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Classifications

Harrison's Part

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Inheritance

1

Autosomal recessive HP:0000007

Biallelic (homozygous or compound heterozygous) TRAPPC12 variants are required. Reported families include consanguineous unions with homozygous variants and non-consanguineous families with compound-heterozygous variants.

Autosomal recessive inheritance

Show evidence (1 reference)

PMID:28777934 SUPPORT Human Clinical

"Three individuals from two unrelated families have either a homozygous deleterious variant...or compound-heterozygous variants"

A homozygous variant in one family and compound-heterozygous variants in another establish recessive inheritance.

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Discussions and Knowledge Gaps

4

Which neuronal or glial mechanisms connect the affected-person fibroblast organelle and transport abnormalities to selective progressive brain atrophy and encephalopathy?

KNOWLEDGE GAP OPEN gap_trappc12_trafficking_to_neural_selectivity

Attached to

pathophysiology#Golgi Fragmentation pathophysiology#Delayed ER-to-Golgi Transport pathophysiology#Progressive Brain Atrophy

Human genetics and affected-person fibroblasts establish a proximal TRAPPC12-dependent secretory-pathway defect, but no patient-derived neural model defines the intervening cell-death, developmental, or circuit process.

Show evidence (1 reference)

PMID:28777934 SUPPORT In Vitro

"Fibroblasts derived from all three individuals showed a fragmented Golgi that could be rescued by expression of wild-type TRAPPC12."

Establishes rescue of the Golgi morphology specifically while leaving both the transport-to-neural bridge and transport rescue unresolved.

Does TRAPPC12-dependent oligodendrocyte differentiation failure cause the human white-matter imaging phenotype?

HUMAN MODEL MISMATCH OPEN mismatch_trappc12_opc_to_human_white_matter

Attached to

pathophysiology#Impaired Oligodendrocyte Differentiation phenotypes#Hyperintensity of cerebral white matter on MRI animal_models#Oligodendrocyte-lineage Mea6 conditional-knockout mouse

A rat CG4 CRISPR-knockout line and primary mouse OPC shRNA culture support an oligodendroglial differentiation phenotype, but the in-vivo mouse has conditional Mea6—not Trappc12—ablation. No patient-derived oligodendrocyte or TRAPPC12 disease animal model currently connects those readouts to the increased cerebral white-matter T2 signal reported in affected people.

Proposed experiments

Isogenic affected-person iPSC oligodendrocyte differentiation and trafficking study

exp_trappc12_isogenic_human_oligodendrocytes

Generate oligodendrocytes from affected-person iPSCs and CRISPR-corrected isogenic controls, then measure lineage progression, MBP-positive cell fraction, myelin-sheath formation, Golgi morphology, synchronized ER-to-Golgi cargo transport, and cell survival across maturation.

Decision criterion

Concordant rescue of oligodendrocyte differentiation and myelin formation by correction, with rescue tracking a specific TRAPPC12 cellular readout, would support the proposed human pathway; normal differentiation despite correction-sensitive fibroblast phenotypes would refute direct oligodendroglial mediation of the MRI signal.

Show evidence (2 references)

PMID:38439956 SUPPORT In Vitro

"Here, we found that Trappc12 deficiency in CG4 and oligodendrocyte progenitor cells (OPCs) affects their differentiation and maturation."

Directly supports the culture result that motivates the question.

PMID:38439956 SUPPORT Model Organism

"Mea6/cTAGE5 ablation in OPCs affects their proliferation and differentiation, leading to marked hypomyelination, compromised synaptic functionality, and aberrant behaviors in mice."

Identifies the gene mismatch in the only in-vivo model used to support the white-matter pathway.

Does prolonged mitotic progression contribute to the human neural phenotype, and do ciliary or autophagic functions form additional disease branches?

EMERGING HYPOTHESIS OPEN hypothesis_trappc12_mitosis_cilia_autophagy

Attached to

pathophysiology#Biallelic TRAPPC12 Dysfunction pathophysiology#Prolonged Mitotic Progression

All three founding fibroblast lines show prolonged prophase-to-anaphase timing, while TRAPPC12 depletion perturbs chromosome congression and cilium disassembly in human cell lines and a 2026 Aspergillus study places a TRAPPC11/12/13 subcomplex in autophagy. No experiment links these functions to affected-person neural tissue, so their disease contribution remains provisional.

Show evidence (4 references)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT In Vitro

"1:II-8, 2:II-1, and 2:II-4 showed a significant lengthening of the time from prophase until the onset of anaphase"

Establishes the affected-person mitotic readout while leaving neural relevance unresolved.

PMID:25918224 SUPPORT In Vitro

"Depletion of TRAMM resulted in noncongressed chromosomes and arrested cells in mitosis."

Establishes the mitotic cell-line phenotype, not its disease relevance.

PMID:32258032 SUPPORT In Vitro

"TRAPPC12 depletion causes increased ciliary length because TRAPPC12 is required for the disassembly of primary cilia."

Establishes a cilium-disassembly phenotype in hTERT-RPE1 cells.

+ 1 more reference

Do disease-associated TRAPPC12 variants alter TRAPPIII Rab-GEF activity in affected human cells?

KNOWLEDGE GAP OPEN gap_trappc12_patient_variant_gef_activity

Attached to

pathophysiology#Biallelic TRAPPC12 Dysfunction pathophysiology#Reduced COPII Outer-Coat Assembly

Purified mammalian TRAPPIII has GEF activity toward Rab1 and Rab43, but no cited patient-cell experiment directly measures nucleotide-exchange activity or shows that altered GEF activity mediates the COPII, Golgi, or cargo-transport readouts. Normal complex function must therefore not be converted into a patient-specific mechanism without testing.

Show evidence (1 reference)

PMID:34229011 SUPPORT In Vitro

"GEF assays revealed that TRAPPIII has GEF activity against Rab1 and Rab43, with no detectable activity against the other 18 Rabs tested."

Defines the normal purified-complex activity that remains unmeasured for disease-associated variants in affected human cells.

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Pathophysiology

8

Biallelic TRAPPC12 Dysfunction

Biallelic pathogenic variants in TRAPPC12 (also known as TTC15 or TRAMM) perturb protein abundance or function. Full-length protein was absent from fibroblasts of all three founding individuals, who carried homozygous or compound-heterozygous frameshift/missense genotypes. A later homozygous Phe227Val fibroblast study likewise found absent or markedly reduced mature protein but only mild organelle abnormalities. Separately, compound-heterozygous c.954del and c.1677+5G>A variants were found in a family with recurrent fetal hydrocephalus; the former causes premature termination and the latter was shown to alter splicing. A surviving child with a homozygous frameshift means complete loss of detectable full-length protein should not be described as uniformly embryonic lethal.

TRAPPC12 hgnc:24284

Experimental models

Affected-person fibroblast Golgi and secretory-transport model PRIMARY CELL CULTURE The affected-person lines directly reproduce absence of full-length TRAPPC12 for both the homozygous and compound-heterozygous genotypes.

Homozygous Phe227Val affected-person fibroblast model PRIMARY CELL CULTURE Directly tests the Phe227Val genotype and reproduces absent or highly reduced mature TRAPPC12 protein in affected-person fibroblasts.

Downstream

Reduced COPII Outer-Coat Assembly TRAPPC12-null cytosol supports less efficient Sec13/Sec31 outer-coat assembly on COPII vesicles in an in-vitro budding assay.

Golgi Fragmentation Founding affected-person fibroblasts show Golgi fragmentation, and wild-type TRAPPC12 rescues this morphology.

Delayed ER-to-Golgi Transport Cargo transport from the endoplasmic reticulum to and through the Golgi is delayed in founding affected-person fibroblasts; this readout was measured separately from Golgi rescue.

Prolonged Mitotic Progression All three founding affected-person fibroblast lines showed prolonged prophase-to-anaphase timing, although its relevance to neural disease is unknown.

Hypoplasia of the pons Biallelic TRAPPC12 dysfunction is causal for the disorder, but the cellular route to pontine underdevelopment has not been resolved.

Hypoplasia of the corpus callosum The gene-to-structural-phenotype relationship is established clinically, while the intervening developmental mechanism remains unknown.

Agenesis of corpus callosum Complete callosal agenesis occurred in one founding individual and severe partial agenesis/thinning in the other two; the developmental route is unknown.

Ventriculomegaly Ventricular enlargement is linked to biallelic TRAPPC12 disease through unresolved neurodevelopmental intermediates.

Widened subarachnoid space Prominent extra-axial spaces were present in all three founding individuals, but whether they reflect developmental volume loss or another process is unresolved.

Simplified gyral pattern Simplified frontal gyri were present in all three founding individuals; the cortical-development mechanism is unknown.

Cerebellar hypoplasia Mild cerebellar hypoplasia was present in two founding individuals, with no resolved developmental mechanism.

Hypoplastic optic chiasm A small optic chiasm was present in two founding individuals; the tissue-specific route from TRAPPC12 dysfunction is unknown.

Hydrocephalus Compound-heterozygous TRAPPC12 variants segregated with recurrent fetal hydrocephalus, but the intervening developmental mechanism is unknown.

Show evidence (5 references)

PMID:28777934 SUPPORT Human Clinical

"Three individuals from two unrelated families have either a homozygous deleterious variant...or compound-heterozygous variants"

Establishes homozygous and compound-heterozygous founding genotypes.

PMID:28777934 SUPPORT Human Clinical

"TRAPPC12 is a member of the TRAPP protein complex, which functions in membrane trafficking."

Identifies the gene product as a TRAPP-complex subunit.

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT In Vitro

"As expected for the homozygous truncating variant in 1:II-8, western blot analysis failed to detect any full-length...Unexpectedly, the full-length protein was also absent in 2:II-1 and 2:II-4"

Directly grounds loss of full-length protein in the homozygous and compound-heterozygous founding fibroblast lines.

+ 2 more references

Reduced COPII Outer-Coat Assembly

In TRAPPC12-null cell systems, Sec31A turns over more slowly at ER exit sites and less Sec31A is recruited to budded COPII vesicles, while inner-coat Sec23A is unchanged. This is a measured outer-coat assembly defect in engineered cells, not proof of a patient-specific Rab-GEF deficit.

TRAPP complex GO:0030008

endoplasmic reticulum to Golgi vesicle-mediated transport GO:0006888

Experimental models

TRAPPC12-deleted human cell-line COPII trafficking model CELL LINE Direct genetic deletion tests how TRAPPC12 affects COPII outer-coat recruitment and early secretory-pathway organization.

Downstream

Delayed ER-to-Golgi Transport TRAPPC12 deletion produces both reduced outer-coat assembly and delayed ER-to-Golgi cargo movement, but the coat defect was not independently rescued to prove mediation.

Show evidence (1 reference)

PMID:28240221 SUPPORT In Vitro

"Quantification of three independent experiments showed that the amount of Sec31A on COPII vesicles was found to be approximately 3.1% of total input cytosol from wildtype HeLa cells, versus 0.68% from TRAPPC12 deleted cells"

Quantifies the selective outer-coat recruitment defect.

Golgi Fragmentation

Fibroblasts from affected individuals show a fragmented Golgi apparatus and re-expression of wild-type TRAPPC12 rescues that morphology in the founding lines. Phe227Val fibroblasts show milder Golgi disorganization, so severity is genotype-dependent. Rescue has not been shown for the separately measured cargo-transport delay.

Golgi organization GO:0007030

Golgi apparatus GO:0005794

Experimental models

Affected-person fibroblast Golgi and secretory-transport model PRIMARY CELL CULTURE Directly reproduces fragmented Golgi morphology, with genetic complementation tying that readout to TRAPPC12 deficiency.

Homozygous Phe227Val affected-person fibroblast model PRIMARY CELL CULTURE Reproduces a milder Golgi disorganization and slight ER enlargement rather than the marked founding-cell phenotype.

TRAPPC12-deleted human cell-line COPII trafficking model CELL LINE Reproduces dispersed ERGIC and, to a lesser extent, Golgi organization.

Downstream

Progressive Brain Atrophy Patient-cell trafficking dysfunction and progressive brain atrophy coexist in the disorder, but no neuronal or glial death pathway has been established.

Show evidence (2 references)

PMID:28777934 SUPPORT In Vitro

"Fibroblasts derived from all three individuals showed a fragmented Golgi that could be rescued by expression of wild-type TRAPPC12."

Directly demonstrates Golgi fragmentation as a TRAPPC12-dependent phenotype.

url:https://dergipark.org.tr/en/download/article-file/4364382 SUPPORT In Vitro

"the study showed unstable protein expression and mild effects on Golgi and ER structures along with alterations in vesicle distribution throughout the cytoplasm."

Directly reports milder Golgi/ER changes in Phe227Val fibroblasts.

Delayed ER-to-Golgi Transport

Founding affected-person fibroblasts show delayed protein transport from the endoplasmic reticulum to and through the Golgi. Engineered TRAPPC12-null cells independently reproduce delayed cargo movement. The 2025 Phe227Val fibroblast study used Nile-red lipid-vesicle distribution rather than a matched ER-to-Golgi cargo assay, so it cannot establish whether this atomic transport phenotype is present or absent for that genotype.

endoplasmic reticulum to Golgi vesicle-mediated transport GO:0006888

endoplasmic reticulum GO:0005783 endoplasmic reticulum exit site GO:0070971 Golgi apparatus GO:0005794

Experimental models

Affected-person fibroblast Golgi and secretory-transport model PRIMARY CELL CULTURE Directly reproduces delayed cargo movement from the ER to and through the Golgi in all three founding affected-person lines.

TRAPPC12-deleted human cell-line COPII trafficking model CELL LINE Reproduces delayed ER-to-Golgi transport independently of the founding affected-person fibroblast system.

Downstream

Impaired Oligodendrocyte Differentiation TRAPPC12-deficient oligodendroglial cultures show impaired differentiation, but transport delay has not been shown to mediate that phenotype.

Progressive Brain Atrophy Patient-cell transport delay and brain atrophy coexist, but the neuronal or glial injury pathway connecting them is unresolved.

Show evidence (2 references)

PMID:28777934 SUPPORT In Vitro

"Protein transport from the endoplasmic reticulum to and through the Golgi was delayed."

Directly reports the transport delay in founding patient fibroblasts.

PMID:28240221 SUPPORT In Vitro

"Overall, this experiment demonstrated that TRAPPC12 deletion caused a traffic delay at the ER-to-Golgi step"

Independently reproduces the transport delay in engineered cells.

Prolonged Mitotic Progression

Fibroblasts from all three founding individuals took significantly longer from prophase to anaphase than control fibroblasts. This is a direct patient-cell readout, but no experiment shows that it contributes to neural development, brain atrophy, or the clinical encephalopathy.

mitotic cell cycle GO:0000278

Experimental models

Affected-person fibroblast Golgi and secretory-transport model PRIMARY CELL CULTURE All three affected-person fibroblast lines show significantly prolonged progression from prophase to anaphase.

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT In Vitro

"1:II-8, 2:II-1, and 2:II-4 showed a significant lengthening of the time from prophase until the onset of anaphase"

Directly reports prolonged mitotic timing in all three founding fibroblast lines.

Impaired Oligodendrocyte Differentiation

TRAPPC12 associates with COPII components at endoplasmic-reticulum exit sites and interacts with MEA6/cTAGE5. TRAPPC12 deficiency in CG4 cells and cultured oligodendrocyte progenitor cells impairs differentiation and maturation. The in-vivo hypomyelinating mouse in the same study is an oligodendrocyte-lineage Mea6 conditional knockout, not a Trappc12 knockout; it therefore cannot be treated as a TRAPPC12 disease animal model.

oligodendrocyte precursor cell CL:0002453 oligodendrocyte CL:0000128

oligodendrocyte differentiation GO:0048709 myelination GO:0042552

Experimental models

TRAPPC12-knockout rat CG4 oligodendroglial cell-line model CELL LINE Trappc12 knockout directly reduces the differentiated morphology and complexity of the CG4 lineage.

TRAPPC12-knockdown primary mouse oligodendrocyte-progenitor model PRIMARY CELL CULTURE Trappc12 knockdown reduces the MBP-positive differentiated-cell fraction in a primary oligodendrocyte-lineage culture.

Animal models

Oligodendrocyte-lineage Mea6 conditional-knockout mouse Mouse (Mus musculus) partially recapitulates Reproduces an oligodendrocyte differentiation and myelination phenotype in vivo through perturbation of the interacting MEA6 protein.

Downstream

Hyperintensity of cerebral white matter on MRI The cell-culture differentiation phenotype is compatible with the reported human white-matter MRI signal, but no in-vivo TRAPPC12 model links them.

Show evidence (2 references)

PMID:38439956 SUPPORT In Vitro

"Here, we found that Trappc12 deficiency in CG4 and oligodendrocyte progenitor cells (OPCs) affects their differentiation and maturation."

Shows that TRAPPC12 loss impairs oligodendrocyte-progenitor differentiation in a cell-based (CG4/OPC) assay.

PMID:38439956 SUPPORT In Vitro

"We reveal that TRAPPC12 is associated with COPII components at ER exit site"

Links TRAPPC12 to COPII-dependent secretory trafficking at ER exit sites.

Progressive Brain Atrophy

Serial imaging in reported children shows progressive cerebral cortical atrophy, with variable cerebellar involvement. Pontine and callosal hypoplasia and white-matter abnormalities are curated separately as structural phenotypes rather than bundled into this single atrophic process.

Downstream

Progressive Encephalopathy Structural brain loss tracks clinical progression, but the neuronal and circuit intermediates producing the encephalopathy are unknown.

Cerebral cortical atrophy Cerebral cortical atrophy is the principal measured imaging manifestation.

Cerebellar atrophy Cerebellar atrophy is a variable measured component of the imaging phenotype.

Microcephaly Reduced head growth commonly accompanies the atrophic course, although it is not obligate and can be congenital rather than progressive.

Progressive microcephaly Postnatal progressive microcephaly can track brain-volume loss, but this temporal route has not been quantified across the small reported cohort.

Show evidence (1 reference)

PMID:32369837 SUPPORT Human Clinical

"He presented with a phenotype including severe progressive cortical atrophy, moderate cerebellar atrophy, epilepsy, and microcephaly, very similar to the previously reported cases."

Documents progressive cortical and cerebellar atrophy on imaging.

Progressive Encephalopathy

The integrated clinical phenotype is a progressive childhood encephalopathy: severe global developmental delay that can evolve to regression, microcephaly, hearing impairment, a mixed movement disorder and, frequently, epilepsy.

Downstream

Global developmental delay Severe developmental impairment is a defining manifestation of the encephalopathy.

Developmental regression Loss of previously acquired abilities marks clinical progression.

Hearing impairment Hearing loss is characteristic, but its cellular route is unknown.

Spasticity Appendicular spasticity is part of the evolving motor syndrome.

Axial hypotonia Axial hypotonia accompanies the mixed motor phenotype.

Dystonia Dystonia is a reported hyperkinetic manifestation.

Myoclonus Myoclonus is a reported hyperkinetic manifestation.

Epilepsy Epilepsy is variably present and is not required for diagnosis.

Infantile spasms Infantile spasms with hypsarrhythmia occurred in one founding individual.

Optic atrophy Optic-pathway atrophy is reported, but the tissue-specific route is unknown.

Cerebral visual impairment Cerebral visual impairment occurred in two founding individuals.

Dysphagia Bulbar and motor impairment can produce clinically important dysphagia.

Gastroesophageal reflux Reflux accompanies dysphagia and feeding difficulty in the founding cohort.

Neurogenic bladder Neurogenic bladder was reported in one founding individual.

Scoliosis Scoliosis is a secondary musculoskeletal complication of severe neurologic impairment.

Show evidence (1 reference)

PMID:28777934 SUPPORT Human Clinical

"Here, we report that variants in TRAPPC12 result in progressive childhood encephalopathy."

States the integrated clinical outcome.

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

29

Digestive 2

Dysphagia HP:0002015

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Dysphagia and/or reflux...yes...yes (G-tube dependent)...yes (G-tube dependent)"

Supports a feeding/swallowing abnormality but the disjunctive table row does not establish dysphagia separately in all three individuals.

Gastroesophageal reflux HP:0002020

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Dysphagia and/or reflux...yes...yes (G-tube dependent)...yes (G-tube dependent)"

Supports a feeding/reflux abnormality but the disjunctive table row does not establish reflux separately in all three individuals.

Ear 1

Hearing impairment HP:0000365

Show evidence (2 references)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Screening for otoacoustic emissions (hearing loss)...failed...failed (40–60 dB)...failed (40–50 dB)"

The three patient columns document failed screening in all three and measured hearing loss in the two siblings.

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"sister (2:II-1) with profound developmental disability, mixed hearing loss...She failed her newborn hearing screen and has documented bilateral 40–50 dB mixed hearing loss."

Directly documents mixed hearing loss in both founding siblings.

Eye 1

Optic atrophy HP:0000648

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Eyes and/or vision...optic atrophy...mild optic nerve pallor and cortical visual impairment...enlarged cup/disk ratio, cortical visual impairment"

The three patients show optic atrophy in one individual and distinct eye/vision abnormalities in the other two.

Genitourinary 1

Neurogenic bladder HP:0000011

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"2:II-1 developed seizures, increasing spasticity, and a neurogenic bladder."

Directly documents neurogenic bladder in one affected sibling.

Head and Neck 1

Microcephaly HP:0000252

Show evidence (2 references)

PMID:28777934 SUPPORT Human Clinical

"The clinical phenotypes of the three individuals are strikingly similar: severe disability, microcephaly, hearing loss, spasticity, and characteristic brain imaging findings."

Microcephaly is named as a shared cardinal feature of all three individuals in the founding discovery cohort.

PMID:32369837 SUPPORT Human Clinical

"neither clinically manifest epilepsy nor microcephaly, which were previously considered typical findings in PEBAS with TRAPPC12 mutations"

Documents an affected individual without microcephaly, establishing that the feature is typical but not obligate.

Musculoskeletal 2

Spasticity HP:0001257

Show evidence (1 reference)

PMID:28777934 SUPPORT Human Clinical

"The clinical phenotypes of the three individuals are strikingly similar: severe disability, microcephaly, hearing loss, spasticity, and characteristic brain imaging findings."

Spasticity in the founding cohort.

Scoliosis HP:0002650

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Scoliosis ... yes ... yes ... yes"

The founding clinical table reports scoliosis in all three individuals.

Nervous System 13

Global developmental delay HP:0001263

Show evidence (1 reference)

PMID:32369837 SUPPORT Human Clinical

"We report two patients carrying TRAPPC12 variants, one previously reported and one unknown mutation, with severe neurodevelopmental delay and brain atrophy."

Directly reports severe neurodevelopmental delay in two affected children.

Epilepsy Seizure HP:0001250

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Epilepsy ... yes ... yes ... no"

The founding clinical table reports epilepsy in two of three individuals.

Cerebral cortical atrophy HP:0002120

Show evidence (1 reference)

PMID:32369837 SUPPORT Human Clinical

"He presented with a phenotype including severe progressive cortical atrophy, moderate cerebellar atrophy, epilepsy, and microcephaly, very similar to the previously reported cases."

Progressive cortical atrophy on imaging.

Cerebellar atrophy HP:0001272

Show evidence (1 reference)

PMID:32369837 SUPPORT Human Clinical

"The second case, a 9-year-old boy, carried a novel homozygous c.679T > G (p.Phe227Val) variant and presented with mild cortical atrophy, severe cerebellar atrophy"

Severe cerebellar atrophy documented.

Hyperintensity of cerebral white matter on MRI HP:0030890

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"T2 signal is increased in the white matter, consistent with decreased myelination."

Directly reports the MRI signal and preserves the paper's interpretation without promoting it to a distinct delayed-myelination HPO phenotype.

Developmental regression HP:0002376

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Regression ... yes ... yes ... yes"

The founding clinical table reports regression in all three individuals.

Dystonia HP:0001332

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Dystonia and/or myoclonus ... yes ... yes ... yes"

The founding table reports the combined movement-disorder category in all three individuals but does not separate dystonia from myoclonus per person.

Myoclonus HP:0001336

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Dystonia and/or myoclonus ... yes ... yes ... yes"

The founding table reports the combined movement-disorder category in all three individuals but does not separate myoclonus from dystonia per person.

Hypoplasia of the corpus callosum HP:0002079

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Agenesis of the corpus callosum...severe thinning with absent posterior body, isthmus, and splenium...complete absence...severe thinning with absent posterior body, isthmus, and splenium"

Directly reports the partial callosal defect, distinct from complete agenesis.

Agenesis of corpus callosum HP:0001274

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Agenesis of the corpus callosum...severe thinning with absent posterior body, isthmus, and splenium...complete absence...severe thinning with absent posterior body, isthmus, and splenium"

The patient columns document complete absence in one individual and severe partial absence/thinning in the other two.

Cerebellar hypoplasia HP:0001321

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Cerebellar hypoplasia ... no ... mild ... mild"

The founding MRI table reports mild hypoplasia in two individuals.

Ventriculomegaly HP:0002119

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"2:II-4 also has progressive ventriculomegaly beyond what would be expected for cortical volume loss but did not have overt symptoms of increased intracranial pressure."

Directly reports progressive ventriculomegaly in a founding child.

Hydrocephalus HP:0000238

Show evidence (1 reference)

PMID:32347653 SUPPORT Human Clinical

"CONCLUSION: Compound heterozygous variants in TRAPPC12, which encodes a protein involved in Golgi trafficking and mitosis, may disrupt normal brain embryogenesis leading to hydrocephalus and recurrent pregnancy loss."

Documents the reported association while preserving the authors' cautious "may disrupt" causal language.

Other 8

Progressive microcephaly HP:0000253

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"microcephaly...persistent epilepsy, and arrested head growth"

Directly documents microcephaly followed by arrested head growth in one founding child, supporting a progressive rather than merely acquired label.

Infantile spasms HP:0012469

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Initial electroencephalography (EEG) showed hypsarrhythmia...compatible with a diagnosis of West syndrome."

Directly documents the electroclinical infantile-spasm presentation.

Hypoplasia of the pons HP:0012110

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Review of brain imaging for all three affected individuals revealed remarkably similar findings, including pons hypoplasia, agenesis of the corpus callosum, and marked brain atrophy documented by scans from 3 days to 11 months of age"

Directly reports pons hypoplasia in the shared founding imaging pattern.

Axial hypotonia HP:0008936

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Truncal hypotonia ... yes ... yes ... yes"

The founding clinical table reports truncal hypotonia in all three individuals.

Cerebral visual impairment HP:0100704

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Eyes and/or vision...optic atrophy...mild optic nerve pallor and cortical visual impairment...enlarged cup/disk ratio, cortical visual impairment"

The three patients show cortical visual impairment in two individuals, distinct from optic atrophy in the third.

Widened subarachnoid space HP:0012704

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Prominent extra-axial spaces ... yes ... yes ... yes"

The founding MRI table records this feature in all three individuals.

Simplified gyral pattern HP:0009879

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Simplified frontal gyri ... yes ... yes ... yes"

The founding MRI table records this feature in all three individuals.

Hypoplastic optic chiasm HP:0034311

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Small optic chiasm ... yes ... yes ... no"

The founding MRI table reports a small optic chiasm in two individuals.

🧬

Genetic Associations

1

TRAPPC12

Gene: TRAPPC12 hgnc:24284 relationship_type: CAUSATIVE variant_origin: GERMLINE

Autosomal recessive

Show evidence (3 references)

PMID:28777934 SUPPORT Human Clinical

"Here, we report that variants in TRAPPC12 result in progressive childhood encephalopathy."

The founding gene-disease association.

PMID:32369837 SUPPORT Human Clinical

"Biallelic mutations in the TRAPPC12 gene are responsible for early-onset progressive encephalopathy with brain atrophy and spasticity (PEBAS)."

Independent confirmation of the biallelic gene-disease relationship.

PMID:32347653 SUPPORT Human Clinical

"The variant from the father (c.954del) leads to a premature termination of the transcript; the variant from the mother (c.1677+5G>A) affects a splice site which leads to aberrant splicing of the TRAPPC12 transcript."

Distinguishes the c.954del premature-termination allele from the c.1677+5G>A splice-altering allele.

💊

Medical Actions

4

Antiseizure pharmacotherapy

Category: Therapeutic Action: Pharmacotherapy NCIT:C15986

Agent: anticonvulsant agent NCIT:C264

Epilepsy may be treated symptomatically with antiseizure medication. No TRAPPC12-specific drug, comparative response series, or disease-modifying therapy was identified.

Target Phenotypes: Epilepsy HP:0001250

Rehabilitation and supportive therapy

Category: Therapeutic Action: Physical Therapy NCIT:C15302

Multidisciplinary supportive care including physical therapy, occupational therapy and speech/communication therapy for the severe motor and developmental impairment.

Nutritional and feeding support

Category: Therapeutic Action: Nutritional Support NCIT:C15433

Management of dysphagia and gastroesophageal reflux with feeding support, including enteral/tube feeding when oral intake is unsafe.

Genetic counseling

Category: Counseling / Informational Action: Genetic Counseling NCIT:C15240

Genetic counseling for families given autosomal recessive inheritance and the 25% recurrence risk in future pregnancies.

🔬

Diagnosis

3

Exome or Genome Sequencing (Diagnostic when biallelic pathogenic TRAPPC12 variants are identified)

Diagnosis is molecular. Because the clinical picture (progressive encephalopathy, brain atrophy, spasticity, hearing loss) is shared with many other early-onset neurodegenerative disorders and no biochemical marker is available, exome sequencing has been used in reported cases. This is a reported diagnostic route rather than a disease-specific testing guideline; genome sequencing or a broad neurodevelopmental panel may also be considered according to local practice and prior results.

whole exome sequencing NCIT:C101295

Results: Biallelic (homozygous or compound heterozygous) pathogenic TRAPPC12 variants establish the diagnosis. Reported alleles include missense, frameshift, and splice-affecting changes.

Show evidence (1 reference)

PMID:32369837 SUPPORT Human Clinical

"whole-exome sequencing was performed, followed by Sanger sequencing for verification"

Documents the diagnostic route actually used to establish TRAPPC12 genotypes in reported patients — exome sequencing with Sanger confirmation.

Sanger Confirmation of the Candidate Variant

Targeted Sanger sequencing is used to confirm the candidate TRAPPC12 variant identified on exome sequencing and, where samples are available, to demonstrate biallelic inheritance by parental segregation.

molecular genetic testing NCIT:C15709

Results: Confirms the exome call and, with parental samples, establishes that the two variants are in trans.

Show evidence (2 references)

PMID:32369837 SUPPORT Human Clinical

"whole-exome sequencing was performed, followed by Sanger sequencing for verification"

Sanger verification of the exome-identified variant is the reported confirmatory step.

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"the father carries the frameshift variant and the mother carries the missense variant. Neither of the unaffected siblings carries both variants."

Directly supports parental segregation of the two variants and their joint presence in the affected siblings.

Brain Magnetic Resonance Imaging

Cranial imaging is the principal phenotyping investigation and supplies the findings that make the disorder recognizable: progressive cortical atrophy, cerebellar atrophy, pontine hypoplasia, and abnormal white matter. It is supportive rather than diagnostic — the imaging findings direct sequencing, they do not replace it.

brain magnetic resonance imaging NCIT:C16809

Results: Progressive cerebral cortical and cerebellar atrophy with abnormal white matter; severity of the cortical versus cerebellar component varies between patients.

Imaging findings are more variable than the founding cohort suggested, so a single atypical scan does not exclude the diagnosis.

Show evidence (2 references)

PMID:32369837 SUPPORT Human Clinical

"Standard clinical examination and cranial imaging studies were performed in these two unrelated patients."

Cranial imaging is part of the standard diagnostic workup in reported patients.

PMID:32369837 SUPPORT Human Clinical

"Our findings suggest that clinical and brain imaging findings might be more variable than previously anticipated"

Supports the caveat that imaging is supportive and variable rather than pathognomonic.

🩻

Imaging Findings

11

Progressive cerebral cortical atrophy on brain MRI

Serial imaging can show progressive cortical volume loss. Severity is variable, and mild cortical atrophy can coexist with severe cerebellar atrophy.

Mri

Cerebral cortical atrophy HP:0002120

Show evidence (1 reference)

PMID:32369837 SUPPORT Human Clinical

"He presented with a phenotype including severe progressive cortical atrophy, moderate cerebellar atrophy, epilepsy, and microcephaly, very similar to the previously reported cases."

Directly reports severe progressive cortical atrophy in an affected child.

Cerebellar atrophy on brain MRI

Cerebellar volume loss ranges from moderate to severe and may predominate over cortical atrophy in some molecularly confirmed individuals.

Mri

Cerebellar atrophy HP:0001272

Show evidence (1 reference)

PMID:32369837 SUPPORT Human Clinical

"The second case, a 9-year-old boy, carried a novel homozygous c.679T > G (p.Phe227Val) variant and presented with mild cortical atrophy, severe cerebellar atrophy, and neither clinically manifest epilepsy nor microcephaly"

Directly documents the cortical-versus-cerebellar variability.

Pontine hypoplasia on brain MRI

Severe pons hypoplasia was part of the shared founding neuroimaging pattern.

Mri

Hypoplasia of the pons HP:0012110

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Review of brain imaging for all three affected individuals revealed remarkably similar findings, including pons hypoplasia, agenesis of the corpus callosum, and marked brain atrophy documented by scans from 3 days to 11 months of age"

Directly reports pons hypoplasia in the founding imaging review.

Hypoplastic corpus callosum on brain MRI

Severe thinning or hypoplasia of the corpus callosum has been reported as part of the structural imaging phenotype.

Mri

Hypoplasia of the corpus callosum HP:0002079

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Agenesis of the corpus callosum...severe thinning with absent posterior body, isthmus, and splenium...complete absence...severe thinning with absent posterior body, isthmus, and splenium"

Directly reports severe partial callosal absence in two founding MRIs.

Agenesis of the corpus callosum on brain MRI

Complete callosal agenesis occurred in one founding individual and severe partial agenesis/thinning in the other two.

Mri

Agenesis of corpus callosum HP:0001274

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"Agenesis of the corpus callosum...severe thinning with absent posterior body, isthmus, and splenium...complete absence...severe thinning with absent posterior body, isthmus, and splenium"

The patient columns document complete absence in one MRI and severe partial absence/thinning in the other two.

Hyperintensity of cerebral white matter on MRI

Increased cortical white-matter T2 signal was present in the founding imaging series and interpreted by its authors as decreased myelination.

Mri

Hyperintensity of cerebral white matter on MRI HP:0030890

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"T2 signal is increased in the white matter, consistent with decreased myelination."

Directly reports the observed MRI signal and the authors' interpretation.

Prominent extra-axial spaces on brain MRI

Prominent extra-axial spaces were recorded in all three founding MRIs.

Mri

Widened subarachnoid space HP:0012704

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Prominent extra-axial spaces ... yes ... yes ... yes"

The founding MRI table records this finding in all three individuals.

Simplified frontal gyri on brain MRI

Simplified frontal gyri were recorded in all three founding MRIs.

Mri

Simplified gyral pattern HP:0009879

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Simplified frontal gyri ... yes ... yes ... yes"

The founding MRI table records this finding in all three individuals.

Cerebellar hypoplasia on brain MRI

Mild cerebellar hypoplasia was recorded in two founding MRIs.

Mri

Cerebellar hypoplasia HP:0001321

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Cerebellar hypoplasia ... no ... mild ... mild"

The founding MRI table records mild hypoplasia in two individuals.

Hypoplastic optic chiasm on brain MRI

A small optic chiasm was recorded in two founding MRIs.

Mri

Hypoplastic optic chiasm HP:0034311

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT Human Clinical

"MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Small optic chiasm ... yes ... yes ... no"

The founding MRI table records a small optic chiasm in two individuals.

Fetal hydrocephalus on prenatal ultrasound

Recurrent fetal hydrocephalus was detected by prenatal ultrasound in three consecutive pregnancies in one family and represents a severe prenatal presentation associated with compound-heterozygous TRAPPC12 variants.

Ultrasound

Hydrocephalus HP:0000238

Show evidence (1 reference)

PMID:32347653 SUPPORT Human Clinical

"Three consecutive pregnancies of an unrelated couple were found by ultrasound to carry fetuses with hydrocephaly."

Directly documents the prenatal modality and recurrent finding.

📊

Prevalence

1

Global

Cases In Literature Ultra Rare

The founding report described three individuals from two unrelated families; subsequent publications added two unrelated children, a family with recurrent fetal hydrocephalus, and single-case molecular reports. No population-based prevalence study or disease-specific registry was identified, so a precise case count should not be inferred from this incomplete literature.

Show evidence (1 reference)

PMID:28777934 SUPPORT Human Clinical

"Three individuals from two unrelated families"

Documents the small number of individuals reported at first description.

🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from TRAPPC12-Related Encephalopathy:

Neurodevelopmental disorder with epilepsy, spasticity, and brain atrophy MONDO:0032894

Overlapping Features Biallelic TRAPPC4 disease is a close molecular and clinical TRAPPopathy mimic, with early developmental impairment, microcephaly, spasticity, epilepsy, and progressive brain atrophy.

Distinguishing Features

Biallelic pathogenic TRAPPC12 variants establish TRAPPC12-related encephalopathy.
Biallelic pathogenic TRAPPC4 variants establish the TRAPPC4-related disorder.
Pontine hypoplasia and hearing impairment particularly support the TRAPPC12 phenotype, but clinical overlap prevents exclusion by examination alone.

Show evidence (1 reference)

PMID:28777934 SUPPORT Human Clinical

"Variants in several other genes encoding members of the TRAPP complex have been associated with overlapping clinical presentations, indicating shared and distinct functions for each complex member."

Establishes the overlapping TRAPPopathy differential in general; molecular testing is required to distinguish the causal subunit.

Pontocerebellar hypoplasia MONDO:0020135

Overlapping Features Genetic pontocerebellar hypoplasias can overlap through infantile developmental impairment, microcephaly, abnormal tone, seizures, and pontine/cerebellar abnormalities.

Distinguishing Features

The progressive cerebral cortical atrophy, hearing loss, and patient-cell Golgi phenotype support TRAPPC12 disease but are not individually pathognomonic.
Molecular identification of the causal gene is required because imaging patterns overlap.

🧫

Experimental Models

5

Affected-person fibroblast Golgi and secretory-transport model PRIMARY_CELL_CULTURE

Primary fibroblasts from all three founding individuals lack full-length TRAPPC12, reproduce fragmented Golgi morphology and delayed ER-to-Golgi transport, and show prolonged prophase-to-anaphase timing. Re-expression of wild-type TRAPPC12 rescues Golgi fragmentation; rescue of the separate transport and mitotic readouts was not reported.

Organism

human NCBITaxon:9606

Cell source

Primary dermal fibroblasts from affected individuals and controls

Culture

Fibroblast monolayer with immunoblotting, Golgi morphology, cargo-transport, complementation, and live-cell mitotic-timing assays

Publication

PMID:28777934

Pathograph links

Biallelic TRAPPC12 Dysfunction recapitulates fidelity: high The affected-person lines directly reproduce absence of full-length TRAPPC12 for both the homozygous and compound-heterozygous genotypes.

Limitations: Fibroblast protein abundance does not by itself define the consequences in neural lineages or the residual activity of every allele.

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT In Vitro

"As expected for the homozygous truncating variant in 1:II-8, western blot analysis failed to detect any full-length...Unexpectedly, the full-length protein was also absent in 2:II-1 and 2:II-4"

Directly demonstrates the proximal protein-loss phenotype in all three founding fibroblast lines.

Golgi Fragmentation recapitulates fidelity: high Directly reproduces fragmented Golgi morphology, with genetic complementation tying that readout to TRAPPC12 deficiency.

Limitations: Fibroblasts do not reproduce neural cell-type vulnerability, progressive brain atrophy, or the clinical encephalopathy.

Show evidence (1 reference)

PMID:28777934 SUPPORT In Vitro

"Fibroblasts derived from all three individuals showed a fragmented Golgi that could be rescued by expression of wild-type TRAPPC12."

Patient-derived cells and wild-type rescue give this model high fidelity for the proximal Golgi morphology.

Delayed ER-to-Golgi Transport recapitulates fidelity: high Directly reproduces delayed cargo movement from the ER to and through the Golgi in all three founding affected-person lines.

Limitations: The transport delay was measured in fibroblasts and was not shown to be rescued by wild-type TRAPPC12 or to mediate neural degeneration.

Show evidence (1 reference)

PMID:28777934 SUPPORT In Vitro

"Protein transport from the endoplasmic reticulum to and through the Golgi was delayed."

Directly reports the separate transport-delay readout.

Prolonged Mitotic Progression recapitulates fidelity: moderate All three affected-person fibroblast lines show significantly prolonged progression from prophase to anaphase.

Limitations: The readout is direct, but its contribution to human neural development and encephalopathy remains unknown.

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT In Vitro

"1:II-8, 2:II-1, and 2:II-4 showed a significant lengthening of the time from prophase until the onset of anaphase"

Directly reports prolonged mitotic timing in all three lines.

Show evidence (1 reference)

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/ SUPPORT In Vitro

"As expected for the homozygous truncating variant in 1:II-8, western blot analysis failed to detect any full-length...Unexpectedly, the full-length protein was also absent in 2:II-1 and 2:II-4"

Defines the affected-person model and its proximal protein-loss readout.

Homozygous Phe227Val affected-person fibroblast model PRIMARY_CELL_CULTURE

Primary skin fibroblasts from one affected individual homozygous for c.679T>G (p.Phe227Val) show absent or highly reduced mature TRAPPC12, mild Golgi disorganization, slight ER enlargement, and altered neutral-lipid vesicle distribution. The authors described persisting vesicle trafficking, but Nile-red distribution is not a direct ER-to-Golgi cargo assay and cannot establish presence or absence of the atomic transport-delay phenotype.

Organism

human NCBITaxon:9606

Cell source

Primary skin fibroblasts from one affected individual homozygous for c.679T>G (p.Phe227Val), compared with the CCD1079Sk control cell line

Culture

Fibroblast monolayer with TRAPPC12 immunoblotting, Golgi and ER immunofluorescence, and Nile-red neutral-lipid distribution imaging

Publication

DOI:10.26650/experimed.1584823

Pathograph links

Biallelic TRAPPC12 Dysfunction partially recapitulates fidelity: low Directly tests the Phe227Val genotype and reproduces absent or highly reduced mature TRAPPC12 protein in affected-person fibroblasts.

Limitations: The study uses cells from one affected individual and one control line; residual protein identity and allele-specific function remain incompletely resolved.

Show evidence (1 reference)

url:https://dergipark.org.tr/en/download/article-file/4364382 SUPPORT In Vitro

"Protein expression analysis revealed an absence of the mature TRAPPC12 protein and the uncharacterized protein fragment (CGI-87) via mutation compared with the wild-type."

Directly reports the Phe227Val fibroblast protein phenotype.

Golgi Fragmentation partially recapitulates fidelity: low Reproduces a milder Golgi disorganization and slight ER enlargement rather than the marked founding-cell phenotype.

Limitations: The organelle analysis included only one patient line, one control line, and 12 imaged cells per group, limiting precision and generalizability.

Show evidence (1 reference)

url:https://dergipark.org.tr/en/download/article-file/4364382 SUPPORT In Vitro

"the study showed unstable protein expression and mild effects on Golgi and ER structures along with alterations in vesicle distribution throughout the cytoplasm."

Directly characterizes the milder organelle phenotype.

Show evidence (1 reference)

url:https://dergipark.org.tr/en/download/article-file/4364382 SUPPORT In Vitro

"More functional analyses are necessary to confirm these outcomes."

The authors explicitly limit interpretation of this single-person fibroblast study.

TRAPPC12-deleted human cell-line COPII trafficking model CELL_LINE

CRISPR deletion of TRAPPC12 in HeLa and HEK293T-derived cell systems was used to study TRAPPIII interaction with Sec13/Sec31, COPII outer-coat assembly, ERGIC/Golgi organization, and ER-to-Golgi cargo transport.

Organism

human NCBITaxon:9606

Cell source

Engineered HeLa and HEK293T cell lines

Culture

Monolayer CRISPR-deletion, interaction, imaging, and cargo-transport assays

Publication

PMID:28240221

Pathograph links

Reduced COPII Outer-Coat Assembly perturbs fidelity: moderate Direct genetic deletion tests how TRAPPC12 affects COPII outer-coat recruitment and early secretory-pathway organization.

Limitations: The model uses transformed cell lines and a complete engineered deletion, not patient-derived neural cells or specific human disease alleles.

Show evidence (1 reference)

PMID:28240221 SUPPORT In Vitro

"Quantification of three independent experiments showed that the amount of Sec31A on COPII vesicles was found to be approximately 3.1% of total input cytosol from wildtype HeLa cells, versus 0.68% from TRAPPC12 deleted cells"

Directly quantifies reduced COPII outer-coat assembly after deletion.

Golgi Fragmentation recapitulates fidelity: moderate Reproduces dispersed ERGIC and, to a lesser extent, Golgi organization.

Limitations: The engineered cancer-cell model does not establish tissue selectivity or progression in the nervous system.

Show evidence (1 reference)

PMID:28240221 SUPPORT In Vitro

"In cells deleted with TRAPPC12, ERGIC and to a lesser extent, the Golgi became dispersed."

Directly reports the modeled morphology readout.

Delayed ER-to-Golgi Transport recapitulates fidelity: moderate Reproduces delayed ER-to-Golgi transport independently of the founding affected-person fibroblast system.

Limitations: The complete deletion in transformed cells differs from patient alleles, and no complementation assay showed that rescue of this readout reverses the disease-associated cellular phenotype.

Show evidence (1 reference)

PMID:28240221 SUPPORT In Vitro

"ER-to-Golgi transport was also delayed."

Directly reports the separate transport readout.

Show evidence (1 reference)

PMID:28240221 SUPPORT In Vitro

"In this study, we studied the function of TRAPPIII in early secretory pathway using a TRAPPIII-specific subunit, TRAPPC12, as starting point."

Defines the experimental purpose and TRAPPC12-centered model system.

TRAPPC12-knockout rat CG4 oligodendroglial cell-line model CELL_LINE

CRISPR-Cas9 knockout of Trappc12 in the rat-derived CG4 oligodendrocyte progenitor cell line reduced cell complexity after differentiation.

Organism

rat NCBITaxon:10116

Cell source

Rat-derived CG4 oligodendrocyte progenitor cell line

Culture

CRISPR-Cas9 knockout single-clone CG4 cultures followed through induced oligodendroglial differentiation and morphology analysis

Publication

PMID:38439956

Pathograph links

Impaired Oligodendrocyte Differentiation partially recapitulates fidelity: low Trappc12 knockout directly reduces the differentiated morphology and complexity of the CG4 lineage.

Limitations: CG4 is a rat-derived immortalized progenitor line, not patient-derived neural tissue, and cell complexity does not establish the mechanism of the human MRI phenotype.

Show evidence (1 reference)

url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML SUPPORT In Vitro

"To determine whether TRAPPC12 plays a role in oligodendrocyte development, we eliminated...from CG4 cells (an oligodendrocyte progenitor cell line) using CRISPR Cas9 technology"

Defines the rat CG4 CRISPR-knockout model.

Show evidence (1 reference)

url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML SUPPORT In Vitro

"The cell complexity was significantly decreased in...KO cells 4 days after differentiation"

Directly reports the differentiated CG4-cell phenotype.

TRAPPC12-knockdown primary mouse oligodendrocyte-progenitor model PRIMARY_CELL_CULTURE

Lentiviral shRNA knockdown of Trappc12 in primary neonatal mouse oligodendrocyte progenitor cells reduced the proportion of MBP-positive cells after six days of differentiation.

Organism

mouse NCBITaxon:10090

Cell source

Primary OPCs isolated from postnatal-day 0 to 3 mouse brains

Culture

Primary mouse OPC monolayer with lentiviral Trappc12 shRNA knockdown and MBP immunostaining after induced differentiation

Publication

PMID:38439956

Pathograph links

Impaired Oligodendrocyte Differentiation partially recapitulates fidelity: low Trappc12 knockdown reduces the MBP-positive differentiated-cell fraction in a primary oligodendrocyte-lineage culture.

Limitations: The neonatal mouse culture is not patient-derived, shRNA may leave residual Trappc12 or have off-target effects, and no human white-matter imaging correlate was measured.

Show evidence (1 reference)

url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML SUPPORT In Vitro

"We also used shRNA packaged in lentivirus to knock down Trappc12 expression in primary cultured mouse OPCs"

Defines the primary mouse OPC perturbation system.

Show evidence (1 reference)

url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML SUPPORT In Vitro

"The percentage of MBP...cells was significantly lower in the knockdown group after 6 days of differentiation"

Directly reports the system-specific differentiation readout.

🐁

Animal Models

1

Oligodendrocyte-lineage Mea6 conditional-knockout mouse

This interacting-pathway model develops impaired oligodendrocyte proliferation and differentiation, marked hypomyelination, synaptic dysfunction, and behavioral abnormalities. It is not a TRAPPC12 knockout and therefore models a cooperating MEA6 pathway rather than TRAPPC12-related encephalopathy itself.

Species

Mouse (Mus musculus)

Genotype

Conditional Mea6/cTAGE5 ablation in oligodendrocyte progenitor cells

Publication

PMID:38439956

Pathograph links

Impaired Oligodendrocyte Differentiation partially recapitulates fidelity: low Reproduces an oligodendrocyte differentiation and myelination phenotype in vivo through perturbation of the interacting MEA6 protein.

Limitations: The perturbed gene is Mea6, not Trappc12; the model cannot establish that TRAPPC12 disease alleles cause the same in-vivo pathway or human MRI pattern.

Show evidence (1 reference)

PMID:38439956 SUPPORT Model Organism

"Mea6/cTAGE5 ablation in OPCs affects their proliferation and differentiation, leading to marked hypomyelination, compromised synaptic functionality, and aberrant behaviors in mice."

Supports a cooperating in-vivo pathway but not a TRAPPC12 genotype model.

Show evidence (1 reference)

PMID:38439956 SUPPORT Model Organism

"Mea6/cTAGE5 ablation in OPCs affects their proliferation and differentiation, leading to marked hypomyelination, compromised synaptic functionality, and aberrant behaviors in mice."

Directly documents the Mea6 conditional-knockout mouse phenotype and the reason its relevance to TRAPPC12 disease is only partial.

{ }

Source YAML

click to show

name: TRAPPC12-Related Encephalopathy
creation_date: '2026-08-05T00:00:00Z'
category: Mendelian
synonyms:
- PEBAS
- early-onset progressive encephalopathy-hearing loss-pons hypoplasia-brain atrophy syndrome
- early-onset progressive encephalopathy with brain atrophy and spasticity
- TRAPPC12-related childhood encephalopathy
- TRAPPC12-related disorder
- TTC15-related encephalopathy
description: >-
  TRAPPC12-related encephalopathy (PEBAS, "progressive encephalopathy with brain
  atrophy and spasticity") is an ultra-rare autosomal recessive
  neurodevelopmental disorder caused by biallelic pathogenic variants in
  TRAPPC12. Founding frameshift/missense genotypes were associated with absent
  full-length TRAPPC12 in affected-person fibroblasts, while a later Phe227Val
  fibroblast study found absent or markedly reduced mature protein with milder
  organelle abnormalities. Affected children present in early infancy with
  severe global developmental delay that can evolve into developmental
  regression, congenital or progressive (postnatal) microcephaly, hearing loss,
  and a mixed
  movement disorder combining truncal hypotonia with appendicular spasticity,
  dystonia and/or myoclonus. Epilepsy is common but not universal. Serial brain
  imaging can show progressive supratentorial atrophy, pontine hypoplasia,
  callosal agenesis or severe thinning, simplified gyri, widened extra-axial
  spaces and deficient white-matter myelination; cerebellar hypoplasia or atrophy
  is variable. TRAPPC12 encodes a subunit of the
  multisubunit TRAPPIII membrane-trafficking complex. Biochemical studies show
  mammalian TRAPPIII GEF activity toward Rab1 and Rab43, while cell models place
  TRAPPC12 at ER exit sites and link it to COPII-coat assembly. Patient
  fibroblasts from the founding cohort show Golgi fragmentation that is rescued
  by wild-type TRAPPC12 and a separately measured delay in ER-to-Golgi transport.
  The Phe227Val fibroblast study instead found mild Golgi/ER abnormalities and
  persisting vesicle trafficking, showing genotype-dependent cellular severity.
  Published evidence remains limited to small case series, single-case reports,
  and experimental cell systems. No disease-modifying treatment has been
  established.
disease_term:
  preferred_term: TRAPPC12-related encephalopathy
  term:
    id: MONDO:0044696
    label: early-onset progressive encephalopathy-hearing loss-pons hypoplasia-brain atrophy syndrome
parents:
- Mendelian neurodevelopmental disorder
- Progressive encephalopathy
- Membrane trafficking disorder
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:28777934
      reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Here, we report that variants in TRAPPC12 result in progressive childhood encephalopathy.
      explanation: >-
        A monogenic autosomal recessive disorder defined by exome sequencing
        belongs to the genetics chapter.
  - classification_value: NEUROLOGIC
    evidence:
    - reference: PMID:28777934
      reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: 'The clinical phenotypes of the three individuals are strikingly similar: severe disability, microcephaly, hearing loss, spasticity, and characteristic brain imaging findings.'
      explanation: >-
        The presentation is dominated by encephalopathy, microcephaly and motor
        signs, placing the entity in the neurology chapter.
inheritance:
- name: Autosomal recessive
  description: >-
    Biallelic (homozygous or compound heterozygous) TRAPPC12 variants are
    required. Reported families include consanguineous unions with homozygous
    variants and non-consanguineous families with compound-heterozygous variants.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Three individuals from two unrelated families have either a homozygous
      deleterious variant...or compound-heterozygous variants
    explanation: >-
      A homozygous variant in one family and compound-heterozygous variants in
      another establish recessive inheritance.
prevalence:
- population: Global
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    The founding report described three individuals from two unrelated families;
    subsequent publications added two unrelated children, a family with recurrent
    fetal hydrocephalus, and single-case molecular reports. No population-based
    prevalence study or disease-specific registry was identified, so a precise
    case count should not be inferred from this incomplete literature.
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Three individuals from two unrelated families
    explanation: Documents the small number of individuals reported at first description.
pathophysiology:
- name: Biallelic TRAPPC12 Dysfunction
  description: >-
    Biallelic pathogenic variants in TRAPPC12 (also known as TTC15 or TRAMM)
    perturb protein abundance or function. Full-length protein was absent from
    fibroblasts of all three founding individuals, who carried homozygous or
    compound-heterozygous frameshift/missense genotypes. A later homozygous
    Phe227Val fibroblast study likewise found absent or markedly reduced mature
    protein but only mild organelle abnormalities. Separately,
    compound-heterozygous c.954del and c.1677+5G>A variants were found in a
    family with recurrent fetal hydrocephalus; the former causes premature
    termination and the latter was shown to alter splicing. A surviving child
    with a homozygous frameshift means complete loss of detectable full-length
    protein should not be described as uniformly embryonic lethal.
  role: root
  biological_scale: MOLECULAR
  mechanism_confidence: ESTABLISHED
  gene:
    preferred_term: TRAPPC12
    term:
      id: hgnc:24284
      label: TRAPPC12
  downstream:
  - target: Reduced COPII Outer-Coat Assembly
    causal_link_type: DIRECT
    description: >-
      TRAPPC12-null cytosol supports less efficient Sec13/Sec31 outer-coat
      assembly on COPII vesicles in an in-vitro budding assay.
    evidence:
    - reference: PMID:28240221
      reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        COPII vesicles budded from cytosol of TRAPPC12−/− cells contained less
        Sec31A protein than those budded form wildtype cytosol, while
        vesicle-bound Sec23A was similar between two groups
      explanation: >-
        The knockout budding assay directly isolates reduced outer-coat Sec31A
        recruitment while showing similar inner-coat Sec23A.
  - target: Golgi Fragmentation
    causal_link_type: DIRECT
    description: >-
      Founding affected-person fibroblasts show Golgi fragmentation, and
      wild-type TRAPPC12 rescues this morphology.
    evidence:
    - reference: PMID:28777934
      reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Fibroblasts derived from all three individuals showed a fragmented Golgi that could be rescued by expression of wild-type TRAPPC12.
      explanation: >-
        Rescue in affected-person fibroblasts directly links TRAPPC12 dysfunction
        to the cellular Golgi phenotype.
  - target: Delayed ER-to-Golgi Transport
    causal_link_type: DIRECT
    description: >-
      Cargo transport from the endoplasmic reticulum to and through the Golgi is
      delayed in founding affected-person fibroblasts; this readout was measured
      separately from Golgi rescue.
    evidence:
    - reference: PMID:28777934
      reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Protein transport from the endoplasmic reticulum to and through the Golgi was delayed.
      explanation: Directly reports the patient-cell cargo-transport delay.
  - target: Prolonged Mitotic Progression
    causal_link_type: DIRECT
    description: >-
      All three founding affected-person fibroblast lines showed prolonged
      prophase-to-anaphase timing, although its relevance to neural disease is
      unknown.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
      reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        1:II-8, 2:II-1, and 2:II-4 showed a significant lengthening of the time
        from prophase until the onset of anaphase
      explanation: Directly documents mitotic delay in all three founding fibroblast lines.
  - target: Hypoplasia of the pons
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Biallelic TRAPPC12 dysfunction is causal for the disorder, but the cellular
      route to pontine underdevelopment has not been resolved.
  - target: Hypoplasia of the corpus callosum
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The gene-to-structural-phenotype relationship is established clinically,
      while the intervening developmental mechanism remains unknown.
  - target: Agenesis of corpus callosum
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Complete callosal agenesis occurred in one founding individual and severe
      partial agenesis/thinning in the other two; the developmental route is unknown.
  - target: Ventriculomegaly
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Ventricular enlargement is linked to biallelic TRAPPC12 disease through
      unresolved neurodevelopmental intermediates.
  - target: Widened subarachnoid space
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Prominent extra-axial spaces were present in all three founding individuals,
      but whether they reflect developmental volume loss or another process is unresolved.
  - target: Simplified gyral pattern
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Simplified frontal gyri were present in all three founding individuals;
      the cortical-development mechanism is unknown.
  - target: Cerebellar hypoplasia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Mild cerebellar hypoplasia was present in two founding individuals, with
      no resolved developmental mechanism.
  - target: Hypoplastic optic chiasm
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      A small optic chiasm was present in two founding individuals; the
      tissue-specific route from TRAPPC12 dysfunction is unknown.
  - target: Hydrocephalus
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Compound-heterozygous TRAPPC12 variants segregated with recurrent fetal
      hydrocephalus, but the intervening developmental mechanism is unknown.
    evidence:
    - reference: PMID:32347653
      reference_title: Hydrocephaly associated with compound heterozygous alterations in TRAPPC12.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Compound heterozygous variants in TRAPPC12, which encodes a protein involved in Golgi trafficking and mitosis, may disrupt normal brain embryogenesis leading to hydrocephalus and recurrent pregnancy loss.
      explanation: >-
        Supports the genotype-to-hydrocephalus link while explicitly leaving the
        mechanism at the level of possible disruption of embryogenesis.
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Three individuals from two unrelated families have either a homozygous
      deleterious variant...or compound-heterozygous variants
    explanation: Establishes homozygous and compound-heterozygous founding genotypes.
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: TRAPPC12 is a member of the TRAPP protein complex, which functions in membrane trafficking.
    explanation: Identifies the gene product as a TRAPP-complex subunit.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      As expected for the homozygous truncating variant in 1:II-8, western blot
      analysis failed to detect any full-length...Unexpectedly, the full-length
      protein was also absent in 2:II-1 and 2:II-4
    explanation: >-
      Directly grounds loss of full-length protein in the homozygous and
      compound-heterozygous founding fibroblast lines.
  - reference: PMID:32347653
    reference_title: Hydrocephaly associated with compound heterozygous alterations in TRAPPC12.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The variant from the father (c.954del) leads to a premature termination of
      the transcript; the variant from the mother (c.1677+5G>A) affects a splice
      site which leads to aberrant splicing of the TRAPPC12 transcript.
    explanation: Grounds the distinct molecular effects of the two fetal-family alleles.
  - reference: url:https://dergipark.org.tr/en/download/article-file/4364382
    reference_title: "https://dergipark.org.tr/en/download/article-file/4364382"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Protein expression analysis revealed an absence of the mature TRAPPC12
      protein and the uncharacterized protein fragment (CGI-87) via mutation
      compared with the wild-type.
    explanation: >-
      Extends patient-cell protein-loss evidence to the homozygous Phe227Val
      genotype, while the paper cautions that more functional analyses are needed.
- name: Reduced COPII Outer-Coat Assembly
  description: >-
    In TRAPPC12-null cell systems, Sec31A turns over more slowly at ER exit sites
    and less Sec31A is recruited to budded COPII vesicles, while inner-coat Sec23A
    is unchanged. This is a measured outer-coat assembly defect in engineered
    cells, not proof of a patient-specific Rab-GEF deficit.
  biological_scale: MOLECULAR
  mechanism_confidence: PROVISIONAL
  protein_complexes:
  - preferred_term: TRAPP complex
    term:
      id: GO:0030008
      label: TRAPP complex
  biological_processes:
  - preferred_term: endoplasmic reticulum to Golgi vesicle-mediated transport
    term:
      id: GO:0006888
      label: endoplasmic reticulum to Golgi vesicle-mediated transport
  downstream:
  - target: Delayed ER-to-Golgi Transport
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      TRAPPC12 deletion produces both reduced outer-coat assembly and delayed
      ER-to-Golgi cargo movement, but the coat defect was not independently
      rescued to prove mediation.
    evidence:
    - reference: PMID:28240221
      reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Overall, this experiment demonstrated biochemically that the COPII
        outer-layer was, indeed, less efficient in being assembled onto COPII vesicles.
      explanation: >-
        Establishes the upstream coat-assembly defect but not that it mediates
        the separately observed transport delay.
    - reference: PMID:28240221
      reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Overall, this experiment demonstrated that TRAPPC12 deletion caused a
        traffic delay at the ER-to-Golgi step
      explanation: >-
        The matched deletion system also shows the downstream result, supporting
        co-occurrence under one perturbation without proving mediation by the
        coat-assembly defect.
  evidence:
  - reference: PMID:28240221
    reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Quantification of three independent experiments showed that the amount of
      Sec31A on COPII vesicles was found to be approximately 3.1% of total input
      cytosol from wildtype HeLa cells, versus 0.68% from TRAPPC12 deleted cells
    explanation: Quantifies the selective outer-coat recruitment defect.
- name: Golgi Fragmentation
  description: >-
    Fibroblasts from affected individuals show a fragmented Golgi apparatus and
    re-expression of wild-type TRAPPC12 rescues that morphology in the founding
    lines. Phe227Val fibroblasts show milder Golgi disorganization, so severity is
    genotype-dependent. Rescue has not been shown for the separately measured
    cargo-transport delay.
  biological_scale: CELLULAR
  mechanism_confidence: ESTABLISHED
  cellular_components:
  - preferred_term: Golgi apparatus
    term:
      id: GO:0005794
      label: Golgi apparatus
  biological_processes:
  - preferred_term: Golgi organization
    term:
      id: GO:0007030
      label: Golgi organization
  downstream:
  - target: Progressive Brain Atrophy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Patient-cell trafficking dysfunction and progressive brain atrophy coexist
      in the disorder, but no neuronal or glial death pathway has been established.
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Fibroblasts derived from all three individuals showed a fragmented Golgi that could be rescued by expression of wild-type TRAPPC12.
    explanation: Directly demonstrates Golgi fragmentation as a TRAPPC12-dependent phenotype.
  - reference: url:https://dergipark.org.tr/en/download/article-file/4364382
    reference_title: "https://dergipark.org.tr/en/download/article-file/4364382"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      the study showed unstable protein expression and mild effects on Golgi and
      ER structures along with alterations in vesicle distribution throughout
      the cytoplasm.
    explanation: Directly reports milder Golgi/ER changes in Phe227Val fibroblasts.
- name: Delayed ER-to-Golgi Transport
  description: >-
    Founding affected-person fibroblasts show delayed protein transport from the
    endoplasmic reticulum to and through the Golgi. Engineered TRAPPC12-null
    cells independently reproduce delayed cargo movement. The 2025 Phe227Val
    fibroblast study used Nile-red lipid-vesicle distribution rather than a
    matched ER-to-Golgi cargo assay, so it cannot establish whether this atomic
    transport phenotype is present or absent for that genotype.
  biological_scale: CELLULAR
  mechanism_confidence: ESTABLISHED
  cellular_components:
  - preferred_term: endoplasmic reticulum
    term:
      id: GO:0005783
      label: endoplasmic reticulum
  - preferred_term: endoplasmic reticulum exit site
    term:
      id: GO:0070971
      label: endoplasmic reticulum exit site
  - preferred_term: Golgi apparatus
    term:
      id: GO:0005794
      label: Golgi apparatus
  biological_processes:
  - preferred_term: endoplasmic reticulum to Golgi vesicle-mediated transport
    term:
      id: GO:0006888
      label: endoplasmic reticulum to Golgi vesicle-mediated transport
  downstream:
  - target: Impaired Oligodendrocyte Differentiation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      TRAPPC12-deficient oligodendroglial cultures show impaired differentiation,
      but transport delay has not been shown to mediate that phenotype.
  - target: Progressive Brain Atrophy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Patient-cell transport delay and brain atrophy coexist, but the neuronal or
      glial injury pathway connecting them is unresolved.
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Protein transport from the endoplasmic reticulum to and through the Golgi was delayed.
    explanation: Directly reports the transport delay in founding patient fibroblasts.
  - reference: PMID:28240221
    reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Overall, this experiment demonstrated that TRAPPC12 deletion caused a
      traffic delay at the ER-to-Golgi step
    explanation: Independently reproduces the transport delay in engineered cells.
- name: Prolonged Mitotic Progression
  description: >-
    Fibroblasts from all three founding individuals took significantly longer
    from prophase to anaphase than control fibroblasts. This is a direct
    patient-cell readout, but no experiment shows that it contributes to neural
    development, brain atrophy, or the clinical encephalopathy.
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  biological_processes:
  - preferred_term: mitotic cell cycle
    term:
      id: GO:0000278
      label: mitotic cell cycle
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      1:II-8, 2:II-1, and 2:II-4 showed a significant lengthening of the time
      from prophase until the onset of anaphase
    explanation: Directly reports prolonged mitotic timing in all three founding fibroblast lines.
- name: Impaired Oligodendrocyte Differentiation
  description: >-
    TRAPPC12 associates with COPII components at endoplasmic-reticulum exit sites
    and interacts with MEA6/cTAGE5. TRAPPC12 deficiency in CG4 cells and cultured
    oligodendrocyte progenitor cells impairs differentiation and maturation. The
    in-vivo hypomyelinating mouse in the same study is an oligodendrocyte-lineage
    Mea6 conditional knockout, not a Trappc12 knockout; it therefore cannot be
    treated as a TRAPPC12 disease animal model.
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  cell_types:
  - preferred_term: oligodendrocyte precursor cell
    term:
      id: CL:0002453
      label: oligodendrocyte precursor cell
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  biological_processes:
  - preferred_term: oligodendrocyte differentiation
    term:
      id: GO:0048709
      label: oligodendrocyte differentiation
  - preferred_term: myelination
    term:
      id: GO:0042552
      label: myelination
  downstream:
  - target: Hyperintensity of cerebral white matter on MRI
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The cell-culture differentiation phenotype is compatible with the reported
      human white-matter MRI signal, but no in-vivo TRAPPC12 model links them.
    evidence:
    - reference: PMID:38439956
      reference_title: Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Here, we found that Trappc12 deficiency in CG4 and oligodendrocyte progenitor cells (OPCs) affects their differentiation and maturation.
      explanation: >-
        Cell-based evidence supports the upstream differentiation defect but not
        a direct route to the human MRI signal.
  evidence:
  - reference: PMID:38439956
    reference_title: Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: 'Here, we found that Trappc12 deficiency in CG4 and oligodendrocyte progenitor cells (OPCs) affects their differentiation and maturation.'
    explanation: >-
      Shows that TRAPPC12 loss impairs oligodendrocyte-progenitor differentiation
      in a cell-based (CG4/OPC) assay.
  - reference: PMID:38439956
    reference_title: Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: We reveal that TRAPPC12 is associated with COPII components at ER exit site
    explanation: Links TRAPPC12 to COPII-dependent secretory trafficking at ER exit sites.
- name: Progressive Brain Atrophy
  description: >-
    Serial imaging in reported children shows progressive cerebral cortical
    atrophy, with variable cerebellar involvement. Pontine and callosal
    hypoplasia and white-matter abnormalities are curated separately as structural
    phenotypes rather than bundled into this single atrophic process.
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  downstream:
  - target: Progressive Encephalopathy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Structural brain loss tracks clinical progression, but the neuronal and
      circuit intermediates producing the encephalopathy are unknown.
  - target: Cerebral cortical atrophy
    causal_link_type: DIRECT
    description: Cerebral cortical atrophy is the principal measured imaging manifestation.
    evidence:
    - reference: PMID:32369837
      reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: He presented with a phenotype including severe progressive cortical atrophy, moderate cerebellar atrophy, epilepsy, and microcephaly, very similar to the previously reported cases.
      explanation: Directly reports progressive cortical atrophy in an affected child.
  - target: Cerebellar atrophy
    causal_link_type: DIRECT
    description: Cerebellar atrophy is a variable measured component of the imaging phenotype.
    evidence:
    - reference: PMID:32369837
      reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The second case, a 9-year-old boy, carried a novel homozygous c.679T > G (p.Phe227Val) variant and presented with mild cortical atrophy, severe cerebellar atrophy, and neither clinically manifest epilepsy nor microcephaly
      explanation: Shows that cerebellar atrophy may predominate over cortical atrophy.
  - target: Microcephaly
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Reduced head growth commonly accompanies the atrophic course, although it
      is not obligate and can be congenital rather than progressive.
  - target: Progressive microcephaly
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Postnatal progressive microcephaly can track brain-volume loss, but this
      temporal route has not been quantified across the small reported cohort.
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: He presented with a phenotype including severe progressive cortical atrophy, moderate cerebellar atrophy, epilepsy, and microcephaly, very similar to the previously reported cases.
    explanation: Documents progressive cortical and cerebellar atrophy on imaging.
- name: Progressive Encephalopathy
  description: >-
    The integrated clinical phenotype is a progressive childhood encephalopathy:
    severe global developmental delay that can evolve to regression,
    microcephaly, hearing impairment, a mixed movement disorder and, frequently,
    epilepsy.
  biological_scale: ORGANISM
  mechanism_confidence: ESTABLISHED
  downstream:
  - target: Global developmental delay
    causal_link_type: DIRECT
    description: Severe developmental impairment is a defining manifestation of the encephalopathy.
  - target: Developmental regression
    causal_link_type: DIRECT
    description: Loss of previously acquired abilities marks clinical progression.
  - target: Hearing impairment
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Hearing loss is characteristic, but its cellular route is unknown.
  - target: Spasticity
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Appendicular spasticity is part of the evolving motor syndrome.
  - target: Axial hypotonia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Axial hypotonia accompanies the mixed motor phenotype.
  - target: Dystonia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Dystonia is a reported hyperkinetic manifestation.
  - target: Myoclonus
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Myoclonus is a reported hyperkinetic manifestation.
  - target: Epilepsy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Epilepsy is variably present and is not required for diagnosis.
  - target: Infantile spasms
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Infantile spasms with hypsarrhythmia occurred in one founding individual.
  - target: Optic atrophy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Optic-pathway atrophy is reported, but the tissue-specific route is unknown.
  - target: Cerebral visual impairment
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Cerebral visual impairment occurred in two founding individuals.
  - target: Dysphagia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Bulbar and motor impairment can produce clinically important dysphagia.
  - target: Gastroesophageal reflux
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Reflux accompanies dysphagia and feeding difficulty in the founding cohort.
  - target: Neurogenic bladder
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Neurogenic bladder was reported in one founding individual.
  - target: Scoliosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Scoliosis is a secondary musculoskeletal complication of severe neurologic impairment.
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Here, we report that variants in TRAPPC12 result in progressive childhood encephalopathy.
    explanation: States the integrated clinical outcome.
phenotypes:
- category: Neurologic
  name: Global developmental delay
  description: >-
    Affected children show severe global or neurodevelopmental delay from infancy.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report two patients carrying TRAPPC12 variants, one previously reported
      and one unknown mutation, with severe neurodevelopmental delay and brain atrophy.
    explanation: Directly reports severe neurodevelopmental delay in two affected children.
- category: Neurologic
  name: Microcephaly
  description: >-
    Microcephaly is a cardinal feature, present in all three individuals of the
    founding discovery cohort. Onset is heterogeneous — congenital in two of the
    three and acquired/postnatal in one — so the unqualified term is used for the
    general finding, with the progressive subset recorded separately below.
    Microcephaly is not fully penetrant: a later-reported patient with a novel
    TRAPPC12 variant lacked it.
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: 'The clinical phenotypes of the three individuals are strikingly similar: severe disability, microcephaly, hearing loss, spasticity, and characteristic brain imaging findings.'
    explanation: >-
      Microcephaly is named as a shared cardinal feature of all three individuals
      in the founding discovery cohort.
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: neither clinically manifest epilepsy nor microcephaly, which were previously considered typical findings in PEBAS with TRAPPC12 mutations
    explanation: >-
      Documents an affected individual without microcephaly, establishing that the
      feature is typical but not obligate.
- category: Neurologic
  name: Progressive microcephaly
  description: >-
    In one founding child, microcephaly was acquired/postnatal and the clinical
    course included arrested head growth. Recorded separately from the general
    Microcephaly entry because this serial-growth qualifier applies to only one
    of the three individuals in the founding cohort.
  phenotype_term:
    preferred_term: Progressive microcephaly
    term:
      id: HP:0000253
      label: Progressive microcephaly
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: microcephaly...persistent epilepsy, and arrested head growth
    explanation: >-
      Directly documents microcephaly followed by arrested head growth in one
      founding child, supporting a progressive rather than merely acquired label.
- category: Neurologic
  name: Hearing impairment
  description: >-
    Hearing impairment is a cardinal feature. The founding cohort failed newborn
    or otoacoustic screening, and measured loss in the two siblings was mixed;
    the evidence does not justify restricting the phenotype to sensorineural loss.
  phenotype_term:
    preferred_term: Hearing impairment
    term:
      id: HP:0000365
      label: Hearing impairment
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Screening for otoacoustic emissions (hearing loss)...failed...failed (40–60
      dB)...failed (40–50 dB)
    explanation: >-
      The three patient columns document failed screening in all three and
      measured hearing loss in the two siblings.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      sister (2:II-1) with profound developmental disability, mixed hearing
      loss...She failed her newborn hearing screen and has documented bilateral
      40–50 dB mixed hearing loss.
    explanation: Directly documents mixed hearing loss in both founding siblings.
- category: Neurologic
  name: Spasticity
  description: Appendicular spasticity, often with spastic tetraplegia, on a background of axial hypotonia.
  phenotype_term:
    preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: 'The clinical phenotypes of the three individuals are strikingly similar: severe disability, microcephaly, hearing loss, spasticity, and characteristic brain imaging findings.'
    explanation: Spasticity in the founding cohort.
- category: Neurologic
  name: Epilepsy
  description: >-
    Seizures/epilepsy are common but not universal; one reported patient with a
    missense genotype lacked clinically manifest epilepsy.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Epilepsy ... yes ... yes
      ... no
    explanation: The founding clinical table reports epilepsy in two of three individuals.
- category: Neurologic
  name: Infantile spasms
  description: >-
    One of the three founding individuals presented at five months with flexion
    seizures and an EEG showing hypsarrhythmia compatible with West syndrome.
  phenotype_term:
    preferred_term: Infantile spasms
    term:
      id: HP:0012469
      label: Infantile spasms
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Initial electroencephalography (EEG) showed hypsarrhythmia...compatible with
      a diagnosis of West syndrome.
    explanation: Directly documents the electroclinical infantile-spasm presentation.
- category: Neuroimaging
  name: Cerebral cortical atrophy
  description: Progressive cerebral cortical atrophy on serial imaging.
  phenotype_term:
    preferred_term: Cerebral cortical atrophy
    term:
      id: HP:0002120
      label: Cerebral cortical atrophy
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: He presented with a phenotype including severe progressive cortical atrophy, moderate cerebellar atrophy, epilepsy, and microcephaly, very similar to the previously reported cases.
    explanation: Progressive cortical atrophy on imaging.
- category: Neuroimaging
  name: Cerebellar atrophy
  description: Cerebellar atrophy, which can be severe, accompanies the cortical changes.
  phenotype_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The second case, a 9-year-old boy, carried a novel homozygous c.679T > G (p.Phe227Val) variant and presented with mild cortical atrophy, severe cerebellar atrophy
    explanation: Severe cerebellar atrophy documented.
- category: Neuroimaging
  name: Hypoplasia of the pons
  description: Pontine (brainstem) hypoplasia is part of the characteristic imaging signature.
  phenotype_term:
    preferred_term: Hypoplasia of the pons
    term:
      id: HP:0012110
      label: Hypoplasia of the pons
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Review of brain imaging for all three affected individuals revealed
      remarkably similar findings, including pons hypoplasia, agenesis of the
      corpus callosum, and marked brain atrophy documented by scans from 3 days to
      11 months of age
    explanation: >-
      Directly reports pons hypoplasia in the shared founding imaging pattern.
- category: Neuroimaging
  name: Hyperintensity of cerebral white matter on MRI
  description: >-
    The founding MRIs show increased T2 signal in cortical white matter. The
    authors interpreted this as decreased myelination, but the observed human
    phenotype is curated as the MRI signal rather than inferred delayed myelination.
  phenotype_term:
    preferred_term: Hyperintensity of cerebral white matter on MRI
    term:
      id: HP:0030890
      label: Hyperintensity of cerebral white matter on MRI
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      T2 signal is increased in the white matter, consistent with decreased myelination.
    explanation: >-
      Directly reports the MRI signal and preserves the paper's interpretation
      without promoting it to a distinct delayed-myelination HPO phenotype.
- category: Neurologic
  name: Developmental regression
  description: >-
    Loss of previously acquired skills accompanies the progressive course. Reported
    in all three individuals of the founding discovery cohort (Milev et al., 2017);
    documented in the full-text case descriptions rather than the abstract, so it
    is recorded here without a quotable abstract snippet.
  phenotype_term:
    preferred_term: Developmental regression
    term:
      id: HP:0002376
      label: Developmental regression
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Regression ... yes ...
      yes ... yes
    explanation: The founding clinical table reports regression in all three individuals.
- category: Neurologic
  name: Axial hypotonia
  description: >-
    Truncal (axial) hypotonia is present from infancy and coexists with the
    appendicular spasticity. Reported in all three founding individuals (Milev et
    al., 2017); documented in the full text rather than the abstract.
  phenotype_term:
    preferred_term: Axial hypotonia
    term:
      id: HP:0008936
      label: Axial hypotonia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Truncal hypotonia ...
      yes ... yes ... yes
    explanation: The founding clinical table reports truncal hypotonia in all three individuals.
- category: Neurologic
  name: Dystonia
  description: >-
    A combined dystonia and/or myoclonus category was positive in all three
    founding individuals, but the table does not resolve how many had dystonia
    specifically.
  phenotype_term:
    preferred_term: Dystonia
    term:
      id: HP:0001332
      label: Dystonia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Dystonia and/or
      myoclonus ... yes ... yes ... yes
    explanation: >-
      The founding table reports the combined movement-disorder category in all
      three individuals but does not separate dystonia from myoclonus per person.
- category: Neurologic
  name: Myoclonus
  description: >-
    A combined dystonia and/or myoclonus category was positive in all three
    founding individuals, but the table does not resolve how many had myoclonus
    specifically.
  phenotype_term:
    preferred_term: Myoclonus
    term:
      id: HP:0001336
      label: Myoclonus
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Dystonia and/or
      myoclonus ... yes ... yes ... yes
    explanation: >-
      The founding table reports the combined movement-disorder category in all
      three individuals but does not separate myoclonus from dystonia per person.
- category: Ophthalmologic
  name: Optic atrophy
  description: >-
    Optic atrophy was recorded in one founding individual. All three had a broader
    eye or vision abnormality, but the other two instead had optic-nerve/cup-disk
    findings with cortical visual impairment.
  phenotype_term:
    preferred_term: Optic atrophy
    term:
      id: HP:0000648
      label: Optic atrophy
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Eyes and/or vision...optic atrophy...mild optic nerve pallor and cortical
      visual impairment...enlarged cup/disk ratio, cortical visual impairment
    explanation: >-
      The three patients show optic atrophy in one individual and distinct
      eye/vision abnormalities in the other two.
- category: Ophthalmologic
  name: Cerebral visual impairment
  description: >-
    Cortical/cerebral visual impairment was reported in two of the three founding
    individuals, distinct from the optic atrophy in the third.
  phenotype_term:
    preferred_term: Cerebral visual impairment
    term:
      id: HP:0100704
      label: Cerebral visual impairment
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Eyes and/or vision...optic atrophy...mild optic nerve pallor and cortical
      visual impairment...enlarged cup/disk ratio, cortical visual impairment
    explanation: >-
      The three patients show cortical visual impairment in two individuals,
      distinct from optic atrophy in the third.
- category: Gastrointestinal
  name: Dysphagia
  description: >-
    The founding table records a combined "dysphagia and/or reflux" finding in
    all three individuals, with two gastrostomy dependent. It does not resolve
    how many had dysphagia specifically.
  phenotype_term:
    preferred_term: Dysphagia
    term:
      id: HP:0002015
      label: Dysphagia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Dysphagia and/or reflux...yes...yes (G-tube dependent)...yes (G-tube dependent)
    explanation: >-
      Supports a feeding/swallowing abnormality but the disjunctive table row
      does not establish dysphagia separately in all three individuals.
- category: Gastrointestinal
  name: Gastroesophageal reflux
  description: >-
    The founding table records a combined "dysphagia and/or reflux" finding in
    all three individuals, with two gastrostomy dependent. It does not resolve
    how many had gastroesophageal reflux specifically.
  phenotype_term:
    preferred_term: Gastroesophageal reflux
    term:
      id: HP:0002020
      label: Gastroesophageal reflux
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Dysphagia and/or reflux...yes...yes (G-tube dependent)...yes (G-tube dependent)
    explanation: >-
      Supports a feeding/reflux abnormality but the disjunctive table row does
      not establish reflux separately in all three individuals.
- category: Genitourinary
  name: Neurogenic bladder
  description: Neurogenic bladder developed in one of the three founding individuals.
  phenotype_term:
    preferred_term: Neurogenic bladder
    term:
      id: HP:0000011
      label: Neurogenic bladder
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: 2:II-1 developed seizures, increasing spasticity, and a neurogenic bladder.
    explanation: Directly documents neurogenic bladder in one affected sibling.
- category: Musculoskeletal
  name: Scoliosis
  description: >-
    Scoliosis develops in the context of severe hypotonia and neurologic
    impairment. Reported in all three founding individuals (Milev et al., 2017);
    documented in the full text rather than the abstract.
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Features ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Scoliosis ... yes ...
      yes ... yes
    explanation: The founding clinical table reports scoliosis in all three individuals.
- category: Neuroimaging
  name: Hypoplasia of the corpus callosum
  description: >-
    Severe thinning with absence of posterior callosal segments occurred in two
    founding individuals; complete agenesis is curated separately.
  phenotype_term:
    preferred_term: Hypoplasia of the corpus callosum
    term:
      id: HP:0002079
      label: Hypoplasia of the corpus callosum
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Agenesis of the corpus callosum...severe thinning with absent posterior
      body, isthmus, and splenium...complete absence...severe thinning with
      absent posterior body, isthmus, and splenium
    explanation: >-
      Directly reports the partial callosal defect, distinct from complete agenesis.
- category: Neuroimaging
  name: Agenesis of corpus callosum
  description: >-
    One founding individual had complete callosal agenesis; the other two had
    severe thinning with absent posterior segments.
  phenotype_term:
    preferred_term: Agenesis of corpus callosum
    term:
      id: HP:0001274
      label: Agenesis of corpus callosum
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Agenesis of the corpus callosum...severe thinning with absent posterior
      body, isthmus, and splenium...complete absence...severe thinning with
      absent posterior body, isthmus, and splenium
    explanation: >-
      The patient columns document complete absence in one individual and severe
      partial absence/thinning in the other two.
- category: Neuroimaging
  name: Widened subarachnoid space
  description: Prominent extra-axial spaces were recorded in all three founding MRIs.
  phenotype_term:
    preferred_term: Widened subarachnoid space
    term:
      id: HP:0012704
      label: Widened subarachnoid space
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Prominent extra-axial
      spaces ... yes ... yes ... yes
    explanation: The founding MRI table records this feature in all three individuals.
- category: Neuroimaging
  name: Simplified gyral pattern
  description: Simplified frontal gyri were recorded in all three founding MRIs.
  phenotype_term:
    preferred_term: Simplified gyral pattern
    term:
      id: HP:0009879
      label: Simplified gyral pattern
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Simplified frontal
      gyri ... yes ... yes ... yes
    explanation: The founding MRI table records this feature in all three individuals.
- category: Neuroimaging
  name: Cerebellar hypoplasia
  description: >-
    Mild cerebellar hypoplasia was recorded in two of three founding individuals;
    this developmental finding is distinct from later-reported cerebellar atrophy.
  phenotype_term:
    preferred_term: Cerebellar hypoplasia
    term:
      id: HP:0001321
      label: Cerebellar hypoplasia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Cerebellar hypoplasia
      ... no ... mild ... mild
    explanation: The founding MRI table reports mild hypoplasia in two individuals.
- category: Neuroimaging
  name: Hypoplastic optic chiasm
  description: A small optic chiasm was recorded in two of three founding MRIs.
  phenotype_term:
    preferred_term: Hypoplastic optic chiasm
    term:
      id: HP:0034311
      label: Hypoplastic optic chiasm
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Small optic chiasm ...
      yes ... yes ... no
    explanation: The founding MRI table reports a small optic chiasm in two individuals.
- category: Neuroimaging
  name: Ventriculomegaly
  description: >-
    Progressive ventriculomegaly beyond that expected for cortical volume loss
    occurred in one founding child without signs of raised intracranial pressure.
    Fetal hydrocephalus is curated separately.
  phenotype_term:
    preferred_term: Ventriculomegaly
    term:
      id: HP:0002119
      label: Ventriculomegaly
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      2:II-4 also has progressive ventriculomegaly beyond what would be expected
      for cortical volume loss but did not have overt symptoms of increased
      intracranial pressure.
    explanation: Directly reports progressive ventriculomegaly in a founding child.
- category: Neurologic
  name: Hydrocephalus
  description: >-
    At the most severe (fetal/lethal) end of the TRAPPC12 spectrum, compound
    heterozygous variants were associated with recurrent fetal hydrocephaly and
    pregnancy loss; the cited report describes a possible developmental mechanism.
  phenotype_term:
    preferred_term: Hydrocephalus
    term:
      id: HP:0000238
      label: Hydrocephalus
  evidence:
  - reference: PMID:32347653
    reference_title: Hydrocephaly associated with compound heterozygous alterations in TRAPPC12.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: 'CONCLUSION: Compound heterozygous variants in TRAPPC12, which encodes a protein involved in Golgi trafficking and mitosis, may disrupt normal brain embryogenesis leading to hydrocephalus and recurrent pregnancy loss.'
    explanation: >-
      Documents the reported association while preserving the authors' cautious
      "may disrupt" causal language.
imaging_findings:
- name: Progressive cerebral cortical atrophy on brain MRI
  modality: MRI
  description: >-
    Serial imaging can show progressive cortical volume loss. Severity is
    variable, and mild cortical atrophy can coexist with severe cerebellar
    atrophy.
  phenotype_term:
    preferred_term: Cerebral cortical atrophy
    term:
      id: HP:0002120
      label: Cerebral cortical atrophy
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: He presented with a phenotype including severe progressive cortical atrophy, moderate cerebellar atrophy, epilepsy, and microcephaly, very similar to the previously reported cases.
    explanation: Directly reports severe progressive cortical atrophy in an affected child.
- name: Cerebellar atrophy on brain MRI
  modality: MRI
  description: >-
    Cerebellar volume loss ranges from moderate to severe and may predominate over
    cortical atrophy in some molecularly confirmed individuals.
  phenotype_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The second case, a 9-year-old boy, carried a novel homozygous c.679T > G (p.Phe227Val) variant and presented with mild cortical atrophy, severe cerebellar atrophy, and neither clinically manifest epilepsy nor microcephaly
    explanation: Directly documents the cortical-versus-cerebellar variability.
- name: Pontine hypoplasia on brain MRI
  modality: MRI
  description: >-
    Severe pons hypoplasia was part of the shared founding neuroimaging pattern.
  phenotype_term:
    preferred_term: Hypoplasia of the pons
    term:
      id: HP:0012110
      label: Hypoplasia of the pons
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Review of brain imaging for all three affected individuals revealed
      remarkably similar findings, including pons hypoplasia, agenesis of the
      corpus callosum, and marked brain atrophy documented by scans from 3 days to
      11 months of age
    explanation: Directly reports pons hypoplasia in the founding imaging review.
- name: Hypoplastic corpus callosum on brain MRI
  modality: MRI
  description: >-
    Severe thinning or hypoplasia of the corpus callosum has been reported as part
    of the structural imaging phenotype.
  phenotype_term:
    preferred_term: Hypoplasia of the corpus callosum
    term:
      id: HP:0002079
      label: Hypoplasia of the corpus callosum
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Agenesis of the corpus callosum...severe thinning with absent posterior
      body, isthmus, and splenium...complete absence...severe thinning with
      absent posterior body, isthmus, and splenium
    explanation: Directly reports severe partial callosal absence in two founding MRIs.
- name: Agenesis of the corpus callosum on brain MRI
  modality: MRI
  description: >-
    Complete callosal agenesis occurred in one founding individual and severe
    partial agenesis/thinning in the other two.
  phenotype_term:
    preferred_term: Agenesis of corpus callosum
    term:
      id: HP:0001274
      label: Agenesis of corpus callosum
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Agenesis of the corpus callosum...severe thinning with absent posterior
      body, isthmus, and splenium...complete absence...severe thinning with
      absent posterior body, isthmus, and splenium
    explanation: >-
      The patient columns document complete absence in one MRI and severe
      partial absence/thinning in the other two.
- name: Hyperintensity of cerebral white matter on MRI
  modality: MRI
  description: >-
    Increased cortical white-matter T2 signal was present in the founding imaging
    series and interpreted by its authors as decreased myelination.
  phenotype_term:
    preferred_term: Hyperintensity of cerebral white matter on MRI
    term:
      id: HP:0030890
      label: Hyperintensity of cerebral white matter on MRI
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: T2 signal is increased in the white matter, consistent with decreased myelination.
    explanation: Directly reports the observed MRI signal and the authors' interpretation.
- name: Prominent extra-axial spaces on brain MRI
  modality: MRI
  description: Prominent extra-axial spaces were recorded in all three founding MRIs.
  phenotype_term:
    preferred_term: Widened subarachnoid space
    term:
      id: HP:0012704
      label: Widened subarachnoid space
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Prominent extra-axial
      spaces ... yes ... yes ... yes
    explanation: The founding MRI table records this finding in all three individuals.
- name: Simplified frontal gyri on brain MRI
  modality: MRI
  description: Simplified frontal gyri were recorded in all three founding MRIs.
  phenotype_term:
    preferred_term: Simplified gyral pattern
    term:
      id: HP:0009879
      label: Simplified gyral pattern
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Simplified frontal
      gyri ... yes ... yes ... yes
    explanation: The founding MRI table records this finding in all three individuals.
- name: Cerebellar hypoplasia on brain MRI
  modality: MRI
  description: Mild cerebellar hypoplasia was recorded in two founding MRIs.
  phenotype_term:
    preferred_term: Cerebellar hypoplasia
    term:
      id: HP:0001321
      label: Cerebellar hypoplasia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Cerebellar hypoplasia
      ... no ... mild ... mild
    explanation: The founding MRI table records mild hypoplasia in two individuals.
- name: Hypoplastic optic chiasm on brain MRI
  modality: MRI
  description: A small optic chiasm was recorded in two founding MRIs.
  phenotype_term:
    preferred_term: Hypoplastic optic chiasm
    term:
      id: HP:0034311
      label: Hypoplastic optic chiasm
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MRI Feature ... 1:II-8 ... 2:II-1 ... 2:II-4 ... Small optic chiasm ...
      yes ... yes ... no
    explanation: The founding MRI table records a small optic chiasm in two individuals.
- name: Fetal hydrocephalus on prenatal ultrasound
  modality: ULTRASOUND
  description: >-
    Recurrent fetal hydrocephalus was detected by prenatal ultrasound in three
    consecutive pregnancies in one family and represents a severe prenatal
    presentation associated with compound-heterozygous TRAPPC12 variants.
  phenotype_term:
    preferred_term: Hydrocephalus
    term:
      id: HP:0000238
      label: Hydrocephalus
  evidence:
  - reference: PMID:32347653
    reference_title: Hydrocephaly associated with compound heterozygous alterations in TRAPPC12.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Three consecutive pregnancies of an unrelated couple were found by ultrasound to carry fetuses with hydrocephaly.
    explanation: Directly documents the prenatal modality and recurrent finding.
diagnosis:
- name: Exome or Genome Sequencing
  description: >-
    Diagnosis is molecular. Because the clinical picture (progressive
    encephalopathy, brain atrophy, spasticity, hearing loss) is shared with many
    other early-onset neurodegenerative disorders and no biochemical marker is
    available, exome sequencing has been used in reported cases. This is a
    reported diagnostic route rather than a disease-specific testing guideline;
    genome sequencing or a broad neurodevelopmental panel may also be considered
    according to local practice and prior results.
  diagnosis_term:
    preferred_term: whole exome sequencing
    term:
      id: NCIT:C101295
      label: Whole Exome Sequencing
  results: >-
    Biallelic (homozygous or compound heterozygous) pathogenic TRAPPC12 variants
    establish the diagnosis. Reported alleles include missense, frameshift, and
    splice-affecting changes.
  presence: Diagnostic when biallelic pathogenic TRAPPC12 variants are identified
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: whole-exome sequencing was performed, followed by Sanger sequencing for verification
    explanation: >-
      Documents the diagnostic route actually used to establish TRAPPC12
      genotypes in reported patients — exome sequencing with Sanger confirmation.
- name: Sanger Confirmation of the Candidate Variant
  description: >-
    Targeted Sanger sequencing is used to confirm the candidate TRAPPC12 variant
    identified on exome sequencing and, where samples are available, to
    demonstrate biallelic inheritance by parental segregation.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  results: >-
    Confirms the exome call and, with parental samples, establishes that the two
    variants are in trans.
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: whole-exome sequencing was performed, followed by Sanger sequencing for verification
    explanation: Sanger verification of the exome-identified variant is the reported confirmatory step.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the father carries the frameshift variant and the mother carries the
      missense variant. Neither of the unaffected siblings carries both variants.
    explanation: >-
      Directly supports parental segregation of the two variants and their joint
      presence in the affected siblings.
- name: Brain Magnetic Resonance Imaging
  description: >-
    Cranial imaging is the principal phenotyping investigation and supplies the
    findings that make the disorder recognizable: progressive cortical atrophy,
    cerebellar atrophy, pontine hypoplasia, and abnormal white matter. It is
    supportive rather than diagnostic — the imaging findings direct sequencing,
    they do not replace it.
  diagnosis_term:
    preferred_term: brain magnetic resonance imaging
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  results: >-
    Progressive cerebral cortical and cerebellar atrophy with abnormal white
    matter; severity of the cortical versus cerebellar component varies between
    patients.
  notes: >-
    Imaging findings are more variable than the founding cohort suggested, so a
    single atypical scan does not exclude the diagnosis.
  evidence:
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Standard clinical examination and cranial imaging studies were performed in these two unrelated patients.
    explanation: Cranial imaging is part of the standard diagnostic workup in reported patients.
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our findings suggest that clinical and brain imaging findings might be more variable than previously anticipated
    explanation: Supports the caveat that imaging is supportive and variable rather than pathognomonic.
differential_diagnoses:
- name: Neurodevelopmental disorder with epilepsy, spasticity, and brain atrophy
  description: >-
    Biallelic TRAPPC4 disease is a close molecular and clinical TRAPPopathy mimic,
    with early developmental impairment, microcephaly, spasticity, epilepsy, and
    progressive brain atrophy.
  disease_term:
    preferred_term: neurodevelopmental disorder with epilepsy, spasticity, and brain atrophy
    term:
      id: MONDO:0032894
      label: neurodevelopmental disorder with epilepsy, spasticity, and brain atrophy
  distinguishing_features:
  - Biallelic pathogenic TRAPPC12 variants establish TRAPPC12-related encephalopathy.
  - Biallelic pathogenic TRAPPC4 variants establish the TRAPPC4-related disorder.
  - Pontine hypoplasia and hearing impairment particularly support the TRAPPC12 phenotype, but clinical overlap prevents exclusion by examination alone.
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Variants in several other genes encoding members of the TRAPP complex have been associated with overlapping clinical presentations, indicating shared and distinct functions for each complex member.
    explanation: >-
      Establishes the overlapping TRAPPopathy differential in general; molecular
      testing is required to distinguish the causal subunit.
- name: Pontocerebellar hypoplasia
  description: >-
    Genetic pontocerebellar hypoplasias can overlap through infantile developmental
    impairment, microcephaly, abnormal tone, seizures, and pontine/cerebellar
    abnormalities.
  disease_term:
    preferred_term: pontocerebellar hypoplasia
    term:
      id: MONDO:0020135
      label: pontocerebellar hypoplasia
  distinguishing_features:
  - The progressive cerebral cortical atrophy, hearing loss, and patient-cell Golgi phenotype support TRAPPC12 disease but are not individually pathognomonic.
  - Molecular identification of the causal gene is required because imaging patterns overlap.
  notes: >-
    This is a syndrome-level differential; individual pontocerebellar hypoplasia
    genes should be selected according to imaging, systemic findings, and ancestry.
treatments:
- name: Antiseizure pharmacotherapy
  description: >-
    Epilepsy may be treated symptomatically with antiseizure medication. No
    TRAPPC12-specific drug, comparative response series, or disease-modifying
    therapy was identified.
  action_category: THERAPEUTIC
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: anticonvulsant agent
      term:
        id: NCIT:C264
        label: Anticonvulsant Agent
  target_phenotypes:
  - preferred_term: Epilepsy
    term:
      id: HP:0001250
      label: Seizure
  notes: >-
    This is phenotype-directed supportive practice; the cited case literature
    establishes epilepsy but does not provide treatment-effect evidence.
- name: Rehabilitation and supportive therapy
  description: >-
    Multidisciplinary supportive care including physical therapy, occupational
    therapy and speech/communication therapy for the severe motor and
    developmental impairment.
  action_category: THERAPEUTIC
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Physical Therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  notes: >-
    Reasonable supportive care inferred from the severe motor phenotype; no
    TRAPPC12-specific rehabilitation outcome study was identified.
- name: Nutritional and feeding support
  description: >-
    Management of dysphagia and gastroesophageal reflux with feeding support,
    including enteral/tube feeding when oral intake is unsafe.
  action_category: THERAPEUTIC
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Nutritional Support
    term:
      id: NCIT:C15433
      label: Nutritional Support
  notes: >-
    Phenotype-directed supportive practice; no comparative feeding-intervention
    evidence is available for this ultra-rare disorder.
- name: Genetic counseling
  description: >-
    Genetic counseling for families given autosomal recessive inheritance and the
    25% recurrence risk in future pregnancies.
  action_category: COUNSELING_INFORMATIONAL
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  notes: >-
    The recurrence estimate follows standard autosomal recessive segregation and
    presumes both parents carry the relevant familial allele.
genetic:
- name: TRAPPC12
  gene_term:
    preferred_term: TRAPPC12
    term:
      id: hgnc:24284
      label: TRAPPC12
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  presence: Biallelic pathogenic or likely pathogenic variants
  notes: >-
    TRAPPC12 (aliases TTC15, TRAMM, CGI-87) lies at 2p25.3 and encodes a
    TRAPPIII-specific subunit of the TRAPP membrane-tethering complex. Reported
    disease alleles include frameshift variants (c.145delG p.Glu49Argfs, c.360dupC
    p.Glu121Argfs), missense variants (c.1880C>T p.Ala627Val, c.679T>G
    p.Phe227Val), a premature-termination frameshift (c.954del), and a distinct
    splice-altering variant (c.1677+5G>A) in the fetal-hydrocephaly family. A
    deep-intronic variant was subsequently evaluated with RNA sequencing. Because
    database classifications and counts change over time, this entry does not
    present a fixed ClinVar pathogenic-variant count.
  inheritance:
  - name: Autosomal recessive
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:28777934
      reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Three individuals from two unrelated families have either a homozygous
        deleterious variant...or compound-heterozygous variants
      explanation: >-
        The founding report documents both homozygous and compound-heterozygous
        disease genotypes, supporting autosomal recessive inheritance.
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Here, we report that variants in TRAPPC12 result in progressive childhood encephalopathy.
    explanation: The founding gene-disease association.
  - reference: PMID:32369837
    reference_title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Biallelic mutations in the TRAPPC12 gene are responsible for early-onset progressive encephalopathy with brain atrophy and spasticity (PEBAS).
    explanation: Independent confirmation of the biallelic gene-disease relationship.
  - reference: PMID:32347653
    reference_title: Hydrocephaly associated with compound heterozygous alterations in TRAPPC12.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The variant from the father (c.954del) leads to a premature termination of the transcript; the variant from the mother (c.1677+5G>A) affects a splice site which leads to aberrant splicing of the TRAPPC12 transcript.
    explanation: >-
      Distinguishes the c.954del premature-termination allele from the
      c.1677+5G>A splice-altering allele.
experimental_models:
- name: Affected-person fibroblast Golgi and secretory-transport model
  description: >-
    Primary fibroblasts from all three founding individuals lack full-length
    TRAPPC12, reproduce fragmented Golgi morphology and delayed ER-to-Golgi
    transport, and show prolonged prophase-to-anaphase timing. Re-expression of
    wild-type TRAPPC12 rescues Golgi fragmentation; rescue of the separate
    transport and mitotic readouts was not reported.
  experimental_model_type: PRIMARY_CELL_CULTURE
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: Primary dermal fibroblasts from affected individuals and controls
  culture_system: >-
    Fibroblast monolayer with immunoblotting, Golgi morphology,
    cargo-transport, complementation, and live-cell mitotic-timing assays
  publication: PMID:28777934
  modeled_mechanisms:
  - target: Biallelic TRAPPC12 Dysfunction
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      The affected-person lines directly reproduce absence of full-length
      TRAPPC12 for both the homozygous and compound-heterozygous genotypes.
    limitations: >-
      Fibroblast protein abundance does not by itself define the consequences in
      neural lineages or the residual activity of every allele.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
      reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        As expected for the homozygous truncating variant in 1:II-8, western blot
        analysis failed to detect any full-length...Unexpectedly, the full-length
        protein was also absent in 2:II-1 and 2:II-4
      explanation: >-
        Directly demonstrates the proximal protein-loss phenotype in all three
        founding fibroblast lines.
  - target: Golgi Fragmentation
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Directly reproduces fragmented Golgi morphology, with genetic
      complementation tying that readout to TRAPPC12 deficiency.
    limitations: >-
      Fibroblasts do not reproduce neural cell-type vulnerability, progressive
      brain atrophy, or the clinical encephalopathy.
    evidence:
    - reference: PMID:28777934
      reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Fibroblasts derived from all three individuals showed a fragmented Golgi that could be rescued by expression of wild-type TRAPPC12.
      explanation: >-
        Patient-derived cells and wild-type rescue give this model high fidelity
        for the proximal Golgi morphology.
  - target: Delayed ER-to-Golgi Transport
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Directly reproduces delayed cargo movement from the ER to and through the
      Golgi in all three founding affected-person lines.
    limitations: >-
      The transport delay was measured in fibroblasts and was not shown to be
      rescued by wild-type TRAPPC12 or to mediate neural degeneration.
    evidence:
    - reference: PMID:28777934
      reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Protein transport from the endoplasmic reticulum to and through the Golgi was delayed.
      explanation: Directly reports the separate transport-delay readout.
  - target: Prolonged Mitotic Progression
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      All three affected-person fibroblast lines show significantly prolonged
      progression from prophase to anaphase.
    limitations: >-
      The readout is direct, but its contribution to human neural development
      and encephalopathy remains unknown.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
      reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        1:II-8, 2:II-1, and 2:II-4 showed a significant lengthening of the time
        from prophase until the onset of anaphase
      explanation: Directly reports prolonged mitotic timing in all three lines.
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      As expected for the homozygous truncating variant in 1:II-8, western blot
      analysis failed to detect any full-length...Unexpectedly, the full-length
      protein was also absent in 2:II-1 and 2:II-4
    explanation: Defines the affected-person model and its proximal protein-loss readout.
- name: Homozygous Phe227Val affected-person fibroblast model
  description: >-
    Primary skin fibroblasts from one affected individual homozygous for
    c.679T>G (p.Phe227Val) show absent or highly reduced mature TRAPPC12, mild
    Golgi disorganization, slight ER enlargement, and altered neutral-lipid
    vesicle distribution. The authors described persisting vesicle trafficking,
    but Nile-red distribution is not a direct ER-to-Golgi cargo assay and cannot
    establish presence or absence of the atomic transport-delay phenotype.
  experimental_model_type: PRIMARY_CELL_CULTURE
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: >-
    Primary skin fibroblasts from one affected individual homozygous for
    c.679T>G (p.Phe227Val), compared with the CCD1079Sk control cell line
  culture_system: >-
    Fibroblast monolayer with TRAPPC12 immunoblotting, Golgi and ER
    immunofluorescence, and Nile-red neutral-lipid distribution imaging
  publication: DOI:10.26650/experimed.1584823
  modeled_mechanisms:
  - target: Biallelic TRAPPC12 Dysfunction
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      Directly tests the Phe227Val genotype and reproduces absent or highly
      reduced mature TRAPPC12 protein in affected-person fibroblasts.
    limitations: >-
      The study uses cells from one affected individual and one control line;
      residual protein identity and allele-specific function remain incompletely
      resolved.
    evidence:
    - reference: url:https://dergipark.org.tr/en/download/article-file/4364382
      reference_title: "https://dergipark.org.tr/en/download/article-file/4364382"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Protein expression analysis revealed an absence of the mature TRAPPC12
        protein and the uncharacterized protein fragment (CGI-87) via mutation
        compared with the wild-type.
      explanation: Directly reports the Phe227Val fibroblast protein phenotype.
  - target: Golgi Fragmentation
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      Reproduces a milder Golgi disorganization and slight ER enlargement rather
      than the marked founding-cell phenotype.
    limitations: >-
      The organelle analysis included only one patient line, one control line,
      and 12 imaged cells per group, limiting precision and generalizability.
    evidence:
    - reference: url:https://dergipark.org.tr/en/download/article-file/4364382
      reference_title: "https://dergipark.org.tr/en/download/article-file/4364382"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        the study showed unstable protein expression and mild effects on Golgi and
        ER structures along with alterations in vesicle distribution throughout
        the cytoplasm.
      explanation: Directly characterizes the milder organelle phenotype.
  evidence:
  - reference: url:https://dergipark.org.tr/en/download/article-file/4364382
    reference_title: "https://dergipark.org.tr/en/download/article-file/4364382"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      More functional analyses are necessary to confirm these outcomes.
    explanation: >-
      The authors explicitly limit interpretation of this single-person
      fibroblast study.
- name: TRAPPC12-deleted human cell-line COPII trafficking model
  description: >-
    CRISPR deletion of TRAPPC12 in HeLa and HEK293T-derived cell systems was used
    to study TRAPPIII interaction with Sec13/Sec31, COPII outer-coat assembly,
    ERGIC/Golgi organization, and ER-to-Golgi cargo transport.
  experimental_model_type: CELL_LINE
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: Engineered HeLa and HEK293T cell lines
  culture_system: Monolayer CRISPR-deletion, interaction, imaging, and cargo-transport assays
  publication: PMID:28240221
  modeled_mechanisms:
  - target: Reduced COPII Outer-Coat Assembly
    relationship: PERTURBS
    fidelity: MODERATE
    description: >-
      Direct genetic deletion tests how TRAPPC12 affects COPII outer-coat
      recruitment and early secretory-pathway organization.
    limitations: >-
      The model uses transformed cell lines and a complete engineered deletion,
      not patient-derived neural cells or specific human disease alleles.
    evidence:
    - reference: PMID:28240221
      reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Quantification of three independent experiments showed that the amount of
        Sec31A on COPII vesicles was found to be approximately 3.1% of total input
        cytosol from wildtype HeLa cells, versus 0.68% from TRAPPC12 deleted cells
      explanation: Directly quantifies reduced COPII outer-coat assembly after deletion.
  - target: Golgi Fragmentation
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Reproduces dispersed ERGIC and, to a lesser extent, Golgi organization.
    limitations: >-
      The engineered cancer-cell model does not establish tissue selectivity or
      progression in the nervous system.
    evidence:
    - reference: PMID:28240221
      reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: In cells deleted with TRAPPC12, ERGIC and to a lesser extent, the Golgi became dispersed.
      explanation: Directly reports the modeled morphology readout.
  - target: Delayed ER-to-Golgi Transport
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Reproduces delayed ER-to-Golgi transport independently of the founding
      affected-person fibroblast system.
    limitations: >-
      The complete deletion in transformed cells differs from patient alleles,
      and no complementation assay showed that rescue of this readout reverses
      the disease-associated cellular phenotype.
    evidence:
    - reference: PMID:28240221
      reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: ER-to-Golgi transport was also delayed.
      explanation: Directly reports the separate transport readout.
  evidence:
  - reference: PMID:28240221
    reference_title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: In this study, we studied the function of TRAPPIII in early secretory pathway using a TRAPPIII-specific subunit, TRAPPC12, as starting point.
    explanation: Defines the experimental purpose and TRAPPC12-centered model system.
- name: TRAPPC12-knockout rat CG4 oligodendroglial cell-line model
  description: >-
    CRISPR-Cas9 knockout of Trappc12 in the rat-derived CG4 oligodendrocyte
    progenitor cell line reduced cell complexity after differentiation.
  experimental_model_type: CELL_LINE
  organism:
    preferred_term: rat
    term:
      id: NCBITaxon:10116
      label: Rattus norvegicus
  cell_source: Rat-derived CG4 oligodendrocyte progenitor cell line
  culture_system: >-
    CRISPR-Cas9 knockout single-clone CG4 cultures followed through induced
    oligodendroglial differentiation and morphology analysis
  publication: PMID:38439956
  modeled_mechanisms:
  - target: Impaired Oligodendrocyte Differentiation
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      Trappc12 knockout directly reduces the differentiated morphology and
      complexity of the CG4 lineage.
    limitations: >-
      CG4 is a rat-derived immortalized progenitor line, not patient-derived
      neural tissue, and cell complexity does not establish the mechanism of the
      human MRI phenotype.
    evidence:
    - reference: url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML
      reference_title: "Summary"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        To determine whether TRAPPC12 plays a role in oligodendrocyte development,
        we eliminated...from CG4 cells (an oligodendrocyte progenitor cell line)
        using CRISPR Cas9 technology
      explanation: Defines the rat CG4 CRISPR-knockout model.
  evidence:
  - reference: url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML
    reference_title: "Summary"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The cell complexity was significantly decreased in...KO cells 4 days after
      differentiation
    explanation: Directly reports the differentiated CG4-cell phenotype.
- name: TRAPPC12-knockdown primary mouse oligodendrocyte-progenitor model
  description: >-
    Lentiviral shRNA knockdown of Trappc12 in primary neonatal mouse
    oligodendrocyte progenitor cells reduced the proportion of MBP-positive
    cells after six days of differentiation.
  experimental_model_type: PRIMARY_CELL_CULTURE
  organism:
    preferred_term: mouse
    term:
      id: NCBITaxon:10090
      label: Mus musculus
  cell_source: Primary OPCs isolated from postnatal-day 0 to 3 mouse brains
  culture_system: >-
    Primary mouse OPC monolayer with lentiviral Trappc12 shRNA knockdown and
    MBP immunostaining after induced differentiation
  publication: PMID:38439956
  modeled_mechanisms:
  - target: Impaired Oligodendrocyte Differentiation
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      Trappc12 knockdown reduces the MBP-positive differentiated-cell fraction
      in a primary oligodendrocyte-lineage culture.
    limitations: >-
      The neonatal mouse culture is not patient-derived, shRNA may leave residual
      Trappc12 or have off-target effects, and no human white-matter imaging
      correlate was measured.
    evidence:
    - reference: url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML
      reference_title: "Summary"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        We also used shRNA packaged in lentivirus to knock down Trappc12 expression
        in primary cultured mouse OPCs
      explanation: Defines the primary mouse OPC perturbation system.
  evidence:
  - reference: url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML
    reference_title: "Summary"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The percentage of MBP...cells was significantly lower in the knockdown
      group after 6 days of differentiation
    explanation: Directly reports the system-specific differentiation readout.
animal_models:
- name: Oligodendrocyte-lineage Mea6 conditional-knockout mouse
  species: Mouse (Mus musculus)
  genotype: Conditional Mea6/cTAGE5 ablation in oligodendrocyte progenitor cells
  publication: PMID:38439956
  description: >-
    This interacting-pathway model develops impaired oligodendrocyte proliferation
    and differentiation, marked hypomyelination, synaptic dysfunction, and
    behavioral abnormalities. It is not a TRAPPC12 knockout and therefore models
    a cooperating MEA6 pathway rather than TRAPPC12-related encephalopathy itself.
  modeled_mechanisms:
  - target: Impaired Oligodendrocyte Differentiation
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      Reproduces an oligodendrocyte differentiation and myelination phenotype in
      vivo through perturbation of the interacting MEA6 protein.
    limitations: >-
      The perturbed gene is Mea6, not Trappc12; the model cannot establish that
      TRAPPC12 disease alleles cause the same in-vivo pathway or human MRI pattern.
    evidence:
    - reference: PMID:38439956
      reference_title: Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Mea6/cTAGE5 ablation in OPCs affects their proliferation and differentiation, leading to marked hypomyelination, compromised synaptic functionality, and aberrant behaviors in mice.
      explanation: >-
        Supports a cooperating in-vivo pathway but not a TRAPPC12 genotype model.
  evidence:
  - reference: PMID:38439956
    reference_title: Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Mea6/cTAGE5 ablation in OPCs affects their proliferation and differentiation, leading to marked hypomyelination, compromised synaptic functionality, and aberrant behaviors in mice.
    explanation: >-
      Directly documents the Mea6 conditional-knockout mouse phenotype and the
      reason its relevance to TRAPPC12 disease is only partial.
datasets: []
discussions:
- discussion_id: gap_trappc12_trafficking_to_neural_selectivity
  prompt: Which neuronal or glial mechanisms connect the affected-person fibroblast organelle and transport abnormalities to selective progressive brain atrophy and encephalopathy?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Golgi Fragmentation
  - pathophysiology#Delayed ER-to-Golgi Transport
  - pathophysiology#Progressive Brain Atrophy
  rationale: >-
    Human genetics and affected-person fibroblasts establish a proximal
    TRAPPC12-dependent secretory-pathway defect, but no patient-derived neural
    model defines the intervening cell-death, developmental, or circuit process.
  evidence:
  - reference: PMID:28777934
    reference_title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Fibroblasts derived from all three individuals showed a fragmented Golgi that could be rescued by expression of wild-type TRAPPC12.
    explanation: >-
      Establishes rescue of the Golgi morphology specifically while leaving both
      the transport-to-neural bridge and transport rescue unresolved.
- discussion_id: mismatch_trappc12_opc_to_human_white_matter
  prompt: Does TRAPPC12-dependent oligodendrocyte differentiation failure cause the human white-matter imaging phenotype?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Impaired Oligodendrocyte Differentiation
  - phenotypes#Hyperintensity of cerebral white matter on MRI
  - animal_models#Oligodendrocyte-lineage Mea6 conditional-knockout mouse
  rationale: >-
    A rat CG4 CRISPR-knockout line and primary mouse OPC shRNA culture support an
    oligodendroglial differentiation phenotype, but the in-vivo mouse has
    conditional Mea6—not Trappc12—ablation. No patient-derived oligodendrocyte
    or TRAPPC12 disease animal model currently connects those readouts to the
    increased cerebral white-matter T2 signal reported in affected people.
  proposed_experiments:
  - experiment_id: exp_trappc12_isogenic_human_oligodendrocytes
    name: Isogenic affected-person iPSC oligodendrocyte differentiation and trafficking study
    description: >-
      Generate oligodendrocytes from affected-person iPSCs and CRISPR-corrected
      isogenic controls, then measure lineage progression, MBP-positive cell
      fraction, myelin-sheath formation, Golgi morphology, synchronized
      ER-to-Golgi cargo transport, and cell survival across maturation.
    decision_criterion: >-
      Concordant rescue of oligodendrocyte differentiation and myelin formation
      by correction, with rescue tracking a specific TRAPPC12 cellular readout,
      would support the proposed human pathway; normal differentiation despite
      correction-sensitive fibroblast phenotypes would refute direct
      oligodendroglial mediation of the MRI signal.
  evidence:
  - reference: PMID:38439956
    reference_title: Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Here, we found that Trappc12 deficiency in CG4 and oligodendrocyte progenitor cells (OPCs) affects their differentiation and maturation.
    explanation: Directly supports the culture result that motivates the question.
  - reference: PMID:38439956
    reference_title: Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Mea6/cTAGE5 ablation in OPCs affects their proliferation and differentiation, leading to marked hypomyelination, compromised synaptic functionality, and aberrant behaviors in mice.
    explanation: >-
      Identifies the gene mismatch in the only in-vivo model used to support the
      white-matter pathway.
- discussion_id: hypothesis_trappc12_mitosis_cilia_autophagy
  prompt: Does prolonged mitotic progression contribute to the human neural phenotype, and do ciliary or autophagic functions form additional disease branches?
  kind: EMERGING_HYPOTHESIS
  status: OPEN
  attaches_to:
  - pathophysiology#Biallelic TRAPPC12 Dysfunction
  - pathophysiology#Prolonged Mitotic Progression
  rationale: >-
    All three founding fibroblast lines show prolonged prophase-to-anaphase
    timing, while TRAPPC12 depletion perturbs chromosome congression and cilium
    disassembly in human cell lines and a 2026 Aspergillus study places a
    TRAPPC11/12/13 subcomplex in autophagy. No experiment links these functions
    to affected-person neural tissue, so their disease contribution remains
    provisional.
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
    reference_title: "Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      1:II-8, 2:II-1, and 2:II-4 showed a significant lengthening of the time
      from prophase until the onset of anaphase
    explanation: >-
      Establishes the affected-person mitotic readout while leaving neural
      relevance unresolved.
  - reference: PMID:25918224
    reference_title: TRAMM/TrappC12 plays a role in chromosome congression, kinetochore stability, and CENP-E recruitment.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Depletion of TRAMM resulted in noncongressed chromosomes and arrested cells in mitosis.
    explanation: Establishes the mitotic cell-line phenotype, not its disease relevance.
  - reference: PMID:32258032
    reference_title: Distinct Roles of TRAPPC8 and TRAPPC12 in Ciliogenesis via Their Interactions With OFD1.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: TRAPPC12 depletion causes increased ciliary length because TRAPPC12 is required for the disassembly of primary cilia.
    explanation: Establishes a cilium-disassembly phenotype in hTERT-RPE1 cells.
  - reference: PMID:42483769
    reference_title: A Tca17TRAPPC2L/TRAPPC11/12/13 subcomplex directs TRAPPIII to autophagy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: We studied TRAPPC11/12/13 in the related ascomycete Aspergillus nidulans, where TRAPPC11 and TRAPPC12 localize to pre-autophagosomes and their ablation impairs autophagy.
    explanation: >-
      Adds current model-organism evidence for autophagic targeting but does not
      establish a human disease mechanism.
- discussion_id: gap_trappc12_patient_variant_gef_activity
  prompt: Do disease-associated TRAPPC12 variants alter TRAPPIII Rab-GEF activity in affected human cells?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Biallelic TRAPPC12 Dysfunction
  - pathophysiology#Reduced COPII Outer-Coat Assembly
  rationale: >-
    Purified mammalian TRAPPIII has GEF activity toward Rab1 and Rab43, but no
    cited patient-cell experiment directly measures nucleotide-exchange activity
    or shows that altered GEF activity mediates the COPII, Golgi, or
    cargo-transport readouts. Normal complex function must therefore not be converted
    into a patient-specific mechanism without testing.
  evidence:
  - reference: PMID:34229011
    reference_title: Biochemical Insight into Novel Rab-GEF Activity of the Mammalian TRAPPIII Complex.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      GEF assays revealed that TRAPPIII has GEF activity against Rab1 and Rab43,
      with no detectable activity against the other 18 Rabs tested.
    explanation: >-
      Defines the normal purified-complex activity that remains unmeasured for
      disease-associated variants in affected human cells.
references:
- reference: PMID:28777934
  title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.
- reference: PMID:32369837
  title: 'Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.'
- reference: PMID:32347653
  title: Hydrocephaly associated with compound heterozygous alterations in TRAPPC12.
- reference: PMID:39769094
  title: 'TRAPPopathies: Severe Multisystem Disorders Caused by Variants in Genes of the Transport Protein Particle (TRAPP) Complexes.'
- reference: PMID:38439956
  title: Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.
- reference: PMID:34018214
  title: Cryo-EM structure of metazoan TRAPPIII, the multi-subunit complex that activates the GTPase Rab1.
- reference: PMID:34229011
  title: Biochemical Insight into Novel Rab-GEF Activity of the Mammalian TRAPPIII Complex.
- reference: PMID:28240221
  title: Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.
- reference: PMID:25918224
  title: TRAMM/TrappC12 plays a role in chromosome congression, kinetochore stability, and CENP-E recruitment.
- reference: PMID:32258032
  title: Distinct Roles of TRAPPC8 and TRAPPC12 in Ciliogenesis via Their Interactions With OFD1.
- reference: PMID:36995918
  title: 'RNA sequencing to support intronic variant interpretation: A case report of TRAPPC12-related disorder.'
- reference: DOI:10.26650/experimed.1584823
  title: Impact of a Missense Mutation in TRAPPC12 in Patients with Progressive Encephalopathy, Brain Atrophy and Spasticity Phenotype without Microcephaly and Epilepsy
- reference: PMID:42483769
  title: A Tca17TRAPPC2L/TRAPPC11/12/13 subcomplex directs TRAPPIII to autophagy.
- reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/
  title: Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC
- reference: url:https://dergipark.org.tr/en/download/article-file/4364382
  title: https://dergipark.org.tr/en/download/article-file/4364382
- reference: url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML
  title: Summary
review_notes: >-
  Identity review retained MONDO:0044696 and TRAPPC12 HGNC:24284. The disease
  OMIM identifier is 617669; 614139 is the TRAPPC12 gene MIM number and must not
  be used as the disease identifier. Literature was re-searched through
  2026-08-19. PMID:36995918 is a relevant RNA-sequencing case report, but its
  cached PubMed record contains no abstract and its title is not used as
  evidentiary text. The final 2025 Experimed article is represented by its
  sanctioned open-access PDF cache and directly informs the distinct Phe227Val
  fibroblast model. The founding n=3 report supplies cohort counts rather than
  population-frequency enums. Neonatal hypertension and vocal-cord paralysis
  occurred together in one individual, while hip subluxation and polyhydramnios
  were each reported in isolated individuals; presumed respiratory-insufficiency
  death was reported for one sibling but attribution was uncertain. These
  isolated or attribution-uncertain secondary observations remain documented
  here rather than promoted to recurring disease phenotypes. The 2026 Aspergillus
  autophagy study is current functional evidence but not human clinical evidence.
  No GeneReviews chapter, disease-specific public dataset, epidemiologic cohort,
  patient-derived neural model, or TRAPPC12 whole-animal disease model was
  identified. Rat CG4 knockout and primary mouse OPC knockdown cultures are
  represented as distinct low-fidelity systems. The Mea6 conditional-knockout
  mouse is retained only as a low-fidelity interacting-pathway model. Treatment
  entries are explicitly supportive extrapolations because no TRAPPC12-specific
  treatment-outcome study was found. Causal edges with unresolved intermediates
  are marked accordingly rather than upgraded from association.

📚

References & Deep Research

References

16

PMID:28777934

Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction.

No top-level findings curated for this source.

PMID:32369837

Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature.

No top-level findings curated for this source.

PMID:32347653

Hydrocephaly associated with compound heterozygous alterations in TRAPPC12.

No top-level findings curated for this source.

PMID:39769094

TRAPPopathies: Severe Multisystem Disorders Caused by Variants in Genes of the Transport Protein Particle (TRAPP) Complexes.

No top-level findings curated for this source.

PMID:38439956

Mea6/cTAGE5 cooperates with TRAPPC12 to regulate PTN secretion and white matter development.

No top-level findings curated for this source.

PMID:34018214

Cryo-EM structure of metazoan TRAPPIII, the multi-subunit complex that activates the GTPase Rab1.

No top-level findings curated for this source.

PMID:34229011

Biochemical Insight into Novel Rab-GEF Activity of the Mammalian TRAPPIII Complex.

No top-level findings curated for this source.

PMID:28240221

Mammalian TRAPPIII Complex positively modulates the recruitment of Sec13/31 onto COPII vesicles.

No top-level findings curated for this source.

PMID:25918224

TRAMM/TrappC12 plays a role in chromosome congression, kinetochore stability, and CENP-E recruitment.

No top-level findings curated for this source.

PMID:32258032

Distinct Roles of TRAPPC8 and TRAPPC12 in Ciliogenesis via Their Interactions With OFD1.

No top-level findings curated for this source.

PMID:36995918

RNA sequencing to support intronic variant interpretation: A case report of TRAPPC12-related disorder.

No top-level findings curated for this source.

DOI:10.26650/experimed.1584823

Impact of a Missense Mutation in TRAPPC12 in Patients with Progressive Encephalopathy, Brain Atrophy and Spasticity Phenotype without Microcephaly and Epilepsy

No top-level findings curated for this source.

PMID:42483769

A Tca17TRAPPC2L/TRAPPC11/12/13 subcomplex directs TRAPPIII to autophagy.

No top-level findings curated for this source.

url:https://pmc.ncbi.nlm.nih.gov/articles/PMC5544387/

Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction - PMC

No top-level findings curated for this source.

url:https://dergipark.org.tr/en/download/article-file/4364382

https://dergipark.org.tr/en/download/article-file/4364382

No top-level findings curated for this source.

url:https://www.ebi.ac.uk/europepmc/webservices/rest/PMC10909747/fullTextXML

Summary

No top-level findings curated for this source.

Deep Research

1

Falcon ▸

TRAPPC12-Related Encephalopathy: Disease-Characteristics Research Report

Edison Scientific Literature 21 citations 2026-08-05T22:07:27.596624

TRAPPC12-Related Encephalopathy: Disease-Characteristics Research Report

Executive summary

TRAPPC12-related encephalopathy is an ultra-rare autosomal-recessive neurodevelopmental/neurodegenerative disorder caused by biallelic pathogenic variants in TRAPPC12, a metazoan TRAPPIII-complex subunit involved in COPII-associated ER-to-Golgi trafficking. The best-established phenotype combines congenital or acquired microcephaly, profound developmental impairment or regression, hypotonia evolving with appendicular spasticity, dystonia/myoclonus, hearing and visual impairment, epilepsy in some patients, dysphagia, scoliosis, and a characteristic MRI pattern of severe cortical atrophy, corpus-callosum agenesis/hypoplasia, pons hypoplasia, ventriculomegaly, and abnormal white-matter signal. Later reports expanded the spectrum to milder encephalopathy without epilepsy or microcephaly and to severe fetal hydrocephalus. Evidence remains limited to a handful of families, patient fibroblasts, and engineered cell lines; no disease-specific therapy, guideline, epidemiologic study, clinical trial, animal disease model, or validated biomarker is established. (hall2024trappopathiesseveremultisystem pages 12-14, milev2017mutationsintrappc12 pages 1-2, yucesan2023functionalcharacterizationof pages 1-4)

The following table summarizes the most knowledge-base-ready findings.

Domain	Summary	Ontology term suggestions	Key evidence
Definition / names	Ultra-rare Mendelian neurodevelopmental disorder caused by biallelic TRAPPC12 variants, first linked in 2017 to progressive childhood encephalopathy with Golgi dysfunction. Names used in the literature include TRAPPC12-related encephalopathy, progressive encephalopathy with brain atrophy and spasticity (PEBAS), and early-onset progressive encephalopathy–hearing loss–pons hypoplasia–brain atrophy syndrome. MIM/OMIM association reported in the literature: 614139. MONDO, Orphanet, ICD, MeSH: not established from retrieved sources.	MONDO: not established; HP: Neurodevelopmental abnormality [suggest HP:0012759]	(milev2017mutationsintrappc12 pages 1-2, yucesan2023functionalcharacterizationof pages 1-4, hall2024trappopathiesseveremultisystem pages 12-14)
Inheritance	Autosomal recessive / biallelic disease. Discovery cohort included one consanguineous family and one non-consanguineous family.	HP: Autosomal recessive inheritance (suggest HP:0000007)	(milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)
Gene and aliases	Causal gene: TRAPPC12. Reported aliases: TTC15, TRAMM, CGI-87. TRAPPC12 is a TRAPPIII-specific subunit involved in vesicle trafficking; it has no yeast ortholog in retrieved mechanistic studies.	HGNC gene symbol: TRAPPC12; GO CC suggestions: ER exit site, ER-Golgi intermediate compartment, Golgi apparatus	(zhao2017mammaliantrappiiicomplex pages 1-2, sacher2019trappopathiesanemerging pages 24-28, yucesan2023functionalcharacterizationof pages 1-4)
Established variants	Discovery cohort variants: *c.145delG (p.Glu49Argfs14) homozygous; c.360dupC (p.Glu121Argfs7)* and c.1880C>T (p.Ala627Val) compound heterozygous. Additional reported variant from later Turkish report/preprint: c.679T>G (p.Phe227Val) homozygous. 2024 review states ClinVar lists 21 pathogenic/likely pathogenic variants including frameshift, nonsense, and splicing variants, but complete curated list was not extracted here.	SO terms suggested: frameshift_variant, missense_variant, splice_region_variant; HP: Homozygosity / Compound heterozygosity not typically HPO-coded	(milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 3-5, yucesan2023functionalcharacterizationof pages 1-4, hall2024trappopathiesseveremultisystem pages 12-14)
Hallmark phenotypes and discovery-cohort frequencies	In the original 3-patient cohort: severe global developmental delay 3/3, regression 3/3, truncal hypotonia 3/3, appendicular spasticity 3/3, dystonia/myoclonus 3/3, hearing loss/failed otoacoustic screening 3/3, scoliosis 3/3, dysphagia/reflux 3/3, severe disability 3/3; microcephaly 3/3 (acquired in 1, congenital in 2); epilepsy 2/3; West syndrome 1/3; optic pathway/visual abnormalities 3/3; neurogenic bladder 1/3. Later reports broaden phenotype to milder disease and fetal hydrocephalus/ventriculomegaly.	HP suggestions: Global developmental delay HP:0001263; Developmental regression HP:0002376; Hypotonia HP:0001252; Spasticity HP:0001257; Dystonia HP:0001332; Myoclonus HP:0001336; Sensorineural/mixed hearing impairment HP:0000407; Microcephaly HP:0000252; Seizure HP:0001250; West syndrome/Infantile spasms HP:0012469; Scoliosis HP:0002650; Dysphagia HP:0002015; Optic atrophy HP:0000648	(milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3, sacher2019trappopathiesanemerging pages 24-28, yucesan2023functionalcharacterizationof pages 1-4)
MRI / neuroimaging signature	Discovery cohort imaging signature: severe cortical/supratentorial atrophy 3/3, ventriculomegaly 3/3, prominent extra-axial spaces 3/3, increased T2 cortical white matter signal 3/3, severe pons hypoplasia 3/3, agenesis or severe thinning of corpus callosum 3/3, relatively spared basal ganglia 3/3, mild cerebellar hypoplasia 2/3, small optic chiasm 2/3. One patient had progressive ventriculomegaly beyond expected cortical volume loss; later literature mentions severe hydrocephalus/hydrocephaly in some cases.	HP suggestions: Cerebral atrophy HP:0002059; Ventriculomegaly HP:0002119; Abnormal corpus callosum morphology / Agenesis HP:0001274 / HP:0001273; Pontine hypoplasia HP:0007366; Cerebellar hypoplasia HP:0001321; Delayed myelination / abnormal white matter signal HP:0012448	(milev2017mutationsintrappc12 pages 3-5, milev2017mutationsintrappc12 pages 2-3, hall2024trappopathiesseveremultisystem pages 12-14)
Mechanism / pathophysiology	Best-supported mechanism is loss of TRAPPC12 protein leading to Golgi fragmentation and delayed ER-to-Golgi trafficking. Patient fibroblasts showed fragmented Golgi rescued by wild-type TRAPPC12; trafficking into and through the Golgi was delayed. Independent cell studies place TRAPPC12 at ER exit sites and ERGIC, where it promotes Sec13/Sec31 COPII outer-coat recruitment. Additional roles include mitosis/kinetochore function and ciliogenesis via OFD1, but the human encephalopathy phenotype is most directly linked to membrane-trafficking defects.	GO BP suggestions: vesicle-mediated transport, ER to Golgi vesicle-mediated transport, COPII-coated vesicle budding, protein localization to Golgi, ciliogenesis, mitotic chromosome congression; GO CC: ER exit site, ERGIC, Golgi apparatus, kinetochore, primary cilium	(milev2017mutationsintrappc12 pages 3-5, zhao2017mammaliantrappiiicomplex pages 1-2, sacher2019trappopathiesanemerging pages 24-28, zhang2020distinctrolesof pages 1-2)
Diagnostics	Diagnosis in published cases relied on exome sequencing/WES with segregation confirmation by Sanger sequencing. Supportive tests included brain MRI, EEG (hypsarrhythmia in the West syndrome case), newborn otoacoustic emission hearing screening, and clinical neurologic assessment. One case had extensive metabolic workup negative except moderately elevated CSF lactate 3.2 mM. No validated disease-specific biochemical biomarker is established.	NCIT/LOINC-style suggestions not established; HP: Hypsarrhythmia HP:0010849; Abnormal CSF lactate HP:0025435	(milev2017mutationsintrappc12 pages 2-3, milev2017mutationsintrappc12 pages 1-2)
Treatment / management	No disease-modifying therapy established. Published management is supportive/symptom-directed: seizure management, feeding support including G-tube dependence in 2 patients, hearing evaluation, and multidisciplinary neurologic/rehabilitative care. No TRAPPC12-specific interventional clinical trials were identified.	NCIT suggestions: Supportive care; Gastrostomy; Anticonvulsant therapy; Physical therapy; Speech/feeding therapy	(milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)
Epidemiology / population	Extremely rare; only a small number of families/cases reported in the retrieved literature. No validated prevalence or incidence estimate. Discovery paper cites progressive childhood encephalopathy overall at 0.60 per 1,000 live births, but that figure applies to the broad syndrome class, not specifically to TRAPPC12-related disease. No established founder effect, penetrance estimate, carrier frequency for the disease overall, sex ratio, or geographic distribution. Variant-specific population note: p.Phe227Val observed 2/237,118 gnomAD exome alleles in heterozygous state in the 2023 preprint.	MONDO/epidemiology ontology: not established	(milev2017mutationsintrappc12 pages 1-2, yucesan2023functionalcharacterizationof pages 1-4)
Prognosis	Available data suggest early-onset, progressive, high-morbidity encephalopathy with severe long-term disability. In the discovery cohort, 1/3 died at 4 years 9 months (presumed respiratory insufficiency). Later reports indicate phenotypic expansion to milder forms without epilepsy or without microcephaly in some cases, so prognosis appears variable but generally serious. Formal survival curves, life expectancy, and QoL studies are not established.	HP suggestions: Progressive neurologic deterioration HP:0002344; Respiratory insufficiency HP:0002093	(milev2017mutationsintrappc12 pages 2-3, yucesan2023functionalcharacterizationof pages 1-4, hall2024trappopathiesseveremultisystem pages 12-14)
Evidence gaps	No confirmed MONDO/Orphanet/ICD identifier from retrieved sources; no disease-specific guidelines; no controlled treatment studies; no prevalence/incidence study; no penetrance/expressivity quantification; no established modifier genes; no epigenetic, transcriptomic, proteomic, metabolomic, lipidomic, single-cell, spatial, iPSC, organoid, or animal disease model specific to TRAPPC12 retrieved here; no validated preventive intervention beyond genetic counseling/testing in at-risk families.	Suggested annotations: “not established” where identifier or evidence is unavailable	(hall2024trappopathiesseveremultisystem pages 12-14, yucesan2023functionalcharacterizationof pages 1-4, zhao2017mammaliantrappiiicomplex pages 1-2)

Table: This table provides a concise knowledge-base style summary of TRAPPC12-related encephalopathy, emphasizing established human genetic and clinical evidence while clearly marking identifiers and data elements that are not yet established.

Evidence scope and caution

The strongest human evidence is the 2017 discovery report describing three affected children from two unrelated families. Exact percentages below therefore largely use n=3, and should not be interpreted as stable population frequencies. Two 2020 reports broadened the phenotype; a February 9, 2023 preprint functionally studied one previously reported Turkish patient; and a December 2024 review summarized the TRAPPopathy literature and ClinVar landscape. The retrieved sources contain aggregated disease-level interpretation derived from individual cases and patient-derived cells—not EHR-scale evidence, registries, or population cohorts. (hall2024trappopathiesseveremultisystem pages 12-14, milev2017mutationsintrappc12 pages 1-2, yucesan2023functionalcharacterizationof pages 4-7)

1. Disease information

Definition and current understanding

The disorder is a biallelic TRAPPC12-associated, early-onset progressive encephalopathy with severe neurodevelopmental impairment and structural brain abnormalities. The discovery paper defined progressive childhood encephalopathy as progressive CNS dysfunction with broad morbidity and mortality and concluded: “Here, we report that variants in TRAPPC12 result in progressive childhood encephalopathy.” It further observed that all three patient fibroblast lines had a fragmented Golgi and delayed transport from the ER to and through the Golgi. (milev2017mutationsintrappc12 pages 1-2)

Names and identifiers

Preferred descriptive name: TRAPPC12-related encephalopathy.
Published alternatives: progressive childhood encephalopathy and Golgi dysfunction; progressive encephalopathy with brain atrophy and spasticity (PEBAS); early-onset progressive encephalopathy–hearing loss–pons hypoplasia–brain atrophy syndrome; TRAPPC12-related childhood encephalopathy.
OMIM/MIM: 614139 is used in the retrieved literature for the TRAPPC12/PEBAS entry. The gene is also explicitly identified as TRAPPC12 (MIM 614139) in the discovery report. (milev2017mutationsintrappc12 pages 1-2, yucesan2023functionalcharacterizationof pages 1-4)
MONDO: no confidently verified disease-specific MONDO identifier was retrieved; do not populate one without direct MONDO validation.
Orphanet, ICD-10, ICD-11, MeSH: no disease-specific identifiers were established in the retrieved evidence. Broad codes for genetic encephalopathy, developmental disorder, epilepsy, microcephaly, or cerebral atrophy would be nonspecific and should not be represented as disease-equivalent identifiers.
Category: Mendelian, autosomal recessive; part of the broader group termed TRAPPopathies. (sacher2019trappopathiesanemerging pages 24-28, hall2024trappopathiesseveremultisystem pages 12-14)

Core publications

Milev et al., American Journal of Human Genetics, August 3, 2017, “Mutations in TRAPPC12 Manifest in Progressive Childhood Encephalopathy and Golgi Dysfunction,” DOI/URL: https://doi.org/10.1016/j.ajhg.2017.07.006. This is the landmark gene–disease report. (milev2017mutationsintrappc12 pages 1-2)
Aslanger et al., Neuropediatrics 51:430–434, 2020, “Expanding Clinical Phenotype of TRAPPC12-Related Childhood Encephalopathy: Two Cases and Review of Literature,” DOI: https://doi.org/10.1055/s-0040-1710526. Bibliographic details are recorded in the 2023 report. (yucesan2023functionalcharacterizationof pages 7-11)
Gass et al., Birth Defects Research 112:1028–1034, 2020, “Hydrocephaly associated with compound heterozygous alterations in TRAPPC12,” DOI: https://doi.org/10.1002/bdr2.1699. (yucesan2023functionalcharacterizationof pages 4-7, yucesan2023functionalcharacterizationof pages 7-11)
Yucesan et al., preprint posted February 9, 2023, DOI/URL: https://doi.org/10.21203/rs.3.rs-2552844/v1. (yucesan2023functionalcharacterizationof pages 1-4)
Hall et al., International Journal of Molecular Sciences 25:13329, December 2024, DOI/URL: https://doi.org/10.3390/ijms252413329. (hall2024trappopathiesseveremultisystem pages 12-14)

2. Etiology

Causal factor

The primary cause is germline biallelic pathogenic or likely pathogenic variation in TRAPPC12. The discovery cohort demonstrated homozygous or compound-heterozygous segregation in affected children, absence or marked loss of full-length TRAPPC12 protein, cellular dysfunction, and rescue of Golgi morphology by wild-type TRAPPC12. Together, these data support a predominantly loss-of-function/hypomorphic mechanism rather than gain of function. (milev2017mutationsintrappc12 pages 5-8, milev2017mutationsintrappc12 pages 3-5)

Genetic risk factors

Risk is determined principally by inheriting two deleterious alleles. Consanguinity increases the probability that both parents carry the same rare allele, but is not required: one discovery family was consanguineous and one was not. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

Environmental, infectious, and lifestyle risks

No TRAPPC12-specific toxin, infection, diet, lifestyle, occupation, age-related exposure, or other environmental cause has been demonstrated. General acquired causes of childhood encephalopathy—hypoxia, hemorrhage, and toxins—are differential etiologies rather than factors known to modify genetically confirmed TRAPPC12 disease. (milev2017mutationsintrappc12 pages 1-2)

Protective factors, modifiers, and gene–environment interaction

No protective TRAPPC12 variants, modifier genes, environmental protective factors, or reproducible gene–environment interactions have been reported. No evidence shows that avoiding a particular exposure changes penetrance or progression.

3. Phenotypes

Neurologic and developmental manifestations

In the original three-patient cohort, severe global developmental delay, regression, truncal hypotonia, appendicular spasticity, dystonia and/or myoclonus, microcephaly, and severe disability occurred in 3/3 (100%). Microcephaly was congenital in two and acquired in one. Epilepsy occurred in 2/3 (67%), while West syndrome with hypsarrhythmia occurred in 1/3 (33%). One patient presented with flexion seizures and loss of smiling/visual tracking at five months; the two sisters had congenital/prenatal abnormalities and made small developmental gains before plateauing. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

Suggested HPO terms include:

Global developmental delay — HP:0001263
Developmental regression — HP:0002376
Severe intellectual/developmental disability — HP:0010864 where clinically confirmed
Hypotonia — HP:0001252
Spasticity — HP:0001257; spastic quadriplegia — HP:0002510
Dystonia — HP:0001332
Myoclonus — HP:0001336
Seizure — HP:0001250
Infantile spasms — HP:0012469
Hypsarrhythmia — HP:0010849
Microcephaly — HP:0000252

Hearing, vision, feeding, and musculoskeletal manifestations

All three original patients failed otoacoustic-emission screening or had documented hearing impairment (3/3). Visual abnormalities occurred in 3/3: optic atrophy, optic-nerve pallor, enlarged cup-to-disc ratio, or cortical visual impairment. Scoliosis and dysphagia/reflux occurred in 3/3; two were gastrostomy-dependent. Other reported findings included neurogenic bladder (1/3), neonatal hypertension (1/3), vocal-cord paralysis (1/3), hip subluxation (1/3), and polyhydramnios (1/3). (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

Suggested HPO terms: hearing impairment HP:0000365, optic atrophy HP:0000648, cortical visual impairment HP:0100704, scoliosis HP:0002650, dysphagia HP:0002015, gastroesophageal reflux HP:0002020, neurogenic bladder HP:0000011, and hip subluxation HP:0030043.

Neuroimaging

The original cohort showed a highly consistent MRI signature:

Severe cortical atrophy: 3/3
Ventriculomegaly: 3/3
Prominent extra-axial spaces: 3/3
Simplified frontal gyri: 3/3
Increased T2 signal in cortical white matter: 3/3
Severe pons hypoplasia: 3/3
Agenesis or severe thinning of the corpus callosum: 3/3
Relative basal-ganglia sparing: 3/3
Mild cerebellar hypoplasia: 2/3
Small optic chiasm: 2/3. (milev2017mutationsintrappc12 pages 3-5)

Documented volume loss between three days and 11 months in one child supports true progression, not merely congenital hypoplasia. A later child with p.Phe227Val had mild cortical but severe cerebellar atrophy, demonstrating broader radiologic expressivity. Compound-heterozygous fetal cases with ventriculomegaly/hydrocephaly, interhemispheric cysts, and polydactyly suggest a severe prenatal end of the spectrum, although the ciliogenesis connection remains mechanistically suggestive rather than proven in those fetuses. (milev2017mutationsintrappc12 pages 3-5, yucesan2023functionalcharacterizationof pages 4-7)

Suggested HPO terms: cerebral atrophy HP:0002059, ventriculomegaly HP:0002119, agenesis of corpus callosum HP:0001273, pontine hypoplasia HP:0007366, cerebellar hypoplasia HP:0001321, and abnormal cerebral white matter signal HP:0030890.

Laboratory abnormalities

Extensive metabolic testing in the first patient was negative except moderately elevated CSF lactate, 3.2 mM against a stated normal value below 2.1 mM. This isolated result is neither sensitive nor specific and is not a validated disease biomarker. (milev2017mutationsintrappc12 pages 2-3)

Quality-of-life effects

No EQ-5D, SF-36, PROMIS, caregiver-burden, or disease-specific quality-of-life study exists. Nevertheless, profound motor and developmental disability, absent or minimal psychomotor development, hearing/visual impairment, epilepsy, spastic quadriplegia, dysphagia requiring gastrostomy, and scoliosis imply major dependence in mobility, communication, feeding, and self-care. This is a clinical inference from functional manifestations, not a measured patient-reported outcome. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

4. Genetic and molecular information

Gene and protein

Gene: TRAPPC12, chromosome 2 in the hg19 coordinates reported by the discovery study.
Transcript used in the discovery report: NM_016030.5; the 2023 report used NM_016030.6.
Protein aliases: trafficking protein particle complex subunit 12; TTC15, TRAMM (“trafficking of membranes and mitosis”), and CGI-87.
Gene MIM identifier: 614139 in the retrieved sources.
HGNC ID: not independently verified in the retrieved material and should be added only after direct HGNC validation.
Complex: metazoan TRAPPIII; TRAPPC12 has no yeast ortholog. (sacher2019trappopathiesanemerging pages 24-28, zhao2017mammaliantrappiiicomplex pages 1-2)

Reported disease variants

NM_016030.5:c.145delG; p.Glu49Argfs*14, homozygous. It was absent from 49,094 ExAC individuals and an 850-exome Muslim-Arab internal database at the time of publication. Both parents were heterozygous. (milev2017mutationsintrappc12 pages 2-3)
c.360dupC; p.Glu121Argfs*7 plus c.1880C>T; p.Ala627Val, compound heterozygous in two sisters. The father carried the frameshift and mother the missense allele. In the discovery-era gnomAD data, p.Ala627Val occurred twice among 246,176 alleles; no affected homozygote was reported. (milev2017mutationsintrappc12 pages 3-5)
NM_016030.6:c.679T>G; p.Phe227Val, rs1312522735, homozygous in a Turkish patient; both parents were obligate carriers. It appeared in 2/237,118 gnomAD exome alleles, allele frequency approximately 8.43×10⁻⁶, with no homozygote. In-silico evidence was conflicting—13 tools predicted pathogenicity and 11 benignity—but patient-cell protein loss and organelle abnormalities supplied functional evidence. (yucesan2023functionalcharacterizationof pages 4-7, yucesan2023functionalcharacterizationof pages 1-4)
A 2024 review reported 21 ClinVar pathogenic/likely pathogenic variants, including frameshift, nonsense, and splicing alleles. This is a database count, not 21 clinically independent patients, and should be refreshed directly from ClinVar before production use. (hall2024trappopathiesseveremultisystem pages 12-14)

All reported disease alleles are germline. No somatic TRAPPC12 encephalopathy has been described. No large recurrent deletion, translocation, inversion, aneuploidy, repeat expansion, or mitochondrial lesion is established as the cause.

Functional consequences

Full-length TRAPPC12 was absent in all three discovery-cohort fibroblast lines, including cells carrying p.Ala627Val in trans with a frameshift. The alanine lies at position 8 of the third tetratricopeptide-repeat domain, where substitution by bulky valine was predicted to destabilize protein structure. Proteasome inhibition did not restore detectable protein in those cells. For p.Phe227Val, two antibodies also showed absent or extremely low TRAPPC12 and loss of the approximately 35-kDa CGI-87 product. (milev2017mutationsintrappc12 pages 5-8, yucesan2023functionalcharacterizationof pages 4-7)

The most appropriate molecular classification is therefore loss of protein/function, with possible residual activity in some missense genotypes. No dominant-negative or gain-of-function mechanism has been demonstrated.

Modifier and epigenetic information

No validated modifier gene, DNA-methylation signature, histone modification, chromatin alteration, or disease-specific epigenomic profile is available.

5. Environmental information

No environmental toxin, radiation exposure, pollution source, occupational exposure, smoking, alcohol, diet, exercise pattern, or infectious agent is known to cause or trigger TRAPPC12-related encephalopathy. The disease is not infectious or zoonotic. Environmental management may reduce secondary complications—such as aspiration or respiratory infection—but does not prevent the inherited molecular defect.

6. Mechanism and pathophysiology

Best-supported causal chain

Biallelic deleterious TRAPPC12 variants → absent/unstable TRAPPC12 protein → impaired TRAPPIII/COPII interface and ER-exit-site function → defective Sec13/Sec31 outer-coat recruitment, dispersed ERGIC/Golgi, and delayed ER-to-Golgi and intra-/post-Golgi cargo transit → disturbed delivery and homeostasis of membrane/secreted proteins in highly polarized, trafficking-dependent neural cells → abnormal brain development plus progressive neuronal dysfunction/atrophy → developmental regression, spasticity, movement disorder, sensory impairment, and epilepsy.

The upstream steps through trafficking delay are experimentally demonstrated. The neuron-specific link from cargo-trafficking failure to regional brain atrophy remains a strong biologic inference, because no patient-neuron or animal model has yet traced that full chain. (milev2017mutationsintrappc12 pages 3-5, zhao2017mammaliantrappiiicomplex pages 1-2)

ER-to-Golgi trafficking and COPII biology

TRAPPC12 localizes to ER exit sites and the ER–Golgi intermediate compartment. It binds the assembled Sec13/Sec31A tetramer—not either protein alone—and promotes recruitment of the COPII outer coat. TRAPPC12-null HeLa/HEK293T systems showed dispersed ERGIC/Golgi and delayed transport of VSV-G and other cargo. The primary mechanistic abstract states: “TRAPPIII positively modulated the assembly of COPII outer layer during COPII vesicle formation.” (zhao2017mammaliantrappiiicomplex pages 1-2, zhao2017mammaliantrappiiicomplex pages 8-9)

In patient fibroblasts, the Golgi was fragmented, arrival of VSVG-GFP and RUSH cargo at the Golgi was delayed, and VSVG remained in the Golgi longer. Expression of wild-type TRAPPC12 restored a compact, ribbon-like Golgi, providing a direct rescue experiment linking genotype to organelle phenotype. (milev2017mutationsintrappc12 pages 5-8, milev2017mutationsintrappc12 pages 3-5)

Suggested GO annotations include ER-to-Golgi vesicle-mediated transport GO:0006888, vesicle-mediated transport GO:0016192, COPII-coated vesicle budding GO:0090114, Golgi organization GO:0007030, ER exit site, ERGIC, and Golgi apparatus GO:0005794.

TRAPPIII and Rab signaling

Mammalian TRAPPIII is a guanine-nucleotide-exchange complex with Rab1 specificity; Rab1 regulates early secretory trafficking and autophagy. Structural work places TRAPPC12/TRAPPC13 on one peripheral arm of metazoan TRAPPIII, while Rab1 engages the complex elsewhere. TRAPPC12 should therefore be regarded as a complex subunit facilitating architecture/localization rather than a stand-alone enzyme. (yucesan2023functionalcharacterizationof pages 4-7, yucesan2023functionalcharacterizationof pages 1-4)

Mitosis

TRAPPC12/TRAMM also localizes to chromosomes and kinetochores during mitosis and supports kinetochore stability, CENP-E recruitment, chromosome congression, and spindle-checkpoint progression. Patient fibroblasts showed increased prophase-to-anaphase time. However, experts have judged trafficking dysfunction more likely than mitotic delay to account for the principal neurologic phenotype; direct developmental proof is lacking. (sacher2019trappopathiesanemerging pages 24-28, milev2017mutationsintrappc12 pages 5-8)

Suggested GO terms: chromosome congression GO:0051310, kinetochore organization GO:0051383, mitotic spindle-assembly checkpoint GO:0007094, and kinetochore GO:0000776.

Autophagy

TRAPPIII participates in autophagy and Rab1/ATG9-related membrane traffic. TRAPPC12 depletion has been associated experimentally with altered autophagosome abundance/flux, but disease-specific autophagic failure has not been demonstrated in patient neural tissue. Autophagy should therefore be annotated as a plausible associated process, not the established proximal cause of encephalopathy. (zhao2017mammaliantrappiiicomplex pages 1-2)

Suggested GO term: macroautophagy GO:0016236.

Ciliogenesis

TRAPPC12 interacts with OFD1. In hTERT-RPE1 cells, depletion increased primary-cilium length because TRAPPC12 was required for ciliary disassembly. This provides a plausible mechanistic context for fetal hydrocephalus, polydactyly, and interhemispheric cysts, but no direct rescue or causal demonstration has connected altered ciliary length to human TRAPPC12 brain disease. (zhang2020distinctrolesof pages 1-2, yucesan2023functionalcharacterizationof pages 4-7)

Suggested GO terms: cilium assembly GO:0060271, cilium disassembly GO:0061512, primary cilium GO:0072372, and centriolar satellite GO:0034451.

Molecular profiling and advanced technologies

No disease-specific transcriptomics, quantitative proteomics, metabolomics, lipidomics, single-cell analysis, spatial transcriptomics, multi-omics integration, patient iPSC-neuron study, cerebral organoid, or genome-wide CRISPR screen was retrieved. Nile-red imaging showed altered neutral-lipid-droplet distribution in p.Phe227Val fibroblasts, but this is an imaging phenotype—not a validated lipidomic signature. (yucesan2023functionalcharacterizationof pages 4-7)

7. Anatomical structures affected

Organ and system level

The central nervous system is primary. Structures repeatedly affected include cerebral cortex and subcortical white matter, corpus callosum, pons, optic nerves/chiasm, and—variably—cerebellum. The cochlear/auditory system, visual system, bulbar feeding pathways, spinal/upper-motor-neuron system, and musculoskeletal system are clinically involved. Secondary complications include scoliosis, hip subluxation, neurogenic bladder, dysphagia/reflux, and respiratory insufficiency. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 3-5)

Suggested UBERON terms: brain UBERON:0000955, cerebral cortex UBERON:0000956, corpus callosum UBERON:0002336, pons UBERON:0000988, cerebellum UBERON:0002037, optic nerve UBERON:0000962, and spinal cord UBERON:0002240.

Tissue and cell level

No histopathologic patient-brain or single-cell study identifies one selectively vulnerable cell population. Neurons are biologically plausible primary targets because of their polarization and exceptional dependence on membrane trafficking, with oligodendrocytes potentially implicated by reduced myelination/white-matter signal. These remain inferred cell types rather than experimentally confirmed targets.

Suggested CL terms for hypothesis-driven annotation: neuron CL:0000540, cortical neuron CL:0002609, motor neuron CL:0000100, oligodendrocyte CL:0000128, and neural progenitor cell CL:0011020.

Subcellular structures

Experimentally involved compartments are the ER, ER exit sites, COPII vesicles, ERGIC, Golgi apparatus, cytoplasmic vesicles/lipid droplets, kinetochores, centriolar satellites, and primary cilia. No lateralization pattern is established; imaging abnormalities are generally bilateral/diffuse. (zhang2020distinctrolesof pages 1-2, milev2017mutationsintrappc12 pages 3-5, zhao2017mammaliantrappiiicomplex pages 1-2, yucesan2023functionalcharacterizationof pages 4-7)

8. Temporal development

Onset is prenatal, neonatal, or early infantile. Examples include prenatal corpus-callosum agenesis, neonatal jitteriness or hearing-screen failure, and infantile spasms/regression at five months. The course is chronic and usually progressive: initial limited gains may plateau, followed by worsening atrophy, spasticity, seizures, feeding impairment, and severe lifelong disability. No standardized stages have been developed. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

There is no evidence of spontaneous remission. Seizures may be controlled symptomatically in individual patients, but no publication demonstrates reversal of the underlying encephalopathy. Prenatal brain development and the first year—when cortical volume loss was documented—are likely critical vulnerability periods. This timing is observational, not evidence for a proven therapeutic window. (milev2017mutationsintrappc12 pages 3-5)

9. Inheritance and population

Inheritance

Inheritance is autosomal recessive. For two confirmed carrier parents, standard Mendelian counseling assigns each pregnancy a 25% affected, 50% carrier, and 25% non-carrier probability, assuming both parental variants are fully pathogenic and no unusual mosaicism. Both sexes are affected. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

Penetrance appears high for clearly damaging biallelic genotypes in the few reported families, but formal penetrance cannot be estimated. Expressivity is variable: severe congenital disease, progressive infantile PEBAS, and milder disease without epilepsy or microcephaly have been described. No anticipation, germline mosaicism, or established founder effect has been reported. (hall2024trappopathiesseveremultisystem pages 12-14, yucesan2023functionalcharacterizationof pages 1-4)

Epidemiology

No disease-specific prevalence, incidence, carrier frequency, geographic distribution, or sex-ratio estimate exists. The discovery paper’s figure of 0.60 per 1,000 live births concerns progressive childhood encephalopathy overall and must not be attributed to TRAPPC12-related disease. (milev2017mutationsintrappc12 pages 1-2)

Reported families include Palestinian and mixed European/Native American backgrounds, as well as Turkish cases. These observations do not establish ethnic enrichment. Consanguinity aided identification in one family, but compound heterozygosity in an unrelated non-consanguineous family demonstrates that consanguinity is not necessary. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3, yucesan2023functionalcharacterizationof pages 4-7)

10. Diagnostics

Clinical suspicion

Consider TRAPPC12 testing in a child or fetus with combinations of severe developmental delay/regression, microcephaly, hearing loss, hypotonia plus appendicular spasticity/dystonia, seizures, dysphagia, and MRI evidence of cortical atrophy, pons hypoplasia, corpus-callosum agenesis/hypoplasia, or unexplained hydrocephalus. The discovery authors specifically recommended evaluation in sequencing data for neonatal encephalopathy, hearing loss, pontocerebellar hypoplasia, and brain-atrophy disorders. (milev2017mutationsintrappc12 pages 5-8)

Recommended evaluation

Brain MRI, including assessment of cortical volume, myelination/white-matter signal, corpus callosum, pons, cerebellum, ventricles, optic chiasm, and interval progression.
EEG for seizures or regression; hypsarrhythmia supports infantile spasms but is not disease-specific.
Formal audiology, even after failed neonatal otoacoustic-emission screening.
Ophthalmology/neuro-ophthalmology for optic atrophy and cortical visual impairment.
Swallowing and nutritional evaluation; respiratory, orthopedic, rehabilitation, and bladder assessments according to symptoms.
Routine biochemical/metabolic testing to exclude treatable mimics; no TRAPPC12-specific enzyme or metabolite assay exists. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

Genetic testing strategy

First-line: trio WES or WGS for an unexplained complex encephalopathy, or a comprehensive neurodevelopmental/epilepsy/brain-atrophy/pontocerebellar-hypoplasia panel that includes TRAPPC12.
Confirm candidate variants and phase/segregation by parental testing; Sanger confirmation was used in the foundational study.
Ensure analysis detects single-nucleotide variants, small indels, splice variants, and exon-level copy-number changes. WGS may improve detection of noncoding splice, structural, or poorly covered variants, although no comparative TRAPPC12 WGS-yield study exists.
If only one pathogenic allele is found, pursue deletion/duplication analysis, genome sequencing, and—where available—RNA studies.
CMA may identify broad chromosomal causes in the differential but is not sufficient to exclude biallelic sequence-level TRAPPC12 disease. Karyotyping, FISH, mtDNA testing, and repeat-expansion assays are not specifically indicated unless the phenotype or initial results suggest an alternative diagnosis.
Protein immunoblotting and fibroblast Golgi/trafficking assays remain research-level functional tests, not validated clinical diagnostics. (milev2017mutationsintrappc12 pages 3-5, milev2017mutationsintrappc12 pages 2-3, yucesan2023functionalcharacterizationof pages 4-7)

Differential diagnosis

The differential includes congenital infection or hypoxic-ischemic injury; mitochondrial and metabolic encephalopathies; pontocerebellar hypoplasias; tubulinopathies; congenital disorders of glycosylation; hereditary spasticity/brain-atrophy syndromes; and other TRAPPopathies involving TRAPPC4, TRAPPC6B, TRAPPC9, TRAPPC10, TRAPPC11, or TRAPPC2L. The combination of hearing loss, pons hypoplasia, callosal agenesis, and prominent supratentorial atrophy is especially suggestive but not pathognomonic. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 5-8)

Screening

TRAPPC12 is not part of established biochemical newborn screening, and there is no validated dried-blood-spot biomarker or population DNA-screening program. Targeted cascade testing is appropriate for relatives of a molecularly confirmed proband. Carrier, prenatal, and preimplantation testing become technically feasible after familial variants are established.

11. Outcome and prognosis

The disorder generally carries high neurologic morbidity. In the three-patient discovery cohort, all had severe disability and regression; two required gastrostomy, and one developed neurogenic bladder. One of three died at 4 years 9 months, reportedly from presumed respiratory insufficiency. This single death cannot provide a mortality rate or life-expectancy estimate. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

Later cases demonstrate variable severity, including survival to nine years with milder cortical atrophy and absence of epilepsy or microcephaly. Genotypes causing complete protein loss or early truncation may plausibly be more severe, but the patient count is too small for a validated genotype–prognosis rule. No five- or ten-year survival statistics, prognostic model, validated prognostic biomarker, recovery-rate study, or formal quality-of-life dataset exists. (yucesan2023functionalcharacterizationof pages 4-7, yucesan2023functionalcharacterizationof pages 1-4)

Potential complications include refractory epilepsy, aspiration and malnutrition, contractures and scoliosis, hip instability, respiratory insufficiency, visual/hearing disability, and total dependence for daily activities. Recovery of lost developmental function has not been documented; supportive interventions may preserve comfort, positioning, communication, nutrition, and prevent secondary complications.

12. Treatment

Current practice

There is no approved or evidence-based disease-modifying treatment. Management is individualized and supportive:

Standard antiseizure therapy selected by seizure type; infantile spasms require urgent specialist treatment according to general pediatric epilepsy standards.
Gastroesophageal-reflux, swallowing, nutrition, and aspiration management; enteral feeding/gastrostomy when oral feeding is unsafe or inadequate.
Physical and occupational therapy, positioning, stretching, orthotics, tone/spasticity management, and orthopedic surveillance.
Speech/communication therapy and augmentative communication.
Hearing aids or other audiologic intervention when appropriate; low-vision/cortical-visual-impairment services.
Respiratory monitoring, airway clearance, vaccination, and infection management; sleep and secretion assessment where indicated.
Palliative-care involvement for severe progressive disease and shared decision-making.

Gastrostomy dependence in two original patients documents real-world feeding support, but no study reports comparative response rates or adverse-event frequencies. (milev2017mutationsintrappc12 pages 1-2, milev2017mutationsintrappc12 pages 2-3)

Suggested NCIT intervention concepts include Supportive Care, Anticonvulsant Therapy, Gastrostomy, Physical Therapy, Occupational Therapy, Speech Therapy, Hearing Aid, Orthopedic Procedure, and Palliative Care; exact NCIT codes should be verified directly before database import.

Advanced and experimental therapies

No TRAPPC12-specific gene-replacement, gene-editing, cell, antisense, siRNA, mRNA, small-molecule, targeted, or immunotherapy has entered clinical evaluation. No relevant interventional ClinicalTrials.gov study was identified. The successful rescue of patient-cell Golgi morphology by wild-type TRAPPC12 supplies proof of biological reversibility at the cellular level, but it is not preclinical evidence of CNS delivery, developmental rescue, safety, or patient benefit. (milev2017mutationsintrappc12 pages 5-8)

No TRAPPC12-specific pharmacogenomic guidance or treatment algorithm exists.

13. Prevention

Primary lifestyle or environmental prevention is not applicable to an inherited biallelic disorder. The principal preventive strategy is genetic counseling:

Confirm both familial variants and parental phase.
Offer targeted carrier testing to at-risk adult relatives.
Discuss prenatal diagnosis by chorionic-villus sampling or amniocentesis and preimplantation genetic testing for monogenic disease where legally and locally available.
Use targeted fetal imaging, while recognizing that a normal early scan cannot exclude later progressive disease.

Secondary prevention consists of early molecular diagnosis, hearing/vision assessment, seizure surveillance, feeding evaluation, and developmental intervention. Tertiary prevention targets aspiration, malnutrition, respiratory infection, contractures, scoliosis, pressure injury, and caregiver burden. No vaccine, prophylactic medication, public-health intervention, or behavioral modification prevents TRAPPC12 disease itself.

14. Other species and natural disease

No naturally occurring TRAPPC12-related encephalopathy was identified in companion animals, livestock, or wildlife, and no breed association or VBO identifier is established. TRAPPC12 is metazoan-specific in the reviewed cell-biology literature and has no yeast ortholog, limiting direct yeast disease modeling. (zhao2017mammaliantrappiiicomplex pages 1-2)

No zoonotic or cross-species transmission is relevant because this is a germline genetic disorder. Ortholog-specific NCBI Gene and NCBI Taxonomy identifiers were not established in the retrieved evidence and should be sourced directly before annotation.

15. Model organisms and experimental systems

Patient-derived human cells

Primary skin fibroblasts from all three discovery patients are the most disease-relevant models. They reproduced absent TRAPPC12 protein, fragmented Golgi, delayed ER-to-Golgi and through-Golgi trafficking, and mitotic delay; wild-type TRAPPC12 rescued Golgi morphology. Fibroblasts from the p.Phe227Val patient showed absent protein, disrupted Golgi integrity, enlarged ER-associated cell architecture, and altered neutral-lipid-vesicle distribution. These systems directly model patient genotype but cannot reproduce neuronal circuitry, developmental timing, brain regional selectivity, seizures, or behavior. (milev2017mutationsintrappc12 pages 5-8, milev2017mutationsintrappc12 pages 3-5, yucesan2023functionalcharacterizationof pages 4-7)

Engineered cell models

HeLa and HEK293T CRISPR-knockout cells: used to assess COPII assembly, Sec13/Sec31 recruitment, ERGIC/Golgi organization, and secretory trafficking. They establish molecular mechanism but are transformed/non-neural cells. (zhao2017mammaliantrappiiicomplex pages 10-11, zhao2017mammaliantrappiiicomplex pages 8-9)
HeLa RNAi/depletion models: demonstrated Golgi fragmentation, chromosome-congression failure, kinetochore defects, and altered CENP-E recruitment. (sacher2019trappopathiesanemerging pages 24-28)
hTERT-RPE1 cells: demonstrated TRAPPC12–OFD1 interaction and increased ciliary length/impaired disassembly after depletion. This is useful for ciliogenesis but does not establish that ciliary dysfunction causes encephalopathy. (zhang2020distinctrolesof pages 1-2)
CCD1079Sk control fibroblasts: used against p.Phe227Val patient fibroblasts in the 2023 functional report. (yucesan2023functionalcharacterizationof pages 1-4)

No TRAPPC12-specific mouse, rat, zebrafish, Drosophila, C. elegans, iPSC-neuron, cerebral-organoid, conditional knockout, knock-in, or humanized disease model was retrieved. Mouse and other animal phenotypes reported for TRAPPC10 or other TRAPP genes must not be attributed to TRAPPC12.

Recent developments and expert assessment

The key 2023 development was functional analysis of homozygous p.Phe227Val, showing that a nontruncating variant could nevertheless produce nearly absent protein and marked Golgi/ER abnormalities while causing a clinically milder phenotype. Its abstract reports: “Protein expression showed an absence in the TRAPPC12 protein and an uncharacterized protein fragment (CGI-87).” Because this was a preprint in the retrieved record, conclusions should be weighted below peer-reviewed primary studies until final publication is verified. (yucesan2023functionalcharacterizationof pages 4-7, yucesan2023functionalcharacterizationof pages 1-4)

The December 2024 review characterized TRAPPC12 disease as a spectrum of neurological symptoms and noted 21 ClinVar pathogenic/likely pathogenic variants. Its central expert conclusion is that, beyond membrane-trafficking defects in fibroblasts, the pathophysiology remains poorly understood. This appropriately defines the current field: gene–disease validity and ER–Golgi dysfunction are convincing, while selective neural vulnerability, genotype–phenotype relationships, natural history, biomarkers, and therapeutic tractability remain unresolved. (hall2024trappopathiesseveremultisystem pages 12-14)

Knowledge-base conclusions

High-confidence: biallelic TRAPPC12 variants cause an autosomal-recessive encephalopathy; loss of protein, Golgi fragmentation, and delayed ER-to-Golgi trafficking are experimentally established.
Moderate-confidence: the core phenotype includes severe developmental impairment/regression, microcephaly, hypotonia/spasticity, movement disorder, hearing impairment, and a pons–callosum–cortical-atrophy MRI signature.
Variable features: epilepsy, West syndrome, cerebellar atrophy, hydrocephalus, and microcephaly are not obligatory across later cases.
Mechanistically plausible but not proven as the clinical driver: altered mitosis, autophagy, and ciliogenesis.
Not established: disease-specific prevalence, penetrance, founder alleles, modifier genes, biomarkers, natural-history stages, formal QoL or survival estimates, animal disease models, guidelines, clinical trials, and disease-modifying therapy.

For production curation, ClinVar, HGNC, MONDO, HPO, GO, UBERON, CL, NCIT, and current OMIM records should be re-queried directly to validate live identifiers and variant classifications; database counts and classifications can change after the publication dates represented here.

References

(hall2024trappopathiesseveremultisystem pages 12-14): Riley Hall, Vallari Sawant, Jinchao Gu, Tim Sikora, Ben Rollo, Silvia Velasco, Jinkuk Kim, Nava Segev, John Christodoulou, and Nicole J. Van Bergen. Trappopathies: severe multisystem disorders caused by variants in genes of the transport protein particle (trapp) complexes. International Journal of Molecular Sciences, 25:13329, Dec 2024. URL: https://doi.org/10.3390/ijms252413329, doi:10.3390/ijms252413329. This article has 8 citations.
(milev2017mutationsintrappc12 pages 1-2): Miroslav P. Milev, Megan E. Grout, Djenann Saint-Dic, Yong-Han Hank Cheng, Ian A. Glass, Christopher J. Hale, David S. Hanna, Michael O. Dorschner, Keshika Prematilake, Avraham Shaag, Orly Elpeleg, Michael Sacher, Dan Doherty, and Simon Edvardson. Mutations in trappc12 manifest in progressive childhood encephalopathy and golgi dysfunction. American journal of human genetics, 101 2:291-299, Aug 2017. URL: https://doi.org/10.1016/j.ajhg.2017.07.006, doi:10.1016/j.ajhg.2017.07.006. This article has 61 citations and is from a highest quality peer-reviewed journal.
(yucesan2023functionalcharacterizationof pages 1-4): Emrah Yucesan, Beyza Goncu, Gozde Yesil, and Ayca Dilruba Aslanger. Functional characterization of a missense mutation in the trappc12 gene presenting with progressive encephalopathy with brain atrophy and spasticity phenotype without microcephaly and epilepsy. Unknown journal, Feb 2023. URL: https://doi.org/10.21203/rs.3.rs-2552844/v1, doi:10.21203/rs.3.rs-2552844/v1.
(milev2017mutationsintrappc12 pages 2-3): Miroslav P. Milev, Megan E. Grout, Djenann Saint-Dic, Yong-Han Hank Cheng, Ian A. Glass, Christopher J. Hale, David S. Hanna, Michael O. Dorschner, Keshika Prematilake, Avraham Shaag, Orly Elpeleg, Michael Sacher, Dan Doherty, and Simon Edvardson. Mutations in trappc12 manifest in progressive childhood encephalopathy and golgi dysfunction. American journal of human genetics, 101 2:291-299, Aug 2017. URL: https://doi.org/10.1016/j.ajhg.2017.07.006, doi:10.1016/j.ajhg.2017.07.006. This article has 61 citations and is from a highest quality peer-reviewed journal.
(zhao2017mammaliantrappiiicomplex pages 1-2): Shan Zhao, Chun Man Li, Xiao Min Luo, Gavin Ka Yu Siu, Wen Jia Gan, Lin Zhang, William K. K. Wu, Hsiao Chang Chan, and Sidney Yu. Mammalian trappiii complex positively modulates the recruitment of sec13/31 onto copii vesicles. Scientific Reports, Feb 2017. URL: https://doi.org/10.1038/srep43207, doi:10.1038/srep43207. This article has 44 citations and is from a peer-reviewed journal.
(sacher2019trappopathiesanemerging pages 24-28): Michael Sacher, Nassim Shahrzad, Hiba Kamel, and Miroslav P. Milev. Trappopathies: an emerging set of disorders linked to variations in the genes encoding transport protein particle (trapp)‐associated proteins. Traffic, 20:26-5, Sep 2019. URL: https://doi.org/10.1111/tra.12615, doi:10.1111/tra.12615. This article has 106 citations and is from a peer-reviewed journal.
(milev2017mutationsintrappc12 pages 3-5): Miroslav P. Milev, Megan E. Grout, Djenann Saint-Dic, Yong-Han Hank Cheng, Ian A. Glass, Christopher J. Hale, David S. Hanna, Michael O. Dorschner, Keshika Prematilake, Avraham Shaag, Orly Elpeleg, Michael Sacher, Dan Doherty, and Simon Edvardson. Mutations in trappc12 manifest in progressive childhood encephalopathy and golgi dysfunction. American journal of human genetics, 101 2:291-299, Aug 2017. URL: https://doi.org/10.1016/j.ajhg.2017.07.006, doi:10.1016/j.ajhg.2017.07.006. This article has 61 citations and is from a highest quality peer-reviewed journal.
(zhang2020distinctrolesof pages 1-2): Caiyun Zhang, Chunman Li, Gavin Ka Yu Siu, Xiaomin Luo, and Sidney Yu. Distinct roles of trappc8 and trappc12 in ciliogenesis via their interactions with ofd1. Frontiers in Cell and Developmental Biology, Mar 2020. URL: https://doi.org/10.3389/fcell.2020.00148, doi:10.3389/fcell.2020.00148. This article has 15 citations.
(yucesan2023functionalcharacterizationof pages 4-7): Emrah Yucesan, Beyza Goncu, Gozde Yesil, and Ayca Dilruba Aslanger. Functional characterization of a missense mutation in the trappc12 gene presenting with progressive encephalopathy with brain atrophy and spasticity phenotype without microcephaly and epilepsy. Unknown journal, Feb 2023. URL: https://doi.org/10.21203/rs.3.rs-2552844/v1, doi:10.21203/rs.3.rs-2552844/v1.
(yucesan2023functionalcharacterizationof pages 7-11): Emrah Yucesan, Beyza Goncu, Gozde Yesil, and Ayca Dilruba Aslanger. Functional characterization of a missense mutation in the trappc12 gene presenting with progressive encephalopathy with brain atrophy and spasticity phenotype without microcephaly and epilepsy. Unknown journal, Feb 2023. URL: https://doi.org/10.21203/rs.3.rs-2552844/v1, doi:10.21203/rs.3.rs-2552844/v1.
(milev2017mutationsintrappc12 pages 5-8): Miroslav P. Milev, Megan E. Grout, Djenann Saint-Dic, Yong-Han Hank Cheng, Ian A. Glass, Christopher J. Hale, David S. Hanna, Michael O. Dorschner, Keshika Prematilake, Avraham Shaag, Orly Elpeleg, Michael Sacher, Dan Doherty, and Simon Edvardson. Mutations in trappc12 manifest in progressive childhood encephalopathy and golgi dysfunction. American journal of human genetics, 101 2:291-299, Aug 2017. URL: https://doi.org/10.1016/j.ajhg.2017.07.006, doi:10.1016/j.ajhg.2017.07.006. This article has 61 citations and is from a highest quality peer-reviewed journal.
(zhao2017mammaliantrappiiicomplex pages 8-9): Shan Zhao, Chun Man Li, Xiao Min Luo, Gavin Ka Yu Siu, Wen Jia Gan, Lin Zhang, William K. K. Wu, Hsiao Chang Chan, and Sidney Yu. Mammalian trappiii complex positively modulates the recruitment of sec13/31 onto copii vesicles. Scientific Reports, Feb 2017. URL: https://doi.org/10.1038/srep43207, doi:10.1038/srep43207. This article has 44 citations and is from a peer-reviewed journal.
(zhao2017mammaliantrappiiicomplex pages 10-11): Shan Zhao, Chun Man Li, Xiao Min Luo, Gavin Ka Yu Siu, Wen Jia Gan, Lin Zhang, William K. K. Wu, Hsiao Chang Chan, and Sidney Yu. Mammalian trappiii complex positively modulates the recruitment of sec13/31 onto copii vesicles. Scientific Reports, Feb 2017. URL: https://doi.org/10.1038/srep43207, doi:10.1038/srep43207. This article has 44 citations and is from a peer-reviewed journal.

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Discussions and Knowledge Gaps

Pathophysiology

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Phenotypes

Genetic Associations

Medical Actions

Diagnosis

Imaging Findings

Prevalence

Differential Diagnoses

Experimental Models

Animal Models

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References & Deep Research

References

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TRAPPC12-Related Encephalopathy: Disease-Characteristics Research Report

Executive summary

Evidence scope and caution

1. Disease information

Definition and current understanding

Names and identifiers

Core publications

2. Etiology

Causal factor

Genetic risk factors

Environmental, infectious, and lifestyle risks

Protective factors, modifiers, and gene–environment interaction

3. Phenotypes

Neurologic and developmental manifestations

Hearing, vision, feeding, and musculoskeletal manifestations

Neuroimaging

Laboratory abnormalities

Quality-of-life effects

4. Genetic and molecular information

Gene and protein

Reported disease variants

Functional consequences

Modifier and epigenetic information

5. Environmental information

6. Mechanism and pathophysiology

Best-supported causal chain

ER-to-Golgi trafficking and COPII biology

TRAPPIII and Rab signaling

Mitosis

Autophagy

Ciliogenesis

Molecular profiling and advanced technologies

7. Anatomical structures affected

Organ and system level

Tissue and cell level

Subcellular structures

8. Temporal development

9. Inheritance and population

Inheritance

Epidemiology

10. Diagnostics

Clinical suspicion

Recommended evaluation

Genetic testing strategy

Differential diagnosis

Screening

11. Outcome and prognosis

12. Treatment

Current practice

Advanced and experimental therapies

13. Prevention

14. Other species and natural disease

15. Model organisms and experimental systems

Patient-derived human cells

Engineered cell models

Recent developments and expert assessment

Knowledge-base conclusions

Artifacts