This is a mechanism module, not a broad "periventricular heterotopia" disease entry. Disorder entries should use conforms_to only when the core pathograph involves apical radial-glial, ventricular-lining, adherens-junction, ciliary, vesicle-trafficking, or apical progenitor-polarity failure. Do not use this as the primary skeleton for isolated postmitotic microtubule-dependent neuronal migration defects, pial basement-membrane/radial-glial endfoot failure, Reelin terminal-translocation signaling defects, interneuron migration defects, or generic heterotopia without a defended apical-neuroependyma mechanism. NEDD4L-related PVH should conform here only for the PVH/apical positioning branch; broader PI3K-AKT-mTOR cortical overgrowth belongs in a separate mTOR-overgrowth module.
Apical Neuroependyma Integrity Failure Model
apical_neuroependyma_integrity_model
CANONICAL
Evidence: 3
Evidence balance
3 support
Radial glia and neural progenitors maintain an apical ventricular interface through actin scaffolding, cadherin/catenin adhesion, vesicle trafficking, ciliary/basal-body positioning, and regulated progenitor signaling. Pathogenic variants or perturbations in FLNA, ARFGEF2, FAT4, DCHS1, NEDD4L, ERMARD/C6orf70, GNAI2, TMEM67-associated complexes, or interacting pathways can weaken this apical scaffold. The resulting ventricular-lining disruption mispositions progenitors or neurons near the lateral ventricles, alters local progenitor output, and can produce periventricular heterotopic nodules with secondary neuronal migration or terminal-translocation defects.
Which apical-neuroependyma defects are conserved in rodent knockdown or knockout models, and which require human iPSC-derived neuroepithelial rosettes, cortical organoids, fetal tissue, or gyrencephalic models to capture human ventricular-zone and OSVZ biology?
HUMAN MODEL MISMATCH
OPEN
gap_apical_neuroependyma_human_model_translatability
Attached to:
Apical Junction, Ciliary, and Vesicle-Trafficking Perturbation
Ventricular Lining Breaks and Apical Detachment
The seed review repeatedly treats rodent/human mismatch as a knowledge gap for malformations of cortical development. For this module, the key risk is that acute in utero knockdown, mouse knockout, and non-neural cell systems may identify proximal adhesion, trafficking, ciliary, or migration defects but may not fully recapitulate human radial-glial apical organization, oRG/OSVZ context, nodular heterotopia formation, seizure propensity, or developmental compensation. Curation should represent this as a human/model-mismatch knowledge gap until a controlled gap subtype exists.
Proposed experiments:
Isogenic apical-neuroependyma organoid and rosette rescue panel
Apical Junction, Ciliary, and Vesicle-Trafficking Perturbation
trigger
Disease genes and interacting proteins perturb the radial-glial apical apparatus through actin scaffolding, cadherin/catenin adhesion, vesicle trafficking from Golgi or endosomal compartments, cilium/basal-body positioning, or apical signaling. Representative branches include FLNA-dependent actin and receptor scaffolding, ARFGEF2/BIG2-dependent vesicle trafficking, FAT4/DCHS1 cadherin signaling, FLNA-TMEM67/meckelin ciliogenesis, and NEDD4L pathway regulation.
Downstream
-
Ventricular Lining Breaks and Apical Detachment
Ventricular Lining Breaks and Apical Detachment
central effector
The apical ventricular interface loses epithelial continuity, radial-glial endfoot organization, or apical-abscission control. This can denude or break the ventricular lining, weaken radial-glial scaffold continuity, and allow progenitors or newborn neurons to remain near the lateral ventricles.
Downstream
-
Mislocalized Progenitors and Ectopic Periventricular Neurogenesis
-
Secondary Neuronal Positioning and Migration Defects
Mislocalized Progenitors and Ectopic Periventricular Neurogenesis
effector
Apical scaffold failure changes progenitor position, progenitor pool size, and local neurogenic output near the ventricle. Depending on the branch, intermediate progenitors can be mislocalized in the periventricular space, Pax6-positive progenitors can accumulate near ventricles, or local neurovascular signaling can increase ectopic neuron production without necessarily blocking normal neocortical neuron production.
Downstream
-
Periventricular Heterotopic Nodules
Ciliogenesis and Basal Body Positioning Branch
amplifier
In some FLNA-associated or ciliopathy-overlap cases, the apical module may operate through a FLNA-TMEM67/meckelin complex required for cilium assembly, basal-body positioning, Wnt signaling, and apical ventricular organization. This branch should be used only when the disorder entry has evidence that ciliary/basal-body disruption is part of the pathograph.
Downstream
-
Ventricular Lining Breaks and Apical Detachment
-
Mislocalized Progenitors and Ectopic Periventricular Neurogenesis
NEDD4L AKT-mTOR Signaling Branch
amplifier
NEDD4L HECT-domain variants define a PVH branch where an E3 ubiquitin ligase perturbation affects neurogenesis, neuronal positioning, terminal translocation, and PI3K-AKT-mTOR pathway activity. This branch can overlap the broader mTOR cortical-overgrowth module, but in this module it is used only when the pathograph is anchored by PVH/apical positioning rather than generalized cortical overgrowth.
Downstream
-
Secondary Neuronal Positioning and Migration Defects
-
Periventricular Heterotopic Nodules
Secondary Neuronal Positioning and Migration Defects
effector
Some conforming disorders show delayed radial migration, abnormal terminal translocation, impaired neuronal morphology, or failure of newborn neurons to leave the ventricular region. In this module those defects are modeled as downstream or branch-specific consequences unless evidence shows a primary cell-autonomous neuronal locomotion mechanism.
Downstream
-
Periventricular Heterotopic Nodules
Periventricular Heterotopic Nodules
outcome
The downstream anatomic result is ectopic neuronal nodules along the lateral or telencephalic ventricles, often with epilepsy, developmental delay, or additional malformations depending on the branch. This node is a module endpoint, not a disease-entry lumping criterion by itself.