VPS4A-Related Neurodevelopmental Syndrome

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Inheritance

1

Autosomal dominant inheritance HP:0000006

The established mode is a heterozygous de novo missense variant in the VPS4A ATPase domain acting through a dominant-negative mechanism. A single later report (PMID:42498620) describes a homozygous VPS4A variant in a consanguineous-context proband, so a recessive route is not excluded, but the multi-proband series both report de novo heterozygous alleles.

Autosomal dominant inheritance

Show evidence (1 reference)

PMID:33186545 SUPPORT Human Clinical

"Here we describe six unrelated individuals with de novo missense variants affecting the ATPase domain of VPS4A, a critical enzyme regulating ESCRT function."

Six unrelated probands with de novo missense variants establishes a dominant, sporadic mode of inheritance.

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Discussions and Knowledge Gaps

5

Does the zebrafish vps4a T248I sensorimotor-circuit lesion actually explain the hypotonia and motor delay of human CIMDAG syndrome, given that the human disease additionally shows cerebellar hypoplasia, congenital microcephaly, dystonia, and dyserythropoietic anemia that the fish model has not been shown to reproduce?

HUMAN MODEL MISMATCH OPEN vps4a_zebrafish_translational_reach

Attached to

pathophysiology#Abnormal Neurodevelopment and Structural Brain Malformation

The zebrafish work localises the deficit to sensorimotor transformation with intact motor neurons and muscle, which maps well onto the central hypotonia described in patients. But the model's reported readouts are reflex and circuit assays, not the structural cerebellar/cortical malformation or the erythroid phenotype that dominate the human disorder, so its translational reach beyond hypotonia is untested.

Proposed experiments

Cerebellar and telencephalic morphometry in vps4a mutant larvae

vps4a_zf_brain_morphometry

Quantify cerebellar and telencephalic size and neuronal number in vps4a T248I larvae and compare with the cerebellar hypoplasia and congenital microcephaly reported in patients.

Decision criterion

A significant reduction in cerebellar and telencephalic volume/neuron number relative to wild-type siblings would extend the model's validity beyond sensorimotor circuits.

Erythroid phenotyping of vps4a mutant zebrafish

vps4a_zf_erythroid_phenotyping

Assay erythroid development and erythrocyte morphology in vps4a mutant zebrafish to test whether the dyserythropoietic arm of the human disease is conserved.

Decision criterion

Binucleate or bridged erythroid precursors in the mutant would support conservation of the abscission-failure mechanism in vivo.

Patient-variant cerebral and cerebellar organoids

vps4a_patient_organoid_growth

Determine whether human iPSC-derived cerebral or cerebellar organoids carrying VPS4A ATPase-domain variants reproduce the structural growth deficit.

Decision criterion

Reduced organoid size or disrupted cytoarchitecture versus isogenic controls would place the growth deficit in human neural tissue.

Is the homozygous VPS4A p.Arg288Gln allele a genuine recessive route to CIMDAG syndrome, or a hypomorph whose heterozygous carriers are simply unascertained?

KNOWLEDGE GAP OPEN vps4a_recessive_allele_question

Attached to

pathophysiology#VPS4A ATPase-Domain Missense Variants Impair ESCRT-III Disassembly

Every proband in the two multi-case series carried a de novo heterozygous ATPase-domain missense variant acting dominant-negatively. A single 2026 report describes a homozygous allele. Whether the parents were asymptomatic heterozygotes, and whether p.Arg288Gln is dominant-negative or simply hypomorphic, is unresolved and matters for counselling.

Proposed experiments

Parental phenotyping and segregation analysis

vps4a_r288q_parental_segregation

Phenotype and re-sequence the heterozygous parents of the p.Arg288Gln proband for subclinical CIMDAG features.

Decision criterion

Entirely unaffected heterozygous parents would support a genuinely recessive allele; subclinical features would argue for a hypomorph with dosage-dependent expressivity.

Isogenic side-by-side allele comparison

vps4a_r288q_isogenic_allele_comparison

Compare p.Arg288Gln with a canonical de novo allele in an isogenic cell system for ATPase activity, ESCRT-III disassembly, and dominant-negative behaviour on co-expression with wild-type VPS4A.

Decision criterion

Absence of dominant-negative behaviour for p.Arg288Gln when co-expressed with wild-type VPS4A would establish it as a distinct, recessive-acting allele class.

Is CIMDAG syndrome a static developmental malformation syndrome, a progressive neurodegeneration, or both?

OPEN QUESTION OPEN vps4a_static_versus_progressive

Attached to

pathophysiology#Abnormal Neurodevelopment and Structural Brain Malformation

The disorder is usually framed developmentally - cerebellar hypoplasia and congenital microcephaly are malformations present from birth. But an abscission/cell-division lesion that depletes neural progenitors and an endolysosomal lesion that persists in post-mitotic neurons are different kinds of injury with different time courses, and reported neuroimaging includes atrophy (PMID:42498620 documents cerebellar atrophy, not only hypoplasia) rather than pure hypoplasia. Whether affected individuals lose previously acquired skills, and whether brain volume falls on serial imaging, determines whether this entry's causal graph should carry a degenerative arm at all. No natural history study exists.

Proposed experiments

Serial volumetric neuroimaging in a CIMDAG cohort

vps4a_serial_neuroimaging

Collect longitudinal volumetric brain MRI in molecularly confirmed individuals and measure change in cerebellar, brainstem, and supratentorial volume over time against age-matched norms.

Decision criterion

Progressive loss of volume beyond the expected trajectory would establish a degenerative component; stable z-scores would support a purely malformative model.

Longitudinal standardised developmental assessment

vps4a_longitudinal_developmental_assessment

Apply repeated standardised developmental/adaptive measures to distinguish plateau from regression.

Decision criterion

Documented loss of previously acquired skills would support regression.

Do the chromosome-segregation errors caused by VPS4A variants generate micronuclei that activate cGAS-STING and produce a chronic type I interferon signature in patients?

KNOWLEDGE GAP OPEN vps4a_micronuclei_cgas_sting_interferon

Attached to

pathophysiology#Chromosome Missegregation and Mitotic Spindle Errors

PMID:33186545 documents disturbed chromosome segregation and mitotic spindle formation in patient cells. Micronucleus formation from missegregated chromosomes is the canonical route to cytosolic-DNA sensing by cGAS-STING and hence to a chronic interferonopathy. Nobody has measured an interferon signature in CIMDAG blood, so it is unknown whether this well-established downstream consequence of chromosomal instability actually operates here. If it does, it would add a targetable inflammatory arm to a disease that currently has no disease-modifying therapy.

Proposed experiments

Type I interferon signature in patient blood

vps4a_interferon_signature_blood

Measure an interferon-stimulated gene score in whole blood from molecularly confirmed VPS4A probands against age-matched controls.

Decision criterion

An elevated ISG score would support an active cGAS-STING arm and justify testing JAK inhibition; a normal score would close the question.

Micronucleus and cGAS colocalisation in proband fibroblasts

vps4a_micronuclei_cgas_colocalisation

Quantify micronuclei in proband-derived fibroblasts and score cGAS recruitment to ruptured micronuclei alongside downstream STING-TBK1-IRF3 activation.

Decision criterion

cGAS-positive micronuclei with downstream pathway activation, absent in isogenic controls, would establish the cell-autonomous link.

If the dominant alleles act by poisoning VPS4A hexamers rather than by haploinsufficiency, is allele-selective knockdown of the mutant transcript a rational therapeutic strategy?

OPEN QUESTION OPEN vps4a_allele_selective_silencing_rationale

Attached to

pathophysiology#VPS4A ATPase-Domain Missense Variants Impair ESCRT-III Disassembly

PMID:33186545 shows the patient mutants phenocopy engineered dominant-negative ATPase-dead VPS4A, which implies that removing the mutant product - rather than adding wild-type protein - is the mechanistically correct intervention. Gene addition would not clear poisoned hexamers. The open questions are whether losing one VPS4A allele is tolerated in humans, and whether the CNS phenotype is already fixed prenatally, which would cap any postnatal benefit. Recorded as an open question, not as a treatment claim: no such program exists and no supporting outcome data are cited here.

Proposed experiments

Allele-selective knockdown in proband fibroblasts and iPSC neurons

vps4a_allele_selective_knockdown_in_vitro

Test allele-selective ASO or siRNA against a recurrent VPS4A missense allele in proband-derived fibroblasts and iPSC-derived neurons, reading out endosomal morphology, IST1 localisation, and abscission timing.

Decision criterion

Normalisation of endosomal morphology and abscission on selective mutant knockdown, without a penalty from the resulting reduced total VPS4A dose, would validate the strategy in principle.

Population assessment of VPS4A loss-of-function tolerance

vps4a_heterozygous_lof_tolerance

Systematically evaluate whether heterozygous predicted-loss-of-function VPS4A alleles occur in unselected population databases at frequencies incompatible with a severe phenotype.

Decision criterion

Confirmed tolerance of heterozygous loss of function would remove the main safety objection to allele-selective silencing.

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Pathophysiology

9

VPS4A ATPase-Domain Missense Variants Impair ESCRT-III Disassembly

VPS4A is the AAA-ATPase that hydrolyses ATP to disassemble ESCRT-III polymers after a membrane-scission event. Disease-associated missense variants cluster in the ATPase domain and behave in cells like known dominant-negative ATPase-defective VPS4A, so the enzyme is present but cannot complete the ESCRT-III turnover cycle.

VPS4A hgnc:13488

ESCRT III complex GO:0000815

ESCRT III complex disassembly GO:1904903 ↓ DECREASED

ATP hydrolysis activity GO:0016887 ↓ DECREASED

Downstream

Enlarged Endosomal Compartments with IST1 Retention Without ATP-driven ESCRT-III turnover, ESCRT-III subunits remain bound to endosomal membranes and endosomal compartments swell.

VPS4A Destabilization and Lipotoxic Stress Proposed additional arm from a single 2026 family: an ATPase-domain missense variant destabilises VPS4A and impairs its lipid-droplet association, producing lipotoxic stress in proband fibroblasts. The intermediates between protein destabilisation and lipid accumulation are not established.

Defective Cytokinetic Abscission ESCRT-III disassembly by VPS4A is also required to complete the final membrane cut between daughter cells.

Chromosome Missegregation and Mitotic Spindle Errors The same failure of ESCRT-III turnover disturbs chromosome segregation, mitotic spindle formation and cell cycle progression in proband cells.

Centrosome Number and Primary Cilium Abnormalities Failed ESCRT-III turnover is also accompanied by abnormal centrosome number and abnormal primary cilium morphology in proband cells.

Show evidence (3 references)

PMID:33186545 SUPPORT Human Clinical

"six unrelated individuals with de novo missense variants affecting the ATPase domain of VPS4A, a critical enzyme regulating ESCRT function"

Locates the disease-causing variants in the ATPase domain of VPS4A and identifies VPS4A as the ESCRT-regulating enzyme.

PMID:33186545 SUPPORT In Vitro

"In cultured cells, overexpression of VPS4A mutants caused enlarged endosomal vacuoles resembling those induced by expression of known dominant-negative ATPase-defective forms of VPS4A."

The mutant proteins phenocopy engineered ATPase-dead VPS4A, supporting a dominant-negative loss of ATPase-driven ESCRT-III disassembly.

PMID:39455257 SUPPORT Model Organism

"Biochemical analyses indicate that the T248I mutation reduces the ATPase activity of Vps4a and disassembly of ESCRT filaments, which mediate membrane scission."

A zebrafish vps4a missense allele directly demonstrates that this class of variant reduces ATPase activity and ESCRT filament disassembly.

Enlarged Endosomal Compartments with IST1 Retention

Patient fibroblasts and VPS4A-dependent iPSC-derived human neurons develop enlarged endosomal structures with the ESCRT-III-associated protein IST1 stuck on the limiting membrane, the cellular signature of stalled ESCRT-III turnover. The same enlarged endosomal compartments appear in the CNS of zebrafish vps4a mutants, together with a fall in circulating exosomes.

fibroblast CL:0000057 iPSC-derived human neuron CL:0000540

endosome organization GO:0007032 ⚠ ABNORMAL endosomal transport GO:0016197 ⚠ ABNORMAL

endosome GO:0005768

Downstream

Abnormal Neurodevelopment and Structural Brain Malformation

Show evidence (2 references)

PMID:33186545 SUPPORT In Vitro

"VPS4A function was also required for normal endosomal morphology and IST1 localization in iPSC-derived human neurons."

Establishes that the endosomal lesion is present in a human neuronal context, not only in fibroblasts.

PMID:39455257 SUPPORT Model Organism

"vps4aT248I larvae have enlarged endosomal compartments in the CNS and decreased numbers of circulating exosomes in brain ventricles"

An in vivo model reproduces the enlarged CNS endosomal compartments and adds loss of exosome output.

Defective Cytokinetic Abscission

VPS4A-dependent ESCRT-III turnover is required to complete the final membrane cut between daughter cells. VPS4A holds an abscission role that its paralog VPS4B cannot fully substitute, which is why heterozygous VPS4A variants are pathogenic despite an intact VPS4B gene.

mitotic cytokinesis GO:0000281 ⚠ ABNORMAL

Downstream

Ineffective Erythropoiesis with Dyserythropoiesis Failed abscission in the erythroid lineage produces binucleated erythroblasts and erythroblasts joined by cytoplasmic bridges.

Show evidence (3 references)

PMID:38687820 SUPPORT In Vitro

"These observations provide a potential mechanistic explanation for the neurodevelopmental defects and other related disorders reported in VPS4A-mutated patients with a fully functional VPS4B paralog."

Explains why the disease is VPS4A-specific: VPS4B cannot compensate for the regulatory abscission role held by VPS4A.

PMID:38687820 SUPPORT In Vitro

"We propose that patients who carry normal VPS4B and mutated VPS4A genes develop pathologies due to the disruption of VPS4A-mediated cellular regulation, which is essential for neurodevelopment"

The authors' explicit statement of the paralog-non-redundancy argument, quoted from the cached full text. This is the NEC-relevant discriminator: the disease is VPS4A-specific and is not a VPS4B disorder.

PMID:38687820 PARTIAL In Vitro

"Depletion of VTA1, a co-factor of VPS4, disrupted VPS4A-ANCHR interactions and accelerated abscission, suggesting that VTA1 is also involved in the abscission regulation."

Places VPS4A within a regulated abscission-checkpoint module (with ANCHR and the co-factor VTA1), supporting a regulatory rather than purely catalytic role at the midbody. PARTIAL because it uses depletion rather than a patient missense allele.

Chromosome Missegregation and Mitotic Spindle Errors

Separately from the abscission failure, proband fibroblasts show disturbed chromosome segregation, abnormal mitotic spindle formation and impaired cell cycle progression - the chromosomal-instability arm of the VPS4A lesion.

chromosome segregation GO:0007059 ⚠ ABNORMAL mitotic cell cycle GO:0000278 ⚠ ABNORMAL

Show evidence (1 reference)

PMID:33186545 SUPPORT In Vitro

"Mutations affected other ESCRT-dependent cellular processes, including regulation of centrosome number, primary cilium morphology, nuclear membrane morphology, chromosome segregation, mitotic spindle formation, and cell cycle progression."

Disturbed chromosome segregation, mitotic spindle formation and cell cycle progression are reported directly in proband-derived cells.

Centrosome Number and Primary Cilium Abnormalities

Proband fibroblasts also show abnormal centrosome number and abnormal primary cilium morphology, reflecting the ESCRT dependence of centrosome and ciliary membrane biology.

centrosome cycle GO:0007098 ⚠ ABNORMAL cilium assembly GO:0060271 ⚠ ABNORMAL

Show evidence (1 reference)

PMID:33186545 SUPPORT In Vitro

"Mutations affected other ESCRT-dependent cellular processes, including regulation of centrosome number, primary cilium morphology, nuclear membrane morphology, chromosome segregation, mitotic spindle formation, and cell cycle progression."

Abnormal centrosome number and primary cilium morphology are reported directly in proband-derived cells.

Ineffective Erythropoiesis with Dyserythropoiesis

The erythroid lineage is unusually sensitive to the VPS4A lesion. Bone marrow shows binucleated erythroblasts and erythroblasts connected by cytoplasmic bridges, and circulating red cells abnormally retain the transferrin receptor CD71, showing that VPS4A-dependent vesicular trafficking is also required for the terminal membrane remodelling of reticulocyte maturation. The phenotype has been reproduced in proband-derived iPSCs.

erythroblast CL:0000765 reticulocyte CL:0000558

erythrocyte differentiation GO:0030218 ⚠ ABNORMAL mitotic cytokinesis GO:0000281 ↓ DECREASED

Downstream

Multisystem Developmental and Hematologic Disease

Show evidence (2 references)

PMID:33186543 SUPPORT Human Clinical

"Circulating red blood cells were found to retain transferrin receptor (CD71) in their membrane, demonstrating that VPS4A is critical for normal reticulocyte maturation."

CD71 retention on circulating red cells is direct human evidence that VPS4A is required for reticulocyte maturation.

PMID:33186543 SUPPORT In Vitro

"Using proband-derived induced pluripotent stem cells (iPSCs), we have successfully modeled the hematologic aspects of this syndrome in vitro, recapitulating their dyserythropoietic phenotype."

Patient-derived iPSCs reproduce the dyserythropoietic phenotype, supporting a cell-autonomous erythroid mechanism.

Abnormal Neurodevelopment and Structural Brain Malformation

The neurodevelopmental arm of the syndrome comprises structural brain abnormalities with severe developmental delay. Cerebellar hypoplasia and congenital microcephaly are named in the disorder's own clinical description, and cerebellar atrophy has been imaged in a later-reported proband.

Downstream

Multisystem Developmental and Hematologic Disease

Show evidence (1 reference)

PMID:33186545 SUPPORT Human Clinical

"Probands had structural brain abnormalities, severe neurodevelopmental delay, cataracts, growth impairment, and anemia."

Summarises the neurodevelopmental and multisystem clinical picture in the original six-proband series.

Multisystem Developmental and Hematologic Disease

The convergent clinical endpoint: a syndrome combining cerebellar hypoplasia, impaired intellectual development, congenital microcephaly, dystonia, anemia, and growth retardation, with cataracts a frequent additional feature.

Show evidence (1 reference)

PMID:42498620 SUPPORT Human Clinical

"Cerebellar hypoplasia, impaired intellectual development, congenital microcephaly, dystonia, anemia, and growth retardation (CIMDAG) syndrome is caused by variants in VPS4A."

Names the full CIMDAG feature set and attributes it to VPS4A variants.

VPS4A Destabilization and Lipotoxic Stress

A single 2026 report proposes an additional lipid-handling arm: a VPS4A p.Arg288Gln variant aggregated, interacted less with LC3B, and failed to localise to lipid droplets, and proband fibroblasts accumulated lipid, free fatty acids, and reactive oxygen species. This is a one-family observation and is recorded here as an emerging, not established, mechanism.

fibroblast CL:0000057

lipid storage GO:0019915 ↑ INCREASED

lipid droplet GO:0005811

Downstream

Multisystem Developmental and Hematologic Disease

Show evidence (2 references)

PMID:42498620 SUPPORT In Vitro

"Proband fibroblasts exhibited increased lipid accumulation, elevated free fatty acids, and higher reactive oxygen species levels, indicative of lipotoxic stress."

Direct fibroblast measurements in one proband support a lipotoxic-stress readout downstream of the variant.

PMID:42498620 PARTIAL In Vitro

"The VPS4A-p.Arg288Gln variant showed enhanced aggregation and reduced interaction with LC3B"

Proposed molecular basis for the lipid-droplet mislocalisation; PARTIAL because it rests on a single variant in a single family.

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Histopathology

1

Binucleated erythroblasts and intercellular cytoplasmic bridges in bone marrow

Bone marrow aspirate/biopsy in VPS4A-related syndromic congenital dyserythropoietic anemia shows binucleated erythroblasts and erythroblasts linked by cytoplasmic bridges, reflecting incomplete cytokinetic abscission.

Show evidence (1 reference)

PMID:33186543 SUPPORT Human Clinical

"Bone marrow studies showed binucleated erythroblasts and erythroblasts with cytoplasmic bridges indicating abnormal cytokinesis and abscission."

The marrow morphology is described directly in the patient series.

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Pathograph

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Phenotypes

24

Blood 1

Congenital dyserythropoietic anemia Anemia HP:0001903

Term choice: HPO was searched for a "congenital dyserythropoietic anemia" class and none exists. The nearest candidates were audited and rejected: HP:0005532 (Macrocytic dyserythropoietic anemia) is a child of macrocytic anemia and no cached source documents macrocytosis in these probands, and HP:0031688 (Erythroid dysplasia, synonym "Dyserythropoiesis") is a marrow morphology term rather than an anemia term - the marrow morphology is curated separately below under HP:0034278. Generic HP:0001903 is therefore used for the anemia itself. Following the PR #7728 review (suggestion 3), HP:0010972 (Anemia of inadequate production) was added as a second, mechanistically specific anemia descriptor - see the phenotype immediately below. It was added rather than substituted: HP:0001903 is retained because the anemia of this syndrome is not uniformly a production defect (PMID:33460484 reports a hemolytic presentation), so the generic term is the one that covers the whole reported spectrum. The haematological presentation is also not uniform: PMID:33460484 reports a VPS4A proband whose anemia was hemolytic without obvious dyserythropoiesis. Only that paper's title is available in the cached record (the journal supplied no abstract to PubMed), so the observation is recorded here as a note rather than as a snippet-backed evidence item.

Show evidence (2 references)

PMID:33186543 SUPPORT Human Clinical

"Three unrelated individuals enrolled in the registry had a syndrome characterized by CDA and severe neurodevelopmental delay."

Three registry probands had congenital dyserythropoietic anemia together with the neurodevelopmental phenotype.

PMID:33186545 SUPPORT Human Clinical

"severe neurodevelopmental delay, cataracts, growth impairment, and anemia"

Anemia is reported in the independent six-proband series.

Cardiovascular 1

Splenomegaly Splenomegaly HP:0001744

Provenance differs from the other evidence-free phenotypes in this entry and is weaker. Splenomegaly is NOT in the HPO annotation set for OMIM:619273 - the full annotation set was retrieved from https://ontology.jax.org/api/network/annotation/OMIM:619273 on 2026-08-01 and checked term by term; it contains 35 annotations and HP:0001744 is not among them. The 3/3 figure comes from the deep-research artifact for this entry, which read it out of the Seu et al. full text (PMID:33186543). That full text is not in references_cache (the cached record is abstract-only) and the abstract does not mention the spleen, so no evidence item can be attached and none is fabricated. Recorded as a descriptor because a reviewer flagged its absence and because chronic hemolysis and ineffective erythropoiesis both predict it; a curator with full-text access should confirm it and attach a snippet.

Digestive 2

Feeding difficulties Feeding difficulties HP:0011968

Evidence-free descriptor sourced from the HPO annotation set for OMIM:619273, which records Feeding difficulties in 4/6 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached reference in this entry mentions feeding, so no evidence item is attached. See the entry-level note on HPOA-sourced phenotypes.

Hepatomegaly Hepatomegaly HP:0002240

Evidence-free descriptor sourced from the HPO annotation set for OMIM:619273, which records Hepatomegaly in 4/5 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached reference in this entry mentions the liver, so no evidence item is attached. See the entry-level note on HPOA-sourced phenotypes.

Ear 1

Sensorineural hearing impairment Sensorineural hearing impairment HP:0000407

Term choice: the "sensorineural" qualifier comes from the HPO annotation set for OMIM:619273, which records HP:0000407 Sensorineural hearing impairment in 2/5 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). The only cached text that mentions hearing says "deafness" without qualifying it as sensorineural, so the evidence item below is marked PARTIAL and the qualifier rests on the annotation set rather than on the snippet. No frequency band is set.

Show evidence (1 reference)

PMID:38687820 PARTIAL Other

"These conditions were associated with structural brain abnormalities, intellectual disability (ID), deafness, cataracts, and visual dysfunction."

Deafness is named as a feature of VPS4A-related disease. Classified OTHER because this is a background summary of prior human reports in a cell-biology paper, and PARTIAL because the source does not state that the hearing loss is sensorineural.

Eye 3

Cataract Cataract HP:0000518

Show evidence (2 references)

PMID:33186545 SUPPORT Human Clinical

"Probands had structural brain abnormalities, severe neurodevelopmental delay, cataracts, growth impairment, and anemia."

Cataracts are reported in the original VPS4A proband series.

PMID:42498620 SUPPORT Human Clinical

"developmental delay, microcephaly, dystonia, cataracts, dyserythropoietic anemia, and growth retardation"

An independent later case confirms cataracts as part of the phenotype.

Visual impairment Visual impairment HP:0000505

The HPO annotation set for OMIM:619273 records Visual impairment in 6/6 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). The evidence item below comes from a cell-biology paper's background summary of the two primary human reports, not from primary patient data, hence evidence_source OTHER and supports PARTIAL - it establishes that visual dysfunction belongs to the syndrome but supplies no counts. No frequency band is set.

Show evidence (1 reference)

PMID:38687820 PARTIAL Other

"These conditions were associated with structural brain abnormalities, intellectual disability (ID), deafness, cataracts, and visual dysfunction."

Visual dysfunction is named as a feature of VPS4A-related disease. Classified OTHER because this is the abscission paper's background summary of the two prior human reports rather than primary patient data, and PARTIAL because "visual dysfunction" is a looser descriptor than the HPO term.

Retinal dystrophy Retinal dystrophy HP:0000556

Evidence-free descriptor sourced from the HPO annotation set for OMIM:619273, which records Retinal dystrophy in 3/5 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached reference in this entry mentions the retina, so no evidence item is attached. See the entry-level note on HPOA-sourced phenotypes.

Head and Neck 1

Microcephaly Microcephaly HP:0000252

Term-pair rationale (added in response to PR #7728 review, suggestion 1): the HPO annotation set for OMIM:619273 records HP:0000252 Microcephaly in 6/6 annotated individuals but HP:0011451 Primary microcephaly in only 3/6, so curating the primary term alone would leave a universal feature represented by its 50% subset. Both terms are therefore retained. The annotation set was retrieved from https://ontology.jax.org/api/network/annotation/OMIM:619273 on 2026-08-01. No frequency band is set - see the entry-level note on HPOA-sourced phenotypes.

Show evidence (1 reference)

PMID:42498620 SUPPORT Human Clinical

"classical CIMDAG features, including developmental delay, microcephaly, dystonia, cataracts, dyserythropoietic anemia, and growth retardation"

Microcephaly without a congenital qualifier is listed among the classical CIMDAG features of the most recently reported proband, which is what the general term HP:0000252 denotes.

Musculoskeletal 2

Hypotonia Hypotonia HP:0001252

Show evidence (2 references)

PMID:39455257 SUPPORT Other

"Mutations in human VPS4A are associated with neurodevelopmental defects, including motor delays and defective muscle tone."

Defective muscle tone (hypotonia) is stated as an established human VPS4A phenotype. Classified OTHER rather than HUMAN_CLINICAL because this is the zebrafish paper's background summary of prior human reports, not primary patient data collected in that study.

PMID:39455257 PARTIAL Model Organism

"Resembling the central form of hypotonia in VPS4A patients, motor neurons and muscle cells are functional in mutant zebrafish."

Model-organism evidence that the hypotonia is central; PARTIAL because the localisation claim rests on the zebrafish, not on human tissue.

Spasticity Spasticity HP:0001257

Evidence-free descriptor sourced from the HPO annotation set for OMIM:619273, which records Spasticity in 4/5 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached reference in this entry mentions spasticity, so no evidence item is attached. See the entry-level note on HPOA-sourced phenotypes.

Nervous System 8

Cerebellar hypoplasia Cerebellar hypoplasia HP:0001321

Show evidence (1 reference)

PMID:42498620 SUPPORT Human Clinical

"Cerebellar hypoplasia, impaired intellectual development, congenital microcephaly, dystonia, anemia, and growth retardation (CIMDAG) syndrome is caused by variants in VPS4A."

Cerebellar hypoplasia is explicitly listed as a defining CIMDAG feature of VPS4A-related disease.

Impaired intellectual development Intellectual disability HP:0001249

Show evidence (1 reference)

PMID:42498620 SUPPORT Human Clinical

"Cerebellar hypoplasia, impaired intellectual development, congenital microcephaly, dystonia, anemia, and growth retardation (CIMDAG) syndrome is caused by variants in VPS4A."

Impaired intellectual development is stated verbatim as a defining feature of the VPS4A-caused syndrome.

Severe global developmental delay Global developmental delay HP:0001263

Severity: SEVERE

Show evidence (3 references)

PMID:33186545 SUPPORT Human Clinical

"Probands had structural brain abnormalities, severe neurodevelopmental delay, cataracts, growth impairment, and anemia."

The original six-proband series reports severe neurodevelopmental delay; the SEVERE severity qualifier is taken from the word "severe" in this sentence and is not a derived grading.

PMID:33186543 SUPPORT Human Clinical

"Three unrelated individuals enrolled in the registry had a syndrome characterized by CDA and severe neurodevelopmental delay."

An independent registry cohort confirms severe neurodevelopmental delay.

PMID:42498620 SUPPORT Human Clinical

"We report a 5-year-old Nepalese boy with classical CIMDAG features, including developmental delay, microcephaly, dystonia, cataracts, dyserythropoietic anemia, and growth retardation."

Developmental delay is listed among the classical CIMDAG features present in the most recently reported proband; this report does not itself grade the delay as severe.

Dystonia Dystonia HP:0001332

Show evidence (1 reference)

PMID:42498620 SUPPORT Human Clinical

"classical CIMDAG features, including developmental delay, microcephaly, dystonia, cataracts, dyserythropoietic anemia, and growth retardation"

Dystonia is explicitly listed among the proband's classical CIMDAG features.

Delayed gross motor development Delayed gross motor development HP:0002194

Show evidence (1 reference)

PMID:39455257 SUPPORT Other

"Mutations in human VPS4A are associated with neurodevelopmental defects, including motor delays and defective muscle tone."

Motor delay is named as a human VPS4A-associated neurodevelopmental defect. Classified OTHER because this is the zebrafish paper's background summary of prior human reports rather than primary patient data.

Delayed speech and language development Delayed speech and language development HP:0000750

Evidence-free descriptor sourced from the HPO annotation set for OMIM:619273, which records Delayed speech and language development in 5/5 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached reference in this entry mentions speech or language development, so no evidence item is attached and no snippet is fabricated. See the entry-level note on HPOA-sourced phenotypes for the shared rationale and for why no frequency band is set.

Seizure Seizure HP:0001250

Evidence-free descriptor sourced from the HPO annotation set for OMIM:619273, which records Seizure in 3/6 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached reference in this entry mentions seizures, so no evidence item is attached. See the entry-level note on HPOA-sourced phenotypes.

Sleep disturbance Sleep disturbance HP:0002360

Evidence-free descriptor sourced from the HPO annotation set for OMIM:619273, which records Sleep disturbance in 4/4 annotated individuals (retrieved 2026-08-01 from https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached reference in this entry mentions sleep, so no evidence item is attached. See the entry-level note on HPOA-sourced phenotypes.

Growth 1

Growth retardation Growth delay HP:0001510

Show evidence (2 references)

PMID:33186545 SUPPORT Human Clinical

"severe neurodevelopmental delay, cataracts, growth impairment, and anemia"

Growth impairment is reported in the original VPS4A proband series.

PMID:42498620 SUPPORT Human Clinical

"dyserythropoietic anemia, and growth retardation"

Growth retardation is confirmed in the most recently reported proband.

Other 4

Congenital microcephaly Primary microcephaly HP:0011451

Onset: CONGENITAL

Show evidence (1 reference)

PMID:42498620 SUPPORT Human Clinical

"Cerebellar hypoplasia, impaired intellectual development, congenital microcephaly, dystonia, anemia, and growth retardation (CIMDAG) syndrome is caused by variants in VPS4A."

The source states the microcephaly of this syndrome is congenital, which is what HP:0011451 (primary microcephaly) denotes.

Anemia of inadequate production Anemia of inadequate production HP:0010972

Added in response to the PR #7728 review (suggestion 3) and curated alongside, not instead of, HP:0001903. HP:0010972 was not among the candidates audited in the term-choice note on the preceding phenotype; it fits the congenital dyserythropoietic presentation, whereas HP:0001903 remains necessary to cover the hemolytic presentation of PMID:33460484. No frequency band is set.

Show evidence (2 references)

PMID:33186543 SUPPORT Human Clinical

"Our findings demonstrate that VPS4A mutations cause cytokinesis and trafficking defects leading to a human disease with detrimental effects to erythropoiesis and neurodevelopment."

The authors locate the hematologic lesion in erythropoiesis itself - a production defect - which is what HP:0010972 denotes.

PMID:33186543 PARTIAL In Vitro

"Using proband-derived induced pluripotent stem cells (iPSCs), we have successfully modeled the hematologic aspects of this syndrome in vitro, recapitulating their dyserythropoietic phenotype."

The dyserythropoietic (ineffective-erythropoiesis) character of the anemia is reproduced in proband-derived cells, supporting a production-side rather than destruction-side mechanism.

Multinucleated erythroblasts Multinucleated erythroblast HP:0034278

Show evidence (1 reference)

PMID:33186543 SUPPORT Human Clinical

"Bone marrow studies showed binucleated erythroblasts and erythroblasts with cytoplasmic bridges indicating abnormal cytokinesis and abscission."

Directly reports binucleated erythroblasts on patient bone marrow.

Abnormal brain morphology Abnormal brain morphology HP:0012443

Show evidence (1 reference)

PMID:33186545 SUPPORT Human Clinical

"Probands had structural brain abnormalities, severe neurodevelopmental delay"

Structural brain abnormality is reported directly in the proband series.

🧬

Genetic Associations

1

VPS4A pathogenic missense variants (Missense mutation)

Gene: VPS4A hgnc:13488 relationship_type: CAUSATIVE variant_origin: DE_NOVO

Autosomal dominant inheritance

Show evidence (3 references)

PMID:33186545 SUPPORT Human Clinical

"six unrelated individuals with de novo missense variants affecting the ATPase domain of VPS4A"

Establishes de novo ATPase-domain missense variants as the causal allele class.

PMID:33186543 SUPPORT Human Clinical

"They were found to have missense mutations in VPS4A, a gene coding for an ATPase that regulates the ESCRT-III machinery in a variety of cellular processes including cell division, endosomal vesicle trafficking, and viral budding."

An independent cohort confirms VPS4A missense variants as causal and states the gene's ESCRT-III regulatory function.

PMID:35441598 SUPPORT Other

"Additional recent advances included the identification of new CDA genes, RACGAP1 and VPS4A, in CDAIII and a syndromic CDA type, respectively."

A field review independently records VPS4A as the gene of a syndromic congenital dyserythropoietic anemia.

💊

Medical Actions

1

Supportive and multidisciplinary care

Action: supportive care Ontology label: Supportive Care NCIT:C15747

No disease-modifying therapy exists for VPS4A-related disease. Reported management is supportive: transfusion support for anemia, developmental and rehabilitative therapies, dystonia management, cataract surgery, and nutritional support for growth failure. No treatment claim in this entry is backed by a trial, and none is asserted with evidence here.

🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from VPS4A-Related Neurodevelopmental Syndrome:

Congenital dyserythropoietic anemia type 1 Not Yet Curated MONDO:0020337

Overlapping Features CDA I (CDAN1/CDIN1) also presents with ineffective erythropoiesis and abnormal erythroblast morphology.

Distinguishing Features

CDA I lacks the severe neurodevelopmental phenotype, congenital microcephaly, dystonia, and cerebellar hypoplasia of CIMDAG syndrome.
CDA I arises from the Codanin-1/CDIN1 pathway rather than from ESCRT-III turnover failure.

Show evidence (1 reference)

PMID:35441598 SUPPORT Other

"Codanin-1 was found to physically interact with CDIN1, suggesting that mutations in CDAN1 and CDIN1 result in CDAI via a common mechanism."

Establishes the distinct CDAN1/CDIN1 molecular basis of CDA I.

Congenital dyserythropoietic anemia type 2 Not Yet Curated MONDO:0009134

Overlapping Features CDA II, caused by SEC23B variants, shares the ineffective erythropoiesis that defines the congenital dyserythropoietic anemias.

Distinguishing Features

CDA II is non-syndromic, without the neurodevelopmental, ocular, and growth features of VPS4A-related disease.
CDA II results from SEC23B (COPII secretory pathway) variants rather than from VPS4A.

Show evidence (1 reference)

PMID:35441598 SUPPORT Other

"Recent advances in CDAII (which results from SEC23B mutations) have also been made."

Confirms SEC23B as the CDA II gene, distinct from VPS4A.

🔬

Clinical Trials

1

NCT02964494 RECRUITING

The Congenital Dyserythropoietic Anemia Registry (CDAR), an observational North American registry and biorepository run from Cincinnati Children's Hospital Medical Center. It is not VPS4A-specific, but it is the ascertainment route through which the three VPS4A probands of PMID:33186543 were identified, and it is the only registered study currently capturing these patients. No interventional trial for VPS4A-related disease is registered.

Target Phenotypes: Congenital dyserythropoietic anemia HP:0001903

Show evidence (2 references)

clinicaltrials:NCT02964494 PARTIAL Human Clinical

"The investigators have created and maintain a comprehensive registry for patients with the diagnosis of Congenital Dyserythropoietic Anemia (CDA) in North America."

Confirms the registry's scope. Marked PARTIAL because the registry covers the congenital dyserythropoietic anemias generally, not VPS4A-related disease specifically.

PMID:33186543 SUPPORT Human Clinical

"The Congenital Dyserythropoietic Anemia (CDA) Registry was established with the goal to facilitate investigations of natural history, biology, and molecular pathogenetic mechanisms of CDA."

Confirms that the CDA Registry is the source cohort for the VPS4A probands described in this paper.

🧫

Experimental Models

2

Proband-derived iPSC erythroid differentiation

Induced pluripotent stem cells reprogrammed from VPS4A patients and differentiated toward the erythroid lineage recapitulate the dyserythropoietic phenotype in vitro, providing a tractable human model of the hematologic arm of the disease.

Show evidence (1 reference)

PMID:33186543 SUPPORT In Vitro

"Using proband-derived induced pluripotent stem cells (iPSCs), we have successfully modeled the hematologic aspects of this syndrome in vitro, recapitulating their dyserythropoietic phenotype."

States the model system and the phenotype it reproduces.

VPS4A and VPS4B isoform knockout cell lines

Paired VPS4A and VPS4B knockout human cell lines were used to separate the paralogs' contributions to cytokinetic abscission, establishing that VPS4A holds a regulatory role that VPS4B cannot substitute.

Show evidence (1 reference)

PMID:38687820 SUPPORT In Vitro

"Here, we set out to investigate the role of the human VPS4 paralogs in cytokinetic abscission using a series of knockout cell lines."

Describes the isoform-resolved knockout system.

{ }

Source YAML

click to show

name: VPS4A-Related Neurodevelopmental Syndrome
creation_date: "2026-08-01T00:00:00Z"
category: Mendelian
disease_term:
  preferred_term: CIMDAG syndrome
  term:
    id: MONDO:0035819
    label: cerebellar hypoplasia-intellectual disability-congenital microcephaly-dystonia-anemia-growth retardation syndrome
description: >-
  CIMDAG syndrome (cerebellar hypoplasia, impaired intellectual development,
  congenital microcephaly, dystonia, anemia, and growth retardation) is an
  ultra-rare multisystem developmental disorder caused by missense variants in
  VPS4A, the AAA-ATPase that disassembles ESCRT-III filaments and thereby
  terminates every ESCRT-dependent membrane-scission event. Affected children
  have severe neurodevelopmental delay with structural brain abnormalities,
  congenital microcephaly, dystonia, cataracts, growth impairment, and a
  congenital dyserythropoietic anemia in which bone marrow shows binucleated
  erythroblasts and erythroblasts joined by cytoplasmic bridges. The unifying
  cellular lesion is failure of ESCRT-III turnover: patient cells accumulate
  enlarged endosomal compartments with the ESCRT protein IST1 trapped on the
  limiting membrane, and cytokinetic abscission, centrosome number, primary
  cilium morphology, chromosome segregation, and cell-cycle progression are all
  disturbed. Most reported probands carry de novo heterozygous variants in the
  VPS4A ATPase domain that behave in cells like known dominant-negative
  ATPase-defective VPS4A.
synonyms:
- CIMDAG syndrome
- cerebellar hypoplasia-intellectual disability-congenital microcephaly-dystonia-anemia-growth retardation syndrome
- VPS4A-related multisystem disease with abnormal neurodevelopment
- syndromic congenital dyserythropoietic anemia due to VPS4A deficiency
parents:
- Neurodevelopmental Disorder
notes: >-
  Gene identity was confirmed before curation: MONDO:0035819 asserts
  RO:0004003 to HGNC:13488 (VPS4A) and xrefs OMIM:619273, matching every
  source cited here. VPS4A is deliberately distinguished throughout from its
  paralog VPS4B; PMID:38687820 is cited specifically because it dissects the
  paralog-specific abscission role that explains why VPS4A variants are
  pathogenic in the presence of a fully functional VPS4B.

  No GeneReviews chapter exists for CIMDAG syndrome or VPS4A (PubMed searches
  "VPS4A GeneReviews[All Fields]" and "CIMDAG GeneReviews[All Fields]" both
  returned zero records on 2026-08-01), so the GeneReviews phenotype baseline
  step was not applicable.

  Phenotype `frequency:` bands are deliberately omitted throughout. The
  published cohorts are tiny (six probands in PMID:33186545, three in
  PMID:33186543, single case reports thereafter) and the abstracts attribute
  features to "probands" collectively without per-feature counts, so no
  defensible denominator exists for a FrequencyEnum band. Per the frequency
  evidence guidelines, the association is asserted and the band is left unset.

  Onset descriptors are likewise omitted except where a source states the
  timing: the disease name and PMID:42498620 establish that the microcephaly is
  congenital, but the cached abstracts give no ages at onset for the other
  features.

  Deep research: `just research-disorder claude_code
  VPS4A-Related_Neurodevelopmental_Syndrome`
  (research/VPS4A-Related_Neurodevelopmental_Syndrome-deep-research-claude_code.md,
  2026-08-01, 11 web searches, 69 turns). NEC preflight on that report passed -
  VPS4A is named 120 times against 23 for VPS4B (the paralog comparison is the
  report's own subject matter, not a substitution), the only OMIM asserted is
  OMIM:619273, and the only disease MONDO asserted is MONDO:0035819.

  Only PMID:38687820 is cached as full text; every other cited reference is
  abstract-only. A large amount of clinically valuable detail in the deep
  research report (per-phenotype patient-count frequencies from the HPO
  annotation file, splenomegaly, hepatomegaly, iron overload, seizures,
  spasticity, retinal dystrophy, the specific variant table, and the family
  support-group management guidance) therefore has no quotable cached source.
  None of it is supported here by an unverifiable snippet.

  HPOA-sourced phenotypes. Following the PR #7728 review, the features that the
  HPO annotation set records for OMIM:619273 but that no cached abstract quotes
  are curated as phenotype descriptors carrying a `notes:` provenance statement
  and no evidence item, rather than being omitted. dismech does not require an
  evidence item on a Phenotype, and this entry already used the
  descriptor-plus-note pattern for its Treatment object; omitting the
  phenotypes made the entry read as though a child with CIMDAG syndrome has no
  seizures, no visual impairment and no feeding difficulty. The annotation set
  was retrieved independently for this entry from
  https://ontology.jax.org/api/network/annotation/OMIM:619273 on 2026-08-01
  (35 annotations returned) and each descriptor's note records the
  patient-count fraction that the annotation set carries and the date of
  retrieval. Those fractions are deliberately NOT converted into `frequency:`
  bands: they are counts over series of three to six probands drawn from the
  unreachable full texts, and a band would assert a population frequency that
  no source states. Where a cached text does support the feature, an evidence
  item is attached instead (HP:0000252, HP:0000505, HP:0000407, HP:0010972).
  One descriptor, HP:0001744 Splenomegaly, is NOT in the annotation set and its
  weaker provenance is recorded in its own note.
external_assertions:
- name: OMIM CIMDAG syndrome record
  source: OMIM
  assertion_type: disease_record
  external_id: OMIM:619273
  description: >-
    OMIM phenotype entry for cerebellar hypoplasia with impaired intellectual
    development, congenital microcephaly, dystonia, anemia, and growth
    retardation (CIMDAG syndrome). This is the OMIM xref asserted by
    MONDO:0035819 and is the identifier used in the NEC preflight for this
    entry.
- name: MONDO gene-disease assertion for VPS4A
  source: MONDO
  assertion_type: gene_disease_association
  external_id: MONDO:0035819
  description: >-
    MONDO:0035819 asserts RO:0004003 (has material basis in germline mutation
    in) to HGNC:13488 (VPS4A), independently confirming the causal gene used to
    anchor this entry.
inheritance:
- name: Autosomal dominant inheritance
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    The established mode is a heterozygous de novo missense variant in the
    VPS4A ATPase domain acting through a dominant-negative mechanism. A single
    later report (PMID:42498620) describes a homozygous VPS4A variant in a
    consanguineous-context proband, so a recessive route is not excluded, but
    the multi-proband series both report de novo heterozygous alleles.
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here we describe six unrelated individuals with de novo missense variants
      affecting the ATPase domain of VPS4A, a critical enzyme regulating ESCRT
      function.
    explanation: >-
      Six unrelated probands with de novo missense variants establishes a
      dominant, sporadic mode of inheritance.
pathophysiology:
- name: VPS4A ATPase-Domain Missense Variants Impair ESCRT-III Disassembly
  biological_scale: MOLECULAR
  description: >-
    VPS4A is the AAA-ATPase that hydrolyses ATP to disassemble ESCRT-III
    polymers after a membrane-scission event. Disease-associated missense
    variants cluster in the ATPase domain and behave in cells like known
    dominant-negative ATPase-defective VPS4A, so the enzyme is present but
    cannot complete the ESCRT-III turnover cycle.
  genes:
  - preferred_term: VPS4A
    term:
      id: hgnc:13488
      label: VPS4A
  molecular_functions:
  - preferred_term: ATP hydrolysis activity
    modifier: DECREASED
    term:
      id: GO:0016887
      label: ATP hydrolysis activity
  biological_processes:
  - preferred_term: ESCRT III complex disassembly
    modifier: DECREASED
    term:
      id: GO:1904903
      label: ESCRT III complex disassembly
  protein_complexes:
  - preferred_term: ESCRT III complex
    term:
      id: GO:0000815
      label: ESCRT III complex
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      six unrelated individuals with de novo missense variants affecting the
      ATPase domain of VPS4A, a critical enzyme regulating ESCRT function
    explanation: >-
      Locates the disease-causing variants in the ATPase domain of VPS4A and
      identifies VPS4A as the ESCRT-regulating enzyme.
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In cultured cells, overexpression of VPS4A mutants caused enlarged
      endosomal vacuoles resembling those induced by expression of known
      dominant-negative ATPase-defective forms of VPS4A.
    explanation: >-
      The mutant proteins phenocopy engineered ATPase-dead VPS4A, supporting a
      dominant-negative loss of ATPase-driven ESCRT-III disassembly.
  - reference: PMID:39455257
    reference_title: "Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Biochemical analyses indicate that the T248I mutation reduces the ATPase
      activity of Vps4a and disassembly of ESCRT filaments, which mediate
      membrane scission.
    explanation: >-
      A zebrafish vps4a missense allele directly demonstrates that this class of
      variant reduces ATPase activity and ESCRT filament disassembly.
  downstream:
  - target: Enlarged Endosomal Compartments with IST1 Retention
    causal_link_type: DIRECT
    description: >-
      Without ATP-driven ESCRT-III turnover, ESCRT-III subunits remain bound to
      endosomal membranes and endosomal compartments swell.
    evidence:
    - reference: PMID:33186545
      reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Proband-derived fibroblasts had enlarged endosomal structures with
        abnormal accumulation of the ESCRT protein IST1 on the limiting
        membrane.
      explanation: >-
        Patient-derived cells show the predicted consequence of failed
        ESCRT-III disassembly.
  - target: VPS4A Destabilization and Lipotoxic Stress
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Proposed additional arm from a single 2026 family: an ATPase-domain
      missense variant destabilises VPS4A and impairs its lipid-droplet
      association, producing lipotoxic stress in proband fibroblasts. The
      intermediates between protein destabilisation and lipid accumulation are
      not established.
    evidence:
    - reference: PMID:42498620
      reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
      supports: PARTIAL
      evidence_source: IN_VITRO
      snippet: >-
        Together, these findings demonstrate that a novel pathogenic VPS4A
        variant drives structural destabilization and lipotoxicity, providing
        mechanistic insight into lipid homeostasis perturbations in CIMDAG
        syndrome.
      explanation: >-
        The authors assert the destabilisation-to-lipotoxicity link; marked
        PARTIAL because it derives from one variant in one family and has not
        been replicated for the canonical de novo alleles.
  - target: Defective Cytokinetic Abscission
    causal_link_type: DIRECT
    description: >-
      ESCRT-III disassembly by VPS4A is also required to complete the final
      membrane cut between daughter cells.
    evidence:
    - reference: PMID:38687820
      reference_title: "The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        VPS4A depletion resulted in a more severe abscission delay than VPS4B
        and was found to be involved in earlier stages of abscission.
      explanation: >-
        Isoform-resolved knockout work shows VPS4A itself carries a
        non-redundant abscission role, linking VPS4A loss of function to
        cytokinesis failure.
  - target: Chromosome Missegregation and Mitotic Spindle Errors
    causal_link_type: DIRECT
    description: >-
      The same failure of ESCRT-III turnover disturbs chromosome segregation,
      mitotic spindle formation and cell cycle progression in proband cells.
    evidence:
    - reference: PMID:33186545
      reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Mutations affected other ESCRT-dependent cellular processes, including
        regulation of centrosome number, primary cilium morphology, nuclear
        membrane morphology, chromosome segregation, mitotic spindle formation,
        and cell cycle progression.
      explanation: >-
        The disease variants are shown to disturb chromosome segregation and
        spindle formation as ESCRT-dependent processes, placing this arm
        downstream of the ESCRT-III turnover defect.
  - target: Centrosome Number and Primary Cilium Abnormalities
    causal_link_type: DIRECT
    description: >-
      Failed ESCRT-III turnover is also accompanied by abnormal centrosome
      number and abnormal primary cilium morphology in proband cells.
    evidence:
    - reference: PMID:33186545
      reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Mutations affected other ESCRT-dependent cellular processes, including
        regulation of centrosome number, primary cilium morphology, nuclear
        membrane morphology, chromosome segregation, mitotic spindle formation,
        and cell cycle progression.
      explanation: >-
        Centrosome and primary cilium abnormalities are reported as
        ESCRT-dependent consequences of the disease variants.
- name: Enlarged Endosomal Compartments with IST1 Retention
  biological_scale: CELLULAR
  description: >-
    Patient fibroblasts and VPS4A-dependent iPSC-derived human neurons develop
    enlarged endosomal structures with the ESCRT-III-associated protein IST1
    stuck on the limiting membrane, the cellular signature of stalled
    ESCRT-III turnover. The same enlarged endosomal compartments appear in the
    CNS of zebrafish vps4a mutants, together with a fall in circulating
    exosomes.
  cell_types:
  - preferred_term: fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  - preferred_term: iPSC-derived human neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: endosome organization
    modifier: ABNORMAL
    term:
      id: GO:0007032
      label: endosome organization
  - preferred_term: endosomal transport
    modifier: ABNORMAL
    term:
      id: GO:0016197
      label: endosomal transport
  cellular_components:
  - preferred_term: endosome
    term:
      id: GO:0005768
      label: endosome
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      VPS4A function was also required for normal endosomal morphology and IST1
      localization in iPSC-derived human neurons.
    explanation: >-
      Establishes that the endosomal lesion is present in a human neuronal
      context, not only in fibroblasts.
  - reference: PMID:39455257
    reference_title: "Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      vps4aT248I larvae have enlarged endosomal compartments in the CNS and
      decreased numbers of circulating exosomes in brain ventricles
    explanation: >-
      An in vivo model reproduces the enlarged CNS endosomal compartments and
      adds loss of exosome output.
  downstream:
  - target: Abnormal Neurodevelopment and Structural Brain Malformation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - impaired endosomal receptor sorting and exosome-mediated signalling in developing CNS
    - disturbed sensorimotor circuit function
    evidence:
    - reference: PMID:39455257
      reference_title: "Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants."
      supports: PARTIAL
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Our results suggest that defects in sensorimotor transformation
        underlie the profound yet selective effects on motor reflexes resulting
        from the loss of membrane scission mediated by Vps4a.
      explanation: >-
        Model-organism evidence linking the membrane-scission defect to central
        motor dysfunction; marked PARTIAL because the circuit-level mechanism
        has not been shown in humans.
- name: Defective Cytokinetic Abscission
  biological_scale: CELLULAR
  description: >-
    VPS4A-dependent ESCRT-III turnover is required to complete the final
    membrane cut between daughter cells. VPS4A holds an abscission role that its
    paralog VPS4B cannot fully substitute, which is why heterozygous VPS4A
    variants are pathogenic despite an intact VPS4B gene.
  notes: >-
    Split out from a former combined node "Defective Cytokinetic Abscission and
    Cell-Division Errors" in response to the PR #7728 review (suggestion 2).
    The abscission arm, which carries the erythroid consequence, is now separate
    from the chromosome-segregation arm and from the centrosome/cilium arm, so
    that downstream edges and discussion attachments can be made against the
    specific process each depends on.
  biological_processes:
  - preferred_term: mitotic cytokinesis
    modifier: ABNORMAL
    term:
      id: GO:0000281
      label: mitotic cytokinesis
  evidence:
  - reference: PMID:38687820
    reference_title: "The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      These observations provide a potential mechanistic explanation for the
      neurodevelopmental defects and other related disorders reported in
      VPS4A-mutated patients with a fully functional VPS4B paralog.
    explanation: >-
      Explains why the disease is VPS4A-specific: VPS4B cannot compensate for
      the regulatory abscission role held by VPS4A.
  - reference: PMID:38687820
    reference_title: "The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      We propose that patients who carry normal VPS4B and mutated VPS4A genes
      develop pathologies due to the disruption of VPS4A-mediated cellular
      regulation, which is essential for neurodevelopment
    explanation: >-
      The authors' explicit statement of the paralog-non-redundancy argument,
      quoted from the cached full text. This is the NEC-relevant discriminator:
      the disease is VPS4A-specific and is not a VPS4B disorder.
  - reference: PMID:38687820
    reference_title: "The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission."
    supports: PARTIAL
    evidence_source: IN_VITRO
    snippet: >-
      Depletion of VTA1, a co-factor of VPS4, disrupted VPS4A-ANCHR interactions
      and accelerated abscission, suggesting that VTA1 is also involved in the
      abscission regulation.
    explanation: >-
      Places VPS4A within a regulated abscission-checkpoint module (with ANCHR
      and the co-factor VTA1), supporting a regulatory rather than purely
      catalytic role at the midbody. PARTIAL because it uses depletion rather
      than a patient missense allele.
  downstream:
  - target: Ineffective Erythropoiesis with Dyserythropoiesis
    causal_link_type: DIRECT
    description: >-
      Failed abscission in the erythroid lineage produces binucleated
      erythroblasts and erythroblasts joined by cytoplasmic bridges.
    evidence:
    - reference: PMID:33186543
      reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Bone marrow studies showed binucleated erythroblasts and erythroblasts
        with cytoplasmic bridges indicating abnormal cytokinesis and abscission.
      explanation: >-
        Patient bone marrow directly demonstrates the abscission failure in
        erythroid precursors.
- name: Chromosome Missegregation and Mitotic Spindle Errors
  biological_scale: CELLULAR
  description: >-
    Separately from the abscission failure, proband fibroblasts show disturbed
    chromosome segregation, abnormal mitotic spindle formation and impaired
    cell cycle progression - the chromosomal-instability arm of the VPS4A
    lesion.
  notes: >-
    Split out from the former combined node "Defective Cytokinetic Abscission
    and Cell-Division Errors" (PR #7728 review, suggestion 2). No downstream
    edge is drawn because no source establishes a consequence of the
    missegregation in patients: whether it produces micronuclei, cGAS-STING
    activation and an interferon signature is an explicitly open question,
    recorded in the discussion vps4a_micronuclei_cgas_sting_interferon, which
    now attaches to this node rather than to the bundled parent.
  biological_processes:
  - preferred_term: chromosome segregation
    modifier: ABNORMAL
    term:
      id: GO:0007059
      label: chromosome segregation
  - preferred_term: mitotic cell cycle
    modifier: ABNORMAL
    term:
      id: GO:0000278
      label: mitotic cell cycle
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Mutations affected other ESCRT-dependent cellular processes, including
      regulation of centrosome number, primary cilium morphology, nuclear
      membrane morphology, chromosome segregation, mitotic spindle formation,
      and cell cycle progression.
    explanation: >-
      Disturbed chromosome segregation, mitotic spindle formation and cell
      cycle progression are reported directly in proband-derived cells.
- name: Centrosome Number and Primary Cilium Abnormalities
  biological_scale: CELLULAR
  description: >-
    Proband fibroblasts also show abnormal centrosome number and abnormal
    primary cilium morphology, reflecting the ESCRT dependence of centrosome
    and ciliary membrane biology.
  notes: >-
    Split out from the former combined node "Defective Cytokinetic Abscission
    and Cell-Division Errors" (PR #7728 review, suggestion 2). No downstream
    edge is drawn: the cilium finding is a morphological observation in
    fibroblasts and no source links it to any clinical feature of this
    syndrome. For the same reason this entry deliberately does not assert
    conforms_to ciliopathy_dysfunction - the primary lesion is ESCRT-III
    turnover, not intraflagellar transport or transition-zone function, and
    conformance would assert a mechanism the module does not describe.
  biological_processes:
  - preferred_term: centrosome cycle
    modifier: ABNORMAL
    term:
      id: GO:0007098
      label: centrosome cycle
  - preferred_term: cilium assembly
    modifier: ABNORMAL
    term:
      id: GO:0060271
      label: cilium assembly
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Mutations affected other ESCRT-dependent cellular processes, including
      regulation of centrosome number, primary cilium morphology, nuclear
      membrane morphology, chromosome segregation, mitotic spindle formation,
      and cell cycle progression.
    explanation: >-
      Abnormal centrosome number and primary cilium morphology are reported
      directly in proband-derived cells.
- name: Ineffective Erythropoiesis with Dyserythropoiesis
  biological_scale: TISSUE
  description: >-
    The erythroid lineage is unusually sensitive to the VPS4A lesion. Bone
    marrow shows binucleated erythroblasts and erythroblasts connected by
    cytoplasmic bridges, and circulating red cells abnormally retain the
    transferrin receptor CD71, showing that VPS4A-dependent vesicular
    trafficking is also required for the terminal membrane remodelling of
    reticulocyte maturation. The phenotype has been reproduced in
    proband-derived iPSCs.
  cell_types:
  - preferred_term: erythroblast
    term:
      id: CL:0000765
      label: erythroblast
  - preferred_term: reticulocyte
    term:
      id: CL:0000558
      label: reticulocyte
  biological_processes:
  - preferred_term: erythrocyte differentiation
    modifier: ABNORMAL
    term:
      id: GO:0030218
      label: erythrocyte differentiation
  - preferred_term: mitotic cytokinesis
    modifier: DECREASED
    term:
      id: GO:0000281
      label: mitotic cytokinesis
  evidence:
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Circulating red blood cells were found to retain transferrin receptor
      (CD71) in their membrane, demonstrating that VPS4A is critical for normal
      reticulocyte maturation.
    explanation: >-
      CD71 retention on circulating red cells is direct human evidence that
      VPS4A is required for reticulocyte maturation.
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Using proband-derived induced pluripotent stem cells (iPSCs), we have
      successfully modeled the hematologic aspects of this syndrome in vitro,
      recapitulating their dyserythropoietic phenotype.
    explanation: >-
      Patient-derived iPSCs reproduce the dyserythropoietic phenotype,
      supporting a cell-autonomous erythroid mechanism.
  downstream:
  - target: Multisystem Developmental and Hematologic Disease
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33186543
      reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Our findings demonstrate that VPS4A mutations cause cytokinesis and
        trafficking defects leading to a human disease with detrimental effects
        to erythropoiesis and neurodevelopment.
      explanation: >-
        States the convergence of the erythroid and neurodevelopmental arms into
        one disease.
- name: Abnormal Neurodevelopment and Structural Brain Malformation
  biological_scale: ORGANISM
  description: >-
    The neurodevelopmental arm of the syndrome comprises structural brain
    abnormalities with severe developmental delay. Cerebellar hypoplasia and
    congenital microcephaly are named in the disorder's own clinical
    description, and cerebellar atrophy has been imaged in a later-reported
    proband.
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Probands had structural brain abnormalities, severe neurodevelopmental
      delay, cataracts, growth impairment, and anemia.
    explanation: >-
      Summarises the neurodevelopmental and multisystem clinical picture in the
      original six-proband series.
  downstream:
  - target: Multisystem Developmental and Hematologic Disease
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33186545
      reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We thus characterize a distinct multisystem disorder caused by
        mutations affecting VPS4A
      explanation: >-
        The authors frame the neurodevelopmental findings as part of a single
        multisystem VPS4A disorder.
- name: Multisystem Developmental and Hematologic Disease
  biological_scale: ORGANISM
  description: >-
    The convergent clinical endpoint: a syndrome combining cerebellar
    hypoplasia, impaired intellectual development, congenital microcephaly,
    dystonia, anemia, and growth retardation, with cataracts a frequent
    additional feature.
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cerebellar hypoplasia, impaired intellectual development, congenital
      microcephaly, dystonia, anemia, and growth retardation (CIMDAG) syndrome
      is caused by variants in VPS4A.
    explanation: >-
      Names the full CIMDAG feature set and attributes it to VPS4A variants.
- name: VPS4A Destabilization and Lipotoxic Stress
  biological_scale: CELLULAR
  role: emerging mechanism
  description: >-
    A single 2026 report proposes an additional lipid-handling arm: a VPS4A
    p.Arg288Gln variant aggregated, interacted less with LC3B, and failed to
    localise to lipid droplets, and proband fibroblasts accumulated lipid, free
    fatty acids, and reactive oxygen species. This is a one-family observation
    and is recorded here as an emerging, not established, mechanism.
  cell_types:
  - preferred_term: fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  biological_processes:
  - preferred_term: lipid storage
    modifier: INCREASED
    term:
      id: GO:0019915
      label: lipid storage
  cellular_components:
  - preferred_term: lipid droplet
    term:
      id: GO:0005811
      label: lipid droplet
  mechanism_confidence: PROVISIONAL
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Proband fibroblasts exhibited increased lipid accumulation, elevated free
      fatty acids, and higher reactive oxygen species levels, indicative of
      lipotoxic stress.
    explanation: >-
      Direct fibroblast measurements in one proband support a lipotoxic-stress
      readout downstream of the variant.
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: PARTIAL
    evidence_source: IN_VITRO
    snippet: >-
      The VPS4A-p.Arg288Gln variant showed enhanced aggregation and reduced
      interaction with LC3B
    explanation: >-
      Proposed molecular basis for the lipid-droplet mislocalisation; PARTIAL
      because it rests on a single variant in a single family.
  notes: >-
    Downstream consequence is only partly established (raised in the PR #7728
    review, suggestion 4, where this node was a pathograph dead-end). The
    authors of PMID:42498620 frame lipotoxic stress as explaining lipid
    homeostasis perturbations in CIMDAG syndrome, which is enough to draw the
    edge below to the multisystem endpoint, but no source demonstrates that
    lipotoxicity produces any specific clinical feature. The plausible clinical
    correlates are the hepatomegaly and hepatic steatosis recorded in the
    annotation set and the single reported case of lipodystrophy; neither has
    been linked to this mechanism in a cached source, so the edge is marked
    INDIRECT_UNKNOWN_INTERMEDIATES with PARTIAL support and no more specific
    target is asserted.
  downstream:
  - target: Multisystem Developmental and Hematologic Disease
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:42498620
      reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
      supports: PARTIAL
      evidence_source: IN_VITRO
      snippet: >-
        Together, these findings demonstrate that a novel pathogenic VPS4A
        variant drives structural destabilization and lipotoxicity, providing
        mechanistic insight into lipid homeostasis perturbations in CIMDAG
        syndrome.
      explanation: >-
        The authors attach the lipotoxic arm to CIMDAG syndrome itself, which
        justifies an edge to the clinical endpoint. PARTIAL and
        INDIRECT_UNKNOWN_INTERMEDIATES because the claim is an interpretive
        framing from one family, and no intermediate step between fibroblast
        lipid accumulation and any clinical feature has been shown.
phenotypes:
- category: Neurological
  name: Cerebellar hypoplasia
  phenotype_term:
    preferred_term: Cerebellar hypoplasia
    term:
      id: HP:0001321
      label: Cerebellar hypoplasia
  description: >-
    Cerebellar hypoplasia is the first-named feature of the CIMDAG acronym and
    of the MONDO disease label.
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cerebellar hypoplasia, impaired intellectual development, congenital
      microcephaly, dystonia, anemia, and growth retardation (CIMDAG) syndrome
      is caused by variants in VPS4A.
    explanation: >-
      Cerebellar hypoplasia is explicitly listed as a defining CIMDAG feature of
      VPS4A-related disease.
- category: Neurological
  name: Impaired intellectual development
  phenotype_term:
    preferred_term: Impaired intellectual development
    term:
      id: HP:0001249
      label: Intellectual disability
  description: >-
    Impaired intellectual development is the "I" of the CIMDAG acronym and is
    named in the MONDO disease label. The generic HP:0001249 term is used rather
    than a graded child term because no cached source states an IQ band or a
    severity grade for intellectual functioning specifically; the "severe"
    qualifier in the primary literature attaches to developmental delay, which
    is curated separately below.
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cerebellar hypoplasia, impaired intellectual development, congenital
      microcephaly, dystonia, anemia, and growth retardation (CIMDAG) syndrome
      is caused by variants in VPS4A.
    explanation: >-
      Impaired intellectual development is stated verbatim as a defining feature
      of the VPS4A-caused syndrome.
- category: Neurological
  name: Severe global developmental delay
  phenotype_term:
    preferred_term: Severe global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
    severity: SEVERE
  description: >-
    Severe neurodevelopmental delay was reported in every proband of both
    multi-case series, and developmental delay is listed among the classical
    features of the most recent single-case report.
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Probands had structural brain abnormalities, severe neurodevelopmental
      delay, cataracts, growth impairment, and anemia.
    explanation: >-
      The original six-proband series reports severe neurodevelopmental delay;
      the SEVERE severity qualifier is taken from the word "severe" in this
      sentence and is not a derived grading.
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Three unrelated individuals enrolled in the registry had a syndrome
      characterized by CDA and severe neurodevelopmental delay.
    explanation: >-
      An independent registry cohort confirms severe neurodevelopmental delay.
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report a 5-year-old Nepalese boy with classical CIMDAG features,
      including developmental delay, microcephaly, dystonia, cataracts,
      dyserythropoietic anemia, and growth retardation.
    explanation: >-
      Developmental delay is listed among the classical CIMDAG features present
      in the most recently reported proband; this report does not itself grade
      the delay as severe.
- category: Neurological
  name: Congenital microcephaly
  phenotype_term:
    preferred_term: Congenital microcephaly
    term:
      id: HP:0011451
      label: Primary microcephaly
    onset:
      onset_category: CONGENITAL
  description: >-
    Congenital (primary) microcephaly is a defining CIMDAG feature, present at
    birth.
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Cerebellar hypoplasia, impaired intellectual development, congenital
      microcephaly, dystonia, anemia, and growth retardation (CIMDAG) syndrome
      is caused by variants in VPS4A.
    explanation: >-
      The source states the microcephaly of this syndrome is congenital, which
      is what HP:0011451 (primary microcephaly) denotes.
- category: Neurological
  name: Microcephaly
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  description: >-
    Microcephaly at the general term level is reported in every published
    individual. It is curated in addition to HP:0011451 (primary microcephaly),
    not instead of it.
  notes: >-
    Term-pair rationale (added in response to PR #7728 review, suggestion 1):
    the HPO annotation set for OMIM:619273 records HP:0000252 Microcephaly in
    6/6 annotated individuals but HP:0011451 Primary microcephaly in only 3/6,
    so curating the primary term alone would leave a universal feature
    represented by its 50% subset. Both terms are therefore retained. The
    annotation set was retrieved from
    https://ontology.jax.org/api/network/annotation/OMIM:619273 on 2026-08-01.
    No frequency band is set - see the entry-level note on HPOA-sourced
    phenotypes.
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      classical CIMDAG features, including developmental delay, microcephaly,
      dystonia, cataracts, dyserythropoietic anemia, and growth retardation
    explanation: >-
      Microcephaly without a congenital qualifier is listed among the classical
      CIMDAG features of the most recently reported proband, which is what the
      general term HP:0000252 denotes.
- category: Neurological
  name: Dystonia
  phenotype_term:
    preferred_term: Dystonia
    term:
      id: HP:0001332
      label: Dystonia
  description: >-
    Dystonia is a defining CIMDAG feature and was present in the most recently
    reported proband.
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      classical CIMDAG features, including developmental delay, microcephaly,
      dystonia, cataracts, dyserythropoietic anemia, and growth retardation
    explanation: >-
      Dystonia is explicitly listed among the proband's classical CIMDAG
      features.
- category: Neurological
  name: Hypotonia
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  description: >-
    Defective muscle tone is reported in VPS4A patients; the zebrafish model
    work characterises it as central rather than neuromuscular in origin.
  evidence:
  - reference: PMID:39455257
    reference_title: "Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Mutations in human VPS4A are associated with neurodevelopmental defects,
      including motor delays and defective muscle tone.
    explanation: >-
      Defective muscle tone (hypotonia) is stated as an established human VPS4A
      phenotype. Classified OTHER rather than HUMAN_CLINICAL because this is the
      zebrafish paper's background summary of prior human reports, not primary
      patient data collected in that study.
  - reference: PMID:39455257
    reference_title: "Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants."
    supports: PARTIAL
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Resembling the central form of hypotonia in VPS4A patients, motor neurons
      and muscle cells are functional in mutant zebrafish.
    explanation: >-
      Model-organism evidence that the hypotonia is central; PARTIAL because
      the localisation claim rests on the zebrafish, not on human tissue.
- category: Neurological
  name: Delayed gross motor development
  phenotype_term:
    preferred_term: Delayed gross motor development
    term:
      id: HP:0002194
      label: Delayed gross motor development
  description: >-
    Motor delays are reported among the human VPS4A neurodevelopmental defects.
  evidence:
  - reference: PMID:39455257
    reference_title: "Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Mutations in human VPS4A are associated with neurodevelopmental defects,
      including motor delays and defective muscle tone.
    explanation: >-
      Motor delay is named as a human VPS4A-associated neurodevelopmental
      defect. Classified OTHER because this is the zebrafish paper's background
      summary of prior human reports rather than primary patient data.
- category: Neurological
  name: Delayed speech and language development
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  description: >-
    Speech and language development is delayed in every individual for whom it
    was assessed; many remain non-verbal.
  notes: >-
    Evidence-free descriptor sourced from the HPO annotation set for
    OMIM:619273, which records Delayed speech and language development in 5/5
    annotated individuals (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached
    reference in this entry mentions speech or language development, so no
    evidence item is attached and no snippet is fabricated. See the entry-level
    note on HPOA-sourced phenotypes for the shared rationale and for why no
    frequency band is set.
- category: Neurological
  name: Spasticity
  phenotype_term:
    preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
  description: >-
    Appendicular spasticity is reported alongside the axial hypotonia, giving
    the characteristic mixed tone pattern.
  notes: >-
    Evidence-free descriptor sourced from the HPO annotation set for
    OMIM:619273, which records Spasticity in 4/5 annotated individuals
    (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached
    reference in this entry mentions spasticity, so no evidence item is
    attached. See the entry-level note on HPOA-sourced phenotypes.
- category: Neurological
  name: Seizure
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  description: >-
    Seizures of several semiologies occur in a subset of individuals and are
    one of the two highest-burden features reported by families.
  notes: >-
    Evidence-free descriptor sourced from the HPO annotation set for
    OMIM:619273, which records Seizure in 3/6 annotated individuals (retrieved
    2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached
    reference in this entry mentions seizures, so no evidence item is attached.
    See the entry-level note on HPOA-sourced phenotypes.
- category: Neurological
  name: Sleep disturbance
  phenotype_term:
    preferred_term: Sleep disturbance
    term:
      id: HP:0002360
      label: Sleep disturbance
  description: >-
    Sleep disturbance is reported in every individual for whom it was assessed
    and is a leading source of caregiver burden.
  notes: >-
    Evidence-free descriptor sourced from the HPO annotation set for
    OMIM:619273, which records Sleep disturbance in 4/4 annotated individuals
    (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached
    reference in this entry mentions sleep, so no evidence item is attached.
    See the entry-level note on HPOA-sourced phenotypes.
- category: Ophthalmological
  name: Cataract
  phenotype_term:
    preferred_term: Cataract
    term:
      id: HP:0000518
      label: Cataract
  description: >-
    Cataracts were present in the original six-proband series and in the most
    recently reported case, and are not captured by the CIMDAG acronym.
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Probands had structural brain abnormalities, severe neurodevelopmental
      delay, cataracts, growth impairment, and anemia.
    explanation: >-
      Cataracts are reported in the original VPS4A proband series.
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      developmental delay, microcephaly, dystonia, cataracts, dyserythropoietic
      anemia, and growth retardation
    explanation: >-
      An independent later case confirms cataracts as part of the phenotype.
- category: Ophthalmological
  name: Visual impairment
  phenotype_term:
    preferred_term: Visual impairment
    term:
      id: HP:0000505
      label: Visual impairment
  description: >-
    Visual impairment is the single most consistently annotated ophthalmological
    feature and is multifactorial: cataract, retinal dystrophy and cortical
    visual involvement all contribute.
  notes: >-
    The HPO annotation set for OMIM:619273 records Visual impairment in 6/6
    annotated individuals (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). The evidence
    item below comes from a cell-biology paper's background summary of the two
    primary human reports, not from primary patient data, hence
    evidence_source OTHER and supports PARTIAL - it establishes that visual
    dysfunction belongs to the syndrome but supplies no counts. No frequency
    band is set.
  evidence:
  - reference: PMID:38687820
    reference_title: "The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission."
    supports: PARTIAL
    evidence_source: OTHER
    snippet: >-
      These conditions were associated with structural brain abnormalities,
      intellectual disability (ID), deafness, cataracts, and visual
      dysfunction.
    explanation: >-
      Visual dysfunction is named as a feature of VPS4A-related disease.
      Classified OTHER because this is the abscission paper's background
      summary of the two prior human reports rather than primary patient data,
      and PARTIAL because "visual dysfunction" is a looser descriptor than the
      HPO term.
- category: Ophthalmological
  name: Retinal dystrophy
  phenotype_term:
    preferred_term: Retinal dystrophy
    term:
      id: HP:0000556
      label: Retinal dystrophy
  description: >-
    Retinal dystrophy is present in a majority of individuals examined and is
    one contributor to the near-universal visual impairment.
  notes: >-
    Evidence-free descriptor sourced from the HPO annotation set for
    OMIM:619273, which records Retinal dystrophy in 3/5 annotated individuals
    (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached
    reference in this entry mentions the retina, so no evidence item is
    attached. See the entry-level note on HPOA-sourced phenotypes.
- category: Auditory
  name: Sensorineural hearing impairment
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  description: >-
    Hearing impairment, annotated as sensorineural, affects a minority of
    reported individuals.
  notes: >-
    Term choice: the "sensorineural" qualifier comes from the HPO annotation
    set for OMIM:619273, which records HP:0000407 Sensorineural hearing
    impairment in 2/5 annotated individuals (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). The only
    cached text that mentions hearing says "deafness" without qualifying it as
    sensorineural, so the evidence item below is marked PARTIAL and the
    qualifier rests on the annotation set rather than on the snippet. No
    frequency band is set.
  evidence:
  - reference: PMID:38687820
    reference_title: "The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission."
    supports: PARTIAL
    evidence_source: OTHER
    snippet: >-
      These conditions were associated with structural brain abnormalities,
      intellectual disability (ID), deafness, cataracts, and visual
      dysfunction.
    explanation: >-
      Deafness is named as a feature of VPS4A-related disease. Classified OTHER
      because this is a background summary of prior human reports in a
      cell-biology paper, and PARTIAL because the source does not state that
      the hearing loss is sensorineural.
- category: Gastrointestinal
  name: Feeding difficulties
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  description: >-
    Feeding difficulty is common and severe enough in half of reported
    individuals to require assisted feeding.
  notes: >-
    Evidence-free descriptor sourced from the HPO annotation set for
    OMIM:619273, which records Feeding difficulties in 4/6 annotated
    individuals (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached
    reference in this entry mentions feeding, so no evidence item is attached.
    See the entry-level note on HPOA-sourced phenotypes.
- category: Hepatic
  name: Hepatomegaly
  phenotype_term:
    preferred_term: Hepatomegaly
    term:
      id: HP:0002240
      label: Hepatomegaly
  description: >-
    Hepatomegaly is reported in most individuals examined, in some cases with
    hepatic steatosis - the clinical counterpart of the lipid-handling arm
    described in the pathophysiology section.
  notes: >-
    Evidence-free descriptor sourced from the HPO annotation set for
    OMIM:619273, which records Hepatomegaly in 4/5 annotated individuals
    (retrieved 2026-08-01 from
    https://ontology.jax.org/api/network/annotation/OMIM:619273). No cached
    reference in this entry mentions the liver, so no evidence item is
    attached. See the entry-level note on HPOA-sourced phenotypes.
- category: Hematological
  name: Congenital dyserythropoietic anemia
  phenotype_term:
    preferred_term: Congenital dyserythropoietic anemia
    term:
      id: HP:0001903
      label: Anemia
  description: >-
    Anemia is a defining CIMDAG feature. In most reported individuals it is a
    congenital dyserythropoietic anemia with binucleated erythroblasts on
    marrow examination.
  notes: >-
    Term choice: HPO was searched for a "congenital dyserythropoietic anemia"
    class and none exists. The nearest candidates were audited and rejected:
    HP:0005532 (Macrocytic dyserythropoietic anemia) is a child of macrocytic
    anemia and no cached source documents macrocytosis in these probands, and
    HP:0031688 (Erythroid dysplasia, synonym "Dyserythropoiesis") is a marrow
    morphology term rather than an anemia term - the marrow morphology is
    curated separately below under HP:0034278. Generic HP:0001903 is therefore
    used for the anemia itself.

    Following the PR #7728 review (suggestion 3), HP:0010972 (Anemia of
    inadequate production) was added as a second, mechanistically specific
    anemia descriptor - see the phenotype immediately below. It was added
    rather than substituted: HP:0001903 is retained because the anemia of this
    syndrome is not uniformly a production defect (PMID:33460484 reports a
    hemolytic presentation), so the generic term is the one that covers the
    whole reported spectrum.

    The haematological presentation is also not uniform: PMID:33460484 reports a
    VPS4A proband whose anemia was hemolytic without obvious dyserythropoiesis.
    Only that paper's title is available in the cached record (the journal
    supplied no abstract to PubMed), so the observation is recorded here as a
    note rather than as a snippet-backed evidence item.
  evidence:
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Three unrelated individuals enrolled in the registry had a syndrome
      characterized by CDA and severe neurodevelopmental delay.
    explanation: >-
      Three registry probands had congenital dyserythropoietic anemia together
      with the neurodevelopmental phenotype.
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      severe neurodevelopmental delay, cataracts, growth impairment, and anemia
    explanation: >-
      Anemia is reported in the independent six-proband series.
- category: Hematological
  name: Anemia of inadequate production
  phenotype_term:
    preferred_term: Anemia of inadequate production
    term:
      id: HP:0010972
      label: Anemia of inadequate production
  description: >-
    In the dyserythropoietic presentations the anemia arises from ineffective
    erythropoiesis - erythroblasts fail cytokinesis and mature asynchronously -
    rather than from peripheral red cell loss. HP:0010972 captures that
    production-side mechanism, which the generic anemia term does not.
  notes: >-
    Added in response to the PR #7728 review (suggestion 3) and curated
    alongside, not instead of, HP:0001903. HP:0010972 was not among the
    candidates audited in the term-choice note on the preceding phenotype; it
    fits the congenital dyserythropoietic presentation, whereas HP:0001903
    remains necessary to cover the hemolytic presentation of PMID:33460484.
    No frequency band is set.
  evidence:
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our findings demonstrate that VPS4A mutations cause cytokinesis and
      trafficking defects leading to a human disease with detrimental effects
      to erythropoiesis and neurodevelopment.
    explanation: >-
      The authors locate the hematologic lesion in erythropoiesis itself - a
      production defect - which is what HP:0010972 denotes.
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: PARTIAL
    evidence_source: IN_VITRO
    snippet: >-
      Using proband-derived induced pluripotent stem cells (iPSCs), we have
      successfully modeled the hematologic aspects of this syndrome in vitro,
      recapitulating their dyserythropoietic phenotype.
    explanation: >-
      The dyserythropoietic (ineffective-erythropoiesis) character of the
      anemia is reproduced in proband-derived cells, supporting a
      production-side rather than destruction-side mechanism.
- category: Hematological
  name: Splenomegaly
  phenotype_term:
    preferred_term: Splenomegaly
    term:
      id: HP:0001744
      label: Splenomegaly
  description: >-
    Persistent splenomegaly was reported in the three registry probands of
    PMID:33186543.
  notes: >-
    Provenance differs from the other evidence-free phenotypes in this entry
    and is weaker. Splenomegaly is NOT in the HPO annotation set for
    OMIM:619273 - the full annotation set was retrieved from
    https://ontology.jax.org/api/network/annotation/OMIM:619273 on 2026-08-01
    and checked term by term; it contains 35 annotations and HP:0001744 is not
    among them. The 3/3 figure comes from the deep-research artifact for this
    entry, which read it out of the Seu et al. full text (PMID:33186543). That
    full text is not in references_cache (the cached record is
    abstract-only) and the abstract does not mention the spleen, so no
    evidence item can be attached and none is fabricated. Recorded as a
    descriptor because a reviewer flagged its absence and because chronic
    hemolysis and ineffective erythropoiesis both predict it; a curator with
    full-text access should confirm it and attach a snippet.
- category: Hematological
  name: Multinucleated erythroblasts
  phenotype_term:
    preferred_term: Binucleated erythroblasts
    term:
      id: HP:0034278
      label: Multinucleated erythroblast
  description: >-
    Bone marrow examination shows binucleated erythroblasts and erythroblasts
    connected by cytoplasmic bridges, the morphological hallmark of failed
    abscission in the erythroid lineage.
  diagnostic: true
  evidence:
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Bone marrow studies showed binucleated erythroblasts and erythroblasts
      with cytoplasmic bridges indicating abnormal cytokinesis and abscission.
    explanation: >-
      Directly reports binucleated erythroblasts on patient bone marrow.
- category: Growth
  name: Growth retardation
  phenotype_term:
    preferred_term: Growth delay
    term:
      id: HP:0001510
      label: Growth delay
  description: >-
    Growth retardation is a defining CIMDAG feature; the original series
    described growth impairment in the probands.
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      severe neurodevelopmental delay, cataracts, growth impairment, and anemia
    explanation: >-
      Growth impairment is reported in the original VPS4A proband series.
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      dyserythropoietic anemia, and growth retardation
    explanation: >-
      Growth retardation is confirmed in the most recently reported proband.
- category: Neurological
  name: Abnormal brain morphology
  phenotype_term:
    preferred_term: Structural brain abnormality
    term:
      id: HP:0012443
      label: Abnormal brain morphology
  description: >-
    Structural brain abnormalities were present in the original six probands.
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Probands had structural brain abnormalities, severe neurodevelopmental
      delay
    explanation: >-
      Structural brain abnormality is reported directly in the proband series.
imaging_findings:
- name: Cerebellar atrophy on brain MRI
  modality: MRI
  imaging_finding_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  description: >-
    Brain MRI in a reported CIMDAG proband showed mild cerebellar atrophy,
    complementing the cerebellar hypoplasia in the syndrome definition.
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Magnetic resonance imaging showed mild cerebellar atrophy.
    explanation: >-
      Directly reports the MRI finding in a molecularly confirmed CIMDAG
      proband.
histopathology:
- name: Binucleated erythroblasts and intercellular cytoplasmic bridges in bone marrow
  description: >-
    Bone marrow aspirate/biopsy in VPS4A-related syndromic congenital
    dyserythropoietic anemia shows binucleated erythroblasts and erythroblasts
    linked by cytoplasmic bridges, reflecting incomplete cytokinetic abscission.
  diagnostic: true
  evidence:
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Bone marrow studies showed binucleated erythroblasts and erythroblasts
      with cytoplasmic bridges indicating abnormal cytokinesis and abscission.
    explanation: >-
      The marrow morphology is described directly in the patient series.
genetic:
- name: VPS4A pathogenic missense variants
  association: Missense mutation
  relationship_type: CAUSATIVE
  presence: Pathogenic
  variant_origin: DE_NOVO
  gene_term:
    preferred_term: VPS4A
    term:
      id: hgnc:13488
      label: VPS4A
  inheritance:
  - name: Autosomal dominant inheritance
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
    evidence:
    - reference: PMID:33186545
      reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Here we describe six unrelated individuals with de novo missense
        variants affecting the ATPase domain of VPS4A
      explanation: >-
        De novo heterozygous alleles in six unrelated probands support a
        dominant mode for this gene-disease relationship.
  features: >-
    Reported disease alleles are missense changes in the VPS4A AAA-ATPase
    domain. In the original series all six were de novo and behaved like
    dominant-negative ATPase-dead VPS4A in cells. A later single report
    describes a homozygous p.Arg288Gln allele affecting a conserved arginine in
    the same domain.
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      six unrelated individuals with de novo missense variants affecting the
      ATPase domain of VPS4A
    explanation: >-
      Establishes de novo ATPase-domain missense variants as the causal allele
      class.
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They were found to have missense mutations in VPS4A, a gene coding for an
      ATPase that regulates the ESCRT-III machinery in a variety of cellular
      processes including cell division, endosomal vesicle trafficking, and
      viral budding.
    explanation: >-
      An independent cohort confirms VPS4A missense variants as causal and
      states the gene's ESCRT-III regulatory function.
  - reference: PMID:35441598
    reference_title: "The congenital dyserythropoieitic anemias: genetics and pathophysiology."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Additional recent advances included the identification of new CDA genes,
      RACGAP1 and VPS4A, in CDAIII and a syndromic CDA type, respectively.
    explanation: >-
      A field review independently records VPS4A as the gene of a syndromic
      congenital dyserythropoietic anemia.
variants:
- name: "VPS4A c.863G>A (p.Arg288Gln)"
  description: >-
    Homozygous missense variant reported in a single Nepalese proband with
    classical CIMDAG features. Arg288 lies in the AAA-ATPase domain; the variant
    destabilises the protein, promotes aggregation, and reduces LC3B
    interaction.
  gene:
    preferred_term: VPS4A
    term:
      id: hgnc:13488
      label: VPS4A
  type: MISSENSE
  clinical_significance: PATHOGENIC
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Trio exome sequencing identified a homozygous VPS4A variant (c.863G>A;
      p.Arg288Gln), predicted to be deleterious.
    explanation: >-
      Reports the variant, its zygosity, and the sequencing method used to find
      it.
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: >-
      Structural analyses revealed disruption of a conserved Arginine-288
      residue within the ATPases associated with diverse cellular activities
      domain, leading to loss of stability and increased disorder.
    explanation: >-
      In silico structural analysis places the residue in the AAA-ATPase domain
      and predicts destabilisation.
diagnosis:
- name: Trio exome sequencing
  description: >-
    Molecular diagnosis rests on identifying a pathogenic VPS4A variant. The
    most recently reported proband was ascertained by trio exome sequencing;
    the cached abstracts of the two original series do not state the sequencing
    modality used, so no broader claim about the diagnostic route is made here.
  diagnosis_term:
    preferred_term: Exome sequencing
    term:
      id: NCIT:C101295
      label: Whole Exome Sequencing
  evidence:
  - reference: PMID:42498620
    reference_title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Trio exome sequencing identified a homozygous VPS4A variant (c.863G>A;
      p.Arg288Gln), predicted to be deleterious.
    explanation: >-
      Trio exome sequencing is the method that established the molecular
      diagnosis in this proband.
- name: Bone marrow examination for dyserythropoiesis
  description: >-
    Marrow morphology showing binucleated erythroblasts and erythroblasts with
    cytoplasmic bridges supports the congenital dyserythropoietic anemia
    component and can direct genetic testing.
  evidence:
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Bone marrow studies showed binucleated erythroblasts and erythroblasts
      with cytoplasmic bridges indicating abnormal cytokinesis and abscission.
    explanation: >-
      The marrow findings that make the dyserythropoietic diagnosis are stated
      directly.
differential_diagnoses:
- name: Congenital dyserythropoietic anemia type 1
  disease_term:
    preferred_term: congenital dyserythropoietic anemia type 1
    term:
      id: MONDO:0020337
      label: congenital dyserythropoietic anemia type 1
  description: >-
    CDA I (CDAN1/CDIN1) also presents with ineffective erythropoiesis and
    abnormal erythroblast morphology.
  distinguishing_features:
  - CDA I lacks the severe neurodevelopmental phenotype, congenital microcephaly, dystonia, and cerebellar hypoplasia of CIMDAG syndrome.
  - CDA I arises from the Codanin-1/CDIN1 pathway rather than from ESCRT-III turnover failure.
  evidence:
  - reference: PMID:35441598
    reference_title: "The congenital dyserythropoieitic anemias: genetics and pathophysiology."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Codanin-1 was found to physically interact with CDIN1, suggesting that
      mutations in CDAN1 and CDIN1 result in CDAI via a common mechanism.
    explanation: >-
      Establishes the distinct CDAN1/CDIN1 molecular basis of CDA I.
- name: Congenital dyserythropoietic anemia type 2
  disease_term:
    preferred_term: congenital dyserythropoietic anemia type 2
    term:
      id: MONDO:0009134
      label: congenital dyserythropoietic anemia type 2
  description: >-
    CDA II, caused by SEC23B variants, shares the ineffective erythropoiesis
    that defines the congenital dyserythropoietic anemias.
  distinguishing_features:
  - CDA II is non-syndromic, without the neurodevelopmental, ocular, and growth features of VPS4A-related disease.
  - CDA II results from SEC23B (COPII secretory pathway) variants rather than from VPS4A.
  evidence:
  - reference: PMID:35441598
    reference_title: "The congenital dyserythropoieitic anemias: genetics and pathophysiology."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Recent advances in CDAII (which results from SEC23B mutations) have also
      been made.
    explanation: >-
      Confirms SEC23B as the CDA II gene, distinct from VPS4A.
treatments:
- name: Supportive and multidisciplinary care
  description: >-
    No disease-modifying therapy exists for VPS4A-related disease. Reported
    management is supportive: transfusion support for anemia, developmental and
    rehabilitative therapies, dystonia management, cataract surgery, and
    nutritional support for growth failure. No treatment claim in this entry is
    backed by a trial, and none is asserted with evidence here.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  therapeutic_modality: OTHER
  notes: >-
    Deliberately left without evidence items: no cached reference in this entry
    reports treatment outcomes for CIMDAG syndrome, and asserting a supportive
    care regimen with a mechanistic snippet would be a claim/snippet mismatch.

    Management components described in the secondary literature but NOT curated
    as separate evidenced Treatment objects, because the only sources are a
    family-support-group guide and full-text passages that cannot be verified
    against a cached abstract: red cell transfusion for the anemia, iron
    chelation for transfusional plus ineffective-erythropoiesis iron loading,
    cataract extraction, gastrostomy for feeding failure, anti-seizure
    medication, physiotherapy/occupational therapy/speech therapy with
    augmentative communication, orthotics and spinal surveillance, and genetic
    counselling. Recorded here per the dismech SOP (move an unquotable but
    well-established claim to notes rather than fabricating a snippet).

    No disease-modifying therapy exists and no interventional trial for VPS4A
    or CIMDAG syndrome is registered.
clinical_trials:
- name: NCT02964494
  status: RECRUITING
  description: >-
    The Congenital Dyserythropoietic Anemia Registry (CDAR), an observational
    North American registry and biorepository run from Cincinnati Children's
    Hospital Medical Center. It is not VPS4A-specific, but it is the ascertainment
    route through which the three VPS4A probands of PMID:33186543 were identified,
    and it is the only registered study currently capturing these patients. No
    interventional trial for VPS4A-related disease is registered.
  target_phenotypes:
  - preferred_term: Congenital dyserythropoietic anemia
    term:
      id: HP:0001903
      label: Anemia
  evidence:
  - reference: clinicaltrials:NCT02964494
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The investigators have created and maintain a comprehensive registry for
      patients with the diagnosis of Congenital Dyserythropoietic Anemia (CDA)
      in North America.
    explanation: >-
      Confirms the registry's scope. Marked PARTIAL because the registry covers
      the congenital dyserythropoietic anemias generally, not VPS4A-related
      disease specifically.
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The Congenital Dyserythropoietic Anemia (CDA) Registry was established
      with the goal to facilitate investigations of natural history, biology,
      and molecular pathogenetic mechanisms of CDA.
    explanation: >-
      Confirms that the CDA Registry is the source cohort for the VPS4A probands
      described in this paper.
animal_models:
- species: Danio rerio
  genotype: vps4a T248I homozygous missense mutant larvae
  category: GENETIC
  description: >-
    A zebrafish vps4a missense allele that reduces Vps4a ATPase activity and
    ESCRT filament disassembly, producing enlarged CNS endosomal compartments,
    reduced circulating exosomes, and severe but selective sensorimotor
    deficits with intact motor neurons and muscle - a model of the central
    hypotonia seen in patients.
  genes:
  - preferred_term: VPS4A
    term:
      id: hgnc:13488
      label: VPS4A
  evidence:
  - reference: PMID:39455257
    reference_title: "Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Here we identified a mutation in zebrafish vps4a, T248I, that affects
      sensorimotor transformation.
    explanation: >-
      Identifies the model allele and the phenotype it produces.
experimental_models:
- name: Proband-derived iPSC erythroid differentiation
  description: >-
    Induced pluripotent stem cells reprogrammed from VPS4A patients and
    differentiated toward the erythroid lineage recapitulate the
    dyserythropoietic phenotype in vitro, providing a tractable human model of
    the hematologic arm of the disease.
  evidence:
  - reference: PMID:33186543
    reference_title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Using proband-derived induced pluripotent stem cells (iPSCs), we have
      successfully modeled the hematologic aspects of this syndrome in vitro,
      recapitulating their dyserythropoietic phenotype.
    explanation: >-
      States the model system and the phenotype it reproduces.
- name: VPS4A and VPS4B isoform knockout cell lines
  description: >-
    Paired VPS4A and VPS4B knockout human cell lines were used to separate the
    paralogs' contributions to cytokinetic abscission, establishing that VPS4A
    holds a regulatory role that VPS4B cannot substitute.
  evidence:
  - reference: PMID:38687820
    reference_title: "The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Here, we set out to investigate the role of the human VPS4 paralogs in
      cytokinetic abscission using a series of knockout cell lines.
    explanation: >-
      Describes the isoform-resolved knockout system.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    Fewer than 15 molecularly confirmed individuals have been published: six in
    PMID:33186545, three in PMID:33186543, and subsequent single-case reports
    (PMID:33460484, PMID:42498620). No population-based prevalence estimate
    exists; the class is recorded qualitatively rather than as a rate.
  evidence:
  - reference: PMID:33186545
    reference_title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here we describe six unrelated individuals with de novo missense variants
      affecting the ATPase domain of VPS4A
    explanation: >-
      Supports the case-count basis for the ultra-rare classification; it does
      not itself state a population prevalence, hence PARTIAL.
discussions:
- discussion_id: vps4a_zebrafish_translational_reach
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Does the zebrafish vps4a T248I sensorimotor-circuit lesion actually explain
    the hypotonia and motor delay of human CIMDAG syndrome, given that the
    human disease additionally shows cerebellar hypoplasia, congenital
    microcephaly, dystonia, and dyserythropoietic anemia that the fish model
    has not been shown to reproduce?
  attaches_to:
  - "pathophysiology#Abnormal Neurodevelopment and Structural Brain Malformation"
  rationale: >-
    The zebrafish work localises the deficit to sensorimotor transformation
    with intact motor neurons and muscle, which maps well onto the central
    hypotonia described in patients. But the model's reported readouts are
    reflex and circuit assays, not the structural cerebellar/cortical
    malformation or the erythroid phenotype that dominate the human disorder,
    so its translational reach beyond hypotonia is untested.
  proposed_experiments:
  - experiment_id: vps4a_zf_brain_morphometry
    name: Cerebellar and telencephalic morphometry in vps4a mutant larvae
    description: >-
      Quantify cerebellar and telencephalic size and neuronal number in vps4a
      T248I larvae and compare with the cerebellar hypoplasia and congenital
      microcephaly reported in patients.
    decision_criterion: >-
      A significant reduction in cerebellar and telencephalic volume/neuron
      number relative to wild-type siblings would extend the model's validity
      beyond sensorimotor circuits.
  - experiment_id: vps4a_zf_erythroid_phenotyping
    name: Erythroid phenotyping of vps4a mutant zebrafish
    description: >-
      Assay erythroid development and erythrocyte morphology in vps4a mutant
      zebrafish to test whether the dyserythropoietic arm of the human disease
      is conserved.
    decision_criterion: >-
      Binucleate or bridged erythroid precursors in the mutant would support
      conservation of the abscission-failure mechanism in vivo.
  - experiment_id: vps4a_patient_organoid_growth
    name: Patient-variant cerebral and cerebellar organoids
    description: >-
      Determine whether human iPSC-derived cerebral or cerebellar organoids
      carrying VPS4A ATPase-domain variants reproduce the structural growth
      deficit.
    decision_criterion: >-
      Reduced organoid size or disrupted cytoarchitecture versus isogenic
      controls would place the growth deficit in human neural tissue.
- discussion_id: vps4a_recessive_allele_question
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Is the homozygous VPS4A p.Arg288Gln allele a genuine recessive route to
    CIMDAG syndrome, or a hypomorph whose heterozygous carriers are simply
    unascertained?
  attaches_to:
  - "pathophysiology#VPS4A ATPase-Domain Missense Variants Impair ESCRT-III Disassembly"
  rationale: >-
    Every proband in the two multi-case series carried a de novo heterozygous
    ATPase-domain missense variant acting dominant-negatively. A single 2026
    report describes a homozygous allele. Whether the parents were
    asymptomatic heterozygotes, and whether p.Arg288Gln is dominant-negative or
    simply hypomorphic, is unresolved and matters for counselling.
  proposed_experiments:
  - experiment_id: vps4a_r288q_parental_segregation
    name: Parental phenotyping and segregation analysis
    description: >-
      Phenotype and re-sequence the heterozygous parents of the p.Arg288Gln
      proband for subclinical CIMDAG features.
    decision_criterion: >-
      Entirely unaffected heterozygous parents would support a genuinely
      recessive allele; subclinical features would argue for a hypomorph with
      dosage-dependent expressivity.
  - experiment_id: vps4a_r288q_isogenic_allele_comparison
    name: Isogenic side-by-side allele comparison
    description: >-
      Compare p.Arg288Gln with a canonical de novo allele in an isogenic cell
      system for ATPase activity, ESCRT-III disassembly, and dominant-negative
      behaviour on co-expression with wild-type VPS4A.
    decision_criterion: >-
      Absence of dominant-negative behaviour for p.Arg288Gln when co-expressed
      with wild-type VPS4A would establish it as a distinct, recessive-acting
      allele class.
- discussion_id: vps4a_static_versus_progressive
  kind: OPEN_QUESTION
  status: OPEN
  prompt: >-
    Is CIMDAG syndrome a static developmental malformation syndrome, a
    progressive neurodegeneration, or both?
  attaches_to:
  - "pathophysiology#Abnormal Neurodevelopment and Structural Brain Malformation"
  rationale: >-
    The disorder is usually framed developmentally - cerebellar hypoplasia and
    congenital microcephaly are malformations present from birth. But an
    abscission/cell-division lesion that depletes neural progenitors and an
    endolysosomal lesion that persists in post-mitotic neurons are different
    kinds of injury with different time courses, and reported neuroimaging
    includes atrophy (PMID:42498620 documents cerebellar atrophy, not only
    hypoplasia) rather than pure hypoplasia. Whether affected individuals lose
    previously acquired skills, and whether brain volume falls on serial
    imaging, determines whether this entry's causal graph should carry a
    degenerative arm at all. No natural history study exists.
  proposed_experiments:
  - experiment_id: vps4a_serial_neuroimaging
    name: Serial volumetric neuroimaging in a CIMDAG cohort
    description: >-
      Collect longitudinal volumetric brain MRI in molecularly confirmed
      individuals and measure change in cerebellar, brainstem, and supratentorial
      volume over time against age-matched norms.
    decision_criterion: >-
      Progressive loss of volume beyond the expected trajectory would establish a
      degenerative component; stable z-scores would support a purely
      malformative model.
  - experiment_id: vps4a_longitudinal_developmental_assessment
    name: Longitudinal standardised developmental assessment
    description: >-
      Apply repeated standardised developmental/adaptive measures to distinguish
      plateau from regression.
    decision_criterion: >-
      Documented loss of previously acquired skills would support regression.
- discussion_id: vps4a_micronuclei_cgas_sting_interferon
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Do the chromosome-segregation errors caused by VPS4A variants generate
    micronuclei that activate cGAS-STING and produce a chronic type I
    interferon signature in patients?
  attaches_to:
  - "pathophysiology#Chromosome Missegregation and Mitotic Spindle Errors"
  rationale: >-
    PMID:33186545 documents disturbed chromosome segregation and mitotic spindle
    formation in patient cells. Micronucleus formation from missegregated
    chromosomes is the canonical route to cytosolic-DNA sensing by cGAS-STING and
    hence to a chronic interferonopathy. Nobody has measured an interferon
    signature in CIMDAG blood, so it is unknown whether this well-established
    downstream consequence of chromosomal instability actually operates here.
    If it does, it would add a targetable inflammatory arm to a disease that
    currently has no disease-modifying therapy.
  proposed_experiments:
  - experiment_id: vps4a_interferon_signature_blood
    name: Type I interferon signature in patient blood
    description: >-
      Measure an interferon-stimulated gene score in whole blood from molecularly
      confirmed VPS4A probands against age-matched controls.
    decision_criterion: >-
      An elevated ISG score would support an active cGAS-STING arm and justify
      testing JAK inhibition; a normal score would close the question.
  - experiment_id: vps4a_micronuclei_cgas_colocalisation
    name: Micronucleus and cGAS colocalisation in proband fibroblasts
    description: >-
      Quantify micronuclei in proband-derived fibroblasts and score cGAS
      recruitment to ruptured micronuclei alongside downstream STING-TBK1-IRF3
      activation.
    decision_criterion: >-
      cGAS-positive micronuclei with downstream pathway activation, absent in
      isogenic controls, would establish the cell-autonomous link.
- discussion_id: vps4a_allele_selective_silencing_rationale
  kind: OPEN_QUESTION
  status: OPEN
  prompt: >-
    If the dominant alleles act by poisoning VPS4A hexamers rather than by
    haploinsufficiency, is allele-selective knockdown of the mutant transcript a
    rational therapeutic strategy?
  attaches_to:
  - "pathophysiology#VPS4A ATPase-Domain Missense Variants Impair ESCRT-III Disassembly"
  rationale: >-
    PMID:33186545 shows the patient mutants phenocopy engineered
    dominant-negative ATPase-dead VPS4A, which implies that removing the mutant
    product - rather than adding wild-type protein - is the mechanistically
    correct intervention. Gene addition would not clear poisoned hexamers. The
    open questions are whether losing one VPS4A allele is tolerated in humans,
    and whether the CNS phenotype is already fixed prenatally, which would cap
    any postnatal benefit. Recorded as an open question, not as a treatment
    claim: no such program exists and no supporting outcome data are cited here.
  proposed_experiments:
  - experiment_id: vps4a_allele_selective_knockdown_in_vitro
    name: Allele-selective knockdown in proband fibroblasts and iPSC neurons
    description: >-
      Test allele-selective ASO or siRNA against a recurrent VPS4A missense
      allele in proband-derived fibroblasts and iPSC-derived neurons, reading out
      endosomal morphology, IST1 localisation, and abscission timing.
    decision_criterion: >-
      Normalisation of endosomal morphology and abscission on selective mutant
      knockdown, without a penalty from the resulting reduced total VPS4A dose,
      would validate the strategy in principle.
  - experiment_id: vps4a_heterozygous_lof_tolerance
    name: Population assessment of VPS4A loss-of-function tolerance
    description: >-
      Systematically evaluate whether heterozygous predicted-loss-of-function
      VPS4A alleles occur in unselected population databases at frequencies
      incompatible with a severe phenotype.
    decision_criterion: >-
      Confirmed tolerance of heterozygous loss of function would remove the main
      safety objection to allele-selective silencing.
references:
- reference: PMID:33186545
  title: "De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment."
- reference: PMID:33186543
  title: "VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects."
- reference: PMID:38687820
  title: "The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission."
- reference: PMID:39455257
  title: "Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants."
- reference: PMID:42498620
  title: "A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome."
- reference: PMID:35441598
  title: "The congenital dyserythropoieitic anemias: genetics and pathophysiology."
- reference: PMID:33460484
  title: "VPS4A mutation in syndromic congenital hemolytic anemia without obvious signs of dyserythropoiesis."

📚

References & Deep Research

References

7

PMID:33186545

De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment.

No top-level findings curated for this source.

PMID:33186543

VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects.

No top-level findings curated for this source.

PMID:38687820

The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission.

No top-level findings curated for this source.

PMID:39455257

Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants.

No top-level findings curated for this source.

PMID:42498620

A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome.

No top-level findings curated for this source.

PMID:35441598

The congenital dyserythropoieitic anemias: genetics and pathophysiology.

No top-level findings curated for this source.

PMID:33460484

VPS4A mutation in syndromic congenital hemolytic anemia without obvious signs of dyserythropoiesis.

No top-level findings curated for this source.

Deep Research

1

Claude Code ▸

1. Disease Information

claude-haiku-4-5-20251001, claude-opus-5[1m] 18 citations 2026-08-01T10:00:11.379626

1. Disease Information

Overview

VPS4A-related neurodevelopmental syndrome — formally CIMDAG syndrome — is an ultra-rare multisystem Mendelian disorder caused by missense variants in VPS4A, which encodes the AAA-ATPase that disassembles and recycles the ESCRT-III membrane-remodeling machinery. The clinical core is a severe, congenital-onset neurodevelopmental phenotype (profound global developmental delay, severe primary microcephaly, dystonia, structural brain malformation) combined with a transfusion-dependent congenital dyserythropoietic/hemolytic anemia, congenital cataracts and retinal dystrophy, and severe growth retardation. It is one of the very few human diseases in which a core ESCRT component is the primary genetic lesion, and it is mechanistically distinctive in that pathogenesis is dominant-negative poisoning of a hexameric enzyme, not haploinsufficiency.

The acronym CIMDAG expands to: cerebellar hypoplasia and cataracts, intellectual disability, congenital microcephaly, dystonia and dyserythropoietic anaemia, growth retardation (Unique/Rare Chromosome Disorder Support Group, 2024).

Key identifiers

Resource	Identifier
MONDO	`MONDO:0035819` — "cerebellar hypoplasia-intellectual disability-congenital microcephaly-dystonia-anemia-growth retardation syndrome"
OMIM (phenotype)	#619273 — CIMDAG SYNDROME; CIMDAG
OMIM (gene)	*609982 — VACUOLAR PROTEIN SORTING 4 HOMOLOG A; VPS4A
Orphanet	ORPHA:603448
MedGen	UID 1780242
UMLS	C5543287
GARD	0018020
HGNC	HGNC:13488 (VPS4A)
NCBI Gene	27183
Ensembl	ENSG00000132612
UniProt	Q9UN37 (VPS4A_HUMAN)
RefSeq transcript	NM_013245.3
Cytoband	16q22.1
ICD-11	No specific code; best fit `LD2F.1Y` (other specified syndromes with CNS anomalies as major feature) / `4A00.1` family not applicable. Not separately coded.
ICD-10	No specific code; Q87.8 (other specified congenital malformation syndromes) used pragmatically
MeSH	No dedicated descriptor as of 2026

Cross-references verified via OLS4 (MONDO term record) and HGNC REST.

Synonyms and alternative names

CIMDAG syndrome (preferred acronym)
VPS4A-related neurodevelopmental disorder (VPS4A-ND) — the label used by the Unique family guide
Cerebellar hypoplasia–intellectual disability–congenital microcephaly–dystonia–anemia–growth retardation syndrome (MONDO/Orphanet long form)
Syndromic congenital dyserythropoietic anemia due to VPS4A (hematology literature framing; Seu et al.)
Syndromic congenital hemolytic anemia with neurodevelopmental impairment (Lunati et al. framing)
Gene aliases relevant to older literature: SKD1, SKD1A, SKD2, VPS4, VPS4-1, hVPS4

Nature of the evidence base

Entirely individual-patient derived, not aggregated. The whole disease concept rests on ~11 published probands described in four primary reports plus deep single-patient functional workups. There is no EHR-based cohort, no registry-derived prevalence, and no natural history study. The only registry involvement is indirect: three of the probands were ascertained through the Congenital Dyserythropoietic Anemia Registry (CDAR, NCT02964494, Cincinnati Children's, observational, actively recruiting), which is a CDA-wide registry rather than a VPS4A-specific one. Aggregated resources (OMIM, Orphanet, HPO annotation file) are themselves derived from the same handful of case reports — so HPO frequencies such as "6/6" and "4/5" are literally patient counts from Rodger et al., not epidemiologic estimates.

2. Etiology

Primary causal factor

Monogenic. Heterozygous de novo missense variants in the AAA-ATPase domain of VPS4A are the dominant cause (autosomal dominant, dominant-negative mechanism). A minority of cases are biallelic (homozygous) missense, arising in consanguineous families and acting through a distinct, milder loss-of-function-like route.

Rodger et al. (PMID:33186545) frame the causal claim as [abstract]:

"Here we describe six unrelated individuals with de novo missense variants affecting the ATPase domain of VPS4A, a critical enzyme regulating ESCRT function. Probands had structural brain abnormalities, severe neurodevelopmental delay, cataracts, growth impairment, and anemia."

Genetic risk factors

Causal variants: see §4. All published pathogenic alleles are missense; no truncating, splice, or structural pathogenic alleles have been reported.
Position-specific risk: the ATP-binding pocket arginine finger Arg284 is a mutational hotspot (5 of 11 reported probands), and pore-loop-1 residues Gly203/Glu206 form a second hotspot cluster.
Consanguinity is the relevant risk factor for the recessive form (Seu proband 3, homozygous p.Ala28Val, both parents unaffected heterozygous carriers; Gupta 2026 Nepalese proband, homozygous p.Arg288Gln).
Advanced paternal age — plausible but not demonstrated for this gene; no data. Treat as unknown.
Modifier genes: none identified. VPS4B is a mechanistically obvious candidate modifier (see §4, §6): Seu et al. observed [body/derived] "significantly increased VPS4B expression in proband 3, indicating that VPS4B may partially, but not adequately, compensate for the VPS4A loss of function in the homozygous p.Ala28Val variant." No germline VPS4B modifier alleles have been tested.
Susceptibility loci / GWAS: none. No GWAS Catalog signal is relevant to this Mendelian phenotype.

Environmental risk factors

None identified. As a de novo germline missense disorder, no toxin, infectious, occupational, nutritional, or lifestyle exposure has been implicated in causation. The Unique guide states explicitly to families: "This happens naturally and is not due to the parents' diet, environment or lifestyle." Sex is not a risk factor (see §9). This should be recorded as NO_EVIDENCE rather than left blank.

Protective factors

Genetic: no protective alleles known. The only relevant observation is paralog buffering — an intact VPS4B is insufficient to prevent disease when VPS4A is mutated (see PMID:38687820), which argues against paralog dosage as a protective modifier in the dominant form but leaves it plausible in the recessive form.
Environmental: none. Secondary/tertiary protective interventions (iron chelation, cataract extraction, seizure control) modify morbidity, not disease occurrence — record under §12/§13, not here.

Gene–environment interactions

No documented GxE. One clinically actionable pseudo-interaction deserves note: iron overload in this disease is disproportionate to transfusion burden because ineffective erythropoiesis itself drives hyperabsorption — Unique states that "Defective red blood cell development (dyserythropoiesis) and ineffective red blood cell production (ineffective erythropoiesis) may cause iron overload disproportionate to the number of transfusions." This is a genotype-driven amplification of a treatment exposure (transfusional iron) rather than a true environmental interaction, but it belongs in the causal graph.

3. Phenotypes

3.1 HPO annotation set (source: HPO annotation file for OMIM:619273, retrieved via `ontology.jax.org` API)

Frequencies are literal patient-count fractions from the source publications, not population estimates. Inheritance annotation: HP:0000006 Autosomal dominant inheritance.

Neurodevelopmental / neurological (core)

HP ID	Term	Frequency	Notes
HP:0011344	Severe global developmental delay	6/6 (100%)	Congenital onset; core
HP:0010864	Severe intellectual disability	6/6 (100%)	Core
HP:0000252	Microcephaly	6/6 (100%)	"Z scores < −5" universal [body/derived]
HP:0011451	Primary microcephaly	3/6 (50%)	Congenital subset
HP:0001332	Dystonia	5/6 (83%)	Axial hypotonia + appendicular hypertonia pattern
HP:0001252	Hypotonia	5/6 (83%)	Neonatal onset; central in origin (zebrafish data)
HP:0001257	Spasticity	4/5 (80%)	Appendicular
HP:0001270	Motor delay	5/5 (100%)	None achieve independent walking
HP:0000750	Delayed speech and language development	5/5 (100%)
HP:0001344	Absent speech	2/5 (40%)	Many remain non-verbal
HP:0001250	Seizure	3/6 (50%)	Multiple semiologies
HP:0001251	Ataxia	2/4 (50%)
HP:0002072	Chorea	1/5 (20%)
HP:0002360	Sleep disturbance	4/4 (100%)	High QoL impact; often medicated

Brain structural (neuroimaging)

HP ID	Term	Frequency
HP:0001321	Cerebellar hypoplasia	2/6 (also 5/6 by full-text count, see note)
HP:0001320	Cerebellar vermis hypoplasia	1/6
HP:0006879	Pontocerebellar atrophy	1/6
HP:0033725	Thin corpus callosum	2/6
HP:0002059	Cerebral atrophy	1/6
HP:0002126	Polymicrogyria	1/6

Note the discrepancy: the HPO annotation file records cerebellar hypoplasia as 2/6, but the Rodger full text states cerebellar hypoplasia in five of six probands. Seu et al. independently describe [body/derived] "moderate to marked deficiency of hemispheric white matter with global cerebral volume loss, thin corpus callosum, and atrophy of the cerebellum and the pons, suggestive of a neurodegenerative syndrome." For a dismech entry, curate cerebellar hypoplasia at the higher (full-text) frequency with the Rodger PMID, and flag the HPOA discrepancy in a discussions block.

Ophthalmologic

HP ID	Term	Frequency
HP:0000505	Visual impairment	6/6 (100%)
HP:0000519	Developmental cataract	4/5 (80%)
HP:0000556	Retinal dystrophy	3/5 (60%)
HP:0025405	Visual fixation instability	3/6 (50%)
HP:0030854	Scleral staphyloma	1/3

One proband had Leber congenital amaurosis and/or cortical blindness (Seu proband 1) — consider HP:0000548 (Leber congenital amaurosis is HP:0000548? verify; MONDO:0018998 is the disease-level term) or curate as retinal dystrophy + cortical visual impairment.

Hematologic

Underrepresented in HPOA (the annotation file returned no anemia term, a genuine gap, because the anemia was characterized primarily in the companion paper, Seu et al., which is annotated to the same OMIM entry only partially). Curate from primary literature:

Suggested HP ID	Term	Evidence
HP:0001878	Hemolytic anemia	Lunati 2021 (PMID:33460484)
HP:0031688	Erythroid dysplasia	Seu 2020 — binucleate erythroblasts, internuclear cytoplasmic bridges
HP:0005532	Macrocytic dyserythropoietic anemia	Partial fit (MCV 80–100 fL = normocytic in the Seu probands, so this term over-specifies)
HP:0010972	Anemia of inadequate production	Fits ineffective erythropoiesis
HP:0001744	Splenomegaly	Persistent in 3/3 Seu probands
HP:0011031	Abnormal iron homeostasis / iron overload	Ferritin 470–4093 ng/mL; LIC 6.5–12.1 mg/g dry weight
HP:0001081	Cholelithiasis	1/5 (HPOA) — consistent with chronic hemolysis

Rodger et al. report anemia in 3/6, dyserythropoietic in 2 [body/derived]: "Three subjects had anemia, which was characterized as dyserythropoietic in two." Combining cohorts (Rodger 3/6 + Seu 3/3 + Lunati 1/1), anemia is present in roughly 7/10 published patients — i.e. FREQUENT in HPO frequency terms. Note the Lunati case demonstrates the anemia can be hemolytic without overt dyserythropoiesis, so the hematologic phenotype should be curated as a spectrum, not a single entity.

Growth and gastrointestinal

HP ID	Term	Frequency / source
HP:0011968	Feeding difficulties	4/6 (assisted feeding in 3/6)
HP:0002240	Hepatomegaly	4/5
HP:0001433	Hepatosplenomegaly	4/6 "hepatosplenomegaly and/or steatosis" (Rodger)
HP:0001414	Microvesicular hepatic steatosis	1/5
HP:0009125	Lipodystrophy	1/5
HP:0001510	Growth delay	Most probands; "severe growth retardation across most cases"
HP:0004322 / HP:0004325	Short stature / decreased body weight	Derived from growth retardation
HP:0002019	Constipation	Unique guide (families)
HP:0002020	Gastroesophageal reflux	Unique guide (families)

Other systems

HP ID	Term	Frequency
HP:0000407	Sensorineural hearing impairment	2/5 (40%)
HP:0002719	Recurrent infections	1/5
HP:0000135	Hypogonadism	1/4
HP:0100613	Death in early adulthood	2/6

Unique additionally reports, from family experience (not peer-reviewed case series, so lower evidence tier): dental abnormalities (late eruption, overcrowding, weak enamel, bruxism, eruption cysts), talipes/club foot, scoliosis/kyphosis, peripheral acrocyanosis and cold extremities, neonatal jaundice, and small hands and feet.

One Seu proband had chronic kidney disease stage II–III (HP:0012622) and one had macrocephaly rather than microcephaly (the homozygous p.Ala28Val proband) — an important genotype–phenotype exception.

3.2 Phenotype characteristics

Age of onset: congenital / neonatal for essentially all core features. Microcephaly is present at birth (primary microcephaly in half). Hypotonia is "profound neonatal-onset." Cataracts are congenital in the majority. Anemia is "apparent from early infancy."
Severity: uniformly severe to profound for the neurodevelopmental domain in the heterozygous dominant-negative genotypes. The homozygous p.Ala28Val (MIT-domain) genotype is milder — Seu et al. note [body/derived] "the phenotype is somewhat milder than the clinical picture secondary to de novo heterozygous variants in the large ATPase domain which appear to exert a more detrimental, dominant-negative effect."
Progression: predominantly static/developmental rather than degenerative in most descriptions, but imaging language in Seu et al. is explicitly "suggestive of a neurodegenerative syndrome" (progressive cerebral volume loss, pontocerebellar atrophy). This is an unresolved question — curate as a KNOWLEDGE_GAP discussion: is CIMDAG a static malformation syndrome, a progressive neurodegeneration, or both? Anemia is chronic and lifelong; feeding difficulties often improve after early childhood per Unique.
Frequency across individuals: given above per phenotype.

3.3 Quality-of-life impact (per phenotype)

No EQ-5D, PedsQL, SF-36, or PROMIS data exist for this disorder — this is a genuine and complete gap. Qualitative, family-reported impacts from the Unique guide:

Motor/dystonia: dominant driver of disability — independent sitting, standing, or walking "may not be achieved"; requires orthotics, callipers, wheelchair, hydrotherapy; caregiver-dependent for all mobility and transfers.
Speech/communication: profound; many remain non-verbal, requiring AAC (pictograms, gestures, high-tech aided communication). Families describe first successful interaction via auditory/tactile channels: "Hearing and making funny noises paired with touching was our first possibility to interact and bring a smile and later laughter to our son's face."
Sleep disturbance (4/4): high family burden; frequently medicated.
Feeding: NGT/PEG in a substantial subset; aspiration risk.
Anemia: transfusion every 2 weeks to 6 months → recurrent hospital contact, venous access burden, and lifelong chelation.
Seizures: "Seizures can cause a lot of worry for families and can be frightening to observe."
Vision: cataract + retinal dystrophy compounds developmental deprivation; cataract is surgically correctable ("if a cataract is diagnosed it can be easily removed with a small surgery").
Temperament: counterbalancing positive — "most have a happy disposition."

4. Genetic / Molecular Information

Causal gene

VPS4A — vacuolar protein sorting 4 homolog A. HGNC:13488 · NCBI Gene 27183 · Ensembl ENSG00000132612 · UniProt Q9UN37 · OMIM 609982 · RefSeq NM_013245.3 / NP_037377 · chromosome 16q22.1*.

Protein: 437 aa, 48,898 Da. Type I AAA+ ATPase (EC 3.6.4.6). Domain architecture (UniProt Q9UN37): - MIT domain, aa 2–80 — "Microtubule Interacting and Trafficking" domain; binds ESCRT-III MIM motifs (CHMP1A/B, CHMP2A/B, IST1). Key ESCRT-III contact residues include Val-13 and Leu-64. - AAA+ ATPase cassette (central) — Walker A P-loop aa 167–174 (ATP binding), catalytic Lys-173, Walker B glutamate Glu-228 (the residue mutated in the canonical experimental dominant negative E228Q), pore loop 1 containing Trp201/Leu202/Gly203 and Glu206, and the arginine finger Arg284. - β-domain / Vps4_C — substrate and VTA1 co-factor engagement.

Pathogenic variants (all reported cases)

Variant (NM_013245.3)	Protein	Domain / residue role	Zygosity	Origin	n	Reference
c.850A>T	p.Arg284Trp	Arginine finger, ATP pocket	Heterozygous	De novo	4	PMID:33186545
c.850A>T	p.Arg284Trp	Arginine finger	Heterozygous	De novo	1 (proband 1)	PMID:33186543
c.850A>G	p.Arg284Gly	Arginine finger	Heterozygous	De novo	1	PMID:33186545
c.616G>A	p.Glu206Lys	Pore loop 1 region	Heterozygous	De novo	1	PMID:33186545
c.608G>A	p.Gly203Glu	Pore loop 1, central pore	Heterozygous	De novo	1 (proband 2)	PMID:33186543
c.83C>T	p.Ala28Val	MIT domain	Homozygous	Inherited (unaffected het parents)	1 (proband 3)	PMID:33186543
c.863G>A	p.Arg288Gln	AAA domain, conserved Arg	Homozygous	Consanguineous, Nepal	1	PMID:42498620
(not specified in retrieved abstract)	—	—	Heterozygous	De novo	1	PMID:33460484

Variants of uncertain significance reported and functionally excluded by Rodger et al.: c.502C>T (p.Pro168Ser) and c.1009A>G (p.Ile337Val) — associated with non-specific intellectual disability, deemed unlikely pathogenic. UniProt additionally flags a variant at position 193 as a VUS with a CIMDAG-like presentation.

Variant class: exclusively missense. No pathogenic PTVs, splice, CNV, or structural variants have been reported for this phenotype.

Population allele frequency: the pathogenic alleles are absent from gnomAD, ExAC, and TOPMed and fall "in regions highly constrained for variation in control populations" [body/derived, Rodger et al.]. I was unable to retrieve numeric gnomAD constraint metrics (pLI/LOEUF) — the browser is JS-rendered and the GraphQL endpoint requires POST; record this as a data gap rather than inventing a value. The qualitatively decisive constraint statement is the opposite of what one might expect and is central to the mechanism (below).

Somatic vs germline: all disease-causing variants are germline. VPS4A does appear in somatic cancer contexts — it is a well-known synthetic-lethal partner of VPS4B in 18q-deleted cancers, and recent work implicates it in oxaliplatin resistance in colorectal cancer (PMID:40558556), radioresistance via MYO1C in esophageal squamous carcinoma (PMID:41654990), EPHB2-driven autophagy in oral squamous carcinoma (PMID:40017157), and STING-driven anti-tumor immunity when VPS4 is pharmacologically targeted in rhabdomyosarcoma (PMID:42032367). None of this is relevant to CIMDAG pathogenesis and should not be conflated with it in a disease entry — but the VPS4A/VPS4B synthetic-lethal literature is the reason a VPS4 inhibitor chemical toolkit exists at all.

Functional consequence: dominant negative, explicitly not haploinsufficiency

This is the single most important molecular fact for the entry. Rodger et al. state [body/derived]:

"Multiple heterozygous VPS4A loss-of-function mutations are present in general population databases, indicating that a haploinsufficiency mechanism is unlikely."

and

"Our data and published evidence point to the p.Glu206Lys, p.Arg284Trp, and p.Arg284Gly mutants having a dominant-negative effect."

The structural logic is hexamer poisoning [body/derived]:

"As VPS4A protein stability is unaltered in proband cells, assuming equal expression of wild-type and mutant VPS4A we expect that a large majority of VPS4A hexamers will have impaired function as they will contain at least one mutant subunit."

with the proximate defect being "incorporation of the ATPase-defective protein into VPS4 hexamers and subsequent failure of disassembly of the ESCRT complexes."

Residue-level mechanism (Seu et al.) [body/derived]: - Arg284: "one of two arginine fingers functioning in the ATP binding pocket… interaction with the γ-phosphate of ATP, promoting hydrolysis. Therefore, alteration of Arg284 would be expected to compromise ATP hydrolysis and the function of VPS4A as an ATPase." - Gly203: "part of the pore loop 1 motif which forms the central pore of the active hexamer… is highly conserved, as it is the only amino acid that permits the packing and conformation required for the adjacent pore loop 1 residues Trp201 and Leu202 to create binding pockets for the sidechains of the ESCRT-III subunits passing through the pore." - Ala28 (MIT): "putatively disrupts VPS4A interaction with ESCRT-III proteins due to altered structure of the MIT domain, rather than directly affecting its ATPase activity" — a mechanistically distinct, recessive, hypomorphic route, consistent with its milder phenotype and requirement for biallelic dosage. - Arg288 (homozygous, 2026): "disruption of a conserved Arginine-288 residue within the ATPases associated with diverse cellular activities domain" causing loss of protein stability (PMID:42498620).

This yields a clean two-mechanism model worth curating as separate pathophysiology branches: 1. Dominant-negative branch (heterozygous ATPase-domain missense: R284W/G, E206K, G203E) → severe classic CIMDAG. 2. Recessive hypomorphic branch (biallelic A28V MIT-domain, R288Q destabilizing) → milder/atypical presentations, partial VPS4B compensation.

Modifier genes, epigenetics, chromosomal abnormalities

Modifiers: VPS4B is the only credible candidate (compensatory upregulation observed; paralog-specific non-redundancy demonstrated in PMID:38687820). Not formally tested as a modifier.
Epigenetics: no data. No methylation episignature has been described for VPS4A; it is not in the published EpiSign panels. This is a concrete, tractable gap worth flagging — episignatures exist for many chromatin and trafficking NDDs and would be diagnostically useful here.
Chromosomal abnormalities: none causal. 16q22.1 deletions encompassing VPS4A would produce haploinsufficiency, which the population data indicate is tolerated — so CMA-detectable deletions should not be expected to cause CIMDAG. This is a useful negative for differential-diagnosis reasoning.

5. Environmental Information

Environmental factors: none implicated. CTD lists chemical–VPS4A expression interactions (as for most genes), but none has any established role in this disease.
Lifestyle factors: not applicable to causation. Relevant only downstream (nutrition/feeding, dental hygiene, mobility/physiotherapy).
Infectious agents: not causal. There is an interesting inverse biological connection worth noting but not curating as etiology: VPS4A is the ATPase hijacked by many enveloped viruses (HIV-1, Ebola) for ESCRT-dependent budding (GO:0039702 viral budding via host ESCRT complex). Recurrent infections were reported in 1/5 patients, but there is no evidence of a systematic immunodeficiency or of altered viral susceptibility in patients.

6. Mechanism / Pathophysiology

6.1 The core causal chain

[MOLECULAR] De novo heterozygous missense in VPS4A ATPase domain (R284W/G, E206K, G203E)
     │  mutant subunit is stably expressed (protein abundance unchanged)
     ▼
[MOLECULAR] Poisoning of the hexameric VPS4A AAA-ATPase
     │  ≥1 mutant subunit per hexamer → loss of ATP hydrolysis / substrate translocation
     ▼
[MOLECULAR] Failure of ESCRT-III filament disassembly and recycling  (GO:1904903)
     │  IST1 (atypical ESCRT-III) accumulates on limiting membranes; core CHMP2B distribution preserved
     ▼
     ├──► [CELLULAR] Enlarged endo-lysosomal compartments (CD63+/LAMP1+/cathepsin D+)
     ├──► [CELLULAR] Cytokinetic abscission failure at the midbody (GO:0061952)
     ├──► [CELLULAR] Centrosome amplification → multipolar spindles → chromosome missegregation
     ├──► [CELLULAR] Nuclear envelope reformation defect (GO:0007084) → irregular nuclei, γH2AX↑
     ├──► [CELLULAR] Primary ciliogenesis failure ("dot cilium", basal body only)
     ├──► [CELLULAR] Impaired autophagosome closure / LC3B engagement; lipid droplet mishandling
     └──► [CELLULAR] Failed exosome release during reticulocyte maturation (CD71 retention)
     ▼
[TISSUE]  Neural progenitor depletion & aberrant corticogenesis │ Ineffective erythropoiesis │ Lens/retina degeneration
     ▼
[ORGANISM] Microcephaly, cerebellar hypoplasia, dystonia, ID │ Transfusion-dependent anemia, iron overload │ Cataract, retinal dystrophy │ Growth failure

6.2 Molecular pathways

ESCRT (endosomal sorting complexes required for transport) pathway — the sole primary pathway. VPS4A is the terminal, energy-consuming step that disassembles ESCRT-III polymers so they can be reused. Reactome: Membrane Trafficking → ESCRT-dependent MVB biogenesis. KEGG: hsa04144 (Endocytosis).
Downstream/secondary: autophagy–lysosome axis (PMID:42498620 — impaired LC3B interaction); cGAS-STING innate immune signaling is engaged when VPS4 is inhibited pharmacologically (PMID:42032367) — mechanistically interesting, unproven in patients; cell-cycle/mitotic checkpoint (Aurora B/ANCHR abscission checkpoint via ZFYVE19/VTA1).
Not implicated: Wnt, MAPK, mTOR, PI3K-AKT as primary drivers. Do not assert these.

6.3 Suggested GO biological process terms

GO ID	Label	Direction
GO:1904903	ESCRT III complex disassembly	DECREASED
GO:1904896	ESCRT complex disassembly	DECREASED
GO:0071985	multivesicular body sorting pathway	ABNORMAL
GO:0032509	endosome transport via multivesicular body sorting pathway	DECREASED
GO:0061952	midbody abscission	DECREASED
GO:0007084	mitotic nuclear membrane reassembly	DECREASED
GO:0060271	cilium assembly	DECREASED
GO:0007059	chromosome segregation	ABNORMAL
GO:0000226	microtubule cytoskeleton organization (spindle)	ABNORMAL
GO:0006914	autophagy	DECREASED
GO:0070887 / GO:0006979	response to oxidative stress	INCREASED
GO:0070925	organelle assembly (lipid droplet)	ABNORMAL
GO:0006281	DNA repair / DNA damage response (γH2AX↑)	INCREASED

Molecular function: GO:0016887 ATP hydrolysis activity (DECREASED); GO:0140657 ATP-dependent activity. Cellular component: GO:0005770 late endosome, GO:0005769 early endosome, GO:0005764 lysosome, GO:0030496 midbody, GO:0090543 Flemming body, GO:0005813 centrosome, GO:0000922 spindle pole, GO:0005635 nuclear envelope, GO:0005811 lipid droplet, GO:0000815 ESCRT III complex.

6.4 Cellular processes — the experimental evidence

Endosomal morphology (patient fibroblasts and heterologous overexpression) — Rodger et al. [abstract]:

"In cultured cells, overexpression of VPS4A mutants caused enlarged endosomal vacuoles resembling those induced by expression of known dominant-negative ATPase-defective forms of VPS4A. Proband-derived fibroblasts had enlarged endosomal structures with abnormal accumulation of the ESCRT protein IST1 on the limiting membrane."

Critically, the defect is selective, not a global endosomal collapse [body/derived]: "Heterozygous expression of mutant VPS4A in proband cells does not affect the cellular distribution of a core ESCRT-III complex member, prevent formation of ILVs, or adversely affect the degradation of EGFR" — indeed EGFR degradation was increased at 180 min. This partial-penetrance-at-the-cell-biology-level is what makes the disease survivable and is worth modeling as a distinct node.

Mitosis and genome stability — proband fibroblasts show [body/derived] "an anomalous centrosome number and morphology in interphase"; "Multipolar spindles were observed during mitosis, resulting in a high frequency of aberrant chromosome alignment during metaphase"; "Aberrant chromosome segregation was documented by the presence of both lagging and bridging chromosomes during anaphase and telophase"; increased micronuclei; G2/M accumulation on BrdU flow cytometry; "increased number of γH2AX foci… indicating increased spontaneous DNA damage."

Primary cilium — "Normal cilia were absent in fibroblasts expressing the VPS4A-p.Arg284Gly mutant, which instead showed a visible basal body (dot cilium)"; R284W cells show a dot cilium or occasionally an elongated/normal cilium. Seu et al. additionally report altered "length, number, and Arl13b composition of primary cilia." This makes CIMDAG partially a ciliopathy-adjacent disorder — relevant to the retinal dystrophy, cerebellar hypoplasia, and renal involvement, and a plausible conforms_to link to ciliopathy_dysfunction#Basal Body and Transition Zone Dysfunction in the dismech module set (flag as partial/atypical, since the primary lesion is ESCRT not IFT).

Neurons (iPSC-derived i³Neurons + CRISPRi knockdown) — Rodger et al. [abstract]: "VPS4A function was also required for normal endosomal morphology and IST1 localization in iPSC-derived human neurons." Full text: "a significant increase in the percentage of neurons that had enlarged structures marked by CD63, LAMP1, or the lysosomal enzyme cathepsin D", and — a striking result — overexpression of mutant VPS4A was "incompatible with neuronal survival." CRISPRi VPS4A knockdown "largely recapitulates phenotypes that are observed in proband cells expressing dominant-negative VPS4A at physiological heterozygous levels."

Erythroid lineage — Seu et al. [abstract]:

"Bone marrow studies showed binucleated erythroblasts and erythroblasts with cytoplasmic bridges indicating abnormal cytokinesis and abscission. Circulating red blood cells were found to retain transferrin receptor (CD71) in their membrane, demonstrating that VPS4A is critical for normal reticulocyte maturation. Using proband-derived induced pluripotent stem cells (iPSCs), we have successfully modeled the hematologic aspects of this syndrome in vitro, recapitulating their dyserythropoietic phenotype."

Two mechanistically separable erythroid defects therefore coexist: (i) abscission failure → binucleate erythroblasts → ineffective erythropoiesis (dyserythropoiesis), and (ii) failure of exosome-mediated CD71/transferrin-receptor shedding → arrested reticulocyte maturation → shortened RBC survival (hemolysis). The Lunati case, in which hemolysis dominated without obvious dyserythropoiesis, is the clinical proof that these two arms can dissociate.

Paralog non-redundancy — Dvilansky et al., PLoS Biol 2024 (PMID:38687820) [abstract]:

"Mutations in the human AAA-ATPase VPS4 isoform, VPS4A, cause severe neurodevelopmental defects and congenital dyserythropoietic anemia (CDA). VPS4 is a crucial component of the endosomal sorting complex required for transport (ESCRT) system… while most organisms encode for a single VPS4 gene, human cells have 2 VPS4 paralogs, namely VPS4A and VPS4B, but the functional differences between these paralogs is mostly unknown."

Findings: "VPS4A depletion resulted in a more severe abscission delay than VPS4B and was found to be involved in earlier stages of abscission"; "Depletion of VTA1, a co-factor of VPS4, disrupted VPS4A-ANCHR interactions and accelerated abscission"; STORM imaging showed "the decrease in IST1 density in late intercellular bridges is driven by the VPS4B isoform." Disease relevance stated directly: "Patients who carry normal VPS4B and mutated VPS4A genes develop pathologies due to the disruption of VPS4A-mediated cellular regulation, which is essential for neurodevelopment and cannot be compensated by VPS4B." This is the mechanistic answer to "why doesn't the paralog rescue?" and belongs in the entry.

6.5 Metabolic and lipid changes (newest mechanism, 2026)

Gupta et al., J Clin Lipidol 2026 (PMID:42498620) add a lipotoxicity arm from the homozygous p.Arg288Gln case: loss of protein stability, impaired LC3B interaction, reduced lipid-droplet localization, and cellular "increased lipid accumulation, elevated free fatty acids, and higher reactive oxygen species levels." This provides a candidate unifying explanation for the otherwise puzzling hepatic steatosis (1/5), hepatomegaly (4/5), and lipodystrophy (1/5) in the HPO annotation set. Treat as EMERGING (mechanistic_hypotheses status), single-patient, in-vitro-supported.

6.6 Immune involvement

Not a primary feature. Recurrent infections in 1/5. Pharmacological VPS4 inhibition activates cGAS-STING-TBK1-IRF3 (PMID:42032367, rhabdomyosarcoma models) — mechanistically this predicts that ESCRT dysfunction could produce cytosolic-DNA-driven interferon signaling (consistent with the micronuclei observed in patient fibroblasts). This is an untested hypothesis in patients and is the single most interesting unexplored mechanism: micronuclei + cGAS-STING is the canonical route to a chronic interferonopathy, and no one has looked for an interferon signature in CIMDAG blood. Worth curating as a KNOWLEDGE_GAP with a proposed experiment.

6.7 Tissue damage mechanisms

CNS: proliferative failure of neural progenitors (abscission defect → the classic microcephaly mechanism shared with other cytokinesis/centrosome microcephaly genes) plus post-mitotic neuronal endolysosomal dysfunction and reduced neuronal survival. Zebrafish data (below) localize the hypotonia to a central sensorimotor transformation defect, not to motor neuron or muscle failure.
Erythron: ineffective erythropoiesis + peripheral hemolysis + secondary iron loading → hepatosplenomegaly, cholelithiasis, liver iron accumulation.
Lens/retina: presumed proteostasis/trafficking failure in lens fiber cells and photoreceptor outer-segment turnover (an ESCRT/exosome-dependent process); mechanism not directly demonstrated.
Oxidative stress: elevated ROS documented in the R288Q model.

6.8 Molecular profiling status

Modality	Status
Transcriptomics	No patient RNA-seq published. Zebrafish shows atf3/jun stress-response upregulation in affected brain regions.
Proteomics	None patient-derived. (VPS4A appears as a PBMC biomarker candidate in sporadic Ménière disease, PMID:37603046 — unrelated.)
Metabolomics	None.
Lipidomics	Cell-model lipid quantification only (PMID:42498620). No patient lipidomics.
Single-cell / spatial	None. iPSC-derived i³Neurons and iPSC-erythroid cultures are the closest.
Functional genomics screens	VPS4A is a prominent DepMap synthetic-lethal hit paired with VPS4B; not exploited for CIMDAG.
Epigenomics	None (see §4).

7. Anatomical Structures Affected

Organ level

Primary: - Brain / CNS (UBERON:0000955) — cerebrum (UBERON:0000956 cerebral cortex), cerebellum (UBERON:0002037), cerebellar vermis (UBERON:0004720), corpus callosum (UBERON:0002336), pons (UBERON:0000988), basal ganglia (UBERON:0002420), cerebral white matter (UBERON:0002316) - Bone marrow / erythron (UBERON:0002371) - Eye (UBERON:0000970) — lens (UBERON:0000965), retina (UBERON:0000966), sclera (UBERON:0001773)

Secondary: - Liver (UBERON:0002107) — hepatomegaly, steatosis, iron loading - Spleen (UBERON:0002106) — splenomegaly from extravascular hemolysis - Kidney (UBERON:0002113) — CKD in 1 proband - Gallbladder / biliary (UBERON:0002110) — cholelithiasis - Inner ear / cochlea (UBERON:0001844) — sensorineural hearing loss - Skeletal muscle (UBERON:0001134) — secondary to central tone abnormality, not primary myopathy - Adipose tissue (UBERON:0001013) — lipodystrophy (1/5) - Skeleton (spine UBERON:0001130, foot UBERON:0002387) — scoliosis, talipes - Teeth (UBERON:0001091) — enamel/eruption anomalies

Body systems: nervous (central, dominant), hematopoietic, visual, hepatobiliary, musculoskeletal, growth/endocrine (hypogonadism 1/4), auditory, renal.

Tissue and cell level

Suggested Cell Ontology terms:

CL ID	Cell type	Role
CL:0000047	neuronal stem cell / neural progenitor	Abscission failure → depleted progenitor pool → microcephaly
CL:0000540	neuron	Enlarged endolysosomes; mutant overexpression incompatible with survival
CL:0000121	Purkinje cell	Inferred from cerebellar hypoplasia/atrophy (not directly demonstrated)
CL:0000765	erythroblast	Binucleation, cytoplasmic bridges — the primary hematologic cell
CL:0000558	reticulocyte	Failed exosome-mediated CD71 shedding
CL:0000232	erythrocyte	Aberrant CD71-retaining population; shortened survival
CL:0002322	(iPSC — model system)	Patient iPSCs used for both neuronal and erythroid modeling
CL:0000148 / lens fiber `CL:0011004`	lens fiber cell	Cataract
CL:0000210	photoreceptor cell	Retinal dystrophy
CL:0000057	fibroblast	Principal patient-derived assay cell
CL:0000182	hepatocyte	Steatosis, lipid droplet handling
CL:0000855	inner ear hair cell	SNHL (note: zebrafish inner ear function was unaffected, so the human SNHL locus is unresolved)

Tissue types: nervous tissue (dominant), hematopoietic tissue, transparent avascular lens epithelium/fiber, hepatic parenchyma.

Subcellular level (GO Cellular Component)

GO:0005770 late endosome · GO:0005769 early endosome · GO:0005768 endosome · GO:0005764 lysosome · GO:0032585 multivesicular body membrane · GO:0030496 midbody · GO:0090543 Flemming body · GO:0005813 centrosome · GO:0000922 spindle pole · GO:0005635 nuclear envelope · GO:0005811 lipid droplet · GO:0005929 cilium / GO:0036064 ciliary basal body · GO:0000815 ESCRT III complex · GO:0070062 extracellular exosome.

The subcellular level is where this disease actually "lives" — a dismech entry should anchor most MOLECULAR/CELLULAR pathophysiology nodes here rather than at organ level.

Localization and lateralization

Brain involvement is bilateral and symmetric (cerebellar hypoplasia, symmetric white matter loss, bilateral polymicrogyria in one case, bilateral cataracts). Microcephaly is global. No lateralized or asymmetric pattern reported. Cataracts bilateral.

8. Temporal Development

Onset

Congenital / prenatal. Primary microcephaly in 3/6 indicates prenatal onset of the brain growth failure; congenital cataracts confirm in-utero lens involvement.
Neonatal: profound hypotonia, feeding difficulties.
Early infancy: anemia becomes apparent; developmental delay evident by failure to establish head control.
Onset pattern: insidious/congenital rather than acute. There is no asymptomatic interval and no "normal then regressed" trajectory reported.

Progression

Stages: no formal staging system exists. Practically: (1) neonatal hypotonia/feeding/anemia; (2) infancy-early childhood — failure of motor milestones, cataract, seizure onset, transfusion dependence established; (3) later childhood — dystonia/spasticity dominate, iron overload accrues, scoliosis/contractures; (4) adolescence/adult — a minority survive; two deaths in childhood or early adult life.
Rate: the neurodevelopmental phenotype is best described as severe and largely static with superimposed progressive elements. Dystonia is described as progressive by families; imaging in the Seu cohort was read as "suggestive of a neurodegenerative syndrome." The literature does not resolve this — curate as an explicit open question.
Course pattern: chronic, lifelong; seizures may be episodic/isolated or recurrent; anemia is chronic with transfusion-cycle fluctuation.
Duration: lifelong; not self-limited. Feeding difficulties are the one feature Unique describes as often improving: "Feeding issues in the newborn period are common in children with CIMDAG syndrome but usually resolve after babyhood or early childhood."

Patterns

Remission: none spontaneous. Treatment-induced improvement is limited to specific features (cataract extraction restores optical clarity; transfusion corrects Hb; chelation reverses iron loading).
Critical periods: (i) prenatal neurogenesis — the microcephaly window is closed before birth, so no postnatal therapy can address it (Unique: "a complete cure is unlikely, even in the future, since the brain has already formed by the time a diagnosis is made"); (ii) first year of life — the actionable window for cataract detection/extraction and for establishing hematologic monitoring, both explicitly recommended; (iii) from ~1 year — the window to begin annual iron-status monitoring before organ iron accrues.

9. Inheritance and Population

Epidemiology

Prevalence: unknown; ultra-rare. Orphanet has not assigned a prevalence class. Unique (2024): "CIMDAG syndrome is extremely rare. Currently (2024) only 10 individuals with a VPS4A gene variant have been reported in the medical literature but more are known to have been diagnosed." With the 2026 Nepalese case, the published total is ~11. For a structured prevalence record, use prevalence_class: ULTRA_RARE, measure_type: CASES_IN_LITERATURE, count ≈ 11, population: Worldwide, with the Unique guide and the primary case series as evidence. Do not compute a rate_per_100000 — there is no denominator.
Incidence: not estimable.

Inheritance

Predominant: autosomal dominant, de novo (HP:0000006; HPOA inheritance annotation for OMIM:619273 is autosomal dominant). Unique: "In all individuals identified so far (2024), except one, the genetic change was a random (known as 'de novo') change."
Also: autosomal recessive (HP:0000007) in at least two probands — Seu proband 3 (homozygous p.Ala28Val, unaffected heterozygous parents) and the 2026 Nepalese proband (homozygous p.Arg288Gln). Both inheritance modes should be curated, with the AR form tied to MIT-domain/destabilizing alleles and a milder phenotype. This dual-mode architecture (dominant-negative missense vs. recessive hypomorph in the same gene) is a genuinely notable feature of the entry.
Penetrance: complete for the reported pathogenic alleles in the genotypes described. Heterozygous carriers of the recessive p.Ala28Val allele are unaffected, confirming that this allele is non-dominant. Heterozygous VPS4A LoF alleles in population databases are, by inference, also non-penetrant.
Expressivity: variable within genotype. Four probands share p.Arg284Trp yet differ in seizures, hearing loss, anemia severity, and hepatic involvement — so intra-allelic variable expressivity is real and unexplained.
Anticipation: not applicable (no repeat expansion).
Germline mosaicism: not documented, but explicitly retained in counseling as the residual-risk mechanism — Unique: "One reason why there is some residual chance of recurrence is due to the rare phenomenon called germline mosaicism."
Founder effects: none identified.
Consanguinity: directly relevant to the recessive form (Nepalese consanguineous family; Seu proband 3's parents both carriers).
Carrier frequency: not established for any pathogenic allele; all are absent from gnomAD.

Population demographics

Affected populations: no ethnic predilection identified. Reported patients span European, North American, and South Asian (Nepalese) ancestries. With n≈11, no inference is possible.
Geographic distribution: worldwide; reporting is concentrated in the UK/Europe (Rodger, Lunati) and USA (Seu, via CDAR), which is ascertainment bias from where exome sequencing and CDA registries operate — not a true distribution. The one Asian case (Nepal, 2026) suggests underascertainment in low-resource settings.
Sex ratio: no sex bias reported or expected (autosomal). Individual sexes are not consistently extractable from the abstracts; treat as unknown/1:1.
Age distribution: all reported patients ascertained in infancy or childhood; two died in childhood or early adult life; the oldest survivors are young adults.

10. Diagnostics

Genetic testing — the definitive route

Recommended approach: trio exome (WES) or genome (WGS) sequencing. Unique: "CIMDAG syndrome is caused by a VPS4A gene sequence variant that can be identified by a type of genetic test called sequencing (e.g. whole exome sequencing (WES) or whole genome sequencing (WGS))… a genetic test is needed to confirm a suspected diagnosis." All 11 reported cases were identified by exome/genome sequencing, several via GeneMatcher-style matchmaking.

Modality	Utility for CIMDAG
Trio WES	First-line, high yield. Detects all known pathogenic alleles; trio design establishes de novo status, which is essential for interpretation.
WGS	Equivalent or better; preferred where available.
Gene panels	VPS4A is on Genomics England PanelApp "Rare anaemia" panel and on ID/microcephaly panels of some labs. A CDA panel is a reasonable entry point when anemia dominates the presentation.
*Single-gene VPS4A* testing**	Reasonable only for targeted familial testing / cascade testing after a proband variant is known.
Chromosomal microarray	Low yield and mechanistically uninformative — deletions cause haploinsufficiency, which is tolerated. Will be done anyway as first-tier ID/microcephaly workup; expect negative.
Karyotype / FISH	Not indicated.
mtDNA testing	Not indicated, but frequently performed because the phenotype (microcephaly, lactate-free encephalopathy, cerebellar/pontine atrophy, hepatopathy) mimics a mitochondrial disorder — worth listing as a common diagnostic detour.
Repeat expansion testing	Not indicated.

Variant interpretation notes for ACMG/AMP application: pathogenic alleles are absent from gnomAD (PM2), de novo with confirmed parentage (PS2), fall in a well-established functional domain and at a mutational hotspot (PM1), have supporting functional studies (PS3 — the endosomal-vacuole and IST1 assays are essentially a validated functional assay for this gene), and R284W recurs in multiple unrelated probands (PS4_moderate). Critically, PVS1 should never be applied to VPS4A — LoF is not the mechanism. ClinVar holds 52 records classified pathogenic/likely pathogenic under a broad query and ~149 VPS4A variants overall; most non-hotspot missense will be VUS.

Clinical tests

Hematology (essential; Unique explicitly recommends): "It is recommended to check on complete blood count (CBC) and reticulocyte count at the time of the diagnosis and also monitor the iron status regularly (e.g. once a year, starting by 1 year of age)."

Test	Expected finding	LOINC (indicative)
CBC / hemoglobin	Hb 6.1–7.3 g/dL untransfused (Seu probands)	LOINC:718-7
MCV	80–100 fL — normocytic, not macrocytic (distinguishes from CDA type I)	LOINC:787-2
Absolute reticulocyte count	40–500 ×10⁶/µL — inadequately elevated for the degree of anemia (ineffective erythropoiesis)	LOINC:26498-6
Ferritin	470–4093 ng/mL	LOINC:2276-4
Liver iron concentration (MRI R2/T2)	6.5–12.1 mg/g dry weight	—
Haptoglobin, LDH, bilirubin	Hemolysis pattern; neonatal/persistent jaundice	—
Flow cytometry: CD71 on mature RBCs	Abnormal CD71-retaining mature RBC population — a disease-characteristic biomarker	—
Bone marrow aspirate	Binucleated erythroblasts (3–7%), internuclear cytoplasmic bridges; erythroid hyperplasia	—

The CD71-retention flow assay is the closest thing to a functional biomarker for this disease and is worth curating as a biochemical/diagnostic entity — it directly reads out the exosome/ESCRT defect and distinguishes VPS4A-CDA from other CDAs.

Imaging: - Brain MRI (essential): reduced global cerebral volume, thin/hypoplastic corpus callosum, cerebellar and pontine hypoplasia/atrophy, delayed myelination, white matter deficiency, ± polymicrogyria, ± basal ganglia atrophy. Occasional ventriculomegaly ex vacuo. - Abdominal ultrasound: hepatosplenomegaly, gallstones. - Hepatic MRI R2*/FerriScan: iron quantification. - Cardiac T2* MRI: if chronically transfused.

Electrophysiology: EEG / video-telemetry for seizure characterization (Unique lists atypical absence, epileptic spasms, generalized tonic-clonic, myoclonic, tonic semiologies). ERG/VEP for retinal dystrophy vs cortical visual impairment. Auditory brainstem response / newborn hearing screen — note the useful nuance that hearing screens at birth "often give a clear response" despite later SNHL in some, so serial audiology is warranted.

Functional/ophthalmologic: slit-lamp for cataract (recommended from the first year of life and then per specialist), dilated fundoscopy for retinal dystrophy.

Biopsy/histopathology: bone marrow (above) is the only routinely informative biopsy. Skin biopsy for fibroblast culture is valuable for research-grade functional confirmation (enlarged endosomes, IST1 mislocalization, centrosome/cilium assays) — genuinely useful for VUS resolution in this gene given the robust cellular assays published.

Omics-based diagnostics

RNA-seq: no established role (variants are missense, not splice).
Proteomics/metabolomics/liquid biopsy: no role.
Epigenomics: no VPS4A episignature exists — a real opportunity, since an episignature would immediately resolve the VUS burden.

Clinical criteria and differential diagnosis

No consensus diagnostic criteria exist. Diagnosis is molecular, prompted by the gestalt of severe primary microcephaly + profound DD/dystonia + cataract + otherwise-unexplained congenital anemia — a combination that should trigger VPS4A consideration specifically. The anemia is the discriminating clue: severe microcephaly + ID + dystonia has a long differential, but adding transfusion-dependent congenital dyserythropoietic anemia narrows it dramatically.

Differential diagnosis:

Condition	Distinguishing features
*CDA type I (CDAN1, CDIN1)*	Macrocytic anemia, spongy "Swiss cheese" heterochromatin on EM, distal limb anomalies; no severe microcephaly/dystonia
*CDA type II (SEC23B)*	Normocytic anemia, double membrane on EM, SDS-PAGE band 3 pattern; normal neurodevelopment
*CDA type III (KIF23)*	Giant multinucleate erythroblasts; also a cytokinesis gene — the closest mechanistic analog
RACGAP1-related CDA	Another cytokinesis-defect CDA; recently described
*Majeed syndrome (LPIN2)*	CDA + CRMO + inflammation
Pontocerebellar hypoplasia (PCH) types, TSEN54, EXOSC3, CASK	Overlapping imaging; anemia and cataract absent
*Autosomal recessive primary microcephaly (MCPH; ASPM, WDR62, CDK5RAP2, CENPJ)*	Shares the mitotic/centrosome mechanism and microcephaly; no anemia, no cataract, milder ID
Cerebrooculofacioskeletal / Cockayne syndrome	Microcephaly + cataract + growth failure + progressive course — strong mimic; distinguish by photosensitivity, DNA repair assay, absence of dyserythropoiesis
*Marinesco-Sjögren syndrome (SIL1)*	Cataract + cerebellar hypoplasia + ID + myopathy; myopathy present, anemia absent
Congenital disorders of glycosylation (PMM2-CDG)	Cerebellar hypoplasia, multisystem, coagulopathy; distinguish by transferrin isoform analysis
Mitochondrial encephalopathies	Frequent diagnostic detour; distinguish by lactate, mtDNA/nuclear panel
Congenital infection (CMV/toxoplasma)	Microcephaly + cataract + hepatosplenomegaly + thrombocytopenia — must be excluded; serology/PCR
Peroxisomal (Zellweger spectrum)	Hypotonia, hepatomegaly, cataract, seizures; VLCFA testing

Screening

Newborn screening: not included in any NBS panel; not a candidate (no treatable metabolic marker, no presymptomatic-treatment benefit).
Carrier screening: not on expanded carrier screening panels; would only be relevant for the recessive alleles in consanguineous populations.
Cascade screening: for de novo dominant cases, parental testing is for recurrence-risk counseling, not for finding affected relatives. For biallelic families, sibling carrier testing is appropriate.

11. Outcome / Prognosis

Survival and mortality

Life expectancy: reduced, but not uniformly. Rodger et al.: "Two affected individuals died in childhood or early adult life" — i.e. 2/6 (33%) mortality within the reported follow-up. HPO records HP:0100613 Death in early adulthood at 2/6.
No 5-/10-year survival estimates, no formal mortality rate, no actuarial life table exists. Do not manufacture one.
Presumed proximate causes of death (not systematically reported): respiratory infection/aspiration in the context of severe neurodisability, seizure-related events, complications of chronic transfusion and iron overload. Treat as inference, not evidence.

Morbidity and function

Severe lifelong disability is the rule. Non-ambulatory (no reported patient achieved independent walking), largely non-verbal, fully dependent for activities of daily living, requiring assisted feeding in a substantial fraction.
Disability outcome (ICF framing): profound impairment across mobility, communication, self-care, and learning domains; complete dependence on caregivers.
QoL instruments: none applied. No EQ-5D, PedsQL, CPCHILD, or PROMIS data. This is a clean, well-defined evidence gap suitable for a KNOWLEDGE_GAP discussion — and one that matters, because caregiver-reported outcome measures are the plausible endpoint for any future trial in this population.

Complications

Transfusional and disease-related iron overload (disproportionate, due to ineffective erythropoiesis) → hepatic, cardiac, endocrine iron toxicity; cholelithiasis from chronic hemolysis; splenomegaly; recurrent respiratory infection and aspiration; scoliosis and contractures; dental disease; refractory epilepsy in a subset; visual loss from cataract (reversible) and retinal dystrophy (not reversible); chronic kidney disease in at least one patient.

Recovery potential

None for the neurodevelopmental core — the microcephaly and brain malformation are established in utero. Unique is blunt about this: "There is no cure for CIMDAG syndrome since the effects of the genetic change took place during a baby's formation and development… a complete cure is unlikely, even in the future, since the brain has already formed by the time a diagnosis is made." Individual features are correctable (cataract surgery, transfusion, chelation, seizure control).

Prognostic factors

Not formally studied. Reasonable, evidence-anchored predictors to record as hypotheses: 1. Genotype class — the best-supported predictor. Heterozygous ATPase-domain dominant-negative alleles (R284W/G, E206K, G203E) → severe classic phenotype; biallelic MIT-domain/destabilizing hypomorphs (A28V, R288Q) → milder, with preserved head circumference in at least one case (macrocephaly rather than microcephaly). 2. Degree of microcephaly (Z-score) — universal severity marker. 3. Transfusion burden and iron loading — modifiable determinant of long-term organ morbidity. 4. Presence and refractoriness of epilepsy.

Prognostic biomarkers: none validated. Ferritin/LIC are established biomarkers of iron-related risk generically, not of this disease's course.

12. Treatment

There is no disease-modifying or targeted therapy. Management is entirely supportive, multisystem, and multidisciplinary. Unique's management recommendation is the closest thing to a guideline that exists:

"Children with CIMDAG syndrome should be under the care of a multidisciplinary team. The team should include a geneticist and paediatric neurologist who can oversee care so that development and behaviour can be monitored, and the best help given in the form of physiotherapy, occupational therapy, speech therapy and, if needed, behavioural therapy. For signs of anaemia or haemolysis (pallor, jaundice, decreased level of energy, or abnormal CBC/reticulocyte count), evaluation and care by a paediatric haematologist is recommended. Ophthalmology evaluation is also recommended, starting at the first year of life and then as frequently as is recommended by the specialist."

Pharmacotherapy

Treatment	Indication	Suggested NCIT	Modality
Anti-seizure medications — lamotrigine, oxcarbazepine, levetiracetam, clobazam (Unique names these explicitly); rescue diazepam or midazolam	Epilepsy (3/6)	`NCIT:C15986` Pharmacotherapy + `therapeutic_agent` per drug (CHEBI: lamotrigine `CHEBI:6367`, levetiracetam `CHEBI:6437`, clobazam `CHEBI:31413`, diazepam `CHEBI:49575`, midazolam `CHEBI:6931`)	SMALL_MOLECULE
Iron chelation — deferasirox / deferoxamine / deferiprone	Transfusional + ineffective-erythropoiesis iron overload	`NCIT:C15986`; agents `CHEBI:49005` (deferasirox), `CHEBI:4356` (deferoxamine)	SMALL_MOLECULE
Laxatives / stool softeners; magnesium	Constipation (family-reported: "Magnesia helps us a lot due to its beneficial characteristics on muscle soreness and constipation")	`NCIT:C15747` Supportive Care	SMALL_MOLECULE
Anti-reflux therapy	GERD	`NCIT:C15986`	SMALL_MOLECULE
Sleep-directed medication (unspecified; families report use)	Sleep disturbance (4/4)	`NCIT:C15986`	SMALL_MOLECULE
Dystonia-directed pharmacotherapy (trihexyphenidyl, baclofen, botulinum toxin)	Dystonia (5/6) — not specifically documented in CIMDAG literature; extrapolated from standard dystonia care; flag as inferred	`NCIT:C15986`	SMALL_MOLECULE
Phototherapy / bilirubin management	Neonatal and prolonged jaundice	`NCIT:C15747`	DEVICE/OTHER

Pharmacogenomics: nothing VPS4A-specific. Standard PGx applies (e.g. HLA-B*15:02 / HLA-A*31:01 for carbamazepine-family anti-seizure drugs, relevant given oxcarbazepine use; CPIC guideline). Worth recording because this population is disproportionately exposed to aromatic antiepileptics.

Transfusion support

Red cell transfusion is the mainstay for the anemia. Observed intervals in the Seu cohort: every 4–6 weeks (proband 1), every 4–10 weeks (proband 2), every 2–6 months (proband 3). NCIT: NCIT:C15380 Blood Transfusion (verify with OAK) / NCIT:C15747 Supportive Care. Modality: OTHER.

Advanced therapeutics

Approach	Status for CIMDAG
Gene therapy / gene replacement	Not developed. Conceptually poorly suited to the dominant form — adding wild-type VPS4A does not remove poisoned hexamers, and the CNS phenotype is prenatal.
Allele-selective silencing (ASO / siRNA / CRISPR base editing)	The mechanistically correct strategy for the dominant-negative alleles: selectively knock down the mutant transcript, since haploinsufficiency is tolerated (LoF alleles are present in gnomAD). This is an unusually favorable therapeutic logic and deserves to be recorded as a hypothesis. No program exists. The recurrent c.850A>T hotspot in 5/11 patients is an ideal allele-specific target.
Cell therapy / HSCT	Not reported. Would be theoretically rational for the hematologic component only (the erythroid defect is cell-autonomous in HSPCs), leaving the neurological phenotype untouched — a difficult risk/benefit calculus in a child with profound neurodisability. Purely speculative; no case reports.
Targeted small molecules	None. VPS4 inhibitors exist in oncology (PMID:42032367) — the wrong direction pharmacologically for this disease. No VPS4A chaperone/stabilizer program.
Immunotherapy	Not applicable.

Surgical and interventional

Cataract extraction — high-value, low-burden. Unique quotes a family: "Check the eyes on a regular basis – if a cataract is diagnosed it can be easily removed with a small surgery." NCIT: NCIT:C15329 Surgical Procedure (or a specific lens-extraction term if OAK resolves one). Modality: SURGERY.
Gastrostomy (PEG/G-tube) or nasogastric tube — for feeding failure/aspiration in the subset with severe difficulty. NCIT:C15329. Modality: SURGERY/DEVICE.
Orthopedic surgery — talipes correction, scoliosis management. NCIT:C16186 Orthopedic Surgical Procedure. Modality: SURGERY.
Splenectomy — not reported and not recommended in this disease; note explicitly, since it is a standard consideration in other congenital hemolytic anemias and its role here is unknown.
Dental treatment under general anesthesia — frequently required.

Supportive and rehabilitative

Physiotherapy (NCIT:C15302 Physical Therapy, BEHAVIORAL) — including hydrotherapy and hippotherapy, both named by families.
Occupational therapy (NCIT:C121351, BEHAVIORAL).
Speech and language therapy + AAC (NCIT:C159273, BEHAVIORAL) — Unique emphasizes AAC (pictograms, gestures, simplified sign, high-tech aided communication) given that many remain non-verbal.
Orthotics/bracing — insoles, braces, splints, callipers, spinal bracing; wheelchair and mobility aids (DEVICE).
Nutritional support — high-energy formula, positioning for feeds (NCIT:C15433; note the CLAUDE.md caution — do not auto-tag nutritional support as BEHAVIORAL; here the modality is genuinely dietary/behavioral for positioning and formula, so judge per item).
Behavioral therapy and sleep hygiene (NCIT:C181743, BEHAVIORAL).
Genetic counseling (NCIT:C15240).

Experimental treatments / clinical trials

No interventional trial for CIMDAG or VPS4A exists — a ClinicalTrials.gov API query for "VPS4A OR CIMDAG" returns zero studies (checked 2026-08-01).

The one registered study capturing these patients is observational: - NCT02964494 — The Congenital Dyserythropoietic Anemia Registry (CDAR); sponsor Cincinnati Children's Hospital Medical Center; observational patient registry; recruiting; estimated enrollment 10,000; condition: Congenital Dyserythropoietic Anemia. This registry is how the three Seu et al. probands were ascertained, and it maintains a blood/bone-marrow biorepository. It is the correct clinical_trials entry for a dismech CIMDAG page, curated with the caveat that it is CDA-wide rather than VPS4A-specific.

Treatment outcomes

No response-rate data. Transfusion reliably corrects hemoglobin; chelation reliably lowers ferritin/LIC (generic evidence, not CIMDAG-specific). Cataract surgery outcomes not reported in this cohort. Anti-seizure efficacy anecdotal — Unique: "there are currently (2024) no specific recommendations for treating CIMDAG syndrome seizures." Adverse events are those of the generic therapies (chelator nephro/hepatotoxicity and cytopenias; transfusion reactions and alloimmunization; antiepileptic AEs).

Treatment strategy

No algorithm exists. A defensible, evidence-anchored care schedule assembled from the Unique recommendations:

At diagnosis: CBC + reticulocyte count; brain MRI; ophthalmology (slit lamp + fundoscopy); audiology; EEG if paroxysmal events; feeding/swallow assessment; genetic counseling.
Annually from age 1: iron status (ferritin ± LIC by MRI); ophthalmology per specialist; growth and nutrition; audiology; spine and hip surveillance.
Ongoing: PT/OT/SLT; dental review; sleep review; hematology follow-up with transfusion and chelation as indicated.
As needed: cataract extraction; gastrostomy; orthopedic intervention; anti-seizure escalation.

Personalized medicine: genotype currently informs prognosis (dominant-negative vs. biallelic hypomorph) but not therapy. Genotype-guided therapy would become real only with allele-selective silencing.

13. Prevention

Primary prevention: not possible for de novo dominant cases — by definition unpredictable and unpreventable. Unique makes the non-blame point explicitly: "It is important to recognize that no one should be blamed for variants in their DNA and no parent is at fault when a new DNA change occurs in their child." For the recessive form, reduction of consanguinity-associated risk at the population level is the only structural lever, and is a public-health rather than clinical intervention.
Secondary prevention (early detection): the actionable tier. Early molecular diagnosis via trio WES/WGS enables the surveillance schedule above. Unique: "knowing the diagnosis means that appropriate monitoring and interventions can be put in place early to help each child reach their full potential." Specific high-yield items: first-year ophthalmology to catch surgically remediable cataract; CBC/retic at diagnosis to catch anemia; annual iron monitoring from age 1 to pre-empt organ iron loading.
Tertiary prevention: iron chelation to prevent cardiac/hepatic/endocrine iron toxicity; aspiration precautions and gastrostomy to prevent recurrent pneumonia; postural management, orthotics, and spinal surveillance to prevent contracture and scoliosis progression; dental care to prevent decay and erosion from bruxism; seizure control.
Immunization: no disease-specific vaccine. Standard schedule plus enhanced respiratory protection (influenza, pneumococcal, RSV per local policy) is appropriate for a child with severe neurodisability and aspiration risk. Transfusion-dependent patients should be hepatitis B immune.
Genetic screening / reproductive options: prenatal diagnosis and preimplantation genetic testing (PGT-M) are available once the familial variant is known. For de novo cases, recurrence risk is "usually less than 1%" with germline mosaicism as the residual mechanism; for biallelic families, 25% per pregnancy with both parents heterozygous carriers.
Genetic counseling: essential and should be offered at diagnosis and again at reproductive planning for parents and, later, for unaffected siblings (carrier status relevant only in the recessive families). NCIT: NCIT:C15240.
Risk stratification / public health / environmental interventions: not applicable.
Prophylaxis: no disease-specific prophylactic medication.

14. Other Species / Natural Disease

Taxonomy and orthologs

Species	NCBI Taxon	Gene	Identifier
Homo sapiens	NCBITaxon:9606	VPS4A	NCBI Gene 27183; HGNC:13488
Mus musculus	NCBITaxon:10090	Vps4a	MGI:1890520; NCBI Gene 116733; Chr8:107,757,901–107,772,392 (+)
Danio rerio	NCBITaxon:7955	vps4a	ZFIN (see model below)
Drosophila melanogaster	NCBITaxon:7227	Vps4	Single ortholog
Caenorhabditis elegans	NCBITaxon:6239	vps-4	Single ortholog
Saccharomyces cerevisiae	NCBITaxon:4932	VPS4/END13	Single ortholog

Evolutionary conservation is the key comparative fact and it has direct disease relevance: most organisms encode one VPS4; only vertebrates/mammals have the VPS4A/VPS4B paralog pair. Dvilansky et al. showed the paralogs are functionally non-redundant — VPS4A acts earlier in abscission and cannot be substituted by VPS4B — which is precisely why a heterozygous VPS4A missense allele causes human disease despite an intact VPS4B. Any invertebrate or yeast model necessarily collapses this paralog distinction and therefore cannot model the human genetics faithfully, only the core ESCRT biochemistry. The affected residues (Ala28, Gly203, Glu206, Arg284, Arg288) are deeply conserved across all these orthologs.

Breed

Not applicable (VBO: no entries).

Natural disease in other species

None known. An OMIA search for VPS4A returns no entries in any species — no naturally occurring VPS4A disease has been described in companion animals, livestock, or wildlife. Record this as an explicit negative rather than omitting the section.

Comparative pathology

Only engineered models exist (§15). The cross-species comparison that has been made — zebrafish vps4a T248I vs. human patients — is informative: the fish reproduce the central origin of hypotonia ("Resembling the central form of hypotonia in VPS4A patients, motor neurons and muscle cells are functional in mutant zebrafish") and the endosomal/exosome defect, but the fish inner ear is unaffected, unlike the SNHL seen in 2/5 human patients.

Transmission

Not applicable — non-infectious, non-zoonotic, no cross-species susceptibility.

15. Model Organisms

15.1 Zebrafish — the best available whole-organism neurological model

Shipman et al., J Neurosci 2024;44(50):e0680242024. PMID:39455257; PMCID:PMC11638813; DOI:10.1523/JNEUROSCI.0680-24.2024

Abstract [abstract]:

"Mutations in human VPS4A are associated with neurodevelopmental defects, including motor delays and defective muscle tone. VPS4A encodes a AAA-ATPase required for membrane scission, but how mutations in VPS4A lead to impaired control of motor function is not known. Here we identified a mutation in zebrafish vps4a, T248I, that affects sensorimotor transformation."

Model type: forward-genetic missense allele, vps4a^T248I^, in the AAA-ATPase domain (mechanistically parallel to the human ATPase-domain alleles).
Molecular validation: the mutation "reduces the ATPase activity of Vps4a and disassembly of ESCRT filaments, which mediate membrane scission" — the same primary lesion as in patients.
Phenotypes recapitulated: "Optomotor responses, vestibulospinal, and acoustic startle reflexes are absent or strongly impaired"; larvae "fail to maintain an upright posture" and "swim sideways or upside down"; "decreased numbers of circulating exosomes in brain ventricles"; "enlarged endosomal compartments in the CNS"; upregulation of atf3 and jun stress-response genes.
Key mechanistic dissociation: "Resembling the central form of hypotonia in VPS4A patients, motor neurons and muscle cells are functional in mutant zebrafish" — establishing that the hypotonia/motor phenotype is central, arising at the level of sensorimotor transformation, not neuromuscular.
Limitations: "the function of the inner ear in vps4a^T248I^ larvae is unaffected" and vestibulo-ocular responses to head rotation are normal — so the model does not capture human SNHL. It also does not model microcephaly, cataract, or the anemia, and zebrafish lack the VPS4A/VPS4B paralog split in the mammalian configuration.
Applications: sensorimotor circuit function, exosome biology in vivo, CNS endosomal morphology, small-molecule screening for motor-function rescue.
Resource: ZFIN.

15.2 Mouse

MGI:1890520 (Vps4a). The MGI record lists 19 mutations/alleles across three classes — 6 endonuclease-mediated, 9 gene-trapped, 4 targeted — with 19 strains/lines available through IMSR. Existing phenotype annotations (8 phenotypes from one allele in one background, plus one multigenic phenotype) span craniofacial, digestive, embryonic development, growth/size, hematopoietic, integument, immune, and mortality/aging systems. MGI records no human disease model association for Vps4a — i.e., no mouse has yet been designated a CIMDAG model.

What exists: - Cardiomyocyte-specific Vps4a conditional knockout (PMC10341959): impaired autophagic flux — Vps4a is "mainly involved in the sealing of autophagosome in cardiomyocytes" — with cardiac hypertrophy (increased HW/BW and HW/TL), partial LV dilation, reduced ejection fraction, and partial lethality beginning at 3 months, some surviving beyond 12 months. Confirms an in vivo autophagy role for Vps4a but models no CIMDAG feature (patients have no reported cardiomyopathy). - Double Vps4a/Vps4b heterozygous null MEFs: increased endo/lysosomal organelles with large multi-membrane structures.

The critical gap: no knock-in mouse carrying a patient allele (e.g. Vps4a^R284W/+^) has been reported. This is the single most valuable missing model. Because the mechanism is dominant-negative and the paralog architecture is mammal-specific, a heterozygous knock-in mouse — not a knockout — is the design that would test whether the human genetics reproduce in vivo, and would be the required platform for any allele-selective silencing preclinical program. Note also that a Vps4a knockout mouse would likely be uninformative for CIMDAG, since human heterozygous LoF is tolerated.

Register this as a HUMAN_MODEL_MISMATCH discussion rather than a plain KNOWLEDGE_GAP: model-system evidence exists (zebrafish missense, mouse conditional KO), but its fidelity to the human dominant-negative, paralog-dependent disease is the open question.

15.3 Cellular and in vitro models — the workhorses of this field

Model	Findings	Source
Proband-derived dermal fibroblasts (R284W, R284G)	Enlarged endosomes; IST1 accumulation on limiting membranes; abnormal centrosome number/morphology; multipolar spindles; lagging/bridging chromosomes; micronuclei; irregular nuclei; ↑γH2AX; G2/M accumulation; "dot cilium"	PMID:33186545
Proband-derived iPSCs → i³Neurons (NGN2-induced)	"significant increase in the percentage of neurons that had enlarged structures marked by CD63, LAMP1, or the lysosomal enzyme cathepsin D"; increased IST1 puncta on early/late endosomes; mutant overexpression "incompatible with neuronal survival"	PMID:33186545
*CRISPRi VPS4A* knockdown in i³Neurons**	"largely recapitulates phenotypes that are observed in proband cells expressing dominant-negative VPS4A at physiological heterozygous levels" — an isogenic complement to patient cells	PMID:33186545
Proband-derived iPSC → erythroid differentiation (R284W)	Asynchronous, prematurely maturing erythropoiesis; increased binucleated erythroblasts; poor growth (similar to CDAN1-mutant cells); "persistent cytoplasmic bridges between erythroblasts… even after attempted completion of cytokinesis" — the hematologic phenotype recapitulated in a dish	PMID:33186543
Heterologous overexpression (HeLa/U2OS)	Mutants phenocopy the canonical ATPase-dead E228Q dominant negative: "Expression of VPS4A-p.Arg284Trp, VPS4A-p.Arg284Gly, or VPS4A-p.Glu206Lys caused the development of vacuolar endosomal structures identical to those generated by VPS4A-p.Glu228Gln expression"	PMID:33186545
STORM super-resolution + siRNA paralog depletion	VPS4A vs VPS4B abscission-stage specificity; VTA1/ANCHR checkpoint interplay	PMID:38687820
Structural modeling + cell assays (R288Q)	Loss of stability; impaired LC3B interaction; reduced lipid-droplet localization; ↑lipid accumulation, ↑FFA, ↑ROS	PMID:42498620

Phenotype recapitulation summary: the cellular models are unusually strong — patient fibroblasts and patient iPSC-derived erythroblasts reproduce the disease-defining cellular lesions faithfully, and iPSC-neurons reproduce the endolysosomal lesion. This makes the assay set genuinely usable for VUS resolution (PS3-level functional evidence). What no model yet captures: microcephaly in vivo, cataract, growth failure, and the integrated multisystem phenotype.

15.4 Databases

MGI (informatics.jax.org) · IMSR (19 Vps4a lines) · IMPC · ZFIN · Alliance of Genome Resources · FlyBase · WormBase · SGD · DepMap (VPS4A/VPS4B synthetic lethality) · Cellosaurus (for patient iPSC lines, if deposited).

Appendix A — Consolidated ontology term suggestions for KB entry

Disease: MONDO:0035819 Gene: hgnc:13488 (VPS4A) — note dismech lowercase hgnc: convention Inheritance: HP:0000006 autosomal dominant (primary); HP:0010985? no — use HP:0000007 autosomal recessive for the biallelic branch

Top HPO terms (with frequency band): HP:0011344 severe global developmental delay (OBLIGATE/VERY_FREQUENT, 6/6) · HP:0010864 severe intellectual disability (6/6) · HP:0000252 microcephaly (6/6) · HP:0000505 visual impairment (6/6) · HP:0001332 dystonia (5/6) · HP:0001252 hypotonia (5/6) · HP:0001270 motor delay (5/5) · HP:0000750 delayed speech and language development (5/5) · HP:0000519 developmental cataract (4/5) · HP:0001257 spasticity (4/5) · HP:0002360 sleep disturbance (4/4) · HP:0011968 feeding difficulties (4/6) · HP:0002240 hepatomegaly (4/5) · HP:0001250 seizure (3/6) · HP:0000556 retinal dystrophy (3/5) · HP:0011451 primary microcephaly (3/6) · HP:0001321 cerebellar hypoplasia · HP:0033725 thin corpus callosum · HP:0000407 sensorineural hearing impairment (2/5) · HP:0100613 death in early adulthood (2/6) · HP:0031688 erythroid dysplasia · HP:0001878 hemolytic anemia · HP:0001744 splenomegaly · HP:0001510 growth delay · HP:0001414 microvesicular hepatic steatosis · HP:0009125 lipodystrophy · HP:0001081 cholelithiasis

GO BP: GO:1904903, GO:1904896, GO:0071985, GO:0032509, GO:0061952, GO:0007084, GO:0060271, GO:0007059, GO:0006914 GO CC: GO:0000815, GO:0005770, GO:0005769, GO:0005764, GO:0030496, GO:0090543, GO:0005813, GO:0000922, GO:0005635, GO:0005811, GO:0070062 GO MF: GO:0016887 ATP hydrolysis activity CL: CL:0000047, CL:0000540, CL:0000765, CL:0000558, CL:0000232, CL:0000057, CL:0000121 UBERON: UBERON:0000955, UBERON:0002037, UBERON:0002336, UBERON:0000988, UBERON:0002371, UBERON:0000965, UBERON:0000966, UBERON:0002107, UBERON:0002106 NCIT (treatment): NCIT:C15986, NCIT:C15747, NCIT:C15302, NCIT:C121351, NCIT:C159273, NCIT:C15329, NCIT:C16186, NCIT:C15240, NCIT:C15433

Candidate dismech module conformance: - ciliopathy_dysfunction#Basal Body and Transition Zone Dysfunction — partial/atypical (cilium defect is secondary to ESCRT failure, not an IFT/BBSome lesion). Curate with an explicit caveat. - hemolytic_anemia_erythrocyte_destruction#Premature Erythrocyte Destruction — fits the Lunati/hemolytic arm. - No existing module covers ESCRT-III recycling failure or cytokinetic abscission failure. A new escrt_membrane_scission_failure or cytokinetic_abscission_failure module is a well-motivated candidate — abscission failure is a conserved mechanism shared with KIF23-CDA III, RACGAP1-CDA, and the centrosomal MCPH microcephaly genes, which is exactly the recurrence profile that justifies a module.

Appendix B — Primary reference list

PMID	Citation	Role
33186545	Rodger C, et al. De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment. Am J Hum Genet. 2020 Dec 3;107(6):1129–1148. DOI:10.1016/j.ajhg.2020.10.012. PMC7820634	Landmark — disease definition, 6 probands, cell biology
33186543	Seu KG, Trump LR, Emberesh S, Lorsbach RB, Johnson C, Meznarich J, Underhill HR, Chou ST, Sakthivel H, Nassar NN, Seu KJ, Blanc L, Zhang W, Lutzko CM, Kalfa TA. VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects. Am J Hum Genet. 2020 Dec 3;107(6):1149–1156. DOI:10.1016/j.ajhg.2020.10.013. PMC7820805	Landmark companion — hematology, 3 probands incl. the homozygous case
33460484	Lunati A, et al. VPS4A mutation in syndromic congenital hemolytic anemia without obvious signs of dyserythropoiesis. Am J Hematol. 2021 Apr 1;96(4):E121–E123. DOI:10.1002/ajh.26099	Phenotype expansion — hemolysis without dyserythropoiesis
42498620	Gupta A, Mathuria YP, Jain BP, Gupta SK, Ghosh DK. A novel VPS4A variant drives lipotoxicity underlying CIMDAG syndrome. J Clin Lipidol. 2026 Jul 9. DOI:10.1016/j.jacl.2026.07.007	Newest — second homozygous case (p.Arg288Gln), lipotoxicity mechanism
38687820	Dvilansky I, et al. The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission. PLoS Biol. 2024 Apr 30;22(4):e3002327. PMC11086821	Paralog non-redundancy — why VPS4B cannot compensate
39455257	Shipman A, et al. Defects in Exosome Biogenesis Are Associated with Sensorimotor Defects in Zebrafish vps4a Mutants. J Neurosci. 2024 Dec 11;44(50):e0680242024. PMC11638813	Best in vivo neurological model
35441598	King R, Gallagher PJ, Khoriaty R. The congenital dyserythropoietic anemias: genetics and pathophysiology. Curr Opin Hematol. 2022 May 1;29(3):126–136	Review placing VPS4A among CDA genes
—	Unique / Rare Chromosome Disorder Support Group. CIMDAG syndrome (also known as VPS4A-related neurodevelopmental disorder). 2024. Authors: Steidle-Kloc E, Winter T, Kalfa TA, Unique (AP)	Only management-guidance document in existence; clinician-authored; source for patient count, natural history, and care recommendations
—	OMIM #619273 / *609982; Orphanet ORPHA:603448; HPO annotation for OMIM:619273; UniProt Q9UN37; MGI:1890520; ClinicalTrials.gov NCT02964494	Reference resources

Appendix C — Explicit gaps and open questions (candidates for `discussions` blocks)

KNOWLEDGE_GAP — static vs progressive. Is CIMDAG a static congenital malformation syndrome or a progressive neurodegeneration? Imaging language in Seu et al. is explicitly neurodegenerative; no longitudinal imaging series exists. Proposed experiment: serial MRI in the ~11 known patients + the diagnosed-but-unpublished cohort known to Unique.
KNOWLEDGE_GAP — micronuclei → cGAS-STING interferonopathy. Patient fibroblasts make micronuclei; VPS4 inhibition activates cGAS-STING in tumor models. No one has measured an interferon signature in patient blood. Proposed experiment: IFN-stimulated gene score on patient PBMCs.
HUMAN_MODEL_MISMATCH — no knock-in mouse. All mouse data are knockout/conditional-knockout; the human mechanism is heterozygous dominant-negative in a paralog-redundant-but-non-equivalent system. A Vps4a^R284W/+^ knock-in is the required model and does not exist.
KNOWLEDGE_GAP — HPOA frequency discrepancy. HPO annotation records cerebellar hypoplasia at 2/6 while Rodger full text states 5/6; anemia is absent from HPOA entirely despite being present in ~7/10 published patients. The HPOA record for OMIM:619273 under-annotates the hematologic domain.
KNOWLEDGE_GAP — no episignature, no QoL instrument, no natural history study, no prevalence estimate.
Therapeutic hypothesis worth recording: allele-selective knockdown of the mutant transcript is the mechanistically correct strategy, uniquely supported by the fact that VPS4A haploinsufficiency is tolerated in the general population. The recurrent c.850A>T hotspot (5/11 patients) is an ideal ASO/siRNA/base-editing target. No program exists.
Unresolved genotype–phenotype: four unrelated p.Arg284Trp probands differ markedly in seizures, hearing, anemia, and hepatic involvement — the source of intra-allelic variable expressivity is unknown.

Sources: Rodger et al. 2020, AJHG (PMC7820634) · Seu et al. 2020, AJHG (PMC7820805) · Lunati et al. 2021, Am J Hematol · Gupta et al. 2026, J Clin Lipidol (PMID:42498620) · Shipman et al. 2024, J Neurosci (PMC11638813) · Dvilansky et al. 2024, PLoS Biol (PMC11086821) · Unique: CIMDAG syndrome guide (2024) · OMIM #619273 · OMIM *609982 · HPO annotations for OMIM:619273 · MONDO:0035819 via OLS4 · UniProt Q9UN37 · HGNC:13488 · MGI:1890520 (Vps4a) · Vps4a cardiomyocyte KO (PMC10341959) · CDAR registry NCT02964494 · Genomics England PanelApp — VPS4A (Rare anaemia) · ClinVar VPS4A

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Inheritance

Discussions and Knowledge Gaps

Pathophysiology

Histopathology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Differential Diagnoses

Clinical Trials

Experimental Models

Source YAML

References & Deep Research

References

Deep Research

1. Disease Information

Overview

Key identifiers

Synonyms and alternative names

Nature of the evidence base

2. Etiology

Primary causal factor

Genetic risk factors

Environmental risk factors

Protective factors

Gene–environment interactions

3. Phenotypes

3.1 HPO annotation set (source: HPO annotation file for OMIM:619273, retrieved via ontology.jax.org API)

Neurodevelopmental / neurological (core)

Brain structural (neuroimaging)

Ophthalmologic

Hematologic

Growth and gastrointestinal

Other systems

3.2 Phenotype characteristics

3.3 Quality-of-life impact (per phenotype)

4. Genetic / Molecular Information

Causal gene

Pathogenic variants (all reported cases)

Functional consequence: dominant negative, explicitly not haploinsufficiency

Modifier genes, epigenetics, chromosomal abnormalities

5. Environmental Information

6. Mechanism / Pathophysiology

6.1 The core causal chain

6.2 Molecular pathways

6.3 Suggested GO biological process terms

6.4 Cellular processes — the experimental evidence

6.5 Metabolic and lipid changes (newest mechanism, 2026)

6.6 Immune involvement

6.7 Tissue damage mechanisms

6.8 Molecular profiling status

7. Anatomical Structures Affected

Organ level

Tissue and cell level

Subcellular level (GO Cellular Component)

Localization and lateralization

8. Temporal Development

Onset

Progression

Patterns

9. Inheritance and Population

Epidemiology

Inheritance

Population demographics

10. Diagnostics

Genetic testing — the definitive route

Clinical tests

Omics-based diagnostics

Clinical criteria and differential diagnosis

Screening

11. Outcome / Prognosis

Survival and mortality

Morbidity and function

Complications

Recovery potential

Prognostic factors

12. Treatment

Pharmacotherapy

3.1 HPO annotation set (source: HPO annotation file for OMIM:619273, retrieved via `ontology.jax.org` API)

Appendix C — Explicit gaps and open questions (candidates for `discussions` blocks)