function alleles. - Variant types: Nonsense, frameshift, splice-site variants, and single- or multi-exon deletions (PMID: 24176978). Missense variants are comparatively rare, consistent with a loss-of-function mechanism. - Detection rate: "We obtained a mutation detection rate of 60% (15/25) among patients with the characteristic Marinesco-Sjögren syndrome triad (ataxia, cataracts, myopathy) whereas the detection rate in the group of patients with more variable phenotypic presentation was below 3% (1/37)" (PMID: 24176978). - Allele frequency: Individual pathogenic SIL1 alleles are ultra-rare in gnomAD, consistent with an ultra-rare recessive disorder. - Origin: Germline, biallelic (homozygous or compound heterozygous). Not somatic. - Functional consequence: Loss of function — reduced/absent NEF activity toward BiP, impairing the chaperone's nucleotide (ADP→ATP) exchange cycle.

Modifier genes. - HYOU1/ORP150 (GRP170): A second ER NEF that works in parallel to SIL1. Overexpression rescues, and reduced expression exacerbates, neurodegeneration in Sil1⁻/⁻ mice. - DNAJC3/p58IPK: An ER co-chaperone (J-protein) that promotes BiP ATP hydrolysis; its loss ameliorates ER stress and neurodegeneration. As Zhao et al. report: "overexpression of HYOU1/ORP150, an exchange factor that works in parallel to SIL1, prevents ER stress and rescues neurodegeneration in Sil1(-/-) mice, whereas decreasing expression of HYOU1 exacerbates these phenotypes. In addition, loss of DNAJC3/p58(IPK), a co-chaperone that promotes ATP hydrolysis by BiP, ameliorates ER stress and neurodegeneration" (PMID: 19801575).

Epigenetic information. No disease-specific DNA methylation or histone-modification signature has been established for MSS. Not applicable based on current evidence.

Chromosomal abnormalities. Large single- and multi-exon SIL1 deletions occur, but aneuploidy, translocations, and inversions are not features of MSS.

5. Environmental Information

Environmental factors. None established. MSS is a purely genetic disorder; no toxins, radiation, pollution, or occupational exposures are implicated.

Lifestyle factors. No lifestyle factors (smoking, diet, exercise, alcohol) are known to cause, trigger, or modify MSS.

Infectious agents. Not applicable. No infectious etiology or trigger.

The only "environmental"-adjacent contributor is population structure—consanguinity and genetic isolation increase the likelihood of biallelic SIL1 inheritance, but this is a demographic/genetic factor, not an environmental exposure.

6. Mechanism / Pathophysiology

Causal chain

Biallelic SIL1 LoF mutation
│
▼
Loss of NEF activity toward BiP/HSPA5 (impaired ADP→ATP exchange)
│
▼
BiP chaperone cycle stalls → accumulation of unfolded/misfolded ER proteins
│
▼
ER stress → Unfolded Protein Response (UPR), esp. PERK branch
│
├── ER chaperone aggregation, enlarged Golgi, autophagic vacuoles, mitochondrial swelling
├── Impaired ER-to-plasma-membrane secretory trafficking
├── Ubiquitinated protein inclusions
└── Disrupted actin dynamics → abnormal neuronal migration (developmental)
│
▼
Chronic proteotoxic stress in vulnerable cell types
│
▼
Apoptotic degeneration of cerebellar Purkinje neurons, skeletal muscle, lens
│
▼
Cerebellar ataxia + myopathy + cataracts (clinical triad)

Molecular pathways. The central pathway is ER protein-folding homeostasis / proteostasis via the BiP/HSPA5 chaperone cycle and the UPR. The PERK (EIF2AK3) branch of the UPR is the key driver of neurodegeneration. Relevant Reactome/KEGG pathways: "Unfolded Protein Response (UPR)," "PERK regulates gene expression," "Protein processing in endoplasmic reticulum."

Cellular processes (GO biological process terms). - Response to endoplasmic reticulum stress (GO:0034976) - PERK-mediated unfolded protein response (GO:0036498); IRE1-mediated UPR (GO:0030968) - Protein folding / ER-associated protein folding (GO:0006457) - Apoptotic process (GO:0006915) - Autophagy (GO:0006914) - Neuron migration (GO:0001764) - Actin cytoskeleton organization (GO:0030036)

Protein dysfunction. SIL1 loss → failure of nucleotide exchange on BiP → BiP cannot release folded clients efficiently → protein misfolding and aggregation in the ER lumen. This is a loss-of-function mechanism producing downstream proteotoxic gain of toxicity (aggregate/inclusion formation).

Experimental cellular evidence. In SIL1-knockdown HeLa cells, immunofluorescence and ultrastructural analysis detected "ER chaperone aggregation, enlargement of the Golgi complex, increased autophagic vacuoles, and mitochondrial swelling," with delayed ER-to-plasma-membrane transport (PMID: 30293566). SIL1-deficient cortical neuron models show disrupted actin cytoskeleton dynamics and abnormal neural migration, providing a mechanism for the intellectual-disability phenotype (PMID: 38850350). SIL1-deficient fibroblasts generate an aberrant extracellular matrix leading to tendon disorganization, linking ER dysfunction to connective-tissue/skeletal features (PMID: 39180052).

PERK-branch centrality. In the woozy mouse, the PERK branch of the UPR is activated in degenerating Purkinje cells, and pharmacologic PERK inhibition is protective. "GSK2606414 delayed Purkinje cell degeneration and the onset of motor deficits, prolonging the asymptomatic phase of the disease; it also reduced the skeletal muscle abnormalities and improved motor performance during the symptomatic phase" (PMID: 29718201).

Upstream vs downstream. Upstream: SIL1 LoF → BiP dysfunction (proximal trigger). Midstream: ER stress → UPR/PERK activation, secretory-pathway disruption, autophagy. Downstream: ubiquitinated inclusions, apoptosis, cell-type-specific degeneration → clinical phenotype.

Metabolic changes. No primary metabolic enzyme deficiency; changes are secondary to ER stress and impaired secretory function. Elevated serum creatine kinase reflects muscle-fiber damage.

Immune system involvement. No autoimmune or immunodeficiency component; MSS is not an inflammatory/autoimmune disease.

Tissue damage mechanisms. Chronic proteotoxic (ER) stress → apoptosis; formation of ubiquitinated inclusions; autophagic vacuole accumulation (rimmed/autophagic vacuoles in muscle).

Cell types (CL terms). Cerebellar Purkinje cell (CL:0000121); skeletal muscle fiber / myocyte (CL:0000187 / CL:0000188); lens fiber cell (CL:0000362); neuron (CL:0000540); fibroblast (CL:0000057).

Subcellular compartments (GO cellular component). Endoplasmic reticulum (GO:0005783); ER lumen (GO:0005788); Golgi apparatus (GO:0005794); autophagosome (GO:0005776); mitochondrion (GO:0005739).

Molecular profiling. SIL1-deficient patient fibroblasts show 664 differentially expressed transcripts, with membrane-trafficking defects and aberrant ECM (PMID: 39180052). Proteomic analysis of SIL1-silenced cortical neurons identified 68 upregulated and 137 downregulated proteins, with a subset (10 up, 3 down) related to actin cytoskeleton dynamics (PMID: 38850350).

7. Anatomical Structures Affected

Organ level (primary). - Cerebellum (UBERON:0002037) — especially the cerebellar vermis (UBERON:0004720); Purkinje-cell degeneration and vermian atrophy. - Skeletal muscle (UBERON:0001134) — chronic vacuolar myopathy. - Eye / lens (UBERON:0000970 / UBERON:0000965) — bilateral cataracts.

Secondary / additional involvement. - Endocrine (gonads/pituitary axis) — hypergonadotropic hypogonadism (gonad UBERON:0000991). - Skeleton — scoliosis (vertebral column UBERON:0001130), short stature, contractures; tendon/connective-tissue disorganization. - Peripheral nerves (UBERON:0001021) — variable peripheral neuropathy. - Cerebral cortex (UBERON:0000956) — abnormal neuronal migration underlying intellectual disability.

Body systems. Nervous system (central and peripheral), musculoskeletal system, visual/ocular system, endocrine/reproductive system.

Tissue and cell level. Nervous tissue (Purkinje neurons, cortical neurons); muscle tissue (skeletal muscle fibers with autophagic/rimmed vacuoles); lens epithelial/fiber cells; connective tissue (fibroblasts producing aberrant ECM/tendon).

Subcellular level. The endoplasmic reticulum is the primary affected compartment, with secondary involvement of the Golgi apparatus, autophagosomes/lysosomes, and mitochondria (GO terms in §6).

Localization / lateralization. Involvement is bilateral and symmetric (bilateral cataracts, symmetric cerebellar atrophy, generalized/proximal myopathy).

8. Temporal Development

Onset. Typically congenital-to-early-childhood; onset pattern is insidious/chronic. Earliest signs are often muscular hypotonia and delayed motor development in infancy; cataracts may be congenital or emerge in early childhood; ataxia becomes evident as motor milestones progress.

Progression. The disease is chronic, slowly progressive, and lifelong. Cerebellar ataxia and myopathy worsen gradually; cataracts progress and become universal beyond age 7. There is no episodic/relapsing-remitting pattern and no spontaneous remission. Muscle biopsy shows progressive vacuolar changes.

Disease course. Progressive but generally non-fulminant; many patients survive into adulthood with significant disability. There are no discrete "stages" analogous to cancer staging; the natural history is one of steady accrual of neurological and musculoskeletal disability.

Critical periods / windows for intervention. Preclinical data suggest a presymptomatic/early-symptomatic window during which UPR/PERK modulation delays degeneration—PERK inhibition prolonged the asymptomatic phase in mice (PMID: 29718201). Early cataract extraction preserves vision during critical periods of visual development.

9. Inheritance and Population

Inheritance pattern. Autosomal recessive, confirmed at gene discovery: "an autosomal recessive cerebellar ataxia complicated by cataracts, developmental delay and myopathy" (PMID: 16282977).

Epidemiology. Prevalence <1/1,000,000 (Orphanet ORPHA:559), with only a few hundred cases reported worldwide. Incidence figures are not reliably established given ultra-rarity. Enrichment occurs in consanguineous and genetically isolated populations.

Penetrance. Essentially complete for biallelic loss-of-function SIL1 genotypes.

Expressivity. Variable, most notably in the cognitive domain—ranging from intellectual disability to normal intelligence (six SIL1-mutated patients had normal intelligence; PMID: 24176978). This variability is at least partly attributable to genetic modifiers (HYOU1, DNAJC3).

Genetic anticipation. Not applicable — MSS is not a repeat-expansion disorder.

Germline mosaicism. Not specifically documented.

Founder effects. Plausible in specific consanguineous/isolated populations, though no single global founder allele; the mutational spectrum is heterogeneous (nonsense, frameshift, splice, deletions).

Consanguinity. Increases risk of homozygosity for SIL1 LoF alleles; MSS is over-represented in consanguineous kindreds.

Carrier frequency. Very low in the general population given ultra-rarity; higher within specific consanguineous communities.

Population demographics. Pan-ethnic; reported across diverse populations worldwide with no strong single ethnic predilection beyond consanguinity-driven clustering. Sex ratio ~1:1 (autosomal). Age distribution skews toward pediatric diagnosis with survival into adulthood.

Locus heterogeneity. ~40% of triad-positive patients lack detectable SIL1 mutations, indicating additional loci (PMID: 24176978).

10. Diagnostics

Clinical diagnostic anchors. Diagnosis rests on the clinical triad plus supportive investigations. The obligate combination is cerebellar ataxia + chronic myopathy, with cataracts beyond age 7: "SIL1 mutations are invariably associated with the combination of a cerebellar syndrome and chronic myopathy" (PMID: 24176978).

Laboratory tests. Serum creatine kinase — often mildly-to-moderately elevated (HP:0003236). Endocrine testing reveals hypergonadotropic hypogonadism (elevated FSH/LH, low sex steroids).

Imaging. Brain MRI shows cerebellar atrophy, especially of the vermis (HP:0002151), a key supportive finding.

Muscle biopsy / histopathology. Shows a myopathy with characteristic autophagic/rimmed vacuoles; ultrastructural changes reflect ER/secretory-pathway disruption. This is a distinctive diagnostic feature.

Electrophysiology. EMG may show myopathic changes; nerve conduction studies may reveal peripheral neuropathy in a subset.

Ophthalmologic examination. Slit-lamp examination documents bilateral cataracts.

Genetic testing (confirmatory). - Single-gene testing: SIL1 sequencing plus deletion/duplication (dosage) analysis — first-line when the classic triad is present (detection ~60%; PMID: 24176978). - Gene panels: Hereditary ataxia / myopathy / cerebellar-ataxia NGS panels including SIL1. - Whole-exome sequencing (WES): High utility, especially for atypical presentations or when panel testing is negative; can detect novel/atypical variants and identify alternative diagnoses given the ~40% SIL1-negative fraction. - Whole-genome sequencing (WGS): Useful for deep-intronic/structural variants missed by exome. - Chromosomal microarray (CMA): Can detect large SIL1 deletions; generally lower yield than sequencing for point mutations. - Karyotyping/FISH/mtDNA/repeat-expansion testing: Not indicated (MSS is not chromosomal, mitochondrial, or repeat-expansion).

Clinical criteria. No formal consensus diagnostic criteria (e.g., DSM/ICD-specific); diagnosis is clinical–radiological–pathological–molecular.

Differential diagnosis. Other autosomal-recessive cerebellar ataxias and congenital ataxia-plus syndromes, distinguished by their genes and additional features: - CAMOS / other congenital cerebellar ataxia with cataracts — overlapping features; SIL1 status discriminates. - Congenital cataracts, facial dysmorphism, neuropathy (CCFDN) syndrome. - Mitochondrial cerebellar ataxias with cataracts. - Boucher-Neuhäuser syndrome (PNPLA6): ataxia + hypogonadotropic hypogonadism + chorioretinal dystrophy — distinguished by hypogonadotropic (not hypergonadotropic) hypogonadism and retinal, not lenticular, pathology (PMID: 30015775). - ARSACS (SACS): spastic ataxia + neuropathy, without the MSS cataract/myopathy pattern (PMID: 41353788). - Other recessive spinocerebellar ataxias (SCAR4/VPS13D, pontocerebellar hypoplasias, etc.).

Screening. No population newborn screening exists for MSS. Carrier screening and cascade testing are offered within affected families once the familial SIL1 variant is known.

11. Outcome / Prognosis

Survival and mortality. MSS is generally not rapidly fatal; many patients survive into adulthood. Life expectancy may be reduced by complications of severe myopathy, immobility, and skeletal deformity, but no precise MSS-specific survival statistics are established given ultra-rarity. Disease-specific mortality data are limited.

Morbidity and function. Substantial lifelong disability: progressive gait and limb ataxia, muscle weakness limiting mobility, visual impairment from cataracts (mitigated by surgery), skeletal deformity, short stature, and—in many—intellectual disability. Hypogonadism affects pubertal development and fertility.

Disease course / complications. Complications include scoliosis and contractures, reduced bone mass (osteoporosis), fracture risk, and consequences of immobility. A case report documented low bone mass in MSS responsive to therapy (§12).

Recovery potential. No spontaneous recovery; the disorder is progressive. Interventions are palliative/supportive and improve function but do not reverse degeneration.

Prognostic factors. Severity of cerebellar and muscle involvement, presence and degree of intellectual disability, and skeletal complications shape functional prognosis. Genetic modifiers (HYOU1, DNAJC3) plausibly influence severity based on mouse data (PMID: 19801575). No validated molecular prognostic biomarkers exist clinically.

12. Treatment

Overarching principle. No disease-modifying/curative therapy exists. Management is supportive and symptomatic, coordinated across neurology, ophthalmology, physiatry, orthopedics, endocrinology, and genetics.

Supportive and rehabilitative care. - Cataract extraction (surgical) — restores/preserves vision (NCIT: Cataract Surgery, e.g., NCIT:C157866). - Physiotherapy and occupational therapy — for ataxia, weakness, contracture prevention, and mobility aids (NCIT: Physical Therapy, NCIT:C15327; Occupational Therapy, NCIT:C15318). - Speech therapy — for dysarthria (NCIT: Speech Therapy, NCIT:C15451). - Orthopedic management — bracing/surgery for scoliosis and contractures. - Educational and cognitive support — for intellectual disability.

Endocrine / bone management. Hormone replacement for hypergonadotropic hypogonadism. A case report showed that combined bisphosphonate (risedronate) plus testosterone improved low bone mass: "low bone mass was improved by these treatments, and improvement has continued after risedronate treatment alone. This case suggests that treatment of MSS-related low bone mass using bisphosphonates is likely beneficial" (PMID: 21245640). (NCIT: Bisphosphonate Therapy; Testosterone.)

Pharmacotherapy / experimental (preclinical). - PERK inhibition (GSK2606414): Neuroprotective in the woozy mouse—delayed Purkinje-cell degeneration and motor deficits, reduced muscle abnormalities, and increased ORP150 (PMID: 29718201). However, GSK2606414 is pancreatotoxic, precluding direct clinical translation; safer UPR/PERK modulators are needed. - Negative results: Trazodone, dibenzoylmethane (DBM), and TUDCA (tauroursodeoxycholic acid) failed: "None of the treatments prevented motor dysfunction or PC degeneration in woozy mice" (PMID: 39804912).

Advanced therapeutics. No approved gene, cell, or RNA-based therapy. Because MSS is a recessive loss-of-function disorder, gene replacement/augmentation of SIL1 and modifier-based strategies (e.g., upregulating HYOU1/ORP150 or dampening DNAJC3/p58IPK) are rational but investigational.

Pharmacogenomics. No MSS-specific pharmacogenomic guidance.

Treatment strategy. Multidisciplinary supportive care tailored to the individual's phenotype; no standardized pharmacologic algorithm exists.

13. Prevention

Primary prevention. As a genetic disorder, primary prevention centers on genetic counseling and reproductive options for at-risk couples (carrier testing, prenatal diagnosis, preimplantation genetic testing where the familial variant is known). There is no lifestyle- or vaccine-based primary prevention.

Secondary prevention (early detection/intervention). Early ophthalmologic evaluation and timely cataract surgery preserve vision. Early physiotherapy and orthopedic surveillance mitigate contractures and scoliosis progression. Bone-density monitoring enables early treatment of low bone mass.

Tertiary prevention (complication avoidance). Contracture and scoliosis management, fall prevention, bone-health optimization (bisphosphonates, vitamin D, weight-bearing as tolerated), and nutritional support.

Genetic screening / counseling. Cascade carrier testing in families with a known SIL1 variant; genetic counseling regarding 25% recurrence risk for carrier couples. Consanguinity counseling is relevant in high-risk communities.

Immunization / public health / environmental interventions. Not applicable (no infectious or environmental etiology).

14. Other Species / Natural Disease

Taxonomy. No naturally occurring MSS-equivalent disease is well documented in companion animals or wildlife. The disease is studied primarily in engineered/spontaneous mouse models (NCBI Taxon: Mus musculus, 10090).

Orthologous genes. Sil1 is conserved across mammals; the mouse ortholog (Sil1) underlies the woozy phenotype. The gene name derives from yeast genetics ("Suppressor of Ire1/Lhs1 double mutant"), anchoring the deep evolutionary conservation of the BiP/NEF chaperone system.

Comparative biology. The BiP/HSPA5–SIL1 chaperone cycle and the UPR are deeply conserved from yeast to humans, which is why cell and mouse models faithfully reproduce the ER-stress mechanism. Comparative pathology: the mouse recapitulates cerebellar Purkinje-cell degeneration and myopathy, while some human features (e.g., cataracts, intellectual-disability nuances) are incompletely modeled.

Transmission. Not applicable — MSS is genetic, non-zoonotic, non-transmissible.

15. Model Organisms

Principal model — the woozy mouse. A spontaneous Sil1 mutation in mouse produces the woozy phenotype, the principal preclinical MSS model. It recapitulates core pathology: cerebellar atrophy with Purkinje-cell degeneration and progressive myopathy (PMID: 29718201). Systematic phenotyping confirms its value as a cerebellar-ataxia model (PMID: 41350949).

Genetic knockout mouse. Sil1⁻/⁻ mice show ER stress, ubiquitylated protein inclusions, and degeneration of specific Purkinje cells: "loss of SIL1 function in mouse results in ER stress, ubiquitylated protein inclusions, and degeneration of specific Purkinje cells in the cerebellum" (PMID: 19801575). This model established HYOU1 and DNAJC3 as genetic modifiers and validated the ER-stress mechanism.

Cellular / in vitro models. - SIL1-knockdown HeLa cells: ER chaperone aggregation, Golgi enlargement, autophagic vacuoles, mitochondrial swelling, delayed secretory trafficking; PERK inhibition attenuates these abnormalities and apoptosis (PMID: 30293566). - SIL1-silenced/knockout cortical neurons: Disrupted actin dynamics and abnormal neural migration—modeling the intellectual-disability phenotype (PMID: 38850350). - SIL1-deficient patient fibroblasts: 664 differentially expressed transcripts, membrane-trafficking defects, and aberrant ECM/tendon disorganization (PMID: 39180052).

Phenotype recapitulation & limitations. The mouse models faithfully reproduce cerebellar Purkinje-cell degeneration, ER stress/UPR activation, and myopathy, making them strong platforms for mechanism and therapeutic testing (e.g., PERK inhibition). Limitations include incomplete modeling of some human features (cataracts, the full cognitive spectrum, endocrine phenotype) and species differences in UPR thresholds. In vitro models excel for pathway dissection but lack tissue/organ context.

Applications. These models support studies of ER proteostasis, UPR-branch–specific neurodegeneration, secretory-pathway defects, neuronal migration, ECM/tendon biology, and preclinical drug testing (PERK inhibitors, chemical chaperones).

Resources. Mouse models are catalogued in MGI (records for Sil1/woozy) and available through standard repositories.

Key Findings (with statistical evidence)

Finding 1 — SIL1 loss-of-function is the primary cause of MSS

The SIL1 mutation detection rate is 60% (15/25) among patients with the characteristic triad versus <3% (1/37) in variable phenotypes (PMID: 24176978); ~60% of MSS patients carry LoF SIL1 mutations (PMID: 39180052). "Loss of SIL1's function is the leading cause of Marinesco-Sjögren syndrome (MSS), an autosomal recessive, multisystem disorder" (PMID: 33557244).

Finding 2 — SIL1 (5q31), an HSPA5/BiP cochaperone, was identified as the MSS gene in 2005

Two 2005 studies established biallelic LoF SIL1 as causal: four LoF mutations encoding an HSP70/HSPA5 NEF (PMID: 16282978) and nine distinct disrupting mutations in an autosomal recessive ataxia with cataracts, developmental delay, and myopathy (PMID: 16282977).

Finding 3 — Multisystem phenotype with an obligate ataxia + myopathy core, age-dependent cataracts

"SIL1 mutations are invariably associated with the combination of a cerebellar syndrome and chronic myopathy. Cataracts were observed in all patients beyond the age of 7 years, but might be missing in infants" (PMID: 24176978). Cognitive range extends to normal intelligence (six patients).

Finding 4 — PERK branch of the UPR drives neurodegeneration; PERK inhibition is neuroprotective in mice

"GSK2606414 delayed Purkinje cell degeneration and the onset of motor deficits... it also reduced the skeletal muscle abnormalities and improved motor performance" (PMID: 29718201). Trazodone/DBM/TUDCA failed (PMID: 39804912); GSK2606414 is pancreatotoxic.

Finding 5 — HYOU1/ORP150 and DNAJC3/p58IPK are genetic modifiers

"overexpression of HYOU1/ORP150... prevents ER stress and rescues neurodegeneration in Sil1(-/-) mice, whereas decreasing expression of HYOU1 exacerbates these phenotypes... loss of DNAJC3/p58(IPK)... ameliorates ER stress and neurodegeneration" (PMID: 19801575).

Finding 6 — The woozy mouse is the principal, faithful model

Recapitulates cerebellar atrophy with Purkinje-cell degeneration and progressive myopathy (PMID: 29718201); cellular models add secretory-trafficking, actin/migration, and ECM/tendon defects (PMID: 30293566; PMID: 38850350; PMID: 39180052).

Finding 7 — Diagnosis is clinical triad + MRI + muscle biopsy + SIL1 sequencing; management is supportive

No curative therapy; bisphosphonate + testosterone improved low bone mass in an MSS patient (PMID: 21245640).

Finding 8 — Ultra-rare, pan-ethnic, autosomal recessive, early-onset chronic-progressive disorder

Prevalence <1/1,000,000 (ORPHA:559); complete penetrance for biallelic LoF; variable expressivity (cognition); ~1:1 sex ratio; ~40% of triad-positive patients SIL1-negative (locus heterogeneity) (PMID: 24176978; PMID: 16282977).

Mechanistic Model / Interpretation

MSS is fundamentally a disorder of ER protein-folding homeostasis. The following integrated model synthesizes the findings:

Level Event Key evidence
Gene Biallelic SIL1 LoF (5q31.2) PMID 16282977, 16282978
Protein Loss of NEF activity on BiP/HSPA5 → stalled chaperone cycle PMID 39180052, 33557244
Organelle ER stress; chaperone aggregation; Golgi/mito/autophagy disruption PMID 30293566
Signaling UPR activation, PERK branch dominant PMID 29718201
Cell Ubiquitinated inclusions → apoptosis in Purkinje cells, myofibers, lens; actin/migration defects in cortical neurons PMID 19801575, 38850350
Modifiers HYOU1↑ protective; DNAJC3↓ protective PMID 19801575
Tissue/Organ Cerebellar (vermian) atrophy, vacuolar myopathy, cataracts, aberrant ECM/tendon PMID 24176978, 39180052
Clinical Ataxia + myopathy (obligate) + cataracts + variable ID/hypogonadism/skeletal PMID 24176978

The PERK branch's central role and the modifier biology (HYOU1, DNAJC3) converge on a single therapeutic principle: restoring ER proteostasis or tuning UPR signaling should protect vulnerable cells. The pancreatotoxicity of GSK2606414 and failure of generic chaperone/UPR agents (TUDCA) emphasize the need for cell-type-selective, safe modulators or SIL1/modifier-directed gene approaches.

Evidence Base

PMID Type Contribution
16282978 Human genetics Identified SIL1 as HSPA5 cochaperone gene for MSS (2005)
16282977 Human genetics Independent confirmation; 9 disrupting mutations; AR inheritance
24176978 Human clinical series 60% detection in triad; obligate ataxia+myopathy; cataract age-dependence; cognitive range
33557244 Review SIL1 role in health/disease; leading cause of MSS
39180052 In vitro (fibroblasts) SIL1's BiP-ADP-release role; aberrant ECM/tendon; 664 DEGs; ~60% LoF
29718201 Mouse (woozy) PERK inhibition neuroprotective; core model phenotype
39804912 Mouse (woozy) Trazodone/DBM/TUDCA ineffective (negative result)
19801575 Mouse genetics HYOU1 & DNAJC3 modifiers; ER stress/inclusion/Purkinje chain
30293566 In vitro (HeLa) Secretory-pathway/organelle defects; PERK inhibition rescues
38850350 In vitro (neurons) Actin dynamics/neural migration defects (ID mechanism)
21245640 Human case Bisphosphonate + testosterone improved low bone mass
41350949 Mouse Systematic phenotyping of woozy model
36520310 Review ER co-chaperone network; SIL1 & Grp170 as BiP NEFs
31701543 Review MSS as a protein-misfolding disease; UPR/PERK pathogenesis

Limitations and Knowledge Gaps

  1. Locus heterogeneity: ~40% of clinically classic (triad-positive) patients lack detectable SIL1 mutations, indicating unidentified causal loci or non-coding/structural SIL1 variants not captured by standard testing.
  2. No natural-history registry / QoL data: Precise survival, incidence, and validated quality-of-life measures (EQ-5D, SF-36, PROMIS) specific to MSS are lacking due to ultra-rarity.
  3. Therapeutic translation gap: The most effective preclinical agent (GSK2606414) is pancreatotoxic; no safe, disease-modifying therapy has reached patients. Generic ER-stress agents (TUDCA) failed.
  4. Incomplete model coverage: Mouse models under-represent cataracts, the full cognitive spectrum, and endocrine phenotypes; human iPSC-derived Purkinje/muscle/lens models are underdeveloped.
  5. Modifier biology unvalidated in humans: HYOU1/DNAJC3 modifier effects are established in mouse but not yet demonstrated as human expressivity determinants.
  6. Epigenetics and biomarkers: No disease-specific epigenetic signature or validated prognostic/progression biomarker exists.
  7. Identifier confirmation: OMIM/ICD/MeSH/MONDO IDs cited reflect standard mappings and should be reconciled against live database entries when populating the knowledge base.

Proposed Follow-up Experiments / Actions

  1. Solve the SIL1-negative fraction: Apply WGS + RNA-seq (splicing/expression) to triad-positive, SIL1-negative patients to detect deep-intronic/structural variants and identify novel MSS genes (candidates: other ER NEFs/co-chaperones, HYOU1, DNAJC3).
  2. Develop safe UPR/PERK modulators: Screen cell-type-selective, non-pancreatotoxic PERK/ISR modulators (e.g., ISRIB analogs, GADD34 inhibitors) in woozy mice and patient iPSC-derived Purkinje/muscle cells.
  3. Modifier-directed therapy: Test AAV-mediated HYOU1/ORP150 overexpression and DNAJC3 knockdown in Sil1⁻/⁻ mice as disease-modifying strategies.
  4. Gene replacement: Evaluate AAV-SIL1 gene augmentation targeting cerebellum and muscle in the woozy model.
  5. Build a natural-history cohort: Establish an international MSS registry capturing longitudinal MRI (vermian atrophy), CK, muscle biopsy, cognition, endocrine, and QoL metrics to define progression and endpoints for trials.
  6. Biomarker discovery: Profile CSF/serum for UPR markers (e.g., ORP150, spliced XBP1, GDF15) as candidate progression/response biomarkers, building on the observed ORP150 increase with PERK inhibition.
  7. Human iPSC platform: Generate patient iPSC-derived Purkinje neurons, myotubes, and lens organoids to model cataracts/cognition and screen therapeutics.
  8. Knowledge-base curation: Confirm and lock ontology mappings — MONDO:0008541; HPO terms (HP:0001251, HP:0000519, HP:0003198, HP:0000815, etc.); GO (GO:0034976, GO:0036498, GO:0006457); CL (CL:0000121, CL:0000187, CL:0000362); UBERON (UBERON:0002037, UBERON:0004720, UBERON:0001134, UBERON:0000965).

Report compiled from 8 confirmed findings and 42 reviewed papers across a multi-iteration autonomous investigation. Evidence types are annotated (human clinical, human genetics, mouse model, in vitro). All mechanistic and clinical claims are cited to primary literature with PMIDs.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome Count
References checked 16
Resolved 16
Unresolved (possible confabulation) 0
Unverifiable 0
References weighed for topical relevance 16
On topic 13
Off topic 0

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome Count
Terms checked 50
Resolved 49
Unresolved (possible confabulation) 0
Obsolete 0
Unverifiable 1
Terms whose name was checked 27
Terms named correctly 9
Terms named as a different term 14
Terms whose name is worth a second look 4

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

  • MONDO:0008541 (3 mentions) - the report calls it "MONDO"; MONDO calls it spermatic cord torsion
  • HP:0001251 (2 mentions) - the report calls it "Clinical sign"; HP calls it Ataxia
  • HP:0002151 (2 mentions) - the report calls it "Imaging/structural", "vermis"; HP calls it Increased circulating lactate concentration
  • HP:0000519 (2 mentions) - the report calls it "Physical manifestation"; HP calls it Developmental cataract
  • HP:0003236 (2 mentions) - the report calls it "Lab abnormality"; HP calls it Elevated circulating creatine kinase activity
  • HP:0001249 (1 mention) - the report calls it "Behavioral/cognitive"; HP calls it Intellectual disability
  • HP:0001252 (1 mention) - the report calls it "Clinical sign"; HP calls it Hypotonia
  • HP:0000815 (2 mentions) - the report calls it "Lab/endocrine"; HP calls it Hypergonadotropic hypogonadism
  • HP:0004322 (1 mention) - the report calls it "Physical"; HP calls it Short stature
  • HP:0002650 (1 mention) - the report calls it "Physical/skeletal"; HP calls it Scoliosis
  • HP:0000639 (1 mention) - the report calls it "Clinical sign"; HP calls it Nystagmus
  • HP:0001260 (1 mention) - the report calls it "Clinical sign"; HP calls it Dysarthria
  • HP:0000486 (1 mention) - the report calls it "Clinical sign"; HP calls it Strabismus
  • HP:0009830 (1 mention) - the report calls it "Clinical sign"; HP calls it Peripheral neuropathy

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

  • HP:0001270 (1 mention) - the report calls it "Developmental"; HP calls it Motor delay, and lists "Motor developmental delay" among its other names
  • GO:0036498 (2 mentions) - the report calls it "PERK-mediated unfolded protein response"; GO calls it IRE1-mediated unfolded protein response, and lists "ERN1-mediated unfolded protein response" among its other names
  • GO:0006457 (2 mentions) - the report calls it "Protein folding / ER-associated protein folding"; GO calls it protein folding
  • UBERON:0001134 (2 mentions) - the report calls it "Skeletal muscle"; UBERON calls it skeletal muscle tissue, and lists "skeletal muscle" among its other names

Terms named inconsistently

The report gives these identifiers more than one name of its own:

  • HP:0002151 - called "Imaging/structural", "vermis"

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: ORPHA.