Congenital Zika Syndrome

Infectious Disease MONDO:0000890 Pathograph 13 Show in embeddings browser Microcephaly

Congenital Zika syndrome (CZS) is a non-genetic malformation of cortical development caused by intrauterine infection with Zika virus (ZIKV), a mosquito-borne flavivirus. After maternal infection — most consequential for fetal neurodevelopment during the first and second trimesters — ZIKV crosses the placenta and reaches the developing fetal central nervous system, where it is neurotropic for apical and outer radial glia and other neural progenitor cells of the cortical ventricular and subventricular zones. Productive infection of these founder progenitors dysregulates the cell cycle, triggers caspase-mediated apoptosis, and activates innate antiviral signalling (including the TLR3 pathway and type I interferon responses), collectively depleting the progenitor pool and abrogating neurogenesis during the peak neurogenic window. The resulting deficit of cortical neurons produces the recognizable CZS phenotype: severe (often congenital) microcephaly with a markedly disproportionate skull, agyria/lissencephaly-like smooth cortex, intracranial (cortical and subcortical) calcifications, ventriculomegaly/hydrocephalus, and cortical thinning, frequently accompanied by ocular abnormalities, arthrogryposis, sensorineural hearing loss, seizures, and global developmental delay. CZS is the exemplar infectious (non-Mendelian) cortical malformation mechanism: its proximal cause is a defined viral exposure rather than a germline variant, but it converges on the same progenitor-depletion endpoint as genetic primary microcephaly, distinguished pathologically by a more destructive process with prominent cell death, necrosis, and calcification.

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Discussions and Knowledge Gaps

Which parts of the congenital Zika syndrome mechanism are directly supported in human fetal disease, and which remain model-dependent findings from human iPSC-derived neural progenitors, cerebral organoids, mouse embryos, non-human-primate organoids, or organotypic fetal systems?

HUMAN MODEL MISMATCH OPEN gap_czs_human_model_translatability

Attached to

pathophysiology#Transplacental Viral Transfer to the Fetal Compartment pathophysiology#Neurotropic Entry into Fetal Neural Progenitors pathophysiology#Antiviral Innate Immune Activation pathophysiology#Viral Mitotic and Centrosome Cytopathy pathophysiology#Neural Progenitor Apoptosis and Pool Depletion pathophysiology#Impaired Neurogenesis and Congenital Cortical Malformation

The disease pathograph now conforms to the viral neural progenitor cytopathy module, but much of the causal resolution comes from experimental systems rather than longitudinal human fetal material. Human autopsy anchors viral brain invasion and destructive malformation, while iPSC-derived hNPCs, cerebral organoids, mouse embryos, and non-human-primate organoids resolve entry, TLR3/TBK1 signaling, centrosome perturbation, apoptosis, and strain adaptation. This gap prevents a single model system from being treated as complete proof of the human prenatal disease sequence.

Proposed experiments

CZS cross-model fetal-brain alignment experiment

cross-model viral cortical malformation alignment experiment

exp_czs_cross_model_fetal_alignment

Compare matched ZIKV strains across human iPSC-derived cortical organoids, hNPC/radial-glial cultures, ethically available fetal cortical tissue or organotypic slices, and susceptible in vivo models, then map viral tropism, TLR3/TBK1 signaling, centrosome perturbation, apoptosis, progenitor loss, neurogenesis, and cortical thinning against human fetal autopsy endpoints.

Model systems

Human iPSC-derived cortical organoid ZIKV model

Three-dimensional human cortical organoid system containing radial glia, neural progenitors, and early cortical neurons exposed to clinically relevant ZIKV strains.

ORGANOID namo:Organoid link

human NCBITaxon:9606

cerebral cortex UBERON:0000956

radial glial cell CL:0000681 neural progenitor cell CL:0011020

Human fetal cortical tissue benchmark

Postmortem or organotypic fetal cortical material, where ethically and legally available, used as a benchmark for viral localization, radial glial vulnerability, apoptosis, calcification, and cortical tissue architecture.

PRIMARY CELL CULTURE

human NCBITaxon:9606

cerebral cortex UBERON:0000956

radial glial cell CL:0000681 neural progenitor cell CL:0011020

Perturbations

Matched congenital ZIKV strain exposure

pathophysiology#Neurotropic Entry into Fetal Neural Progenitors

Expose model systems to matched congenital outbreak isolates and laboratory-passaged controls under controlled inoculum and developmental timing.

Readouts

Viral tropism and replication in radial glia and neural progenitors

pathophysiology#Neurotropic Entry into Fetal Neural Progenitors

viral genome replication GO:0019079 ↑ INCREASED

viral RNA quantification immunostaining single-cell RNA sequencing

Direction: POSITIVE

Innate immune and centrosome cytopathy

pathophysiology#Viral Mitotic and Centrosome Cytopathy

toll-like receptor signaling pathway GO:0002224 ↑ INCREASED centrosome cycle GO:0007098 ⚠ ABNORMAL

phospho-TBK1 localization assay centrosome immunostaining single-cell RNA sequencing

Direction: POSITIVE

Progenitor survival and cortical growth

pathophysiology#Neural Progenitor Apoptosis and Pool Depletion

apoptotic process GO:0006915 ↑ INCREASED neurogenesis GO:0022008 ↓ DECREASED

cleaved caspase-3 immunostaining progenitor and neuron marker quantification cortical thickness measurement

Direction: NEGATIVE

Controls

Mock-infected controls

Matched model systems exposed to vehicle without infectious virus.

Strain-matched heat-inactivated viral controls

Controls for innate immune stimulation not requiring productive infection.

Decision criterion

The CZS mechanism is strengthened if human organoids, fetal tissue benchmarks, and susceptible in vivo models show concordant radial-glial or progenitor tropism, TLR3/TBK1 and centrosome perturbation, apoptosis, progenitor depletion, reduced neurogenesis, and cortical thinning under matched strain and developmental timing. Major divergence would localize model-specific branches that should not be generalized to human CZS.

Would support

pathophysiology#Neurotropic Entry into Fetal Neural Progenitors pathophysiology#Antiviral Innate Immune Activation pathophysiology#Viral Mitotic and Centrosome Cytopathy pathophysiology#Neural Progenitor Apoptosis and Pool Depletion pathophysiology#Impaired Neurogenesis and Congenital Cortical Malformation

Would refute

pathophysiology#Viral Mitotic and Centrosome Cytopathy pathophysiology#Neural Progenitor Apoptosis and Pool Depletion

Show evidence (2 references)

PMID:27279226 SUPPORT Other

"Mouse models often fail to reproduce the severely reduced brain size and pathological alterations found in human patients21,22, likely due to significant differences in gestation time and brain development between the two species."

The paper explicitly identifies species and developmental-context differences that limit translation from mouse CZS models.

PMID:27279226 SUPPORT In Vitro

"Finally, our data using a non-human primate organoids suggested that the ZIKVBR might have experienced adaptive changes in human cells."

Supports a strain- and host-cell-context mismatch gap for translating organoid and animal findings to human congenital infection.

No approved antiviral or disease-modifying therapy exists for congenital Zika syndrome; candidate small molecules (e.g., nucleoside analogues) and TLR3-pathway modulation have shown effects only in experimental models. Which interventions, if any, can interrupt the progenitor-cytopathy cascade within the narrow prenatal therapeutic window?

KNOWLEDGE GAP OPEN gap_czs_specific_therapy

Attached to

pathophysiology#Antiviral Innate Immune Activation pathophysiology#Neural Progenitor Apoptosis and Pool Depletion

Experimental evidence (e.g., TLR3 inhibition reducing ZIKV phenotypes in organoids) suggests mechanistically rational intervention points, but no therapy has translated to human prenatal use, and the destructive, early-onset nature of the progenitor cytopathy makes the therapeutic window extremely narrow. This gap motivates prevention (vector control, avoidance of exposure in pregnancy) as the current mainstay.

Does tunneling-nanotube-mediated viral spread operate in the human placenta, and how much of the mouse placental-injury phenotype transfers to human congenital Zika disease?

HUMAN MODEL MISMATCH OPEN mismatch_czs_tnt_placental_transmission

Attached to

pathophysiology#Tunneling Nanotube-Mediated Intercellular Viral Spread pathophysiology#Placental Infection pathophysiology#Placental Architectural and Functional Disruption pathophysiology#Fetal Growth Restriction pathophysiology#Transplacental Viral Transfer to the Fetal Compartment

The TNT arm of transplacental dissemination is established entirely in mouse pregnancy models, by comparing a TNT-competent virus with an NS1 residue-40-52 TNT-deficient mutant. Two distinct translational questions follow. First, TNTs have not been demonstrated to carry ZIKV between cells in human placental tissue in vivo, so the mechanism is a strong candidate rather than an established human route. Second, and more concretely, the architectural readout does not transfer at all: the junctional zone and labyrinth are compartments of the rodent placenta with no direct human homolog, so "altered junctional-to-labyrinth architecture" cannot be restated as a human placental finding. The nearest human comparison points the other way: in full-term placentas from three ZIKV-infected women, viral NS3 antigen localized to Hofbauer cells while the placentas showed no anatomic defects (PMID:31709049, the publication behind the GSE139181 dataset already curated in this entry) — a small series, and not a test of the TNT mechanism, but not obviously the same picture either. Fetal growth restriction is therefore curated as an ORGANISM-scale pathophysiology node carrying model-organism evidence, and is deliberately absent from `phenotypes:`, which would require human evidence.

Proposed experiments

Detection of ZIKV-laden tunneling nanotubes in human placental explants

exp_czs_tnt_human_placenta

Live imaging and correlative electron microscopy of ZIKV-infected primary human trophoblast and placental explant cultures, scoring actin-rich intercellular conduits carrying viral components, with the NS1 residue-40-52 TNT-deficient mutant as the negative control.

Show evidence (3 references)

PMID:42627154 SUPPORT Model Organism

"Here, we investigated the in vivo role of TNTs in ZIKV maternal-fetal transmission using complementary pregnancy models."

Establishes that the in vivo evidence for the TNT arm comes from animal pregnancy models rather than human tissue.

PMID:42627154 SUPPORT Model Organism

"ZIKVΔTNT infection was associated with reduced placental pathology, altered junctional-to-labyrinth architecture, improved placental efficiency, and protection from fetal growth restriction."

Names the junctional-to-labyrinth readout, which is a rodent placental compartment measure with no human equivalent.

PMID:31709049 SUPPORT Human Clinical

"Although ZIKV NS3 antigens co-localised to placental Hofbauer cells, the placentas showed no anatomic defects."

The human placental comparison invoked in this mismatch. Infected human placentas carried viral antigen without the structural defects the mouse models show.

Is the NS1 determinant of tunneling-nanotube formation (residues 40-52) a tractable antiviral target for preventing transplacental ZIKV transmission, and does the same TNT route operate in other vertically transmitted viruses?

KNOWLEDGE GAP OPEN gap_czs_ns1_tnt_therapeutic_target

Attached to

pathophysiology#Tunneling Nanotube-Mediated Intercellular Viral Spread

A discrete viral protein determinant whose loss reduces dissemination, placental injury, and fetal growth restriction without abolishing viral viability is an unusually clean target hypothesis, and it addresses the transmission step rather than the downstream progenitor cytopathy — a much wider therapeutic window than the one the existing therapy gap describes. Nothing here has been tested as an intervention: the evidence is a genetically engineered mutant virus, not a drug or an antibody, and no NS1-directed agent has been shown to block TNT formation. The authors also raise, without testing, whether TNTs matter for other vertically transmitted or emerging viruses; that generalization has no evidence in this entry and should not be curated onto other disease entries on the strength of this paper alone.

Show evidence (2 references)

PMID:42627154 SUPPORT Model Organism

"These findings identify TNTs as a previously underappreciated pathway of viral transmission during pregnancy and suggest new therapeutic targets."

The therapeutic-target claim is the authors' proposal, not a tested intervention, which is what makes this a gap rather than a treatment entry.

PMID:42627154 SUPPORT Model Organism

"More broadly, TNTs may contribute to the pathogenesis of other vertically transmitted or emerging viral infections."

Records the cross-pathogen generalization as an explicitly speculative statement.

Does pre-existing maternal dengue immunity worsen fetal outcome in human congenital Zika syndrome, as it does in macaques?

HUMAN MODEL MISMATCH OPEN gap_czs_dengue_immunity_enhancement

Attached to

pathophysiology#Transplacental Viral Transfer to the Fetal Compartment pathophysiology#Impaired Neurogenesis and Congenital Cortical Malformation animal_models#Dengue-immune cynomolgus macaque ZIKV pregnancy model

Why some ZIKV-exposed fetuses are severely affected and others are not is the largest unexplained variance in this disease, and the entry's timing account does not fully cover it. A nonhuman primate experiment supplies a candidate: fetuses of dengue-immune macaques infected in early pregnancy developed significantly worse CZS than naive controls, with no difference in maternal infection or antibody response — locating the effect in the fetus rather than in maternal viral control. The translational question is unusually consequential because ZIKV and DENV co-circulate across most of the affected geography, so a large share of women entering a Zika outbreak are dengue-immune. If the enhancement operates in humans, prior dengue serostatus would be a risk stratifier available before conception and would also bear on flavivirus vaccination strategy in women of childbearing age. If it does not, the macaque result localises a species-specific branch that should not inform human counselling. This is recorded as a mismatch rather than a knowledge gap because the evidence exists and is strong in the model; what is unknown is whether it transfers.

Proposed experiments

DENV-serostatus-stratified prospective cohort of ZIKV-infected pregnancies

exp_czs_denv_serostatus_stratified_cohort

In a prospective cohort of pregnancies with confirmed ZIKV infection, determine pre-pregnancy or first-trimester DENV serostatus and compare the incidence and severity of CZS between DENV-immune and DENV-naive mothers, stratifying by gestational age at infection so the two risk factors are not confounded.

Would support

pathophysiology#Impaired Neurogenesis and Congenital Cortical Malformation

Supporting outcome

CZS is more frequent or more severe in the offspring of DENV-immune mothers after adjustment for timing, supporting transfer of the macaque enhancement to human pregnancy.

Refuting outcome

CZS incidence and severity are independent of maternal DENV serostatus, indicating the enhancement is model-specific and should not be used for human risk stratification.

⚙

Pathophysiology

Tunneling Nanotube-Mediated Intercellular Viral Spread

ZIKV induces tunneling nanotubes (TNTs) — actin-rich, membrane-bounded intercellular conduits that carry viral components directly from cell to cell, bypassing the extracellular space. TNT-forming capacity maps to residues 40-52 of the viral nonstructural protein NS1: an engineered TNT-deficient mutant (ZIKVΔTNT) disseminates markedly less to maternal and fetal tissues than TNT-competent virus across multiple pregnancy models. Because transfer through a TNT is shielded from the extracellular compartment, this route also appears to let the virus persist in the face of a maternal type III interferon (IFN-lambda) response, implicating TNTs in immune evasion as well as in spread.

tunneling nanotube formation GO:0120031 ↑ INCREASED TNT-shielded escape from maternal type III interferon control GO:0042783 ↑ INCREASED maternal type III interferon (IFN-lambda) signaling at the maternal-fetal interface GO:0038196

Downstream

Placental Infection TNT-mediated spread within the placenta drives productive placental infection.

Transplacental Viral Transfer to the Fetal Compartment TNT-competent virus reaches maternal and fetal tissues far more efficiently than TNT-deficient virus. The edge is retained because that dissemination difference is directly measured, but marked indirect: the route to the fetal compartment runs through placental infection, which is curated as its own node between the two.

Show evidence (4 references)

PMID:42627154 SUPPORT Model Organism

"We previously showed that ZIKV induces tunneling nanotubes (TNTs), actin-rich intercellular conduits that enable direct cell-to-cell transfer of viral components."

Defines TNTs as actin-rich conduits mediating direct cell-to-cell transfer of ZIKV components.

PMID:42627154 SUPPORT Model Organism

"A TNT-deficient ZIKV mutant (ZIKVΔTNT), harboring a change between residues 40 and 52 of the nonstructural protein 1 (NS1), showed markedly reduced viral dissemination to maternal and fetal tissues across all models tested, whereas the TNT-competent ZIKV established a robust infection."

Loss-of-function genetic evidence that NS1-dependent TNT formation is required for maternal and fetal dissemination.

PMID:42627154 SUPPORT Model Organism

"Loss of TNT-forming capacity also limited viral persistence despite maternal type III interferon (IFN-λ) responses, suggesting a role for TNTs in immune evasion."

Links TNT-mediated spread to viral persistence under an active maternal IFN-lambda response.

+ 1 more reference

Placental Infection

ZIKV productively infects the placenta, producing histological placental pathology. The causal role of viral spread is established by the contrast with the TNT-deficient mutant, which produces less placental pathology. The placenta is therefore not merely a barrier ZIKV crosses but a target organ in its own right.

trophoblast cell CL:0000351

placenta UBERON:0001987

Downstream

Placental Architectural and Functional Disruption Placental infection is followed by change in the relative architecture of the placental compartments and a fall in placental efficiency.

Transplacental Viral Transfer to the Fetal Compartment Placental infection and barrier injury permit virus to reach the fetal compartment and the developing central nervous system.

Show evidence (2 references)

PMID:42627154 SUPPORT Model Organism

"Using multiple pregnancy models, we demonstrate that viruses capable of forming these structures disseminate more efficiently, damage the placenta, and lead to fetal growth restriction, whereas TNT-deficient viruses show reduced infection and milder disease."

States directly that TNT-competent virus damages the placenta, across the pregnancy models tested.

PMID:42627154 SUPPORT Model Organism

"ZIKVΔTNT infection was associated with reduced placental pathology, altered junctional-to-labyrinth architecture, improved placental efficiency, and protection from fetal growth restriction."

The reduced placental pathology in the TNT-deficient mutant is the loss-of-function counterpart of the damage claim.

Placental Architectural and Functional Disruption

Infected placentas differ from TNT-deficient-infected controls in the relative architecture of the placental compartments, and in placental efficiency (fetal mass supported per unit placental mass), which improves when viral spread is crippled.

placental architecture and efficiency GO:0001890 ⚠ ABNORMAL

placenta UBERON:0001987

Downstream

Fetal Growth Restriction Reduced placental efficiency limits fetal growth; crippling viral spread protects against the growth deficit.

Show evidence (1 reference)

PMID:42627154 SUPPORT Model Organism

"ZIKVΔTNT infection was associated with reduced placental pathology, altered junctional-to-labyrinth architecture, improved placental efficiency, and protection from fetal growth restriction."

Reports the altered compartment architecture and the improved placental efficiency of the TNT-deficient condition.

Fetal Growth Restriction

The most distal outcome of the placental arm in the pregnancy models tested: TNT-competent ZIKV infection leads to fetal growth restriction, while TNT-deficient infection protects against it.

Show evidence (2 references)

PMID:42627154 SUPPORT Model Organism

"ZIKVΔTNT infection was associated with reduced placental pathology, altered junctional-to-labyrinth architecture, improved placental efficiency, and protection from fetal growth restriction."

Protection from fetal growth restriction in the TNT-deficient condition is the loss-of-function evidence for this outcome.

PMID:42627154 SUPPORT Model Organism

States that TNT-competent virus leads to fetal growth restriction across the models tested.

Transplacental Viral Transfer to the Fetal Compartment

Crossing the maternal-fetal interface is a transport step, distinct from what the virus does once it arrives. Human placental work identifies more than one route rather than a single breach: ZIKV productively infects placental macrophages (Hofbauer cells) and, less efficiently, cytotrophoblasts in term villous tissue, and separately infects cytotrophoblasts, endothelial cells, fibroblasts and Hofbauer cells in chorionic villi together with amniotic epithelial cells and trophoblast progenitors in amniochorionic membranes. Those cells express the Axl, Tyro3 and TIM1 entry cofactors, so the same TAM-family biology operates here as in the fetal brain — but on different cells, in a different organ, supporting a different claim. Curating them as one node conflated the two. Transfer is not uniformly permissive, and the restriction side explains the timing dependence the rest of this entry rests on. Primary human trophoblasts from full-term placentas are refractory to ZIKV and constitutively release type III interferon (IFN-lambda1) that protects both trophoblast and non-trophoblast cells, so virus reaching the fetal compartment must evade or bypass that barrier. Consistent with a barrier that strengthens as gestation proceeds, mid-gestation amniotic epithelial cells support higher viral titres than late-gestation cells.

Hofbauer cell (placental macrophage) CL:3000001 Cytotrophoblast CL:0000523

type III interferon production by trophoblast GO:0034343

placenta UBERON:0001987

Downstream

Neurotropic Entry into Fetal Neural Progenitors Virus that has reached the fetal compartment encounters the developing cortex, where a separate set of receptors and cell types governs entry.

Show evidence (7 references)

PMID:27247001 SUPPORT In Vitro

"Our results suggest a mechanism for intrauterine transmission in which ZIKV gains access to the fetal compartment by directly infecting placental cells and disrupting the placental barrier."

States the transfer mechanism this node curates, in primary human placental cells rather than in a model organism.

PMID:27247001 SUPPORT In Vitro

"infects and replicates in primary human placental macrophages, called Hofbauer cells, and to a lesser extent in cytotrophoblasts, isolated from villous tissue of full-term placentae"

Identifies the two placental cell types curated on this node, with their relative permissiveness.

PMID:27443522 SUPPORT In Vitro

"Our results suggest that ZIKV spreads from basal and parietal decidua to chorionic villi and amniochorionic membranes and that targeting TIM1 could suppress infection at the uterine-placental interface."

The two-route structure of transfer, and the cofactor that is druggable at the uterine-placental interface specifically.

+ 4 more references

Neurotropic Entry into Fetal Neural Progenitors

Once in the fetal brain, ZIKV is neurotropic for radial glia and neural progenitor cells. Candidate entry receptors enriched on these cells — notably the TAM-family receptor tyrosine kinase AXL, which is highly expressed by human radial glia in the developing cortex — are thought to mediate or facilitate viral attachment and entry, establishing infection of the founder progenitor population during corticogenesis. Neuropathology confirms the target: infection of progenitor cells at the germinal matrix has been demonstrated in human material. AXL appears on both sides of this entry's transfer/entry split, and the duplication is real biology rather than a curation artefact: the same TAM-family cofactors are used at the placenta and on radial glia. They are nonetheless different claims about different cells in different organs, and are curated on the node each belongs to.

Radial glial cell CL:0000681 Neural progenitor cell CL:0011020

Viral entry into host cell GO:0046718 ↑ INCREASED Viral genome replication GO:0019079 ↑ INCREASED

Downstream

Antiviral Innate Immune Activation

Viral Mitotic and Centrosome Cytopathy

Spinal Anterior Horn Motor Neuron Loss Virus in the developing fetal CNS also reaches the spinal cord, where anterior horn motor neurons are lost. Whether this reflects the same progenitor-directed cytopathy operating at a second site, or direct infection of postmitotic motor neurons, is not established by the neuropathological material.

Show evidence (2 references)

PMID:27038591 SUPPORT In Vitro

"we found that the candidate viral entry receptor AXL is highly expressed by human radial glial cells, astrocytes, endothelial cells, and microglia in developing human cortex and by progenitor cells in developing retina."

Identifies AXL on human radial glia as a candidate entry receptor enriched on the progenitor population ZIKV targets.

PMID:29167994 SUPPORT Human Clinical

"Infection of progenitor cells at the germinal matrix was demonstrated."

Human neuropathological confirmation that the progenitor population is the infected compartment, rather than this resting on culture systems alone.

Spinal Anterior Horn Motor Neuron Loss

Severe motor nerve cell loss in the anterior horn of the spinal cord is a consistent postmortem finding in congenital ZIKV infection, alongside hypoplasia of the descending tracts (small basis pontis, pyramids and spinal corticospinal tracts) that follows the loss of cortical output. The anterior horn lesion is the one that matters here, because it is what connects this entry's cortical mechanism to a phenotype the cortex cannot explain.

Anterior horn motor neuron CL:2000048

ventral horn of spinal cord UBERON:0002257

Downstream

Fetal Akinesia Loss of the final common motor pathway removes the fetal movement that normal joint development depends on.

Show evidence (2 references)

PMID:29167994 SUPPORT Human Clinical

"Severe nerve motor nerve cell loss is observed in the anterior horn of the spinal cord."

The anterior horn lesion, in human postmortem material. Quoted as written, including the source's duplicated word.

PMID:29167994 SUPPORT Human Clinical

"Hypoplastic lesions secondary to the lack of descending nerve fibers include small basis pontis, pyramids and spinal corticospinal tracts."

The separate, secondary tract hypoplasia that follows cortical loss, kept distinct from the primary anterior horn lesion above.

Fetal Akinesia

Absent or greatly reduced fetal movement, the consequence of losing spinal motor neurons. This node exists because the resulting arthrogryposis is neurogenic rather than articular, and the distinction is testable: in the reported series, high-definition ultrasonography of the joints showed no abnormality, while needle electromyography showed motor unit remodeling and reduced recruitment, and spinal MRI showed apparent cord thinning with reduced ventral roots. The joints are normal; the nerves supplying them are not.

Show evidence (3 references)

PMID:29167994 SUPPORT Human Clinical

"The lack of spinal motor neurons is responsible for fetal acynesia and consequent arthrogryposis."

The causal claim this node and its downstream edge encode, stated by the source. The source's spelling of akinesia is preserved in the quote.

PMID:27509902 SUPPORT Human Clinical

"All the children underwent high definition ultrasonography of the joints, and there was no evidence of abnormalities."

The negative joint imaging that excludes a primary articular cause and so makes the neurogenic account load-bearing rather than assumed.

PMID:27509902 SUPPORT Human Clinical

"MRI of the spine in four children showed apparent thinning of the cord and reduced ventral roots."

Imaging correlate of the anterior horn lesion in living patients, matching the postmortem finding.

Antiviral Innate Immune Activation

ZIKV infection activates innate antiviral signalling within developing neural progenitor systems. Human cerebral organoid and neurosphere data implicate Toll-like receptor 3 (TLR3) activation and type I interferon-linked responses in perturbed neurogenesis, altered cell fate, and downstream progenitor loss; TLR3 inhibition mitigates the phenotype in experimental models.

Neural progenitor cell CL:0011020 Radial glial cell CL:0000681

Innate immune response GO:0045087 ↑ INCREASED Toll-like receptor signaling pathway GO:0002224 ↑ INCREASED Type I interferon-mediated signaling pathway GO:0060337 ↕ DYSREGULATED Defense response to virus GO:0051607 ↕ DYSREGULATED

Downstream

Neural Progenitor Apoptosis and Pool Depletion

Show evidence (2 references)

PMID:27162029 SUPPORT In Vitro

"The innate immune receptor Toll-like-Receptor 3 (TLR3) was upregulated after ZIKV infection of human organoids and mouse neurospheres and TLR3 inhibition reduced the phenotypic effects of ZIKV infection."

Implicates TLR3 innate immune activation in ZIKV-driven progenitor cytopathy, with inhibition reducing the experimental phenotype.

PMID:27162029 SUPPORT In Vitro

"Together, therefore, our findings identify a link between ZIKV-mediated TLR3 activation, perturbed cell fate, and a reduction in organoid volume reminiscent of microcephaly."

Connects ZIKV-triggered TLR3 activation to perturbed cell fate and reduced organoid volume in a human cerebral organoid model.

Viral Mitotic and Centrosome Cytopathy

ZIKV productively infects human neural progenitor cells and radial glia, releasing infectious virus and perturbing cell-cycle progression, mitotic machinery, centrosome integrity, and phospho-TBK1 localization. These mitotic and centrosome defects impair proliferative progenitor divisions and converge on the same neural progenitor centrosome/spindle dysfunction module used by genetic cortical malformation entries.

Neural progenitor cell CL:0011020 Radial glial cell CL:0000681

Mitotic cell cycle GO:0000278 ↕ DYSREGULATED Cell cycle GO:0007049 ↕ DYSREGULATED Mitotic spindle organization GO:0007052 ↕ DYSREGULATED Centrosome cycle GO:0007098 ⚠ ABNORMAL

Downstream

Neural Progenitor Apoptosis and Pool Depletion

Show evidence (3 references)

PMID:26952870 SUPPORT In Vitro

"ZIKV infection increases cell death and dysregulates cell-cycle progression, resulting in attenuated hNPC growth."

Links infection to cell-cycle dysregulation and attenuated progenitor growth.

PMID:27568284 SUPPORT In Vitro

"ZIKV infection of NES cells and RGCs causes centrosomal depletion and mitochondrial sequestration of phospho-TBK1 during mitosis."

Supports mitotic centrosome/TBK1 cytopathy in infected human neuroepithelial stem cells and radial glia.

PMID:28132835 SUPPORT In Vitro

"The main phenotypic effect was premature differentiation of neural progenitors associated with centrosome perturbation, even during early stages of infection, leading to progenitor depletion, disruption of the VZ, impaired neurogenesis, and cortical thinning."

Human brain organoids show ZIKV-associated centrosome perturbation leading to progenitor depletion and cortical thinning.

Neural Progenitor Apoptosis and Pool Depletion

Innate antiviral activation, viral replication, cell-cycle disruption, and mitotic/centrosome stress converge on caspase-mediated apoptosis, autophagy, premature differentiation, and reduced viability of neural progenitors and radial glia. The founder progenitor pool is depleted, leaving too few neuron-generating cells for normal cortical expansion.

Neural progenitor cell CL:0011020 Radial glial cell CL:0000681

Apoptotic process GO:0006915 ↑ INCREASED Neurogenesis GO:0022008 ↓ DECREASED Cell population proliferation GO:0008283 ↓ DECREASED

Downstream

Impaired Neurogenesis and Congenital Cortical Malformation

Show evidence (3 references)

PMID:27064148 SUPPORT In Vitro

"we showed that ZIKV targets human brain cells, reducing their viability and growth as neurospheres and brain organoids. These results suggest that ZIKV abrogates neurogenesis during human brain development."

Demonstrates that ZIKV reduces human neural progenitor viability/growth and abrogates neurogenesis.

PMID:26952870 SUPPORT In Vitro

"ZIKV infection increases cell death and dysregulates cell-cycle progression, resulting in attenuated hNPC growth."

Connects infection-driven cell death and cell-cycle dysregulation to reduced progenitor growth.

PMID:27279226 SUPPORT Model Organism

"ZIKV(BR) crosses the placenta and causes microcephaly by targeting cortical progenitor cells, inducing cell death by apoptosis and autophagy, and impairing neurodevelopment."

Establishes apoptosis and autophagy of cortical progenitors as in vivo mechanisms of ZIKV-induced microcephaly.

Impaired Neurogenesis and Congenital Cortical Malformation

Depletion of the cortical progenitor pool and impaired neurogenesis reduce the complement of cortical neurons, producing severe microcephaly with a disproportionately small brain. Unlike many genetic microcephalies, the CZS cortex shows a more destructive pathology, with near-complete agyria (lissencephaly-like smoothing), multifocal cortical and subcortical calcifications, hydrocephalus/ventriculomegaly, and cortical displacement, reflecting prominent cell death during development.

Neural progenitor cell CL:0011020

Neurogenesis GO:0022008 ↓ DECREASED Cerebral cortex development GO:0021987 ⚠ ABNORMAL

Animal models

Dengue-immune cynomolgus macaque ZIKV pregnancy model Cynomolgus macaque recapitulates Fetuses of DENV-immune macaques infected with ZIKV in early pregnancy developed significantly more severe CZS than naive controls, with reduced cortical thickness and increased neuronal death, haemorrhage, cellular infiltration, calcification and lissencephaly — the same lesion set reported in human postmortem material.

Show evidence (2 references)

PMID:26862926 SUPPORT Human Clinical

"Micrencephaly (an abnormally small brain) was observed, with almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter, with associated cortical displacement and mild focal inflammation."

Human fetal autopsy documenting the destructive cortical malformation phenotype of CZS.

PMID:27179424 SUPPORT Model Organism

"ZIKV infection leads to cell-cycle arrest, apoptosis, and inhibition of NPC differentiation, resulting in cortical thinning and microcephaly."

In vivo recapitulation of cortical thinning and microcephaly as the developmental endpoint.

✶

Histopathology

Destructive cortical injury with calcification and migration disturbance

The postmortem picture is destructive rather than purely hypoplastic, which is what distinguishes CZS from genetic primary microcephaly on tissue. It combines extensive parenchymal destruction, calcification, disturbed neuronal migration, and a reactive glial and microglial response, with occasional perivascular lymphocytic cuffing extending to the meninges.

Show evidence (1 reference)

PMID:29167994 SUPPORT Human Clinical

"there is extensive destruction of the hemispheric parenchyma, calcifications, various disturbances of neuronal migration, reactive gliosis, microglial hyperplasia and occasional perivascular cuffs of lymphocytes, also in the meninges"

The full histological description, including the inflammatory component that a purely developmental account would not predict.

⬡

Pathograph

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

●

Phenotypes

Digestive 1

Dysphagia FREQUENT HP:0002015

Show evidence (3 references)

PMID:41460891 SUPPORT Human Clinical

"In the pooled analyses, dysphagia was common and observed in 46.9% of children."

Pooled frequency across 12 cohorts, the basis for the FREQUENT band.

PMID:27509902 SUPPORT Human Clinical

"Dysphagia was present in six children (86%); two underwent gastrostomy and tracheostomy."

Much higher frequency in the arthrogryposis series, consistent with dysphagia tracking overall neurological severity rather than being an independent feature.

PMID:33320867 SUPPORT Human Clinical

"Dysphagia can increase the risk of bronchoaspiration, resulting in aspiration pneumonia or death from asphyxiation, requiring gastrostomy in the affected infants"

States the mechanism by which dysphagia becomes fatal, which is why it is curated as a phenotype in its own right rather than folded into feeding difficulty.

Ear 1

Sensorineural Hearing Loss OCCASIONAL Sensorineural hearing impairment HP:0000407

Show evidence (2 references)

PMID:27585248 SUPPORT Human Clinical

"Five (7%) infants had sensorineural hearing loss, all of whom had severe microcephaly"

The frequency in an infant series ascertained on microcephaly, and the observation that every affected infant was severely microcephalic.

PMID:30252119 NO_EVIDENCE Human Clinical

"None of the patients evaluated in this study were found to have sensorineural hearing loss."

Cited to record a negative cohort result, graded NO_EVIDENCE rather than REFUTE because this cohort was ZIKV-exposed rather than CZS-affected: it does not bear on whether hearing loss occurs in congenital Zika syndrome, only on how often it is found when microcephaly is not the entry criterion.

Head and Neck 1

Microcephaly HP:0000252

Show evidence (1 reference)

PMID:26862926 SUPPORT Human Clinical

Documents micrencephaly (abnormally small brain) on human fetal autopsy.

Musculoskeletal 1

Spastic Hypertonia VERY_FREQUENT HP:0001276

Course: PROGRESSIVE

Show evidence (3 references)

PMID:41460891 SUPPORT Human Clinical

"Spastic hypertonia was found in seven sites in which they were investigated, with a frequency of 100% in four sites"

Frequency across the cohorts that assessed it; near-universal where ascertained, which is the basis for the VERY_FREQUENT band.

PMID:41460891 SUPPORT Human Clinical

"spastic hypertonia (at >3 months of age), osteotendinous hyperreflexia"

Records the case definition used, including the age threshold, which is why this is not curated as a congenital finding.

PMID:33320867 SUPPORT Human Clinical

"hydrocephalus, hypertonicity, and seizures; (b) in the osteoskeletal system: arthrogryposis and clubfoot"

Independent corroboration from a systematic review of 46 studies, listing hypertonicity among the defining central nervous system signs.

Nervous System 5

Hydrocephalus HP:0000238

Show evidence (1 reference)

PMID:26862926 SUPPORT Human Clinical

"almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications"

Records hydrocephalus in the affected fetal brain.

Cerebellar Hypoplasia HP:0001321

Show evidence (1 reference)

PMID:29167994 SUPPORT Human Clinical

"Cerebellar hypoplasia is also common."

Records cerebellar involvement as a common postmortem finding.

Ventriculomegaly VERY_FREQUENT HP:0002119

Show evidence (2 references)

PMID:29167994 SUPPORT Human Clinical

"microcephaly with ex-vacuo ventriculomegaly and large head circumference associated with obstructive hydrocephalus due to severe midbrain and aqueduct distortion"

Distinguishes the two mechanisms of ventricular enlargement and records that one of them presents with a large head.

PMID:41460891 SUPPORT Human Clinical

"Calcifications and ventriculomegaly were the most consistent and frequent abnormality (around 80%)."

Pooled frequency across 12 Brazilian cohorts, which is the basis for the VERY_FREQUENT band on this phenotype.

Seizures FREQUENT HP:0001250

Onset: INFANTILE

Show evidence (5 references)

PMID:41460891 SUPPORT Human Clinical

"Epilepsy ranged from 30-80% of the children and dysphagia, from 22.2-67.7%."

Pooled range across 12 Brazilian cohorts of children with Zika-related microcephaly; the spread is the basis for the FREQUENT rather than VERY_FREQUENT band.

PMID:32065676 SUPPORT Human Clinical

"Seizures typically began after the third month of life, usually as infantile spasms, with atypical electroencephalographic abnormalities."

Establishes the timing and semiology, which is why onset is curated as infantile rather than neonatal.

PMID:32065676 SUPPORT Human Clinical

"the main type of seizure was infantile spasms (83.1%)"

Infantile spasms as the predominant seizure type in a 91-child cohort followed for 24 months.

+ 2 more references

Global Developmental Delay HP:0001263

Show evidence (1 reference)

PMID:39082517 SUPPORT Human Clinical

"Eighty-nine children with CZS and cerebral palsy undergoing rehabilitation showed evidence of severe developmental delays at the age of 1 year, according to the Bayley Scale of Infant and Toddler Development III (BSID-III)"

Formal developmental assessment in a CZS cohort, establishing severity. The cohort is selected (children already in rehabilitation for cerebral palsy), which is why it supports the phenotype but not a frequency band.

Growth 1

Small for Gestational Age HP:0001518

Show evidence (1 reference)

PMID:33320867 SUPPORT Human Clinical

"abnormal visual function and low birthweight for gestational age"

Low birthweight for gestational age among the defining features in the systematic review.

Other 4

Lissencephaly HP:0001339

Show evidence (1 reference)

PMID:26862926 SUPPORT Human Clinical

"almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter"

Records almost complete agyria (lissencephaly-like) in the affected fetal brain.

Intracranial Calcification VERY_FREQUENT Cerebral calcification HP:0002514

Show evidence (2 references)

PMID:26862926 SUPPORT Human Clinical

"multifocal dystrophic calcifications in the cortex and subcortical white matter"

Documents the characteristic cortical and subcortical calcifications of CZS.

PMID:41460891 SUPPORT Human Clinical

"Calcifications and ventriculomegaly were the most consistent and frequent abnormality (around 80%)."

Pooled frequency across 12 Brazilian cohorts, which is the basis for the VERY_FREQUENT band on this phenotype.

Arthrogryposis Arthrogryposis multiplex congenita HP:0002804

Show evidence (2 references)

PMID:27509902 SUPPORT Human Clinical

"Arthrogryposis was present in the arms and legs of six children (86%) and the legs of one child (14%)."

Distribution and frequency of contractures within the series.

PMID:29167994 SUPPORT Human Clinical

"Babies with severe brain lesions are born with arthrogryposis."

Independent neuropathological confirmation, and the association with lesion severity.

Chorioretinal Abnormalities Chorioretinal atrophy HP:0000533

Show evidence (2 references)

PMID:33320867 SUPPORT Human Clinical

"ocular findings in the posterior and anterior segments, abnormal visual function and low birthweight for gestational age"

Establishes ocular involvement across both segments as a defining feature in a systematic review of 46 studies.

PMID:32920998 SUPPORT Human Clinical

"On follow up of 280 asymptomatic infants, 2/155 (1.3%) had eye abnormalities"

Eye abnormalities in infants who appeared unaffected at birth, which is why ophthalmological screening is recommended irrespective of head size.

💊

Medical Actions

Supportive Care

Action: Supportive Care NCIT:C15747

There is no specific antiviral therapy for congenital Zika syndrome. Management is supportive and multidisciplinary, addressing feeding difficulties, seizures, spasticity, and developmental needs.

Physical and Developmental Therapy

Action: physical therapy Ontology label: Physical Therapy NCIT:C15302

Early rehabilitative and developmental therapy to support motor function and mitigate the consequences of arthrogryposis and spasticity.

🔬

Diagnosis

Maternal gestational age at infection as the dominant risk determinant

Timing of maternal infection is the single strongest predictor of fetal outcome, and is the reason this entry treats first-trimester exposure as the high-risk window rather than as a stylistic emphasis. Neuropathology agrees with the epidemiology: lesion severity tracks gestational age at infection.

Show evidence (2 references)

PMID:32920998 SUPPORT Human Clinical

"Fetal abnormalities were 14.0 (95% CI 7.6-26.0) times more likely with gestational infection occurring in ≤11 weeks."

Quantifies the timing dependence with an effect size and interval.

PMID:29167994 SUPPORT Human Clinical

"The severity of the lesions is directly related to the gestational age, the most severe occurring when the mother is infected in the first trimester."

Independent pathological confirmation of the same gradient, from tissue rather than from outcome statistics.

Screening of apparently unaffected exposed infants

A normal examination at birth does not exclude CZS-spectrum injury. In follow-up of infants classified as asymptomatic, a small proportion had eye abnormalities or CNS imaging findings and a larger proportion had neurological alert signs by three months. Hearing testing is likewise recommended for all infants born to women with evidence of ZIKV infection, including those who appear normal at birth.

Show evidence (2 references)

PMID:32920998 SUPPORT Human Clinical

"On follow up of 280 asymptomatic infants, 2/155 (1.3%) had eye abnormalities, 1/207 (0.5%) had CNS imaging findings and 16/199 (8%) presented neurological alert signs."

Subclinical findings in infants who appeared unaffected, with denominators.

PMID:27585248 SUPPORT Human Clinical

"all infants born to women with evidence of Zika virus infection during pregnancy should have their hearing tested, including infants who appear normal at birth"

The screening recommendation that follows from ascertainment-dependent detection.

📊

Prevalence

Symptomatic ZIKV-infected pregnant women, Brazil (Ribeirao Preto region)

Point Prevalence 2500.0 per 100,000 >1 in 1,000

Major signs of congenital Zika syndrome in 13 of 513 fetuses (2.5%) of symptomatic ZIKV-infected women in a prospective population-based cohort. This is a risk per infected pregnancy, not a population prevalence of the disease, and it is conditioned on the mother being symptomatic.

Show evidence (1 reference)

PMID:32920998 SUPPORT Human Clinical

"Of these, 13 (2.5%; 95% CI 1.5-4.3) presented with major signs of congenital Zika syndrome (CZS)."

The proportion with major CZS signs, with its confidence interval.

Liveborn infants of symptomatic ZIKV-infected women, Brazil

Birth Prevalence 3900.0 per 100,000 >1 in 1,000

Microcephaly or other CNS malformation in 19 of 489 liveborn infants (3.9%). Pregnancy losses occurred separately in 4.7% of the cohort, so the liveborn denominator understates total adverse outcomes.

Show evidence (1 reference)

PMID:32920998 SUPPORT Human Clinical

"Microcephaly or other CNS malformations were diagnosed in 1/4 (25.0%) stillbirths and in 19/489 (3.9%; 95% CI 2.5-5.9) of the liveborn infants."

Birth prevalence among liveborn infants, alongside the stillbirth figure.

🔀

Differential Diagnoses

Conditions with similar clinical presentations that must be differentiated from Congenital Zika Syndrome:

Other congenital (TORCH) infections

Overlapping Features Congenital cytomegalovirus and toxoplasmosis produce overlapping intracranial calcification, microcephaly, chorioretinal disease and hearing loss, and are the principal differential. The pattern of calcification and the presence of arthrogryposis help, but neither is decisive, so discrimination rests on laboratory confirmation of the agent rather than on imaging phenotype.

Distinguishing Features

Arthrogryposis with normal joints and neurogenic electromyographic findings is characteristic of CZS and is not a usual feature of congenital CMV or toxoplasmosis.
Sensorineural hearing loss occurs in CZS at a frequency similar to that seen with other congenital viral infections, so it does not discriminate between them.

Show evidence (1 reference)

PMID:27585248 SUPPORT Human Clinical

"which is similar to that seen in association with other congenital viral infections"

States that the hearing-loss frequency does not separate CZS from the other congenital infections, which is why it is listed as a non-discriminating feature.

Genetic primary microcephaly

Overlapping Features Autosomal recessive primary microcephaly converges on the same progenitor-depletion endpoint but differs pathologically: CZS is a destructive process with prominent cell death, necrosis and calcification, whereas genetic primary microcephaly is hypoplastic without those features. The distinction is made on tissue and imaging rather than on head circumference.

Distinguishing Features

Calcification, parenchymal destruction and perivascular inflammation favour congenital infection over a germline progenitor defect.

Show evidence (1 reference)

PMID:29167994 SUPPORT Human Clinical

"there is extensive destruction of the hemispheric parenchyma, calcifications, various disturbances of neuronal migration, reactive gliosis, microglial hyperplasia"

The destructive, inflammatory signature that separates CZS from hypoplastic genetic microcephaly on histology.

📊

Related Datasets

Human Otic progenitor cell models of congenital hearing loss applied to to Zika virus and cytomegalovirus infections geo:GSE234062

Congenital hearing loss is a common chronic condition affecting children in both developed and developing nations. In many cases, congenital hearing loss is ultimately attributed to viral infection, most often by cytomegalovirus (CMV), but also in Congenital Zika Syndrome (CZS). The mechanisms by which CMV and ZIKV virus cause these cranial developmental defects have not been elucidated. Inner ear development has been particularly difficult to study, given the inaccessibility and scarcity of the tissue in animal models or on human autopsy; however, it is now possible to culture stem-cell derived otic progenitor cells (OPCs).

human BULK RNA SEQ n=36

PMID:38440980

Identified by GEO DataSets index search for Congenital Zika Syndrome (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.

RNA-seq of hiPSCs-derived NPCs from 3 pairs of dizygotic discordant twins for Congenital Zika syndrome geo:GSE102128

Congenital Zika syndrome (CZS), caused by Zika virus (ZIKV) infection, has been associated to impairment of early brain development, particularly related to neural progenitor cells (NPCs) survival and growth. In this work we report in a high-throughput manner (RNA-Seq) the differences in the transcriptomes of hiPSCs(human induced pluripotent stem cells)-derived NPCs from 3 pairs of discordant twins for Congenital Zika syndrome (CZS).

human BULK RNA SEQ n=6

PMID:29396410

Transcriptomics analysis of trimester-specific full-term placentas from three Zika virus-infected women geo:GSE139181

Effects of Zika virus (ZIKV) infection on placental development during pregnancy are unclear. In this study, full-term placentas from three women, each infected with ZIKV during specific pregnancy trimesters, were harvested for anatomic, immunologic and transcriptomic analysis. Each woman exhibited a unique immune response with raised IL-1RA, IP-10, EGF and RANTES expression, and neutrophil numbers during the acute infection phase. Although ZIKV NS3 antigens co-localized to placental Hofbauer cells, the placentas showed no anatomical defects.

human BULK RNA SEQ n=33

PMID:31709049

🐁

Animal Models

Dengue-immune cynomolgus macaque ZIKV pregnancy model

A nonhuman primate model of vertical transmission on a developmental timeline close to the human one, used to ask why some ZIKV-exposed fetuses are severely affected and others are not. Its answer is a maternal immunological one that this entry otherwise has no account of: prior dengue immunity worsens fetal outcome.

Species

Cynomolgus macaque

Genotype

Wild type, DENV-immune prior to ZIKV challenge

Publication

PMID:37878671

Pathograph links

Impaired Neurogenesis and Congenital Cortical Malformation recapitulates fidelity: high Fetuses of DENV-immune macaques infected with ZIKV in early pregnancy developed significantly more severe CZS than naive controls, with reduced cortical thickness and increased neuronal death, haemorrhage, cellular infiltration, calcification and lissencephaly — the same lesion set reported in human postmortem material.

Limitations: The enhancement is demonstrated in macaques and has not been shown to operate in human pregnancy, so it is a candidate explanation for the variable human severity rather than an established one. The model also cannot separate antibody-dependent enhancement from other consequences of prior flavivirus exposure.

Readouts

Fetal head circumference and biparietal diameter by serial ultrasound

Direction: DECREASED

Interpretation: In vivo growth measurement across gestation, directly comparable to the human antenatal measure.

Show evidence (1 reference)

PMID:37878671 SUPPORT Model Organism

"Ultrasound measurements of head circumference and biparietal diameter measurements taken sequentially throughout pregnancy demonstrated CZS in fetuses of DENV-immune pregnant macaques."

The serial antenatal readout establishing microcephaly in the model.

Fetal brain histopathology

Direction: INCREASED

Interpretation: The lesion set matches human CZS neuropathology, which is what makes the model informative rather than merely a growth phenotype.

Show evidence (1 reference)

PMID:37878671 SUPPORT Model Organism

"severe CZS enhanced by DENV immunity was typified by reduced cortical thickness and increased frequency of neuronal death, hemorrhaging, cellular infiltrations, calcifications, and lissencephaly in fetal brains"

The histological readouts, each of which has a human counterpart in this entry.

Show evidence (1 reference)

PMID:37878671 SUPPORT Model Organism

"We found significantly increased severity of congenital Zika syndrome (CZS) in fetuses of DENV-immune cynomolgus macaques infected with ZIKV in early pregnancy compared with naïve controls, which occurred despite no effect on maternal ZIKV infection or antibody responses."

The core result, including the control that makes it a fetal rather than a maternal effect: maternal infection and antibody responses were unchanged.

{ }

Source YAML

click to show

name: Congenital Zika Syndrome
creation_date: "2026-06-10T12:00:00Z"
category: Infectious Disease
disease_term:
  preferred_term: Zika virus congenital syndrome
  term:
    id: MONDO:0000890
    label: Zika virus congenital syndrome
parents:
- Microcephaly
synonyms:
- CZS
- congenital Zika virus syndrome
- Zika virus congenital syndrome
- congenital Zika virus infection
notes: >-
  Two things about this entry are worth knowing before extending it.

  First, the risk figures are lower than the outbreak-era coverage implies and
  should not be quoted from memory. In the largest Brazilian prospective cohort,
  major signs of CZS occurred in 2.5% of fetuses of symptomatic ZIKV-infected
  women and microcephaly or other CNS malformation in 3.9% of liveborn infants.
  What is large is not the absolute risk but its dependence on timing: fetal
  abnormalities were 14 times more likely when maternal infection occurred at or
  before 11 weeks.

  Second, head circumference is not a sufficient case definition, and the entry
  is curated so as not to imply that it is. Ventricular enlargement in CZS can be
  obstructive rather than ex-vacuo and present with a LARGE head; eye
  abnormalities and neurological alert signs occur in infants who appear normal
  at birth; and the reported frequency of sensorineural hearing loss depends
  entirely on whether the cohort was ascertained by microcephaly. Each of those
  is curated with the evidence that establishes it rather than left as caveat
  prose.
description: >-
  Congenital Zika syndrome (CZS) is a non-genetic malformation of cortical
  development caused by intrauterine infection with Zika virus (ZIKV), a
  mosquito-borne flavivirus. After maternal infection — most consequential for
  fetal neurodevelopment during the first and second trimesters — ZIKV crosses
  the placenta and reaches the developing fetal central nervous system, where it
  is neurotropic for apical and outer radial glia and other neural progenitor
  cells of the cortical ventricular and subventricular zones. Productive
  infection of these founder progenitors dysregulates the cell cycle, triggers
  caspase-mediated apoptosis, and activates innate antiviral signalling
  (including the TLR3 pathway and type I interferon responses), collectively
  depleting the progenitor pool and abrogating neurogenesis during the peak
  neurogenic window. The resulting deficit of cortical neurons produces the
  recognizable CZS phenotype: severe (often congenital) microcephaly with a
  markedly disproportionate skull, agyria/lissencephaly-like smooth cortex, intracranial
  (cortical and subcortical) calcifications, ventriculomegaly/hydrocephalus,
  and cortical thinning, frequently accompanied by ocular abnormalities,
  arthrogryposis, sensorineural hearing loss, seizures, and global
  developmental delay. CZS is the exemplar infectious (non-Mendelian) cortical
  malformation mechanism: its proximal cause is a defined viral exposure rather
  than a germline variant, but it converges on the same progenitor-depletion
  endpoint as genetic primary microcephaly, distinguished pathologically by a
  more destructive process with prominent cell death, necrosis, and
  calcification.
pathophysiology:
- name: Tunneling Nanotube-Mediated Intercellular Viral Spread
  biological_scale: CELLULAR
  description: >-
    ZIKV induces tunneling nanotubes (TNTs) — actin-rich, membrane-bounded
    intercellular conduits that carry viral components directly from cell to
    cell, bypassing the extracellular space. TNT-forming capacity maps to
    residues 40-52 of the viral nonstructural protein NS1: an engineered
    TNT-deficient mutant (ZIKVΔTNT) disseminates markedly less to maternal
    and fetal tissues than TNT-competent virus across multiple pregnancy models.
    Because transfer through a TNT is shielded from the extracellular
    compartment, this route also appears to let the virus persist in the face of
    a maternal type III interferon (IFN-lambda) response, implicating TNTs in
    immune evasion as well as in spread.
  biological_processes:
  - preferred_term: tunneling nanotube formation
    term:
      id: GO:0120031
      label: plasma membrane bounded cell projection assembly
    modifier: INCREASED
  - preferred_term: TNT-shielded escape from maternal type III interferon control
    term:
      id: GO:0042783
      label: symbiont-mediated evasion of host immune response
    modifier: INCREASED
  - preferred_term: maternal type III interferon (IFN-lambda) signaling at the maternal-fetal interface
    term:
      id: GO:0038196
      label: type III interferon-mediated signaling pathway
  evidence:
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We previously showed that ZIKV induces tunneling nanotubes (TNTs), actin-rich intercellular conduits that enable direct cell-to-cell transfer of viral components."
    explanation: Defines TNTs as actin-rich conduits mediating direct cell-to-cell transfer of ZIKV components.
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "A TNT-deficient ZIKV mutant (ZIKVΔTNT), harboring a change between residues 40 and 52 of the nonstructural protein 1 (NS1), showed markedly reduced viral dissemination to maternal and fetal tissues across all models tested, whereas the TNT-competent ZIKV established a robust infection."
    explanation: Loss-of-function genetic evidence that NS1-dependent TNT formation is required for maternal and fetal dissemination.
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Loss of TNT-forming capacity also limited viral persistence despite maternal type III interferon (IFN-λ) responses, suggesting a role for TNTs in immune evasion."
    explanation: Links TNT-mediated spread to viral persistence under an active maternal IFN-lambda response.
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Together, these findings provide in vivo evidence that TNTs are a key mechanism by which ZIKV enhances dissemination, promotes placental dysfunction, and drives fetal pathogenesis."
    explanation: The authors' in vivo summary claim placing TNTs upstream of placental dysfunction and fetal pathology.
  notes: >-
    No ontology term exists for the tunneling nanotube itself in GO, CL, or
    UBERON, so the structure is carried as a free-text `preferred_term` over the
    closest available parent process rather than being force-bound to `cytoneme`
    (GO:0035230) or `intercellular bridge` (GO:0045171), which name different
    structures. Recorded as an OBO gap. All evidence for this node is mouse
    in vivo; TNTs have not been demonstrated in human placental tissue in vivo
    (see the discussions block).
  downstream:
  - target: Placental Infection
    description: >-
      TNT-mediated spread within the placenta drives productive placental
      infection.
  - target: Transplacental Viral Transfer to the Fetal Compartment
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      TNT-competent virus reaches maternal and fetal tissues far more
      efficiently than TNT-deficient virus. The edge is retained because that
      dissemination difference is directly measured, but marked indirect: the
      route to the fetal compartment runs through placental infection, which is
      curated as its own node between the two.
- name: Placental Infection
  biological_scale: TISSUE
  description: >-
    ZIKV productively infects the placenta, producing histological placental
    pathology. The causal role of viral spread is established by the contrast
    with the TNT-deficient mutant, which produces less placental pathology. The
    placenta is therefore not merely a barrier ZIKV crosses but a target organ
    in its own right.
  cell_types:
  - preferred_term: trophoblast cell
    term:
      id: CL:0000351
      label: trophoblast cell
  locations:
  - preferred_term: placenta
    term:
      id: UBERON:0001987
      label: placenta
  evidence:
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Using multiple pregnancy models, we demonstrate that viruses capable of forming these structures disseminate more efficiently, damage the placenta, and lead to fetal growth restriction, whereas TNT-deficient viruses show reduced infection and milder disease."
    explanation: States directly that TNT-competent virus damages the placenta, across the pregnancy models tested.
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "ZIKVΔTNT infection was associated with reduced placental pathology, altered junctional-to-labyrinth architecture, improved placental efficiency, and protection from fetal growth restriction."
    explanation: The reduced placental pathology in the TNT-deficient mutant is the loss-of-function counterpart of the damage claim.
  notes: >-
    The trophoblast cell type is not named in PMID:42627154, whose placental
    readouts are the rodent junctional zone and labyrinth; `CL:0000351` is
    supplied from general placental biology as the resident parenchymal cell
    type of the infected organ, not asserted by this reference. All evidence for
    this node is mouse in vivo. No `conforms_to` is declared: the closest
    candidate, `innate_antiviral_interferon_response#Viral Interferon Antagonism
    and Innate Immune Evasion`, is about pathway antagonism (GO:0039502
    symbiont-mediated suppression of interferon signalling), which is a
    different mechanism from the physical compartment-shielding curated here —
    considered and declined rather than overlooked.
  downstream:
  - target: Placental Architectural and Functional Disruption
    description: >-
      Placental infection is followed by change in the relative architecture of
      the placental compartments and a fall in placental efficiency.
  - target: Transplacental Viral Transfer to the Fetal Compartment
    causal_link_type: DIRECT
    description: >-
      Placental infection and barrier injury permit virus to reach the fetal
      compartment and the developing central nervous system.
- name: Placental Architectural and Functional Disruption
  biological_scale: TISSUE
  description: >-
    Infected placentas differ from TNT-deficient-infected controls in the
    relative architecture of the placental compartments, and in placental
    efficiency (fetal mass supported per unit placental mass), which improves
    when viral spread is crippled.
  locations:
  - preferred_term: placenta
    term:
      id: UBERON:0001987
      label: placenta
  biological_processes:
  - preferred_term: placental architecture and efficiency
    term:
      id: GO:0001890
      label: placenta development
    modifier: ABNORMAL
  evidence:
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "ZIKVΔTNT infection was associated with reduced placental pathology, altered junctional-to-labyrinth architecture, improved placental efficiency, and protection from fetal growth restriction."
    explanation: Reports the altered compartment architecture and the improved placental efficiency of the TNT-deficient condition.
  notes: >-
    CRITICAL species caveat: the junctional zone and labyrinth are compartments
    of the *rodent* placenta and have no direct human homolog, so the measured
    "junctional-to-labyrinth architecture" readout cannot be carried over to
    human placental pathology. All evidence for this node is mouse in vivo.
    Scope of what the source states: the architectural readout is reported as
    *altered* in the TNT-deficient condition, with no direction given, so this
    node makes no claim about which way TNT-competent infection shifts it. The
    efficiency change does have a direction — the mutant improves it — and is
    stated as such in the description.
  downstream:
  - target: Fetal Growth Restriction
    description: >-
      Reduced placental efficiency limits fetal growth; crippling viral spread
      protects against the growth deficit.
- name: Fetal Growth Restriction
  biological_scale: ORGANISM
  description: >-
    The most distal outcome of the placental arm in the pregnancy models tested:
    TNT-competent ZIKV infection leads to fetal growth restriction, while
    TNT-deficient infection protects against it.
  evidence:
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "ZIKVΔTNT infection was associated with reduced placental pathology, altered junctional-to-labyrinth architecture, improved placental efficiency, and protection from fetal growth restriction."
    explanation: Protection from fetal growth restriction in the TNT-deficient condition is the loss-of-function evidence for this outcome.
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Using multiple pregnancy models, we demonstrate that viruses capable of forming these structures disseminate more efficiently, damage the placenta, and lead to fetal growth restriction, whereas TNT-deficient viruses show reduced infection and milder disease."
    explanation: States that TNT-competent virus leads to fetal growth restriction across the models tested.
  notes: >-
    Curated as an ORGANISM-scale pathophysiology node carrying MODEL_ORGANISM
    evidence, and deliberately NOT added to `phenotypes:` as a human phenotype:
    the finding is mouse-only, and model-organism evidence should not be the
    sole support for a human phenotype. A human citation would be needed to
    promote it. See the discussions block.
- name: Transplacental Viral Transfer to the Fetal Compartment
  biological_scale: TISSUE
  description: >-
    Crossing the maternal-fetal interface is a transport step, distinct from
    what the virus does once it arrives. Human placental work identifies more
    than one route rather than a single breach: ZIKV productively infects
    placental macrophages (Hofbauer cells) and, less efficiently,
    cytotrophoblasts in term villous tissue, and separately infects
    cytotrophoblasts, endothelial cells, fibroblasts and Hofbauer cells in
    chorionic villi together with amniotic epithelial cells and trophoblast
    progenitors in amniochorionic membranes. Those cells express the Axl, Tyro3
    and TIM1 entry cofactors, so the same TAM-family biology operates here as in
    the fetal brain — but on different cells, in a different organ, supporting a
    different claim. Curating them as one node conflated the two.

    Transfer is not uniformly permissive, and the restriction side explains the
    timing dependence the rest of this entry rests on. Primary human trophoblasts
    from full-term placentas are refractory to ZIKV and constitutively release
    type III interferon (IFN-lambda1) that protects both trophoblast and
    non-trophoblast cells, so virus reaching the fetal compartment must evade or
    bypass that barrier. Consistent with a barrier that strengthens as gestation
    proceeds, mid-gestation amniotic epithelial cells support higher viral titres
    than late-gestation cells.
  cell_types:
  - preferred_term: Hofbauer cell (placental macrophage)
    term:
      id: CL:3000001
      label: Hofbauer cell
  - preferred_term: Cytotrophoblast
    term:
      id: CL:0000523
      label: mononuclear cytotrophoblast cell
  biological_processes:
  - preferred_term: type III interferon production by trophoblast
    term:
      id: GO:0034343
      label: type III interferon production
  locations:
  - preferred_term: placenta
    term:
      id: UBERON:0001987
      label: placenta
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:27247001
    reference_title: "Zika Virus Infects Human Placental Macrophages."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Our results suggest a mechanism for intrauterine transmission in which ZIKV gains access to the fetal compartment by directly infecting placental cells and disrupting the placental barrier."
    explanation: >-
      States the transfer mechanism this node curates, in primary human placental
      cells rather than in a model organism.
  - reference: PMID:27247001
    reference_title: "Zika Virus Infects Human Placental Macrophages."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "infects and replicates in primary human placental macrophages, called Hofbauer cells, and to a lesser extent in cytotrophoblasts, isolated from villous tissue of full-term placentae"
    explanation: Identifies the two placental cell types curated on this node, with their relative permissiveness.
  - reference: PMID:27443522
    reference_title: "Zika Virus Targets Different Primary Human Placental Cells, Suggesting Two Routes for Vertical Transmission."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Our results suggest that ZIKV spreads from basal and parietal decidua to chorionic villi and amniochorionic membranes and that targeting TIM1 could suppress infection at the uterine-placental interface."
    explanation: >-
      The two-route structure of transfer, and the cofactor that is druggable at
      the uterine-placental interface specifically.
  - reference: PMID:27443522
    reference_title: "Zika Virus Targets Different Primary Human Placental Cells, Suggesting Two Routes for Vertical Transmission."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "ZIKV produced NS3 and E proteins and generated higher viral titers in amniotic epithelial cells from mid-gestation compared to late-gestation placentas."
    explanation: >-
      Gestational-age dependence measured at the placenta, which is the
      mechanistic counterpart of the clinical first-trimester risk.
  - reference: PMID:27066743
    reference_title: "Type III Interferons Produced by Human Placental Trophoblasts Confer Protection against Zika Virus Infection."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "PHT cells constitutively release the type III interferon (IFN) IFNλ1, which functions in both a paracrine and autocrine manner to protect trophoblast and non-trophoblast cells from ZIKV infection."
    explanation: >-
      The restriction arm. Transfer has to defeat a constitutive barrier, which
      is why it is inefficient and gestational-age dependent rather than
      obligate.
  - reference: PMID:26862926
    reference_title: "Zika Virus Associated with Microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ZIKV was found in the fetal brain tissue on reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay, with consistent findings on electron microscopy."
    explanation: >-
      Human confirmation that the transfer step completes: virus is recovered
      from fetal brain after maternal infection.
  - reference: PMID:27279226
    reference_title: "The Brazilian Zika virus strain causes birth defects in experimental models."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Here we demonstrate that ZIKV(BR) infects fetuses, causing intrauterine growth restriction, including signs of microcephaly, in mice."
    explanation: In vivo evidence that transfer occurs and is sufficient to produce fetal disease.
  downstream:
  - target: Neurotropic Entry into Fetal Neural Progenitors
    causal_link_type: DIRECT
    description: >-
      Virus that has reached the fetal compartment encounters the developing
      cortex, where a separate set of receptors and cell types governs entry.
- name: Neurotropic Entry into Fetal Neural Progenitors
  biological_scale: CELLULAR
  description: >-
    Once in the fetal brain, ZIKV is neurotropic for radial glia and neural
    progenitor cells. Candidate entry receptors enriched on these cells —
    notably the TAM-family receptor tyrosine kinase AXL, which is highly
    expressed by human radial glia in the developing cortex — are thought to
    mediate or facilitate viral attachment and entry, establishing infection of
    the founder progenitor population during corticogenesis. Neuropathology
    confirms the target: infection of progenitor cells at the germinal matrix
    has been demonstrated in human material.

    AXL appears on both sides of this entry's transfer/entry split, and the
    duplication is real biology rather than a curation artefact: the same
    TAM-family cofactors are used at the placenta and on radial glia. They are
    nonetheless different claims about different cells in different organs, and
    are curated on the node each belongs to.
  conforms_to: viral_neural_progenitor_cytopathy#Fetal Brain Viral Exposure and Progenitor Infection
  cell_types:
  - preferred_term: Radial glial cell
    term:
      id: CL:0000681
      label: radial glial cell
  - preferred_term: Neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  biological_processes:
  - preferred_term: Viral entry into host cell
    term:
      id: GO:0046718
      label: symbiont entry into host cell
    modifier: INCREASED
  - preferred_term: Viral genome replication
    term:
      id: GO:0019079
      label: viral genome replication
    modifier: INCREASED
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:27038591
    reference_title: "Expression Analysis Highlights AXL as a Candidate Zika Virus Entry Receptor in Neural Stem Cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we found that the candidate viral entry receptor AXL is highly expressed by human radial glial cells, astrocytes, endothelial cells, and microglia in developing human cortex and by progenitor cells in developing retina."
    explanation: Identifies AXL on human radial glia as a candidate entry receptor enriched on the progenitor population ZIKV targets.
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infection of progenitor cells at the germinal matrix was demonstrated."
    explanation: >-
      Human neuropathological confirmation that the progenitor population is the
      infected compartment, rather than this resting on culture systems alone.
  downstream:
  - target: Antiviral Innate Immune Activation
  - target: Viral Mitotic and Centrosome Cytopathy
  - target: Spinal Anterior Horn Motor Neuron Loss
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Virus in the developing fetal CNS also reaches the spinal cord, where
      anterior horn motor neurons are lost. Whether this reflects the same
      progenitor-directed cytopathy operating at a second site, or direct
      infection of postmitotic motor neurons, is not established by the
      neuropathological material.
- name: Spinal Anterior Horn Motor Neuron Loss
  biological_scale: TISSUE
  description: >-
    Severe motor nerve cell loss in the anterior horn of the spinal cord is a
    consistent postmortem finding in congenital ZIKV infection, alongside
    hypoplasia of the descending tracts (small basis pontis, pyramids and spinal
    corticospinal tracts) that follows the loss of cortical output. The anterior
    horn lesion is the one that matters here, because it is what connects this
    entry's cortical mechanism to a phenotype the cortex cannot explain.
  cell_types:
  - preferred_term: Anterior horn motor neuron
    term:
      id: CL:2000048
      label: anterior horn motor neuron
  locations:
  - preferred_term: ventral horn of spinal cord
    term:
      id: UBERON:0002257
      label: ventral horn of spinal cord
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Severe nerve motor nerve cell loss is observed in the anterior horn of the spinal cord."
    explanation: >-
      The anterior horn lesion, in human postmortem material. Quoted as written,
      including the source's duplicated word.
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypoplastic lesions secondary to the lack of descending nerve fibers include small basis pontis, pyramids and spinal corticospinal tracts."
    explanation: >-
      The separate, secondary tract hypoplasia that follows cortical loss, kept
      distinct from the primary anterior horn lesion above.
  downstream:
  - target: Fetal Akinesia
    causal_link_type: DIRECT
    description: >-
      Loss of the final common motor pathway removes the fetal movement that
      normal joint development depends on.
- name: Fetal Akinesia
  biological_scale: ORGANISM
  description: >-
    Absent or greatly reduced fetal movement, the consequence of losing spinal
    motor neurons. This node exists because the resulting arthrogryposis is
    neurogenic rather than articular, and the distinction is testable: in the
    reported series, high-definition ultrasonography of the joints showed no
    abnormality, while needle electromyography showed motor unit remodeling and
    reduced recruitment, and spinal MRI showed apparent cord thinning with
    reduced ventral roots. The joints are normal; the nerves supplying them are
    not.
  mechanism_confidence: ESTABLISHED
  evidence:
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The lack of spinal motor neurons is responsible for fetal acynesia and consequent arthrogryposis."
    explanation: >-
      The causal claim this node and its downstream edge encode, stated by the
      source. The source's spelling of akinesia is preserved in the quote.
  - reference: PMID:27509902
    reference_title: "Congenital Zika syndrome with arthrogryposis: retrospective case series study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All the children underwent high definition ultrasonography of the joints, and there was no evidence of abnormalities."
    explanation: >-
      The negative joint imaging that excludes a primary articular cause and so
      makes the neurogenic account load-bearing rather than assumed.
  - reference: PMID:27509902
    reference_title: "Congenital Zika syndrome with arthrogryposis: retrospective case series study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MRI of the spine in four children showed apparent thinning of the cord and reduced ventral roots."
    explanation: >-
      Imaging correlate of the anterior horn lesion in living patients, matching
      the postmortem finding.
- name: Antiviral Innate Immune Activation
  biological_scale: CELLULAR
  description: >-
    ZIKV infection activates innate antiviral signalling within developing
    neural progenitor systems. Human cerebral organoid and neurosphere data
    implicate Toll-like receptor 3 (TLR3) activation and type I interferon-linked
    responses in perturbed neurogenesis, altered cell fate, and downstream
    progenitor loss; TLR3 inhibition mitigates the phenotype in experimental
    models.
  conforms_to: viral_neural_progenitor_cytopathy#Antiviral Innate Immune Activation
  cell_types:
  - preferred_term: Neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  - preferred_term: Radial glial cell
    term:
      id: CL:0000681
      label: radial glial cell
  biological_processes:
  - preferred_term: Innate immune response
    term:
      id: GO:0045087
      label: innate immune response
    modifier: INCREASED
  - preferred_term: Toll-like receptor signaling pathway
    term:
      id: GO:0002224
      label: toll-like receptor signaling pathway
    modifier: INCREASED
  - preferred_term: Type I interferon-mediated signaling pathway
    term:
      id: GO:0060337
      label: type I interferon-mediated signaling pathway
    modifier: DYSREGULATED
  - preferred_term: Defense response to virus
    term:
      id: GO:0051607
      label: defense response to virus
    modifier: DYSREGULATED
  evidence:
  - reference: PMID:27162029
    reference_title: "Zika Virus Depletes Neural Progenitors in Human Cerebral Organoids through Activation of the Innate Immune Receptor TLR3."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The innate immune receptor Toll-like-Receptor 3 (TLR3) was upregulated after ZIKV infection of human organoids and mouse neurospheres and TLR3 inhibition reduced the phenotypic effects of ZIKV infection."
    explanation: Implicates TLR3 innate immune activation in ZIKV-driven progenitor cytopathy, with inhibition reducing the experimental phenotype.
  - reference: PMID:27162029
    reference_title: "Zika Virus Depletes Neural Progenitors in Human Cerebral Organoids through Activation of the Innate Immune Receptor TLR3."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Together, therefore, our findings identify a link between ZIKV-mediated TLR3 activation, perturbed cell fate, and a reduction in organoid volume reminiscent of microcephaly."
    explanation: Connects ZIKV-triggered TLR3 activation to perturbed cell fate and reduced organoid volume in a human cerebral organoid model.
  downstream:
  - target: Neural Progenitor Apoptosis and Pool Depletion
- name: Viral Mitotic and Centrosome Cytopathy
  biological_scale: CELLULAR
  description: >-
    ZIKV productively infects human neural progenitor cells and radial glia,
    releasing infectious virus and perturbing cell-cycle progression, mitotic
    machinery, centrosome integrity, and phospho-TBK1 localization. These
    mitotic and centrosome defects impair proliferative progenitor divisions and
    converge on the same neural progenitor centrosome/spindle dysfunction module
    used by genetic cortical malformation entries.
  conforms_to: viral_neural_progenitor_cytopathy#Viral Mitotic and Centrosome Cytopathy
  cell_types:
  - preferred_term: Neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  - preferred_term: Radial glial cell
    term:
      id: CL:0000681
      label: radial glial cell
  biological_processes:
  - preferred_term: Mitotic cell cycle
    term:
      id: GO:0000278
      label: mitotic cell cycle
    modifier: DYSREGULATED
  - preferred_term: Cell cycle
    term:
      id: GO:0007049
      label: cell cycle
    modifier: DYSREGULATED
  - preferred_term: Mitotic spindle organization
    term:
      id: GO:0007052
      label: mitotic spindle organization
    modifier: DYSREGULATED
  - preferred_term: Centrosome cycle
    term:
      id: GO:0007098
      label: centrosome cycle
    modifier: ABNORMAL
  evidence:
  - reference: PMID:26952870
    reference_title: "Zika Virus Infects Human Cortical Neural Progenitors and Attenuates Their Growth."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "ZIKV infection increases cell death and dysregulates cell-cycle progression, resulting in attenuated hNPC growth."
    explanation: Links infection to cell-cycle dysregulation and attenuated progenitor growth.
  - reference: PMID:27568284
    reference_title: "Zika Virus Disrupts Phospho-TBK1 Localization and Mitosis in Human Neuroepithelial Stem Cells and Radial Glia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "ZIKV infection of NES cells and RGCs causes centrosomal depletion and mitochondrial sequestration of phospho-TBK1 during mitosis."
    explanation: Supports mitotic centrosome/TBK1 cytopathy in infected human neuroepithelial stem cells and radial glia.
  - reference: PMID:28132835
    reference_title: "Recent Zika Virus Isolates Induce Premature Differentiation of Neural Progenitors in Human Brain Organoids."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The main phenotypic effect was premature differentiation of neural progenitors associated with centrosome perturbation, even during early stages of infection, leading to progenitor depletion, disruption of the VZ, impaired neurogenesis, and cortical thinning."
    explanation: Human brain organoids show ZIKV-associated centrosome perturbation leading to progenitor depletion and cortical thinning.
  downstream:
  - target: Neural Progenitor Apoptosis and Pool Depletion
- name: Neural Progenitor Apoptosis and Pool Depletion
  biological_scale: CELLULAR
  description: >-
    Innate antiviral activation, viral replication, cell-cycle disruption, and
    mitotic/centrosome stress converge on caspase-mediated apoptosis, autophagy,
    premature differentiation, and reduced viability of neural progenitors and
    radial glia. The founder progenitor pool is depleted, leaving too few
    neuron-generating cells for normal cortical expansion.
  conforms_to: viral_neural_progenitor_cytopathy#Neural Progenitor Apoptosis and Pool Depletion
  cell_types:
  - preferred_term: Neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  - preferred_term: Radial glial cell
    term:
      id: CL:0000681
      label: radial glial cell
  biological_processes:
  - preferred_term: Apoptotic process
    term:
      id: GO:0006915
      label: apoptotic process
    modifier: INCREASED
  - preferred_term: Neurogenesis
    term:
      id: GO:0022008
      label: neurogenesis
    modifier: DECREASED
  - preferred_term: Cell population proliferation
    term:
      id: GO:0008283
      label: cell population proliferation
    modifier: DECREASED
  evidence:
  - reference: PMID:27064148
    reference_title: "Zika virus impairs growth in human neurospheres and brain organoids."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we showed that ZIKV targets human brain cells, reducing their viability and growth as neurospheres and brain organoids. These results suggest that ZIKV abrogates neurogenesis during human brain development."
    explanation: Demonstrates that ZIKV reduces human neural progenitor viability/growth and abrogates neurogenesis.
  - reference: PMID:26952870
    reference_title: "Zika Virus Infects Human Cortical Neural Progenitors and Attenuates Their Growth."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "ZIKV infection increases cell death and dysregulates cell-cycle progression, resulting in attenuated hNPC growth."
    explanation: Connects infection-driven cell death and cell-cycle dysregulation to reduced progenitor growth.
  - reference: PMID:27279226
    reference_title: "The Brazilian Zika virus strain causes birth defects in experimental models."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "ZIKV(BR) crosses the placenta and causes microcephaly by targeting cortical progenitor cells, inducing cell death by apoptosis and autophagy, and impairing neurodevelopment."
    explanation: Establishes apoptosis and autophagy of cortical progenitors as in vivo mechanisms of ZIKV-induced microcephaly.
  downstream:
  - target: Impaired Neurogenesis and Congenital Cortical Malformation
- name: Impaired Neurogenesis and Congenital Cortical Malformation
  biological_scale: TISSUE
  description: >-
    Depletion of the cortical progenitor pool and impaired neurogenesis reduce
    the complement of cortical neurons, producing severe microcephaly with a
    disproportionately small brain. Unlike many genetic microcephalies, the CZS
    cortex shows a more destructive pathology, with near-complete agyria
    (lissencephaly-like smoothing), multifocal cortical and subcortical
    calcifications, hydrocephalus/ventriculomegaly, and cortical displacement,
    reflecting prominent cell death during development.
  conforms_to: viral_neural_progenitor_cytopathy#Impaired Neurogenesis and Congenital Cortical Malformation
  cell_types:
  - preferred_term: Neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  biological_processes:
  - preferred_term: Neurogenesis
    term:
      id: GO:0022008
      label: neurogenesis
    modifier: DECREASED
  - preferred_term: Cerebral cortex development
    term:
      id: GO:0021987
      label: cerebral cortex development
    modifier: ABNORMAL
  evidence:
  - reference: PMID:26862926
    reference_title: "Zika Virus Associated with Microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Micrencephaly (an abnormally small brain) was observed, with almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter, with associated cortical displacement and mild focal inflammation."
    explanation: Human fetal autopsy documenting the destructive cortical malformation phenotype of CZS.
  - reference: PMID:27179424
    reference_title: "Zika Virus Disrupts Neural Progenitor Development and Leads to Microcephaly in Mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "ZIKV infection leads to cell-cycle arrest, apoptosis, and inhibition of NPC differentiation, resulting in cortical thinning and microcephaly."
    explanation: In vivo recapitulation of cortical thinning and microcephaly as the developmental endpoint.
phenotypes:
- category: Neurologic
  name: Microcephaly
  diagnostic: true
  description: >-
    Severe, frequently congenital microcephaly with a markedly disproportionate
    skull is the hallmark feature of congenital Zika syndrome.
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  evidence:
  - reference: PMID:26862926
    reference_title: "Zika Virus Associated with Microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Micrencephaly (an abnormally small brain) was observed, with almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter, with associated cortical displacement and mild focal inflammation."
    explanation: Documents micrencephaly (abnormally small brain) on human fetal autopsy.
- category: Neurologic
  name: Lissencephaly
  description: >-
    Near-complete agyria (a lissencephaly-like smooth cortex) reflects the
    severe disruption of cortical development.
  phenotype_term:
    preferred_term: Lissencephaly
    term:
      id: HP:0001339
      label: Lissencephaly
  evidence:
  - reference: PMID:26862926
    reference_title: "Zika Virus Associated with Microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter"
    explanation: Records almost complete agyria (lissencephaly-like) in the affected fetal brain.
- category: Neurologic
  name: Intracranial Calcification
  frequency: VERY_FREQUENT
  description: >-
    Multifocal calcifications in the cortex and subcortical white matter are a
    characteristic neuroimaging and pathological feature of CZS.
  phenotype_term:
    preferred_term: Cerebral calcification
    term:
      id: HP:0002514
      label: Cerebral calcification
  evidence:
  - reference: PMID:26862926
    reference_title: "Zika Virus Associated with Microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "multifocal dystrophic calcifications in the cortex and subcortical white matter"
    explanation: Documents the characteristic cortical and subcortical calcifications of CZS.
  - reference: PMID:41460891
    reference_title: "Characterization of 843 children with Zika-related microcephaly in the first three years of life: An individual participant data meta-analysis of 12 cohorts in the Zika Brazilian Cohorts consortium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Calcifications and ventriculomegaly were the most consistent and frequent abnormality (around 80%)."
    explanation: >-
      Pooled frequency across 12 Brazilian cohorts, which is the basis for the
      VERY_FREQUENT band on this phenotype.
- category: Neurologic
  name: Hydrocephalus
  description: >-
    Hydrocephalus/ventriculomegaly accompanies the cortical malformation in
    congenital Zika syndrome.
  phenotype_term:
    preferred_term: Hydrocephalus
    term:
      id: HP:0000238
      label: Hydrocephalus
  evidence:
  - reference: PMID:26862926
    reference_title: "Zika Virus Associated with Microcephaly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications"
    explanation: Records hydrocephalus in the affected fetal brain.
- category: Musculoskeletal
  name: Arthrogryposis
  description: >-
    Congenital joint contractures, present in the arms and legs of six of seven
    children in the defining series and in the legs alone in the seventh, with
    bilateral hip dislocation in all seven. Curated as neurogenic: see the
    Fetal Akinesia node for the joint-imaging and electromyographic evidence
    that separates this from a primary disorder of the joints.
  phenotype_term:
    preferred_term: Arthrogryposis multiplex congenita
    term:
      id: HP:0002804
      label: Arthrogryposis multiplex congenita
  evidence:
  - reference: PMID:27509902
    reference_title: "Congenital Zika syndrome with arthrogryposis: retrospective case series study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Arthrogryposis was present in the arms and legs of six children (86%) and the legs of one child (14%)."
    explanation: Distribution and frequency of contractures within the series.
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Babies with severe brain lesions are born with arthrogryposis."
    explanation: >-
      Independent neuropathological confirmation, and the association with lesion
      severity.
- category: Auditory
  name: Sensorineural Hearing Loss
  description: >-
    Sensorineural hearing loss in 5 of 70 (7%) infants with microcephaly and
    laboratory evidence of ZIKV infection, or 5.8% (4 of 69) after excluding one
    child tested following ototoxic antibiotic treatment. All affected infants
    had severe microcephaly.

    The frequency is ascertainment-dependent and this entry does not generalise
    it. A separate cohort of ZIKV-exposed children not selected for microcephaly
    found no sensorineural hearing loss over two years. Those results are not in
    conflict: they describe different populations, and the contrast is the reason
    the recommendation is to test hearing in all exposed infants rather than only
    those who look affected.
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:27585248
    reference_title: "Hearing Loss in Infants with Microcephaly and Evidence of Congenital Zika Virus Infection - Brazil, November 2015-May 2016."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Five (7%) infants had sensorineural hearing loss, all of whom had severe microcephaly"
    explanation: >-
      The frequency in an infant series ascertained on microcephaly, and the
      observation that every affected infant was severely microcephalic.
  - reference: PMID:30252119
    reference_title: "Zika Virus Infection during Pregnancy and Sensorineural Hearing Loss among Children at 3 and 24 Months Post-Partum."
    supports: NO_EVIDENCE
    evidence_source: HUMAN_CLINICAL
    snippet: "None of the patients evaluated in this study were found to have sensorineural hearing loss."
    explanation: >-
      Cited to record a negative cohort result, graded NO_EVIDENCE rather than
      REFUTE because this cohort was ZIKV-exposed rather than CZS-affected: it
      does not bear on whether hearing loss occurs in congenital Zika syndrome,
      only on how often it is found when microcephaly is not the entry criterion.
- category: Ophthalmologic
  name: Chorioretinal Abnormalities
  description: >-
    Ocular findings involve both the posterior and anterior segments and are
    accompanied by abnormal visual function. They can be the presenting
    abnormality, and were found in a small proportion of infants who were
    otherwise asymptomatic at birth.
  phenotype_term:
    preferred_term: Chorioretinal atrophy
    term:
      id: HP:0000533
      label: Chorioretinal atrophy
  evidence:
  - reference: PMID:33320867
    reference_title: "Congenital Zika syndrome: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ocular findings in the posterior and anterior segments, abnormal visual function and low birthweight for gestational age"
    explanation: >-
      Establishes ocular involvement across both segments as a defining feature
      in a systematic review of 46 studies.
  - reference: PMID:32920998
    reference_title: "Early maternal Zika infection predicts severe neonatal neurological damage: results from the prospective Natural History of Zika Virus Infection in Gestation cohort study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "On follow up of 280 asymptomatic infants, 2/155 (1.3%) had eye abnormalities"
    explanation: >-
      Eye abnormalities in infants who appeared unaffected at birth, which is why
      ophthalmological screening is recommended irrespective of head size.
- category: Neurologic
  name: Cerebellar Hypoplasia
  phenotype_term:
    preferred_term: Cerebellar hypoplasia
    term:
      id: HP:0001321
      label: Cerebellar hypoplasia
  evidence:
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cerebellar hypoplasia is also common."
    explanation: Records cerebellar involvement as a common postmortem finding.
- category: Neurologic
  name: Ventriculomegaly
  frequency: VERY_FREQUENT
  description: >-
    Ventriculomegaly in CZS has two distinct causes that the neuropathology
    separates: ex-vacuo enlargement following parenchymal loss, and genuine
    obstructive hydrocephalus from midbrain and aqueduct distortion. The second
    can present with a large rather than small head, which is the reason head
    circumference alone is an unreliable screen.
  phenotype_term:
    preferred_term: Ventriculomegaly
    term:
      id: HP:0002119
      label: Ventriculomegaly
  evidence:
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "microcephaly with ex-vacuo ventriculomegaly and large head circumference associated with obstructive hydrocephalus due to severe midbrain and aqueduct distortion"
    explanation: >-
      Distinguishes the two mechanisms of ventricular enlargement and records
      that one of them presents with a large head.
  - reference: PMID:41460891
    reference_title: "Characterization of 843 children with Zika-related microcephaly in the first three years of life: An individual participant data meta-analysis of 12 cohorts in the Zika Brazilian Cohorts consortium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Calcifications and ventriculomegaly were the most consistent and frequent abnormality (around 80%)."
    explanation: >-
      Pooled frequency across 12 Brazilian cohorts, which is the basis for the
      VERY_FREQUENT band on this phenotype.
- category: Neurologic
  name: Seizures
  frequency: FREQUENT
  description: >-
    Epilepsy is one of the two dominant post-natal complications of CZS (the
    other is dysphagia) and is a direct clinical consequence of the cortical
    malformation curated at the Impaired Neurogenesis and Congenital Cortical
    Malformation node. Its phenotype is age-structured rather than uniform:
    onset is typically after the third month, most often as infantile spasms,
    with focal epilepsy predominating in the second year. Seizure control is
    poor, which is why this is a driver of long-term care need and not only a
    diagnostic feature.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
    onset:
      onset_category: INFANTILE
  evidence:
  - reference: PMID:41460891
    reference_title: "Characterization of 843 children with Zika-related microcephaly in the first three years of life: An individual participant data meta-analysis of 12 cohorts in the Zika Brazilian Cohorts consortium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Epilepsy ranged from 30-80% of the children and dysphagia, from 22.2-67.7%."
    explanation: >-
      Pooled range across 12 Brazilian cohorts of children with Zika-related
      microcephaly; the spread is the basis for the FREQUENT rather than
      VERY_FREQUENT band.
  - reference: PMID:32065676
    reference_title: "Early epilepsy in children with Zika-related microcephaly in a cohort in Recife, Brazil: Characteristics, electroencephalographic findings, and treatment response."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seizures typically began after the third month of life, usually as infantile spasms, with atypical electroencephalographic abnormalities."
    explanation: >-
      Establishes the timing and semiology, which is why onset is curated as
      infantile rather than neonatal.
  - reference: PMID:32065676
    reference_title: "Early epilepsy in children with Zika-related microcephaly in a cohort in Recife, Brazil: Characteristics, electroencephalographic findings, and treatment response."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the main type of seizure was infantile spasms (83.1%)"
    explanation: >-
      Infantile spasms as the predominant seizure type in a 91-child cohort
      followed for 24 months.
  - reference: PMID:32065676
    reference_title: "Early epilepsy in children with Zika-related microcephaly in a cohort in Recife, Brazil: Characteristics, electroencephalographic findings, and treatment response."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Overall, only 46.1% of the 65 children with epilepsy responded to treatment."
    explanation: >-
      Treatment response, recorded because poor seizure control is what makes
      this phenotype a long-term burden rather than a transient one.
  - reference: PMID:33320867
    reference_title: "Congenital Zika syndrome: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hydrocephalus, hypertonicity, and seizures; (b) in the osteoskeletal system: arthrogryposis and clubfoot"
    explanation: >-
      Independent corroboration from a systematic review of 46 studies, listing
      seizures among the defining central nervous system signs.
- category: Neurologic
  name: Spastic Hypertonia
  frequency: VERY_FREQUENT
  description: >-
    Spastic hypertonia is the motor consequence of the same cortical lesion and
    is the principal contributor to the cerebral-palsy phenotype these children
    carry. It is distinct from the arthrogryposis curated separately: the
    contractures are present at birth and neurogenic in origin, whereas
    hypertonia is assessed after three months of age and progresses.
  phenotype_term:
    preferred_term: Hypertonia
    term:
      id: HP:0001276
      label: Hypertonia
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:41460891
    reference_title: "Characterization of 843 children with Zika-related microcephaly in the first three years of life: An individual participant data meta-analysis of 12 cohorts in the Zika Brazilian Cohorts consortium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Spastic hypertonia was found in seven sites in which they were investigated, with a frequency of 100% in four sites"
    explanation: >-
      Frequency across the cohorts that assessed it; near-universal where
      ascertained, which is the basis for the VERY_FREQUENT band.
  - reference: PMID:41460891
    reference_title: "Characterization of 843 children with Zika-related microcephaly in the first three years of life: An individual participant data meta-analysis of 12 cohorts in the Zika Brazilian Cohorts consortium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "spastic hypertonia (at >3 months of age), osteotendinous hyperreflexia"
    explanation: >-
      Records the case definition used, including the age threshold, which is
      why this is not curated as a congenital finding.
  - reference: PMID:33320867
    reference_title: "Congenital Zika syndrome: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hydrocephalus, hypertonicity, and seizures; (b) in the osteoskeletal system: arthrogryposis and clubfoot"
    explanation: >-
      Independent corroboration from a systematic review of 46 studies, listing
      hypertonicity among the defining central nervous system signs.
- category: Gastrointestinal
  name: Dysphagia
  frequency: FREQUENT
  description: >-
    Swallowing dysfunction is the second dominant post-natal complication and
    the one with the clearest mortality consequence, through aspiration
    pneumonia. It is bulbar in origin, consistent with the brainstem
    involvement recorded in the histopathology section, and frequently forces
    gastrostomy.
  phenotype_term:
    preferred_term: Dysphagia
    term:
      id: HP:0002015
      label: Dysphagia
  evidence:
  - reference: PMID:41460891
    reference_title: "Characterization of 843 children with Zika-related microcephaly in the first three years of life: An individual participant data meta-analysis of 12 cohorts in the Zika Brazilian Cohorts consortium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In the pooled analyses, dysphagia was common and observed in 46.9% of children."
    explanation: >-
      Pooled frequency across 12 cohorts, the basis for the FREQUENT band.
  - reference: PMID:27509902
    reference_title: "Congenital Zika syndrome with arthrogryposis: retrospective case series study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dysphagia was present in six children (86%); two underwent gastrostomy and tracheostomy."
    explanation: >-
      Much higher frequency in the arthrogryposis series, consistent with
      dysphagia tracking overall neurological severity rather than being an
      independent feature.
  - reference: PMID:33320867
    reference_title: "Congenital Zika syndrome: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dysphagia can increase the risk of bronchoaspiration, resulting in aspiration pneumonia or death from asphyxiation, requiring gastrostomy in the affected infants"
    explanation: >-
      States the mechanism by which dysphagia becomes fatal, which is why it is
      curated as a phenotype in its own right rather than folded into feeding
      difficulty.
- category: Neurologic
  name: Global Developmental Delay
  description: >-
    Severe developmental delay across motor, language and cognitive domains is
    the expected long-term outcome of CZS. No frequency band is recorded here
    deliberately. The published pooled prevalences for neurodevelopmental delay
    in ZIKV-exposed children are drawn from infants who were normocephalic and
    apparently unaffected at birth, which is a different population from the
    one this entry describes; applying those figures to CZS would understate
    the delay substantially. The CZS-specific series are small and selected for
    severity, so they establish that the delay is severe without supporting a
    percentage.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:39082517
    reference_title: "Clinical spectrum of congenital Zika virus infection in Brazil: Update and issues for research development."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Eighty-nine children with CZS and cerebral palsy undergoing rehabilitation showed evidence of severe developmental delays at the age of 1 year, according to the Bayley Scale of Infant and Toddler Development III (BSID-III)"
    explanation: >-
      Formal developmental assessment in a CZS cohort, establishing severity.
      The cohort is selected (children already in rehabilitation for cerebral
      palsy), which is why it supports the phenotype but not a frequency band.
- category: Growth
  name: Small for Gestational Age
  phenotype_term:
    preferred_term: Small for gestational age
    term:
      id: HP:0001518
      label: Small for gestational age
  evidence:
  - reference: PMID:33320867
    reference_title: "Congenital Zika syndrome: A systematic review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "abnormal visual function and low birthweight for gestational age"
    explanation: Low birthweight for gestational age among the defining features in the systematic review.

prevalence:
- population: Symptomatic ZIKV-infected pregnant women, Brazil (Ribeirao Preto region)
  measure_type: POINT_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 2500.0
  notes: >-
    Major signs of congenital Zika syndrome in 13 of 513 fetuses (2.5%) of
    symptomatic ZIKV-infected women in a prospective population-based cohort.
    This is a risk per infected pregnancy, not a population prevalence of the
    disease, and it is conditioned on the mother being symptomatic.
  evidence:
  - reference: PMID:32920998
    reference_title: "Early maternal Zika infection predicts severe neonatal neurological damage: results from the prospective Natural History of Zika Virus Infection in Gestation cohort study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of these, 13 (2.5%; 95% CI 1.5-4.3) presented with major signs of congenital Zika syndrome (CZS)."
    explanation: The proportion with major CZS signs, with its confidence interval.
- population: Liveborn infants of symptomatic ZIKV-infected women, Brazil
  measure_type: BIRTH_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 3900.0
  notes: >-
    Microcephaly or other CNS malformation in 19 of 489 liveborn infants (3.9%).
    Pregnancy losses occurred separately in 4.7% of the cohort, so the liveborn
    denominator understates total adverse outcomes.
  evidence:
  - reference: PMID:32920998
    reference_title: "Early maternal Zika infection predicts severe neonatal neurological damage: results from the prospective Natural History of Zika Virus Infection in Gestation cohort study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Microcephaly or other CNS malformations were diagnosed in 1/4 (25.0%) stillbirths and in 19/489 (3.9%; 95% CI 2.5-5.9) of the liveborn infants."
    explanation: Birth prevalence among liveborn infants, alongside the stillbirth figure.

diagnosis:
- name: Maternal gestational age at infection as the dominant risk determinant
  description: >-
    Timing of maternal infection is the single strongest predictor of fetal
    outcome, and is the reason this entry treats first-trimester exposure as
    the high-risk window rather than as a stylistic emphasis. Neuropathology
    agrees with the epidemiology: lesion severity tracks gestational age at
    infection.
  evidence:
  - reference: PMID:32920998
    reference_title: "Early maternal Zika infection predicts severe neonatal neurological damage: results from the prospective Natural History of Zika Virus Infection in Gestation cohort study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Fetal abnormalities were 14.0 (95% CI 7.6-26.0) times more likely with gestational infection occurring in ≤11 weeks."
    explanation: Quantifies the timing dependence with an effect size and interval.
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The severity of the lesions is directly related to the gestational age, the most severe occurring when the mother is infected in the first trimester."
    explanation: >-
      Independent pathological confirmation of the same gradient, from tissue
      rather than from outcome statistics.
- name: Screening of apparently unaffected exposed infants
  description: >-
    A normal examination at birth does not exclude CZS-spectrum injury. In
    follow-up of infants classified as asymptomatic, a small proportion had eye
    abnormalities or CNS imaging findings and a larger proportion had
    neurological alert signs by three months. Hearing testing is likewise
    recommended for all infants born to women with evidence of ZIKV infection,
    including those who appear normal at birth.
  evidence:
  - reference: PMID:32920998
    reference_title: "Early maternal Zika infection predicts severe neonatal neurological damage: results from the prospective Natural History of Zika Virus Infection in Gestation cohort study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "On follow up of 280 asymptomatic infants, 2/155 (1.3%) had eye abnormalities, 1/207 (0.5%) had CNS imaging findings and 16/199 (8%) presented neurological alert signs."
    explanation: Subclinical findings in infants who appeared unaffected, with denominators.
  - reference: PMID:27585248
    reference_title: "Hearing Loss in Infants with Microcephaly and Evidence of Congenital Zika Virus Infection - Brazil, November 2015-May 2016."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "all infants born to women with evidence of Zika virus infection during pregnancy should have their hearing tested, including infants who appear normal at birth"
    explanation: The screening recommendation that follows from ascertainment-dependent detection.

histopathology:
- name: Destructive cortical injury with calcification and migration disturbance
  description: >-
    The postmortem picture is destructive rather than purely hypoplastic, which
    is what distinguishes CZS from genetic primary microcephaly on tissue. It
    combines extensive parenchymal destruction, calcification, disturbed
    neuronal migration, and a reactive glial and microglial response, with
    occasional perivascular lymphocytic cuffing extending to the meninges.
  context: Postmortem CNS of fetuses and neonates infected early in gestation.
  evidence:
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "there is extensive destruction of the hemispheric parenchyma, calcifications, various disturbances of neuronal migration, reactive gliosis, microglial hyperplasia and occasional perivascular cuffs of lymphocytes, also in the meninges"
    explanation: >-
      The full histological description, including the inflammatory component
      that a purely developmental account would not predict.

differential_diagnoses:
- name: Other congenital (TORCH) infections
  description: >-
    Congenital cytomegalovirus and toxoplasmosis produce overlapping
    intracranial calcification, microcephaly, chorioretinal disease and hearing
    loss, and are the principal differential. The pattern of calcification and
    the presence of arthrogryposis help, but neither is decisive, so
    discrimination rests on laboratory confirmation of the agent rather than on
    imaging phenotype.
  distinguishing_features:
  - >-
    Arthrogryposis with normal joints and neurogenic electromyographic findings
    is characteristic of CZS and is not a usual feature of congenital CMV or
    toxoplasmosis.
  - >-
    Sensorineural hearing loss occurs in CZS at a frequency similar to that seen
    with other congenital viral infections, so it does not discriminate between
    them.
  evidence:
  - reference: PMID:27585248
    reference_title: "Hearing Loss in Infants with Microcephaly and Evidence of Congenital Zika Virus Infection - Brazil, November 2015-May 2016."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "which is similar to that seen in association with other congenital viral infections"
    explanation: >-
      States that the hearing-loss frequency does not separate CZS from the other
      congenital infections, which is why it is listed as a non-discriminating
      feature.
- name: Genetic primary microcephaly
  description: >-
    Autosomal recessive primary microcephaly converges on the same
    progenitor-depletion endpoint but differs pathologically: CZS is a
    destructive process with prominent cell death, necrosis and calcification,
    whereas genetic primary microcephaly is hypoplastic without those features.
    The distinction is made on tissue and imaging rather than on head
    circumference.
  distinguishing_features:
  - >-
    Calcification, parenchymal destruction and perivascular inflammation favour
    congenital infection over a germline progenitor defect.
  evidence:
  - reference: PMID:29167994
    reference_title: "Congenital Zika virus infection: a neuropathological review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "there is extensive destruction of the hemispheric parenchyma, calcifications, various disturbances of neuronal migration, reactive gliosis, microglial hyperplasia"
    explanation: >-
      The destructive, inflammatory signature that separates CZS from hypoplastic
      genetic microcephaly on histology.

treatments:
- name: Supportive Care
  description: >-
    There is no specific antiviral therapy for congenital Zika syndrome.
    Management is supportive and multidisciplinary, addressing feeding
    difficulties, seizures, spasticity, and developmental needs.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
- name: Physical and Developmental Therapy
  description: >-
    Early rehabilitative and developmental therapy to support motor function
    and mitigate the consequences of arthrogryposis and spasticity.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: physical therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
animal_models:
- name: Dengue-immune cynomolgus macaque ZIKV pregnancy model
  species: Cynomolgus macaque
  genotype: Wild type, DENV-immune prior to ZIKV challenge
  publication: PMID:37878671
  description: >-
    A nonhuman primate model of vertical transmission on a developmental
    timeline close to the human one, used to ask why some ZIKV-exposed fetuses
    are severely affected and others are not. Its answer is a maternal
    immunological one that this entry otherwise has no account of: prior dengue
    immunity worsens fetal outcome.
  modeled_mechanisms:
  - target: Impaired Neurogenesis and Congenital Cortical Malformation
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Fetuses of DENV-immune macaques infected with ZIKV in early pregnancy
      developed significantly more severe CZS than naive controls, with reduced
      cortical thickness and increased neuronal death, haemorrhage, cellular
      infiltration, calcification and lissencephaly — the same lesion set
      reported in human postmortem material.
    limitations: >-
      The enhancement is demonstrated in macaques and has not been shown to
      operate in human pregnancy, so it is a candidate explanation for the
      variable human severity rather than an established one. The model also
      cannot separate antibody-dependent enhancement from other consequences of
      prior flavivirus exposure.
    readouts:
    - name: Fetal head circumference and biparietal diameter by serial ultrasound
      target: Impaired Neurogenesis and Congenital Cortical Malformation
      direction: DECREASED
      interpretation: >-
        In vivo growth measurement across gestation, directly comparable to the
        human antenatal measure.
      evidence:
      - reference: PMID:37878671
        reference_title: "Exacerbated Zika virus-induced neuropathology and microcephaly in fetuses of dengue-immune nonhuman primates."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Ultrasound measurements of head circumference and biparietal diameter measurements taken sequentially throughout pregnancy demonstrated CZS in fetuses of DENV-immune pregnant macaques."
        explanation: The serial antenatal readout establishing microcephaly in the model.
    - name: Fetal brain histopathology
      target: Impaired Neurogenesis and Congenital Cortical Malformation
      direction: INCREASED
      interpretation: >-
        The lesion set matches human CZS neuropathology, which is what makes the
        model informative rather than merely a growth phenotype.
      evidence:
      - reference: PMID:37878671
        reference_title: "Exacerbated Zika virus-induced neuropathology and microcephaly in fetuses of dengue-immune nonhuman primates."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "severe CZS enhanced by DENV immunity was typified by reduced cortical thickness and increased frequency of neuronal death, hemorrhaging, cellular infiltrations, calcifications, and lissencephaly in fetal brains"
        explanation: The histological readouts, each of which has a human counterpart in this entry.
    evidence:
    - reference: PMID:37878671
      reference_title: "Exacerbated Zika virus-induced neuropathology and microcephaly in fetuses of dengue-immune nonhuman primates."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "We found significantly increased severity of congenital Zika syndrome (CZS) in fetuses of DENV-immune cynomolgus macaques infected with ZIKV in early pregnancy compared with naïve controls, which occurred despite no effect on maternal ZIKV infection or antibody responses."
      explanation: >-
        The core result, including the control that makes it a fetal rather than
        a maternal effect: maternal infection and antibody responses were
        unchanged.

discussions:
- discussion_id: gap_czs_human_model_translatability
  prompt: >-
    Which parts of the congenital Zika syndrome mechanism are directly supported
    in human fetal disease, and which remain model-dependent findings from human
    iPSC-derived neural progenitors, cerebral organoids, mouse embryos,
    non-human-primate organoids, or organotypic fetal systems?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Transplacental Viral Transfer to the Fetal Compartment
  - pathophysiology#Neurotropic Entry into Fetal Neural Progenitors
  - pathophysiology#Antiviral Innate Immune Activation
  - pathophysiology#Viral Mitotic and Centrosome Cytopathy
  - pathophysiology#Neural Progenitor Apoptosis and Pool Depletion
  - pathophysiology#Impaired Neurogenesis and Congenital Cortical Malformation
  rationale: >-
    The disease pathograph now conforms to the viral neural progenitor cytopathy
    module, but much of the causal resolution comes from experimental systems
    rather than longitudinal human fetal material. Human autopsy anchors viral
    brain invasion and destructive malformation, while iPSC-derived hNPCs,
    cerebral organoids, mouse embryos, and non-human-primate organoids resolve
    entry, TLR3/TBK1 signaling, centrosome perturbation, apoptosis, and strain
    adaptation. This gap prevents a single model system from being treated as
    complete proof of the human prenatal disease sequence.
  evidence:
  - reference: PMID:27279226
    reference_title: "The Brazilian Zika virus strain causes birth defects in experimental models."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Mouse models often fail to reproduce the severely reduced brain size and
      pathological alterations found in human patients21,22, likely due to
      significant differences in gestation time and brain development between
      the two species.
    explanation: >-
      The paper explicitly identifies species and developmental-context
      differences that limit translation from mouse CZS models.
  - reference: PMID:27279226
    reference_title: "The Brazilian Zika virus strain causes birth defects in experimental models."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Finally, our data using a non-human primate organoids suggested that the
      ZIKVBR might have experienced adaptive changes in human cells.
    explanation: >-
      Supports a strain- and host-cell-context mismatch gap for translating
      organoid and animal findings to human congenital infection.
  proposed_experiments:
  - experiment_id: exp_czs_cross_model_fetal_alignment
    name: CZS cross-model fetal-brain alignment experiment
    description: >-
      Compare matched ZIKV strains across human iPSC-derived cortical organoids,
      hNPC/radial-glial cultures, ethically available fetal cortical tissue or
      organotypic slices, and susceptible in vivo models, then map viral tropism,
      TLR3/TBK1 signaling, centrosome perturbation, apoptosis, progenitor loss,
      neurogenesis, and cortical thinning against human fetal autopsy endpoints.
    experiment_type:
      preferred_term: cross-model viral cortical malformation alignment experiment
    model_systems:
    - name: Human iPSC-derived cortical organoid ZIKV model
      description: >-
        Three-dimensional human cortical organoid system containing radial glia,
        neural progenitors, and early cortical neurons exposed to clinically
        relevant ZIKV strains.
      experimental_model_type: ORGANOID
      namo_type: namo:Organoid
      organism:
        preferred_term: human
        term:
          id: NCBITaxon:9606
          label: Homo sapiens
      tissue_term:
        preferred_term: cerebral cortex
        term:
          id: UBERON:0000956
          label: cerebral cortex
      cell_types:
      - preferred_term: radial glial cell
        term:
          id: CL:0000681
          label: radial glial cell
      - preferred_term: neural progenitor cell
        term:
          id: CL:0011020
          label: neural progenitor cell
      conditions:
      - congenital Zika syndrome
      - prenatal viral neural progenitor infection
      cell_source: Human induced pluripotent stem cells
      culture_system: Three-dimensional cortical organoid with controlled ZIKV exposure
    - name: Human fetal cortical tissue benchmark
      description: >-
        Postmortem or organotypic fetal cortical material, where ethically and
        legally available, used as a benchmark for viral localization, radial
        glial vulnerability, apoptosis, calcification, and cortical tissue
        architecture.
      experimental_model_type: PRIMARY_CELL_CULTURE
      organism:
        preferred_term: human
        term:
          id: NCBITaxon:9606
          label: Homo sapiens
      tissue_term:
        preferred_term: cerebral cortex
        term:
          id: UBERON:0000956
          label: cerebral cortex
      cell_types:
      - preferred_term: radial glial cell
        term:
          id: CL:0000681
          label: radial glial cell
      - preferred_term: neural progenitor cell
        term:
          id: CL:0011020
          label: neural progenitor cell
      conditions:
      - congenital Zika syndrome
      cell_source: Human fetal cortical tissue
      culture_system: Fetal cortical tissue benchmark or organotypic slice where available
    perturbations:
    - name: Matched congenital ZIKV strain exposure
      target: pathophysiology#Neurotropic Entry into Fetal Neural Progenitors
      description: >-
        Expose model systems to matched congenital outbreak isolates and
        laboratory-passaged controls under controlled inoculum and developmental
        timing.
    readouts:
    - name: Viral tropism and replication in radial glia and neural progenitors
      target: pathophysiology#Neurotropic Entry into Fetal Neural Progenitors
      biological_processes:
      - preferred_term: viral genome replication
        term:
          id: GO:0019079
          label: viral genome replication
        modifier: INCREASED
      assays:
      - preferred_term: viral RNA quantification
      - preferred_term: immunostaining
      - preferred_term: single-cell RNA sequencing
      direction: POSITIVE
    - name: Innate immune and centrosome cytopathy
      target: pathophysiology#Viral Mitotic and Centrosome Cytopathy
      biological_processes:
      - preferred_term: toll-like receptor signaling pathway
        term:
          id: GO:0002224
          label: toll-like receptor signaling pathway
        modifier: INCREASED
      - preferred_term: centrosome cycle
        term:
          id: GO:0007098
          label: centrosome cycle
        modifier: ABNORMAL
      assays:
      - preferred_term: phospho-TBK1 localization assay
      - preferred_term: centrosome immunostaining
      - preferred_term: single-cell RNA sequencing
      direction: POSITIVE
    - name: Progenitor survival and cortical growth
      target: pathophysiology#Neural Progenitor Apoptosis and Pool Depletion
      biological_processes:
      - preferred_term: apoptotic process
        term:
          id: GO:0006915
          label: apoptotic process
        modifier: INCREASED
      - preferred_term: neurogenesis
        term:
          id: GO:0022008
          label: neurogenesis
        modifier: DECREASED
      assays:
      - preferred_term: cleaved caspase-3 immunostaining
      - preferred_term: progenitor and neuron marker quantification
      - preferred_term: cortical thickness measurement
      direction: NEGATIVE
    controls:
    - name: Mock-infected controls
      description: Matched model systems exposed to vehicle without infectious virus.
    - name: Strain-matched heat-inactivated viral controls
      description: Controls for innate immune stimulation not requiring productive infection.
    decision_criterion: >-
      The CZS mechanism is strengthened if human organoids, fetal tissue
      benchmarks, and susceptible in vivo models show concordant radial-glial or
      progenitor tropism, TLR3/TBK1 and centrosome perturbation, apoptosis,
      progenitor depletion, reduced neurogenesis, and cortical thinning under
      matched strain and developmental timing. Major divergence would localize
      model-specific branches that should not be generalized to human CZS.
    would_support:
    - pathophysiology#Neurotropic Entry into Fetal Neural Progenitors
    - pathophysiology#Antiviral Innate Immune Activation
    - pathophysiology#Viral Mitotic and Centrosome Cytopathy
    - pathophysiology#Neural Progenitor Apoptosis and Pool Depletion
    - pathophysiology#Impaired Neurogenesis and Congenital Cortical Malformation
    would_refute:
    - pathophysiology#Viral Mitotic and Centrosome Cytopathy
    - pathophysiology#Neural Progenitor Apoptosis and Pool Depletion
- discussion_id: gap_czs_specific_therapy
  prompt: >-
    No approved antiviral or disease-modifying therapy exists for congenital
    Zika syndrome; candidate small molecules (e.g., nucleoside analogues) and
    TLR3-pathway modulation have shown effects only in experimental models.
    Which interventions, if any, can interrupt the progenitor-cytopathy cascade
    within the narrow prenatal therapeutic window?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Antiviral Innate Immune Activation
  - pathophysiology#Neural Progenitor Apoptosis and Pool Depletion
  rationale: >-
    Experimental evidence (e.g., TLR3 inhibition reducing ZIKV phenotypes in
    organoids) suggests mechanistically rational intervention points, but no
    therapy has translated to human prenatal use, and the destructive,
    early-onset nature of the progenitor cytopathy makes the therapeutic window
    extremely narrow. This gap motivates prevention (vector control, avoidance
    of exposure in pregnancy) as the current mainstay.
- discussion_id: mismatch_czs_tnt_placental_transmission
  prompt: >-
    Does tunneling-nanotube-mediated viral spread operate in the human placenta,
    and how much of the mouse placental-injury phenotype transfers to human
    congenital Zika disease?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Tunneling Nanotube-Mediated Intercellular Viral Spread
  - pathophysiology#Placental Infection
  - pathophysiology#Placental Architectural and Functional Disruption
  - pathophysiology#Fetal Growth Restriction
  - pathophysiology#Transplacental Viral Transfer to the Fetal Compartment
  rationale: >-
    The TNT arm of transplacental dissemination is established entirely in mouse
    pregnancy models, by comparing a TNT-competent virus with an NS1
    residue-40-52 TNT-deficient mutant. Two distinct translational questions
    follow. First, TNTs have not been demonstrated to carry ZIKV between cells
    in human placental tissue in vivo, so the mechanism is a strong candidate
    rather than an established human route. Second, and more concretely, the
    architectural readout does not transfer at all: the junctional zone and
    labyrinth are compartments of the rodent placenta with no direct human
    homolog, so "altered junctional-to-labyrinth architecture" cannot be
    restated as a human placental finding. The nearest human comparison points
    the other way: in full-term placentas from three ZIKV-infected women, viral
    NS3 antigen localized to Hofbauer cells while the placentas showed no
    anatomic defects (PMID:31709049, the publication behind the GSE139181
    dataset already curated in this entry) — a small series, and not a test of
    the TNT mechanism, but not obviously the same picture either. Fetal growth
    restriction is therefore curated as an ORGANISM-scale pathophysiology node
    carrying model-organism evidence, and is deliberately absent from
    `phenotypes:`, which would require human evidence.
  proposed_experiments:
  - experiment_id: exp_czs_tnt_human_placenta
    name: Detection of ZIKV-laden tunneling nanotubes in human placental explants
    description: >-
      Live imaging and correlative electron microscopy of ZIKV-infected primary
      human trophoblast and placental explant cultures, scoring actin-rich
      intercellular conduits carrying viral components, with the NS1
      residue-40-52 TNT-deficient mutant as the negative control.
  evidence:
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Here, we investigated the in vivo role of TNTs in ZIKV maternal-fetal transmission using complementary pregnancy models."
    explanation: Establishes that the in vivo evidence for the TNT arm comes from animal pregnancy models rather than human tissue.
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "ZIKVΔTNT infection was associated with reduced placental pathology, altered junctional-to-labyrinth architecture, improved placental efficiency, and protection from fetal growth restriction."
    explanation: Names the junctional-to-labyrinth readout, which is a rodent placental compartment measure with no human equivalent.
  - reference: PMID:31709049
    reference_title: "Immunological observations and transcriptomic analysis of trimester-specific full-term placentas from three Zika virus-infected women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although ZIKV NS3 antigens co-localised to placental Hofbauer cells, the placentas showed no anatomic defects."
    explanation: >-
      The human placental comparison invoked in this mismatch. Infected human
      placentas carried viral antigen without the structural defects the mouse
      models show.
- discussion_id: gap_czs_ns1_tnt_therapeutic_target
  prompt: >-
    Is the NS1 determinant of tunneling-nanotube formation (residues 40-52) a
    tractable antiviral target for preventing transplacental ZIKV transmission,
    and does the same TNT route operate in other vertically transmitted viruses?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Tunneling Nanotube-Mediated Intercellular Viral Spread
  rationale: >-
    A discrete viral protein determinant whose loss reduces dissemination,
    placental injury, and fetal growth restriction without abolishing viral
    viability is an unusually clean target hypothesis, and it addresses the
    transmission step rather than the downstream progenitor cytopathy — a much
    wider therapeutic window than the one the existing therapy gap describes.
    Nothing here has been tested as an intervention: the evidence is a
    genetically engineered mutant virus, not a drug or an antibody, and no
    NS1-directed agent has been shown to block TNT formation. The authors also
    raise, without testing, whether TNTs matter for other vertically transmitted
    or emerging viruses; that generalization has no evidence in this entry and
    should not be curated onto other disease entries on the strength of this
    paper alone.
  evidence:
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "These findings identify TNTs as a previously underappreciated pathway of viral transmission during pregnancy and suggest new therapeutic targets."
    explanation: The therapeutic-target claim is the authors' proposal, not a tested intervention, which is what makes this a gap rather than a treatment entry.
  - reference: PMID:42627154
    reference_title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "More broadly, TNTs may contribute to the pathogenesis of other vertically transmitted or emerging viral infections."
    explanation: Records the cross-pathogen generalization as an explicitly speculative statement.
- discussion_id: gap_czs_dengue_immunity_enhancement
  prompt: >-
    Does pre-existing maternal dengue immunity worsen fetal outcome in human
    congenital Zika syndrome, as it does in macaques?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Transplacental Viral Transfer to the Fetal Compartment
  - pathophysiology#Impaired Neurogenesis and Congenital Cortical Malformation
  - animal_models#Dengue-immune cynomolgus macaque ZIKV pregnancy model
  rationale: >-
    Why some ZIKV-exposed fetuses are severely affected and others are not is
    the largest unexplained variance in this disease, and the entry's timing
    account does not fully cover it. A nonhuman primate experiment supplies a
    candidate: fetuses of dengue-immune macaques infected in early pregnancy
    developed significantly worse CZS than naive controls, with no difference in
    maternal infection or antibody response — locating the effect in the fetus
    rather than in maternal viral control.

    The translational question is unusually consequential because ZIKV and DENV
    co-circulate across most of the affected geography, so a large share of
    women entering a Zika outbreak are dengue-immune. If the enhancement operates
    in humans, prior dengue serostatus would be a risk stratifier available
    before conception and would also bear on flavivirus vaccination strategy in
    women of childbearing age. If it does not, the macaque result localises a
    species-specific branch that should not inform human counselling.

    This is recorded as a mismatch rather than a knowledge gap because the
    evidence exists and is strong in the model; what is unknown is whether it
    transfers.
  proposed_experiments:
  - experiment_id: exp_czs_denv_serostatus_stratified_cohort
    name: DENV-serostatus-stratified prospective cohort of ZIKV-infected pregnancies
    description: >-
      In a prospective cohort of pregnancies with confirmed ZIKV infection,
      determine pre-pregnancy or first-trimester DENV serostatus and compare the
      incidence and severity of CZS between DENV-immune and DENV-naive mothers,
      stratifying by gestational age at infection so the two risk factors are not
      confounded.
    would_support:
    - pathophysiology#Impaired Neurogenesis and Congenital Cortical Malformation
    supporting_outcome:
    - >-
      CZS is more frequent or more severe in the offspring of DENV-immune
      mothers after adjustment for timing, supporting transfer of the macaque
      enhancement to human pregnancy.
    refuting_outcome:
    - >-
      CZS incidence and severity are independent of maternal DENV serostatus,
      indicating the enhancement is model-specific and should not be used for
      human risk stratification.

datasets:
- accession: geo:GSE234062
  title: Human Otic progenitor cell models of congenital hearing loss applied to to Zika virus and cytomegalovirus infections
  description: Congenital hearing loss is a common chronic condition affecting children in both developed and developing nations. In many cases, congenital hearing loss is ultimately attributed to viral infection, most often by cytomegalovirus (CMV), but also in Congenital Zika Syndrome (CZS). The mechanisms by which CMV and ZIKV virus cause these cranial developmental defects have not been elucidated. Inner ear development has been particularly difficult to study, given the inaccessibility and scarcity of the tissue in animal models or on human autopsy; however, it is now possible to culture stem-cell derived otic progenitor cells (OPCs).
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 36
  publication: PMID:38440980
  notes: Identified by GEO DataSets index search for Congenital Zika Syndrome (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
- accession: geo:GSE102128
  title: RNA-seq of hiPSCs-derived NPCs from 3 pairs of dizygotic discordant twins for Congenital Zika syndrome
  description: Congenital Zika syndrome (CZS), caused by Zika virus (ZIKV) infection, has been associated to impairment of early brain development, particularly related to neural progenitor cells (NPCs) survival and growth. In this work we report in a high-throughput manner (RNA-Seq) the differences in the transcriptomes of hiPSCs(human induced pluripotent stem cells)-derived NPCs from 3 pairs of discordant twins for Congenital Zika syndrome (CZS).
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 6
  publication: PMID:29396410
  notes: Identified by GEO DataSets index search for Congenital Zika Syndrome (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
- accession: geo:GSE139181
  title: Transcriptomics analysis of trimester-specific full-term placentas from three Zika virus-infected women
  description: Effects of Zika virus (ZIKV) infection on placental development during pregnancy are unclear. In this study, full-term placentas from three women, each infected with ZIKV during specific pregnancy trimesters, were harvested for anatomic, immunologic and transcriptomic analysis. Each woman exhibited a unique immune response with raised IL-1RA, IP-10, EGF and RANTES expression, and neutrophil numbers during the acute infection phase. Although ZIKV NS3 antigens co-localized to placental Hofbauer cells, the placentas showed no anatomical defects.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 33
  publication: PMID:31709049
  notes: Identified by GEO DataSets index search for Congenital Zika Syndrome (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.

references:
- reference: PMID:26862926
  title: "Zika Virus Associated with Microcephaly."
- reference: PMID:26952870
  title: "Zika Virus Infects Human Cortical Neural Progenitors and Attenuates Their Growth."
- reference: PMID:27038591
  title: "Expression Analysis Highlights AXL as a Candidate Zika Virus Entry Receptor in Neural Stem Cells."
- reference: PMID:27064148
  title: "Zika virus impairs growth in human neurospheres and brain organoids."
- reference: PMID:27066743
  title: "Type III Interferons Produced by Human Placental Trophoblasts Confer Protection against Zika Virus Infection."
- reference: PMID:27162029
  title: "Zika Virus Depletes Neural Progenitors in Human Cerebral Organoids through Activation of the Innate Immune Receptor TLR3."
- reference: PMID:27179424
  title: "Zika Virus Disrupts Neural Progenitor Development and Leads to Microcephaly in Mice."
- reference: PMID:27247001
  title: "Zika Virus Infects Human Placental Macrophages."
- reference: PMID:27279226
  title: "The Brazilian Zika virus strain causes birth defects in experimental models."
- reference: PMID:27443522
  title: "Zika Virus Targets Different Primary Human Placental Cells, Suggesting Two Routes for Vertical Transmission."
- reference: PMID:27509902
  title: "Congenital Zika syndrome with arthrogryposis: retrospective case series study."
- reference: PMID:27568284
  title: "Zika Virus Disrupts Phospho-TBK1 Localization and Mitosis in Human Neuroepithelial Stem Cells and Radial Glia."
- reference: PMID:27585248
  title: "Hearing Loss in Infants with Microcephaly and Evidence of Congenital Zika Virus Infection - Brazil, November 2015-May 2016."
- reference: PMID:28132835
  title: "Recent Zika Virus Isolates Induce Premature Differentiation of Neural Progenitors in Human Brain Organoids."
- reference: PMID:29167994
  title: "Congenital Zika virus infection: a neuropathological review."
- reference: PMID:30252119
  title: "Zika Virus Infection during Pregnancy and Sensorineural Hearing Loss among Children at 3 and 24 Months Post-Partum."
- reference: PMID:31709049
  title: "Immunological observations and transcriptomic analysis of trimester-specific full-term placentas from three Zika virus-infected women."
- reference: PMID:32065676
  title: "Early epilepsy in children with Zika-related microcephaly in a cohort in Recife, Brazil: Characteristics, electroencephalographic findings, and treatment response."
- reference: PMID:32920998
  title: "Early maternal Zika infection predicts severe neonatal neurological damage: results from the prospective Natural History of Zika Virus Infection in Gestation cohort study."
- reference: PMID:33320867
  title: "Congenital Zika syndrome: A systematic review."
- reference: PMID:37878671
  title: "Exacerbated Zika virus-induced neuropathology and microcephaly in fetuses of dengue-immune nonhuman primates."
- reference: PMID:39082517
  title: "Clinical spectrum of congenital Zika virus infection in Brazil: Update and issues for research development."
- reference: PMID:41460891
  title: "Characterization of 843 children with Zika-related microcephaly in the first three years of life: An individual participant data meta-analysis of 12 cohorts in the Zika Brazilian Cohorts consortium."
- reference: PMID:42627154
  title: "Tunneling nanotubes contribute to Zika virus pathogenesis at the maternal-fetal interface in vivo."

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