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Inheritance

1

Autosomal Dominant HP:0000006

Heterozygous NEDD4L variants act dominantly. Most arise de novo, but low-level parental germline/somatic mosaicism has been documented in two families, and one family transmits the WW-domain variant p.Arg208Gln through a non-mosaic mother with intrafamilial variability ranging from isolated heterotopia to severe epilepsy.

Autosomal dominant inheritance Expressivity: VARIABLE

Show evidence (3 references)

PMID:32117442 SUPPORT Human clinical

"While six pathogenic variants occurred de novo, parental mosaicism accounts for three reported cases"

Summarises the de novo and parental-mosaic origins of the reported variants.

PMID:32117442 SUPPORT Human clinical

"We describe the first familial occurrence, not associated with parental mosaicism, of a pathogenic variant in the NEDD4L gene with broad intra-familial phenotypic variability, varying from relatively well-functioning carriers with isolated PNH on brain MRI, to a severely affected case with..."

Documents dominant transmission with variable expressivity in a single family.

PMID:30393983 SUPPORT Human clinical

"The observation of parental mosaicism in two out of seven families with NEDD4L-associated PVNH warrants caution and should be specifically addressed in parental carrier testing and genetic counseling."

Parental mosaicism raises recurrence risk above that expected for a de novo dominant variant.

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Discussions and Knowledge Gaps

3

Do PVNH7 variants act by increasing NEDD4L ligase activity (gain of function) or by reducing it (loss of function)?

CONTROVERSY OPEN controversy_nedd4l_gain_vs_loss_of_function

Attached to

pathophysiology#Aberrant NEDD4L Ubiquitin Ligase Activity

For HECT-domain variants the functional data point to preserved or enhanced, constitutively activated ubiquitination with self-promoted degradation of the mutant protein, and overexpression of wild-type NEDD4L reproduces the neuronal positioning defect, which is hard to reconcile with simple loss of function. The WW-domain variant p.Arg208Gln is instead interpreted, from structure, as a loss of substrate recognition. Truncating NEDD4L variants are present in population controls, arguing against haploinsufficiency. The net effect on specific substrates in the developing cortex is unmeasured.

Show evidence (3 references)

PMID:27694961 SUPPORT In vitro / ex vivo

"Altogether these results suggest that ubiquitination activity of NEDD4L mutant is preserved and possibly enhanced if we take into account the significant level of ubiquitination activity despite the instability of the protein."

Supports the gain-of-function reading for HECT-domain variants.

PMID:27694961 SUPPORT Human clinical

"Moreover, 3 frameshift and 1 stop gained mutations were reported in the data set of Exome Aggregation Consortium in which individuals affected by severe paediatric disease have been excluded."

Truncating variants in unaffected population controls argue against haploinsufficiency.

PMID:32117442 REFUTE Computational

"We hypothesize that conformational changes cause a loss of function of the WW domain leading to impaired recognition of substrates and ultimately to loss of protein function."

Proposes a loss-of-function mechanism for the WW-domain variant, contrary to the gain-of-function reading.

By what mechanism do NEDD4L variants cause cleft palate, toe syndactyly and hypospadias?

KNOWLEDGE GAP OPEN gap_nedd4l_extraneural_malformations

Attached to

phenotypes#Cleft palate phenotypes#2-3 toe syndactyly phenotypes#Hypospadias

The cortical mechanism has been studied in the embryonic mouse brain, but no study has examined NEDD4L variants in palatal, limb-bud or genital tubercle development, so these consistent extra-neural features have no mechanism node in this entry.

Show evidence (1 reference)

PMID:30393983 SUPPORT Human clinical

"Interestingly, clefting of the palate and syndactyly of the toes 2–3 appear to be quite consistent features, indicating a broader role of the NEDD4L gene product beyond initiation of neuronal migration."

Notes that the extra-neural features imply roles of NEDD4L outside neuronal migration.

By what mechanism do NEDD4L variants produce the seizures, developmental delay and intellectual disability of PVNH7, and does any of it act independently of the heterotopia?

KNOWLEDGE GAP OPEN gap_nedd4l_seizures_and_neurodevelopmental_impairment

Attached to

phenotypes#Seizures phenotypes#Infantile spasms phenotypes#Global developmental delay phenotypes#Intellectual disability

The PVNH7 literature reports how often these features occur, not how they arise, so no causal edge in this entry reaches them. A direct heterotopia-to-seizure edge would rest only on the general association of cortical malformations with epilepsy: within the single reported family carrying p.Arg208Gln, carriers with periventricular nodular heterotopia on MRI ranged from relatively well-functioning with isolated heterotopia to a severely affected case with refractory seizures, so the malformation does not by itself predict the seizure phenotype. A malformation-independent route has been proposed from mouse work: NEDD4L (Nedd4-2) ubiquitinates the AMPA-receptor subunit GluA1 and limits its surface expression, and elevated seizure susceptibility in a Nedd4-2-deficient mouse is corrected by genetically reducing GluA1. That lead does not transfer cleanly to PVNH7, for two reasons recorded in the gain-of-function controversy on this entry: the mouse is a loss of NEDD4L, whereas PVNH7 HECT-domain variants appear to preserve or increase ligase activity, and the variants shown to disrupt GluA1 ubiquitination were from patients with isolated epilepsy, not the PVNH7 variants. It is therefore recorded here as a hypothesis to test rather than as a causal edge.

Proposed experiments

PVNH7 HECT-domain variants in a GluA1 ubiquitination and neuronal-activity assay

ubiquitination and neuronal-activity assay

exp_pvnh7_variant_glua1_ubiquitination_and_activity

Express the PVNH7 HECT-domain variants (for example p.Glu893Lys, p.Gln900Arg) alongside wild-type NEDD4L and assess GluA1 ubiquitination, GluA1 surface expression, and spontaneous neuronal activity, to test whether these gain-of-function-leaning variants alter the GluA1 route in the same direction as the isolated-epilepsy loss-of-function variants.

Readouts

GluA1 ubiquitination and surface expression by PVNH7 variant

phenotypes#Seizures

ubiquitination assay

Direction: ALTERED

Interpretation: A change in GluA1 ubiquitination or surface level with a PVNH7 variant would support a malformation-independent route to the seizure phenotype.

Controls

Wild-type NEDD4L

Wild-type ligase as the GluA1-ubiquitination reference.

Decision criterion

The GluA1 route is supported for PVNH7 if its HECT-domain variants measurably change GluA1 ubiquitination, surface GluA1, or spontaneous neuronal activity relative to wild-type NEDD4L.

Would support

phenotypes#Seizures

Show evidence (2 references)

PMID:32117442 SUPPORT Human clinical

"varying from relatively well-functioning carriers with isolated PNH on brain MRI, to a severely affected case with profound developmental delay, refractory seizures, and PNH-PMG."

Within one p.Arg208Gln family, carriers with heterotopia on MRI span from no seizures to refractory epilepsy, showing the malformation does not by itself explain the seizure phenotype.

PMID:28212375 SUPPORT INDIRECT Model organism

"elevated seizure susceptibility in Nedd4-2andi mice was normalized when GluA1 is genetically reduced"

Mouse evidence for a GluA1-dependent route from NEDD4L dysfunction to seizures. Cited as the hypothesis the proposed experiment would test; it is indirect for PVNH7 because the model is a NEDD4L loss of function and the tested variants are isolated-epilepsy variants, not the PVNH7 HECT-domain variants.

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Pathophysiology

4

NEDD4L Missense Variant

Heterozygous germline missense variants in NEDD4L. Nearly all reported variants map to the C-terminal catalytic HECT domain (for example p.Glu873Lys, p.Glu893Lys, p.Arg897Gln, p.Gln900Arg); the recurrent p.Arg208Gln lies in a WW substrate-recognition domain.

Genetic context variant_origin: GERMLINE

Downstream

Aberrant NEDD4L Ubiquitin Ligase Activity

Show evidence (2 references)

PMID:27694961 SUPPORT Human clinical

"Here we show that missense mutations in NEDD4L mapping to the HECT domain of the encoded E3 ubiquitin ligase lead to PNH associated with toe syndactyly, cleft palate and neurodevelopmental delay."

Establishes HECT-domain missense variants in NEDD4L as the cause of the disease.

PMID:32117442 SUPPORT Human clinical

"All tested patients carry the recurrent variant c.623G > A, p.(Arg208Gln) in the WW domain of NEDD4L."

Extends the variant spectrum beyond the HECT domain to a WW-domain variant.

Aberrant NEDD4L Ubiquitin Ligase Activity

HECT-domain variants leave the ligase catalytically active, apparently enhancing its activity, while making the mutant protein sensitive to proteasomal degradation, so less NEDD4L protein carries more activity per molecule. A WW-domain variant is instead proposed to impair substrate recognition (loss of function); the direction of the net effect is recorded as a controversy in discussions.

NEDD4L hgnc:7728

ubiquitin protein ligase activity GO:0061630 ↕ DYSREGULATED

Downstream

AKT-mTOR and TGF-beta Signalling Deregulation

Show evidence (2 references)

PMID:27694961 SUPPORT In vitro / ex vivo

"Altogether these results suggest that ubiquitination activity of NEDD4L mutant is preserved and possibly enhanced if we take into account the significant level of ubiquitination activity despite the instability of the protein."

In vitro ubiquitination assays show the HECT mutants remain active and possibly hyperactive.

PMID:27694961 SUPPORT In vitro / ex vivo

"Cellular and expression data showed sensitivity of PNH-associated mutants to proteasome degradation."

Shows the mutant proteins are unstable and degraded by the proteasome.

AKT-mTOR and TGF-beta Signalling Deregulation

In neuronal cells, PVNH-associated NEDD4L mutants raise phosphorylated S6 (mTORC1 activity) and phosphorylated AKT (Thr308 and Ser473), and disturb the cross-talk between AKT and Smad2/3 in activin/TGF-beta signalling. A patient lymphoblastoid cell line did not show increased AKT-mTOR activity, so the magnitude of the effect at endogenous expression is uncertain. Dab1 (Reelin pathway) disruption is not recorded here because, in the same study, it was caused by excess wild-type NEDD4L rather than by the patient mutants.

neural progenitor cell CL:0011020 neuron CL:0000540

TORC1 signaling GO:0038202 ↑ INCREASED PI3K/AKT signal transduction GO:0043491 ↑ INCREASED TGF-beta/activin Smad2/3 signalling GO:0007179 ↕ DYSREGULATED

Downstream

Disrupted Neurogenesis and Neuronal Positioning

Show evidence (3 references)

PMID:27694961 SUPPORT In vitro / ex vivo

"In contrast, for AKT, only PNH-associated NEDD4L mutants are associated with significantly increased level of Thr308 and Ser473 phosphorylated forms of Akt"

Mutant-specific AKT hyperactivation in transfected neuronal cells.

PMID:27694961 SUPPORT In vitro / ex vivo

"Collectively, these results suggested that expression of NEDD4L mutant lead to a disruption of the regulated cross talk between Akt and Smad2/3 signalling in activin/TGF-β pathways."

Supports disrupted TGF-beta/Smad2/3 signalling by the mutant ligase.

PMID:28515470 REFUTE In vitro / ex vivo

"our western blot analysis did not show an increased level of AKT-mTOR activity in lymphoblastoid cell lines (LCLs) derived from the patient."

Patient-derived cells at endogenous expression did not reproduce AKT-mTOR hyperactivation, qualifying the overexpression result.

Disrupted Neurogenesis and Neuronal Positioning

In utero electroporation of PVNH mutants into the embryonic mouse cortex arrests neurons in the ventricular/subventricular and intermediate zones with depletion of the cortical plate, alters progenitor proliferation, and disrupts terminal translocation. The arrested neurons still acquire upper-layer identity, so the defect is in positioning rather than fate.

neuron CL:0000540 neural progenitor cell CL:0011020

neuron migration GO:0001764 ↓ DECREASED neurogenesis GO:0022008 ↕ DYSREGULATED

cerebral cortex UBERON:0000956

Downstream

Periventricular nodular heterotopia

Show evidence (2 references)

PMID:27694961 SUPPORT Model organism

"Moreover, an in utero electroporation approach showed that PNH-related mutants and excess wild-type NEDD4L affect neurogenesis, neuronal positioning and terminal translocation."

In vivo demonstration that the patient mutants disturb neurogenesis and neuronal positioning in the developing cortex.

PMID:27694961 SUPPORT Model organism

"However, IUEP of WT NEDD4L, and PNH-related mutants induced a significant arrest of cells within the ventricular/sub-ventricular zone (VZ/SVZ) and intermediate zone (IZ) with a corresponding depletion in the CP"

Neurons expressing the mutants arrest near the ventricle instead of reaching the cortical plate.

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Pathograph

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Phenotypes

13

Eye 2

Foveal hypoplasia Hypoplasia of the fovea HP:0007750

Show evidence (1 reference)

PMID:35577021 SUPPORT Human clinical

"We have summarized the clinical findings that have been reported in this disorder previously and highlight a novel ophthalmic finding of foveal hypoplasia in a new case of NEDD4L-related disorder."

Reports foveal hypoplasia in a single NEDD4L-related case.

Strabismus HP:0000486

Show evidence (1 reference)

PMID:34087865 SUPPORT Human clinical

"such as delayed psychomotor and mental development, seizures and infantile spasms, periventricular nodular heterotopia, polymicrogyria, cleft palate, 2 to 3 toe syndactyly, hypotonia, microretrognathia, strabismus, and absent speech and walking."

Strabismus in a patient with the de novo p.Glu893Lys variant.

Genitourinary 1

Hypospadias HP:0000047

Show evidence (1 reference)

PMID:32117442 SUPPORT Human clinical

"An unrelated patient presented with severe neurodevelopmental delay, seizures, and hypospadias, expanding the phenotypic spectrum."

Reports hypospadias as part of the phenotypic spectrum.

Head and Neck 1

Cleft palate FREQUENT HP:0000175

Show evidence (1 reference)

PMID:36934385 SUPPORT Human clinical

"Among them, 53% also exhibited cleft palate, while 46% experienced seizures."

Cleft palate occurred in 53% of reported patients.

Limbs 2

2-3 toe syndactyly VERY_FREQUENT HP:0004691

Show evidence (2 references)

PMID:36934385 SUPPORT Human clinical

"we observed that nearly all 15 patients (seven male, eight female) in the 11 reported families presented with psychomotor retardation, hypotonia, and variable degrees of syndactyly (usually second/third toe)."

Toe syndactyly, usually of toes 2-3, was present in nearly all reported patients.

PMID:30393983 SUPPORT Human clinical

"The consistently observed syndromic features of cleft palate and syndactyly 2–3 emerge as characteristic hallmarks in the differential diagnosis to FLNA‐associated PVNH."

Toe syndactyly and cleft palate distinguish this disorder from FLNA-related heterotopia.

Talipes equinovarus HP:0001762

Show evidence (1 reference)

PMID:30393983 SUPPORT Human clinical

"In contrast to truncal hypotonia, the girl showed bilateral talipes equinovarus and muscular hypertonia on both legs."

Bilateral talipes equinovarus in a patient with a NEDD4L variant.

Musculoskeletal 1

Hypotonia VERY_FREQUENT HP:0001252

Show evidence (1 reference)

PMID:36934385 SUPPORT Human clinical

"we observed that nearly all 15 patients (seven male, eight female) in the 11 reported families presented with psychomotor retardation, hypotonia, and variable degrees of syndactyly (usually second/third toe)."

Hypotonia was present in nearly all reported patients.

Nervous System 6

Periventricular nodular heterotopia VERY_FREQUENT HP:0032388

Show evidence (1 reference)

PMID:28515470 SUPPORT Human clinical

"All patients reported with NEDD4L HECT domain mutations showed periventricular nodular heterotopia, and most had seizures, cortex anomalies, cleft palate and syndactyly."

Periventricular nodular heterotopia was universal among reported HECT-domain cases.

Polymicrogyria FREQUENT Perisylvian polymicrogyria HP:0012650

Show evidence (2 references)

PMID:36934385 SUPPORT Human clinical

"Previously reported imaging features included bilateral or unilateral PVNH, with 33% exhibiting polymicrogyria."

Gives the frequency of polymicrogyria across reported cases.

PMID:32117442 SUPPORT Human clinical

"MRI revealed bilateral PNH and perisylvian polymicrogyria."

Documents the perisylvian distribution of the polymicrogyria.

Global developmental delay VERY_FREQUENT HP:0001263

Show evidence (1 reference)

PMID:36934385 SUPPORT Human clinical

"we observed that nearly all 15 patients (seven male, eight female) in the 11 reported families presented with psychomotor retardation, hypotonia, and variable degrees of syndactyly (usually second/third toe)."

Psychomotor retardation was present in nearly all 15 reported patients.

Intellectual disability HP:0001249

Show evidence (1 reference)

PMID:34087865 SUPPORT REVIEW SYNTHESIS Human clinical

"All patients suffered from intellectual disability, periventricular nodular heterotopia and syndactyly, predominantly between 2nd and 3rd toes except a patient with 3 to 4 and 3 to 4 to 5 syndactyly."

The case report's summary of the five p.Arg208Gln patients reported by Stouffs et al. (PMID:32117442); the sentence directly follows "Stouffs et al reported 5 patients of which 4 were related". All five had intellectual disability.

Seizures FREQUENT HP:0001250

Show evidence (1 reference)

PMID:36934385 SUPPORT Human clinical

"Among them, 53% also exhibited cleft palate, while 46% experienced seizures."

Seizures occurred in 46% of reported patients.

Infantile spasms HP:0012469

Show evidence (1 reference)

PMID:28515470 SUPPORT Human clinical

"showing severe global developmental delay, infantile spasms, cleft palate, periventricular nodular heterotopia and polymicrogyria."

Infantile spasms in a patient with a de novo HECT-domain variant.

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Genetic Associations

1

NEDD4L

Gene: NEDD4L hgnc:7728 gene page relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (2 references)

PMID:27694961 SUPPORT Human clinical

"Here we show that missense mutations in NEDD4L mapping to the HECT domain of the encoded E3 ubiquitin ligase lead to PNH associated with toe syndactyly, cleft palate and neurodevelopmental delay."

Identifies NEDD4L as the causative gene.

CGGV:assertion_b131d46a-069b-4c2e-a290-e7df2519a2df-2021-11-30T170000.000Z SUPPORT Other

ClinGen classifies the gene-disease relationship as Definitive.

Variants (5)

p.Glu893Lys Pathogenic

De novo HECT-domain missense variant (c.2677G>A) reported in the original series and again in a later case with PVNH, polymicrogyria, cleft palate, toe syndactyly and infantile spasms.

Show evidence (1 reference)

PMID:34087865 SUPPORT Human clinical

"We successfully identified the causative mutation NM_001144967.2(NEDD4L):c.2677G>A:p.Glu893Lys explaining symptoms overlapping those reported for PVNH7."

Identifies p.Glu893Lys as causative in a PVNH7 patient.

p.Glu873Lys Pathogenic

De novo HECT-domain variant (c.2617G>A) in a girl with PVNH, polymicrogyria, infantile spasms and cleft palate.

Show evidence (1 reference)

PMID:28515470 SUPPORT Human clinical

"We identified a novel de novo heterozygous missense mutation in the NEDD4L gene (NM_015277: c.2617G>A; p.Glu873Lys) through whole-exome sequencing"

Reports the de novo p.Glu873Lys variant.

p.Gln900Arg Likely pathogenic

De novo HECT-domain variant; the mutant protein is reduced by about 41% in transfected cells, consistent with constitutive activation and self-degradation.

Show evidence (1 reference)

PMID:36934385 SUPPORT In vitro / ex vivo

"RT-PCR results indicated that the mutation did not affect mRNA expression, whereas WB and IF results indicated that the level of mutant protein was significantly reduced by 41.07%."

The variant reduces NEDD4L protein without changing mRNA.

p.Tyr679His Pathogenic

Variant transmitted from a father with about 10% somatic mosaicism to a daughter with PVNH, cleft palate and toe syndactyly, and to a fetus with hypokinesia and flexion contractures.

Show evidence (1 reference)

PMID:30393983 SUPPORT Human clinical

"Here, we describe a girl with a novel heterozygous NEDD4L missense variant, p.Tyr679His, and characteristic clinical findings, including bilateral periventricular nodular heterotopia, cleft palate and mild toe syndactyly."

Reports the variant and its characteristic phenotype.

p.Arg208Gln Pathogenic

Recurrent WW-domain variant (c.623G>A), familial in one family with marked variability and de novo in an unrelated patient; proposed to cause loss of function by impairing substrate recognition.

Show evidence (1 reference)

PMID:32117442 SUPPORT Human clinical

"All tested patients carry the recurrent variant c.623G > A, p.(Arg208Gln) in the WW domain of NEDD4L. The variant in the unrelated patient occurred de novo."

Reports the recurrent WW-domain variant in a family and an unrelated de novo case.

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Medical Actions

3

Anti-seizure medication

Action: Pharmacotherapy NCIT:C15986

Platform: Small molecule

Symptomatic anti-seizure pharmacotherapy. Seizures are often refractory, although valproate controlled them in one reported patient.

Show evidence (2 references)

PMID:36934385 SUPPORT Human clinical

"Some children will have their first seizure in infancy, and antiepileptic therapy, including in the present patient, has generally been ineffective"

Anti-seizure therapy is used but has generally been ineffective.

PMID:34087865 SUPPORT Human clinical

"The patient was treated with Convulex 300 mg/mL for the successful seizure control and Euthyrox 25mg for the treatment of thyroid malfunction."

Valproate (Convulex) achieved seizure control in one patient.

Cleft palate repair

Action: corrective surgery Ontology label: Surgical Procedure NCIT:C15329

Platform: Surgery

Surgical repair of the cleft palate. The one reported clubfoot repair in this disease was in a patient whose clubfoot the authors attributed to a separate familial cause, so it is not counted here.

Show evidence (1 reference)

PMID:34087865 SUPPORT Human clinical

"Moreover, the patient underwent the corrective surgeries of cleft palate and talipes equinovarus."

Documents surgical correction of the cleft palate in a PVNH7 patient. The talipes equinovarus repaired in the same patient is not counted, because the authors attribute it to a cause shared with a brother who does not carry the NEDD4L variant.

Developmental and rehabilitative therapy

Action: Rehabilitation NCIT:C15315

Platform: Behavioral / lifestyle

Supportive developmental, physical and educational therapy for the developmental delay, hypotonia and intellectual disability. No disease-modifying therapy exists. No PVNH7 publication reports rehabilitation outcomes, so this record is uncited and describes standard supportive care rather than a disease-specific claim.

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Diagnosis

2

Brain MRI

Brain MRI shows the periventricular nodular heterotopia and any associated polymicrogyria. The combination with toe syndactyly, cleft palate or hypospadias points to NEDD4L rather than FLNA.

brain magnetic resonance imaging NCIT:C16809

Show evidence (1 reference)

PMID:32117442 SUPPORT Human clinical

"The combination of PNH and PMG should prompt for careful evaluation for syndactyly, clefts, and/or hypospadias since these findings are highly suggestive of NEDD4L-involvement."

Imaging findings combined with limb, palate or genital anomalies suggest the NEDD4L diagnosis.

Exome sequencing

The diagnosis is confirmed by finding a heterozygous NEDD4L variant, typically by trio exome sequencing. Parental testing should consider low-level mosaicism.

trio exome sequencing NCIT:C101295

Show evidence (1 reference)

PMID:36934385 SUPPORT Human clinical

"Genetic analyses revealed a novel missense mutation Gln900Arg, located in the homologous to E6-APC terminal (HECT) domain of NEDD4L and that the parents were wild-type, suggestive of a de novo mutation."

Trio sequencing identified a de novo HECT-domain variant.

{ }

Source YAML

click to show

name: Periventricular Nodular Heterotopia 7
category: Mendelian
creation_date: "2026-11-07T00:00:00Z"
synonyms:
- PVNH7
- NEDD4L periventricular nodular heterotopia
- periventricular nodular heterotopia caused by mutation in NEDD4L
- NEDD4L-related disorder
description: >-
  Periventricular nodular heterotopia 7 (PVNH7) is an ultra-rare autosomal
  dominant malformation of cortical development caused by heterozygous missense
  variants in NEDD4L, which encodes a HECT-type E3 ubiquitin ligase expressed in
  the ventricular zone and cortical plate of the developing brain. Most variants
  cluster in the catalytic HECT domain and appear to leave the ligase active or
  constitutively activated while making the protein unstable; they deregulate
  AKT-mTOR and TGF-beta/Smad2/3 signalling, and in the embryonic mouse cortex
  they arrest neurons in the ventricular/subventricular and intermediate zones
  and disrupt terminal translocation, producing bilateral nodules of grey matter
  along the lateral ventricles. The syndrome combines periventricular nodular
  heterotopia, frequently with perisylvian polymicrogyria, with global
  developmental delay or intellectual disability, hypotonia, seizures (often
  early-onset and drug-resistant), 2-3 toe syndactyly and cleft palate. Variants
  are usually de novo, but parental mosaicism and a familial variant with
  marked intrafamilial variability are documented.
disease_term:
  preferred_term: periventricular nodular heterotopia 7
  term:
    id: MONDO:0014966
    label: periventricular nodular heterotopia 7
parents:
- Periventricular Nodular Heterotopia
notes: >-
  No GeneReviews chapter covers NEDD4L or PVNH7: a PubMed genereviews[book]
  search on the disease title and on NEDD4L[TIAB] returned no chapter, and the
  three heterotopia chapters returned concern other genes. The phenotype
  baseline is the original nine-patient report (PMID:27694961) and the
  15-patient literature summary in PMID:36934385. The general
  Periventricular_Nodular_Heterotopia entry carries a NEDD4L branch node; this
  entry curates the gene-defined disease itself.
inheritance:
- name: Autosomal Dominant
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  expressivity: VARIABLE
  description: >-
    Heterozygous NEDD4L variants act dominantly. Most arise de novo, but low-level
    parental germline/somatic mosaicism has been documented in two families, and
    one family transmits the WW-domain variant p.Arg208Gln through a
    non-mosaic mother with intrafamilial variability ranging from isolated
    heterotopia to severe epilepsy.
  evidence:
  - reference: PMID:32117442
    reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "While six pathogenic variants occurred de novo, parental mosaicism accounts for three reported cases"
    explanation: Summarises the de novo and parental-mosaic origins of the reported variants.
  - reference: PMID:32117442
    reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe the first familial occurrence, not associated with parental mosaicism, of a pathogenic variant in the NEDD4L gene with broad intra-familial phenotypic variability, varying from relatively well-functioning carriers with isolated PNH on brain MRI, to a severely affected case with profound developmental delay, refractory seizures, and PNH-PMG."
    explanation: Documents dominant transmission with variable expressivity in a single family.
  - reference: PMID:30393983
    reference_title: "Familial NEDD4L variant in periventricular nodular heterotopia and in a fetus with hypokinesia and flexion contractures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The observation of parental mosaicism in two out of seven families with NEDD4L-associated PVNH warrants caution and should be specifically addressed in parental carrier testing and genetic counseling."
    explanation: Parental mosaicism raises recurrence risk above that expected for a de novo dominant variant.
pathophysiology:
- name: NEDD4L Missense Variant
  biological_scale: MOLECULAR
  description: >-
    Heterozygous germline missense variants in NEDD4L. Nearly all reported
    variants map to the C-terminal catalytic HECT domain (for example
    p.Glu873Lys, p.Glu893Lys, p.Arg897Gln, p.Gln900Arg); the recurrent
    p.Arg208Gln lies in a WW substrate-recognition domain.
  genetic_context:
    variant_origin: GERMLINE
  evidence:
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here we show that missense mutations in NEDD4L mapping to the HECT domain of the encoded E3 ubiquitin ligase lead to PNH associated with toe syndactyly, cleft palate and neurodevelopmental delay."
    explanation: Establishes HECT-domain missense variants in NEDD4L as the cause of the disease.
  - reference: PMID:32117442
    reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All tested patients carry the recurrent variant c.623G > A, p.(Arg208Gln) in the WW domain of NEDD4L."
    explanation: Extends the variant spectrum beyond the HECT domain to a WW-domain variant.
  downstream:
  - target: Aberrant NEDD4L Ubiquitin Ligase Activity
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:36934385
      reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Functional experiments demonstrated that Gln900Arg probably did not lead to transcriptional abnormalities in this patient, instead leading to increased ubiquitination activity owing to the constitutive activation of the HECT domain, thereby promoting protein degradation."
      explanation: Links a HECT-domain patient variant to constitutively activated ubiquitination and reduced NEDD4L protein.
- name: Aberrant NEDD4L Ubiquitin Ligase Activity
  biological_scale: MOLECULAR
  description: >-
    HECT-domain variants leave the ligase catalytically active, apparently
    enhancing its activity, while making the mutant protein sensitive to
    proteasomal degradation, so less NEDD4L protein carries more activity per
    molecule. A WW-domain variant is instead proposed to impair substrate
    recognition (loss of function); the direction of the net effect is
    recorded as a controversy in discussions.
  genes:
  - preferred_term: NEDD4L
    term:
      id: hgnc:7728
      label: NEDD4L
  molecular_functions:
  - preferred_term: ubiquitin protein ligase activity
    modifier: DYSREGULATED
    term:
      id: GO:0061630
      label: ubiquitin protein ligase activity
  evidence:
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Altogether these results suggest that ubiquitination activity of NEDD4L mutant is preserved and possibly enhanced if we take into account the significant level of ubiquitination activity despite the instability of the protein."
    explanation: In vitro ubiquitination assays show the HECT mutants remain active and possibly hyperactive.
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Cellular and expression data showed sensitivity of PNH-associated mutants to proteasome degradation."
    explanation: Shows the mutant proteins are unstable and degraded by the proteasome.
  downstream:
  - target: AKT-mTOR and TGF-beta Signalling Deregulation
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:27694961
      reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Excess wild-type NEDD4L leads to disruption of Dab1 and mTORC1 pathways, while PNH-related mutations are associated with deregulation of mTORC1 and AKT activities."
      explanation: Ties the mutant ligase to deregulated mTORC1 and AKT signalling.
- name: AKT-mTOR and TGF-beta Signalling Deregulation
  conforms_to: "apical_neuroependyma_integrity_failure#NEDD4L AKT-mTOR Signaling Branch"
  biological_scale: CELLULAR
  description: >-
    In neuronal cells, PVNH-associated NEDD4L mutants raise phosphorylated S6
    (mTORC1 activity) and phosphorylated AKT (Thr308 and Ser473), and disturb
    the cross-talk between AKT and Smad2/3 in activin/TGF-beta signalling. A
    patient lymphoblastoid cell line did not show increased AKT-mTOR activity,
    so the magnitude of the effect at endogenous expression is uncertain. Dab1
    (Reelin pathway) disruption is not recorded here because, in the same
    study, it was caused by excess wild-type NEDD4L rather than by the patient
    mutants.
  cell_types:
  - preferred_term: neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: TORC1 signaling
    modifier: INCREASED
    term:
      id: GO:0038202
      label: TORC1 signaling
  - preferred_term: PI3K/AKT signal transduction
    modifier: INCREASED
    term:
      id: GO:0043491
      label: phosphatidylinositol 3-kinase/protein kinase B signal transduction
  - preferred_term: TGF-beta/activin Smad2/3 signalling
    modifier: DYSREGULATED
    term:
      id: GO:0007179
      label: transforming growth factor beta receptor signaling pathway
  evidence:
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "In contrast, for AKT, only PNH-associated NEDD4L mutants are associated with significantly increased level of Thr308 and Ser473 phosphorylated forms of Akt"
    explanation: Mutant-specific AKT hyperactivation in transfected neuronal cells.
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Collectively, these results suggested that expression of NEDD4L mutant lead to a disruption of the regulated cross talk between Akt and Smad2/3 signalling in activin/TGF-β pathways."
    explanation: Supports disrupted TGF-beta/Smad2/3 signalling by the mutant ligase.
  - reference: PMID:28515470
    reference_title: "A novel missense mutation in the HECT domain of NEDD4L identified in a girl with periventricular nodular heterotopia, polymicrogyria and cleft palate."
    supports: REFUTE
    evidence_source: IN_VITRO
    snippet: "our western blot analysis did not show an increased level of AKT-mTOR activity in lymphoblastoid cell lines (LCLs) derived from the patient."
    explanation: Patient-derived cells at endogenous expression did not reproduce AKT-mTOR hyperactivation, qualifying the overexpression result.
  downstream:
  - target: Disrupted Neurogenesis and Neuronal Positioning
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:27694961
      reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: MODEL_ORGANISM
      snippet: "However, rapamycin treatment induced only a partial rescue of the neuronal position defect resulting from IUEP of PNH-related mutants"
      explanation: Partial rescue of mutant-induced mispositioning by the mTORC1 inhibitor rapamycin implicates mTORC1 deregulation in part of the positioning defect.
- name: Disrupted Neurogenesis and Neuronal Positioning
  conforms_to: "apical_neuroependyma_integrity_failure#Secondary Neuronal Positioning and Migration Defects"
  biological_scale: TISSUE
  description: >-
    In utero electroporation of PVNH mutants into the embryonic mouse cortex
    arrests neurons in the ventricular/subventricular and intermediate zones
    with depletion of the cortical plate, alters progenitor proliferation, and
    disrupts terminal translocation. The arrested neurons still acquire
    upper-layer identity, so the defect is in positioning rather than fate.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  - preferred_term: neural progenitor cell
    term:
      id: CL:0011020
      label: neural progenitor cell
  biological_processes:
  - preferred_term: neuron migration
    modifier: DECREASED
    term:
      id: GO:0001764
      label: neuron migration
  - preferred_term: neurogenesis
    modifier: DYSREGULATED
    term:
      id: GO:0022008
      label: neurogenesis
  locations:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
  evidence:
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Moreover, an in utero electroporation approach showed that PNH-related mutants and excess wild-type NEDD4L affect neurogenesis, neuronal positioning and terminal translocation."
    explanation: In vivo demonstration that the patient mutants disturb neurogenesis and neuronal positioning in the developing cortex.
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "However, IUEP of WT NEDD4L, and PNH-related mutants induced a significant arrest of cells within the ventricular/sub-ventricular zone (VZ/SVZ) and intermediate zone (IZ) with a corresponding depletion in the CP"
    explanation: Neurons expressing the mutants arrest near the ventricle instead of reaching the cortical plate.
  downstream:
  - target: Periventricular nodular heterotopia
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:30393983
      reference_title: "Familial NEDD4L variant in periventricular nodular heterotopia and in a fetus with hypokinesia and flexion contractures."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: BACKGROUND
      snippet: "PVNH describes the nodular accumulation of neuronal precursor cells at the site of their origin along the lateral walls of both lateral ventricles, most likely resulting from failed initiation of neuronal migration"
      explanation: Attributes the periventricular nodules to failed initiation of neuronal migration from the ventricular wall.
phenotypes:
- name: Periventricular nodular heterotopia
  category: Structural
  description: >-
    Bilateral (occasionally unilateral) nodules of grey matter lining the
    lateral ventricles; the MONDO-defining feature, present in all patients
    in the early case series.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Periventricular nodular heterotopia
    term:
      id: HP:0032388
      label: Periventricular nodular heterotopia
  evidence:
  - reference: PMID:28515470
    reference_title: "A novel missense mutation in the HECT domain of NEDD4L identified in a girl with periventricular nodular heterotopia, polymicrogyria and cleft palate."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients reported with NEDD4L HECT domain mutations showed periventricular nodular heterotopia, and most had seizures, cortex anomalies, cleft palate and syndactyly."
    explanation: Periventricular nodular heterotopia was universal among reported HECT-domain cases.
- name: Polymicrogyria
  category: Structural
  description: >-
    Overlying cortical malformation, typically perisylvian polymicrogyria. The
    one-third frequency counts polymicrogyria of any distribution; the
    perisylvian binding reflects the pattern where one is described.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Perisylvian polymicrogyria
    term:
      id: HP:0012650
      label: Perisylvian polymicrogyria
  evidence:
  - reference: PMID:36934385
    reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Previously reported imaging features included bilateral or unilateral PVNH, with 33% exhibiting polymicrogyria."
    explanation: Gives the frequency of polymicrogyria across reported cases.
  - reference: PMID:32117442
    reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MRI revealed bilateral PNH and perisylvian polymicrogyria."
    explanation: Documents the perisylvian distribution of the polymicrogyria.
- name: Global developmental delay
  category: Neurologic
  description: >-
    Psychomotor delay, often severe, is present in nearly all patients; the
    most mildly affected familial carriers have only mild delay.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:36934385
    reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we observed that nearly all 15 patients (seven male, eight female) in the 11 reported families presented with psychomotor retardation, hypotonia, and variable degrees of syndactyly (usually second/third toe)."
    explanation: Psychomotor retardation was present in nearly all 15 reported patients.
- name: Intellectual disability
  category: Neurologic
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:34087865
    reference_title: "Admixed phenotype of NEDD4L associated periventricular nodular heterotopia: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: "All patients suffered from intellectual disability, periventricular nodular heterotopia and syndactyly, predominantly between 2nd and 3rd toes except a patient with 3 to 4 and 3 to 4 to 5 syndactyly."
    explanation: >-
      The case report's summary of the five p.Arg208Gln patients reported by
      Stouffs et al. (PMID:32117442); the sentence directly follows "Stouffs et
      al reported 5 patients of which 4 were related". All five had
      intellectual disability.
- name: Hypotonia
  category: Neurologic
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Hypotonia
    term:
      id: HP:0001252
      label: Hypotonia
  evidence:
  - reference: PMID:36934385
    reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we observed that nearly all 15 patients (seven male, eight female) in the 11 reported families presented with psychomotor retardation, hypotonia, and variable degrees of syndactyly (usually second/third toe)."
    explanation: Hypotonia was present in nearly all reported patients.
- name: Seizures
  category: Neurologic
  description: >-
    Seizures affect about half of patients, often beginning in infancy
    (including neonatal seizures and infantile spasms) and frequently resistant
    to anti-seizure medication.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:36934385
    reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among them, 53% also exhibited cleft palate, while 46% experienced seizures."
    explanation: Seizures occurred in 46% of reported patients.
- name: Infantile spasms
  category: Neurologic
  phenotype_term:
    preferred_term: Infantile spasms
    term:
      id: HP:0012469
      label: Infantile spasms
  evidence:
  - reference: PMID:28515470
    reference_title: "A novel missense mutation in the HECT domain of NEDD4L identified in a girl with periventricular nodular heterotopia, polymicrogyria and cleft palate."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "showing severe global developmental delay, infantile spasms, cleft palate, periventricular nodular heterotopia and polymicrogyria."
    explanation: Infantile spasms in a patient with a de novo HECT-domain variant.
- name: Cleft palate
  category: Craniofacial
  description: >-
    Cleft palate or bifid uvula in about half of patients; it is absent in the
    WW-domain p.Arg208Gln family.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Cleft palate
    term:
      id: HP:0000175
      label: Cleft palate
  evidence:
  - reference: PMID:36934385
    reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among them, 53% also exhibited cleft palate, while 46% experienced seizures."
    explanation: Cleft palate occurred in 53% of reported patients.
- name: 2-3 toe syndactyly
  category: Skeletal
  description: >-
    Cutaneous syndactyly of the second and third toes, sometimes mild, is a
    characteristic feature that helps distinguish NEDD4L-related from
    FLNA-related heterotopia; finger syndactyly occurs occasionally.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: 2-3 toe syndactyly
    term:
      id: HP:0004691
      label: 2-3 toe syndactyly
  evidence:
  - reference: PMID:36934385
    reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we observed that nearly all 15 patients (seven male, eight female) in the 11 reported families presented with psychomotor retardation, hypotonia, and variable degrees of syndactyly (usually second/third toe)."
    explanation: Toe syndactyly, usually of toes 2-3, was present in nearly all reported patients.
  - reference: PMID:30393983
    reference_title: "Familial NEDD4L variant in periventricular nodular heterotopia and in a fetus with hypokinesia and flexion contractures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The consistently observed syndromic features of cleft palate and syndactyly 2–3 emerge as characteristic hallmarks in the differential diagnosis to FLNA‐associated PVNH."
    explanation: Toe syndactyly and cleft palate distinguish this disorder from FLNA-related heterotopia.
- name: Hypospadias
  category: Genitourinary
  phenotype_term:
    preferred_term: Hypospadias
    term:
      id: HP:0000047
      label: Hypospadias
  evidence:
  - reference: PMID:32117442
    reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "An unrelated patient presented with severe neurodevelopmental delay, seizures, and hypospadias, expanding the phenotypic spectrum."
    explanation: Reports hypospadias as part of the phenotypic spectrum.
- name: Talipes equinovarus
  category: Skeletal
  phenotype_term:
    preferred_term: Talipes equinovarus
    term:
      id: HP:0001762
      label: Talipes equinovarus
  evidence:
  - reference: PMID:30393983
    reference_title: "Familial NEDD4L variant in periventricular nodular heterotopia and in a fetus with hypokinesia and flexion contractures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In contrast to truncal hypotonia, the girl showed bilateral talipes equinovarus and muscular hypertonia on both legs."
    explanation: Bilateral talipes equinovarus in a patient with a NEDD4L variant.
- name: Foveal hypoplasia
  category: Ophthalmologic
  phenotype_term:
    preferred_term: Foveal hypoplasia
    term:
      id: HP:0007750
      label: Hypoplasia of the fovea
  evidence:
  - reference: PMID:35577021
    reference_title: "Ophthalmic Findings Associated with NEDD4L-related Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We have summarized the clinical findings that have been reported in this disorder previously and highlight a novel ophthalmic finding of foveal hypoplasia in a new case of NEDD4L-related disorder."
    explanation: Reports foveal hypoplasia in a single NEDD4L-related case.
- name: Strabismus
  category: Ophthalmologic
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  evidence:
  - reference: PMID:34087865
    reference_title: "Admixed phenotype of NEDD4L associated periventricular nodular heterotopia: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "such as delayed psychomotor and mental development, seizures and infantile spasms, periventricular nodular heterotopia, polymicrogyria, cleft palate, 2 to 3 toe syndactyly, hypotonia, microretrognathia, strabismus, and absent speech and walking."
    explanation: Strabismus in a patient with the de novo p.Glu893Lys variant.
diagnosis:
- name: Brain MRI
  diagnosis_term:
    preferred_term: brain magnetic resonance imaging
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  description: >-
    Brain MRI shows the periventricular nodular heterotopia and any associated
    polymicrogyria. The combination with toe syndactyly, cleft palate or
    hypospadias points to NEDD4L rather than FLNA.
  evidence:
  - reference: PMID:32117442
    reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The combination of PNH and PMG should prompt for careful evaluation for syndactyly, clefts, and/or hypospadias since these findings are highly suggestive of NEDD4L-involvement."
    explanation: Imaging findings combined with limb, palate or genital anomalies suggest the NEDD4L diagnosis.
- name: Exome sequencing
  diagnosis_term:
    preferred_term: trio exome sequencing
    term:
      id: NCIT:C101295
      label: Whole Exome Sequencing
  description: >-
    The diagnosis is confirmed by finding a heterozygous NEDD4L variant,
    typically by trio exome sequencing. Parental testing should consider
    low-level mosaicism.
  evidence:
  - reference: PMID:36934385
    reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genetic analyses revealed a novel missense mutation Gln900Arg, located in the homologous to E6-APC terminal (HECT) domain of NEDD4L and that the parents were wild-type, suggestive of a de novo mutation."
    explanation: Trio sequencing identified a de novo HECT-domain variant.
treatments:
- name: Anti-seizure medication
  description: >-
    Symptomatic anti-seizure pharmacotherapy. Seizures are often refractory,
    although valproate controlled them in one reported patient.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  evidence:
  - reference: PMID:36934385
    reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Some children will have their first seizure in infancy, and antiepileptic therapy, including in the present patient, has generally been ineffective"
    explanation: Anti-seizure therapy is used but has generally been ineffective.
  - reference: PMID:34087865
    reference_title: "Admixed phenotype of NEDD4L associated periventricular nodular heterotopia: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patient was treated with Convulex 300 mg/mL for the successful seizure control and Euthyrox 25mg for the treatment of thyroid malfunction."
    explanation: Valproate (Convulex) achieved seizure control in one patient.
- name: Cleft palate repair
  description: >-
    Surgical repair of the cleft palate. The one reported clubfoot repair in
    this disease was in a patient whose clubfoot the authors attributed to a
    separate familial cause, so it is not counted here.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: corrective surgery
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  evidence:
  - reference: PMID:34087865
    reference_title: "Admixed phenotype of NEDD4L associated periventricular nodular heterotopia: A case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Moreover, the patient underwent the corrective surgeries of cleft palate and talipes equinovarus."
    explanation: >-
      Documents surgical correction of the cleft palate in a PVNH7 patient. The
      talipes equinovarus repaired in the same patient is not counted, because
      the authors attribute it to a cause shared with a brother who does not
      carry the NEDD4L variant.
- name: Developmental and rehabilitative therapy
  description: >-
    Supportive developmental, physical and educational therapy for the
    developmental delay, hypotonia and intellectual disability. No
    disease-modifying therapy exists. No PVNH7 publication reports
    rehabilitation outcomes, so this record is uncited and describes standard
    supportive care rather than a disease-specific claim.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Rehabilitation
    term:
      id: NCIT:C15315
      label: Rehabilitation
genetic:
- name: NEDD4L
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  gene_term:
    preferred_term: NEDD4L
    term:
      id: hgnc:7728
      label: NEDD4L
  notes: >-
    NEDD4L encodes a HECT-type E3 ubiquitin ligase (NEDD4-2) with an N-terminal
    C2 domain, four WW substrate-recognition domains and a C-terminal catalytic
    HECT domain. Dominant missense variants cause PVNH7. Separately, NEDD4L
    regulates the epithelial sodium channel, but that function is not part of
    this disease's pathograph.
  gene_disease_validity:
  - validity_classification: DEFINITIVE
    classified_by: CLINGEN
    external_id: CGGV:assertion_b131d46a-069b-4c2e-a290-e7df2519a2df-2021-11-30T170000.000Z
    evidence:
    - reference: CGGV:assertion_b131d46a-069b-4c2e-a290-e7df2519a2df-2021-11-30T170000.000Z
      reference_title: "NEDD4L / periventricular nodular heterotopia 7 (Definitive)"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "NEDD4L | HGNC:7728 | periventricular nodular heterotopia 7 | MONDO:0014966 | AD | Definitive"
      explanation: ClinGen Brain Malformations GCEP classifies NEDD4L-PVNH7 (AD) as Definitive.
  evidence:
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here we show that missense mutations in NEDD4L mapping to the HECT domain of the encoded E3 ubiquitin ligase lead to PNH associated with toe syndactyly, cleft palate and neurodevelopmental delay."
    explanation: Identifies NEDD4L as the causative gene.
  - reference: CGGV:assertion_b131d46a-069b-4c2e-a290-e7df2519a2df-2021-11-30T170000.000Z
    reference_title: "NEDD4L / periventricular nodular heterotopia 7 (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "NEDD4L | HGNC:7728 | periventricular nodular heterotopia 7 | MONDO:0014966 | AD | Definitive"
    explanation: ClinGen classifies the gene-disease relationship as Definitive.
  variants:
  - name: p.Glu893Lys
    description: >-
      De novo HECT-domain missense variant (c.2677G>A) reported in the original
      series and again in a later case with PVNH, polymicrogyria, cleft palate,
      toe syndactyly and infantile spasms.
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:34087865
      reference_title: "Admixed phenotype of NEDD4L associated periventricular nodular heterotopia: A case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We successfully identified the causative mutation NM_001144967.2(NEDD4L):c.2677G>A:p.Glu893Lys explaining symptoms overlapping those reported for PVNH7."
      explanation: Identifies p.Glu893Lys as causative in a PVNH7 patient.
  - name: p.Glu873Lys
    description: De novo HECT-domain variant (c.2617G>A) in a girl with PVNH, polymicrogyria, infantile spasms and cleft palate.
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:28515470
      reference_title: "A novel missense mutation in the HECT domain of NEDD4L identified in a girl with periventricular nodular heterotopia, polymicrogyria and cleft palate."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We identified a novel de novo heterozygous missense mutation in the NEDD4L gene (NM_015277: c.2617G>A; p.Glu873Lys) through whole-exome sequencing"
      explanation: Reports the de novo p.Glu873Lys variant.
  - name: p.Gln900Arg
    description: De novo HECT-domain variant; the mutant protein is reduced by about 41% in transfected cells, consistent with constitutive activation and self-degradation.
    clinical_significance: LIKELY_PATHOGENIC
    evidence:
    - reference: PMID:36934385
      reference_title: "Genetic analysis of periventricular nodular heterotopia 7 caused by a novel NEDD4L missense mutation: Case and literature summary."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "RT-PCR results indicated that the mutation did not affect mRNA expression, whereas WB and IF results indicated that the level of mutant protein was significantly reduced by 41.07%."
      explanation: The variant reduces NEDD4L protein without changing mRNA.
  - name: p.Tyr679His
    description: Variant transmitted from a father with about 10% somatic mosaicism to a daughter with PVNH, cleft palate and toe syndactyly, and to a fetus with hypokinesia and flexion contractures.
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:30393983
      reference_title: "Familial NEDD4L variant in periventricular nodular heterotopia and in a fetus with hypokinesia and flexion contractures."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Here, we describe a girl with a novel heterozygous NEDD4L missense variant, p.Tyr679His, and characteristic clinical findings, including bilateral periventricular nodular heterotopia, cleft palate and mild toe syndactyly."
      explanation: Reports the variant and its characteristic phenotype.
  - name: p.Arg208Gln
    description: Recurrent WW-domain variant (c.623G>A), familial in one family with marked variability and de novo in an unrelated patient; proposed to cause loss of function by impairing substrate recognition.
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:32117442
      reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "All tested patients carry the recurrent variant c.623G > A, p.(Arg208Gln) in the WW domain of NEDD4L. The variant in the unrelated patient occurred de novo."
      explanation: Reports the recurrent WW-domain variant in a family and an unrelated de novo case.
discussions:
- discussion_id: controversy_nedd4l_gain_vs_loss_of_function
  prompt: >-
    Do PVNH7 variants act by increasing NEDD4L ligase activity (gain of
    function) or by reducing it (loss of function)?
  kind: CONTROVERSY
  status: OPEN
  attaches_to:
  - pathophysiology#Aberrant NEDD4L Ubiquitin Ligase Activity
  rationale: >-
    For HECT-domain variants the functional data point to preserved or
    enhanced, constitutively activated ubiquitination with self-promoted
    degradation of the mutant protein, and overexpression of wild-type NEDD4L
    reproduces the neuronal positioning defect, which is hard to reconcile with
    simple loss of function. The WW-domain variant p.Arg208Gln is instead
    interpreted, from structure, as a loss of substrate recognition. Truncating
    NEDD4L variants are present in population controls, arguing against
    haploinsufficiency. The net effect on specific substrates in the developing
    cortex is unmeasured.
  evidence:
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Altogether these results suggest that ubiquitination activity of NEDD4L mutant is preserved and possibly enhanced if we take into account the significant level of ubiquitination activity despite the instability of the protein."
    explanation: Supports the gain-of-function reading for HECT-domain variants.
  - reference: PMID:27694961
    reference_title: "Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause periventricular nodular heterotopia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Moreover, 3 frameshift and 1 stop gained mutations were reported in the data set of Exome Aggregation Consortium in which individuals affected by severe paediatric disease have been excluded."
    explanation: Truncating variants in unaffected population controls argue against haploinsufficiency.
  - reference: PMID:32117442
    reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
    supports: REFUTE
    evidence_source: COMPUTATIONAL
    snippet: "We hypothesize that conformational changes cause a loss of function of the WW domain leading to impaired recognition of substrates and ultimately to loss of protein function."
    explanation: Proposes a loss-of-function mechanism for the WW-domain variant, contrary to the gain-of-function reading.
- discussion_id: gap_nedd4l_extraneural_malformations
  prompt: >-
    By what mechanism do NEDD4L variants cause cleft palate, toe syndactyly and
    hypospadias?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - phenotypes#Cleft palate
  - phenotypes#2-3 toe syndactyly
  - phenotypes#Hypospadias
  rationale: >-
    The cortical mechanism has been studied in the embryonic mouse brain, but
    no study has examined NEDD4L variants in palatal, limb-bud or genital
    tubercle development, so these consistent extra-neural features have no
    mechanism node in this entry.
  evidence:
  - reference: PMID:30393983
    reference_title: "Familial NEDD4L variant in periventricular nodular heterotopia and in a fetus with hypokinesia and flexion contractures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Interestingly, clefting of the palate and syndactyly of the toes 2–3 appear to be quite consistent features, indicating a broader role of the NEDD4L gene product beyond initiation of neuronal migration."
    explanation: Notes that the extra-neural features imply roles of NEDD4L outside neuronal migration.
- discussion_id: gap_nedd4l_seizures_and_neurodevelopmental_impairment
  prompt: >-
    By what mechanism do NEDD4L variants produce the seizures, developmental
    delay and intellectual disability of PVNH7, and does any of it act
    independently of the heterotopia?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - phenotypes#Seizures
  - phenotypes#Infantile spasms
  - phenotypes#Global developmental delay
  - phenotypes#Intellectual disability
  rationale: >-
    The PVNH7 literature reports how often these features occur, not how they
    arise, so no causal edge in this entry reaches them. A direct
    heterotopia-to-seizure edge would rest only on the general association of
    cortical malformations with epilepsy: within the single reported family
    carrying p.Arg208Gln, carriers with periventricular nodular heterotopia on
    MRI ranged from relatively well-functioning with isolated heterotopia to a
    severely affected case with refractory seizures, so the malformation does
    not by itself predict the seizure phenotype. A malformation-independent
    route has been proposed from mouse work: NEDD4L (Nedd4-2) ubiquitinates the
    AMPA-receptor subunit GluA1 and limits its surface expression, and elevated
    seizure susceptibility in a Nedd4-2-deficient mouse is corrected by
    genetically reducing GluA1. That lead does not transfer cleanly to PVNH7,
    for two reasons recorded in the gain-of-function controversy on this entry:
    the mouse is a loss of NEDD4L, whereas PVNH7 HECT-domain variants appear to
    preserve or increase ligase activity, and the variants shown to disrupt
    GluA1 ubiquitination were from patients with isolated epilepsy, not the
    PVNH7 variants. It is therefore recorded here as a hypothesis to test rather
    than as a causal edge.
  evidence:
  - reference: PMID:32117442
    reference_title: "Recurrent NEDD4L Variant in Periventricular Nodular Heterotopia, Polymicrogyria and Syndactyly."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "varying from relatively well-functioning carriers with isolated PNH on brain MRI, to a severely affected case with profound developmental delay, refractory seizures, and PNH-PMG."
    explanation: >-
      Within one p.Arg208Gln family, carriers with heterotopia on MRI span from
      no seizures to refractory epilepsy, showing the malformation does not by
      itself explain the seizure phenotype.
  - reference: PMID:28212375
    reference_title: "Epilepsy-associated gene Nedd4-2 mediates neuronal activity and seizure susceptibility through AMPA receptors."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    directness: INDIRECT
    snippet: "elevated seizure susceptibility in Nedd4-2andi mice was normalized when GluA1 is genetically reduced"
    explanation: >-
      Mouse evidence for a GluA1-dependent route from NEDD4L dysfunction to
      seizures. Cited as the hypothesis the proposed experiment would test; it
      is indirect for PVNH7 because the model is a NEDD4L loss of function and
      the tested variants are isolated-epilepsy variants, not the PVNH7
      HECT-domain variants.
  proposed_experiments:
  - experiment_id: exp_pvnh7_variant_glua1_ubiquitination_and_activity
    experiment_design: TARGETED_PERTURBATION
    name: PVNH7 HECT-domain variants in a GluA1 ubiquitination and neuronal-activity assay
    description: >-
      Express the PVNH7 HECT-domain variants (for example p.Glu893Lys,
      p.Gln900Arg) alongside wild-type NEDD4L and assess GluA1 ubiquitination,
      GluA1 surface expression, and spontaneous neuronal activity, to test
      whether these gain-of-function-leaning variants alter the GluA1 route in
      the same direction as the isolated-epilepsy loss-of-function variants.
    experiment_type:
      preferred_term: ubiquitination and neuronal-activity assay
    readouts:
    - name: GluA1 ubiquitination and surface expression by PVNH7 variant
      target: phenotypes#Seizures
      assays:
      - preferred_term: ubiquitination assay
      direction: ALTERED
      interpretation: >-
        A change in GluA1 ubiquitination or surface level with a PVNH7 variant
        would support a malformation-independent route to the seizure phenotype.
    controls:
    - name: Wild-type NEDD4L
      description: Wild-type ligase as the GluA1-ubiquitination reference.
    decision_criterion: >-
      The GluA1 route is supported for PVNH7 if its HECT-domain variants
      measurably change GluA1 ubiquitination, surface GluA1, or spontaneous
      neuronal activity relative to wild-type NEDD4L.
    would_support:
    - phenotypes#Seizures

📚

References & Deep Research

Deep Research

1

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

Evaluations and curation notes (1)

Create: Periventricular_Nodular_Heterotopia_7 · 2026-11-07T02:23:39Z · View source

Curated PVNH7 (MONDO:0014966, NEDD4L) from the primary literature: the original nine-patient report (PMID:27694961), later case reports (PMID:28515470, 30393983, 32117442, 34087865, 35577021, 36934385) and the ClinGen Definitive assertion. Built a causal chain from NEDD4L missense variant through dysregulated ubiquitin ligase activity and AKT-mTOR/TGF-beta deregulation to neuronal mispositioning and periventricular heterotopia, conforming two nodes to apical_neuroependyma_integrity_failure. Recorded the gain- versus loss-of-function controversy and the unexplained extra-neural malformations as discussions. No GeneReviews chapter exists. Deep research was requested from falcon and fell back to openscientist (no Edison key); report at research/Periventricular_Nodular_Heterotopia_7-deep-research-openscientist.md. Its validation block resolved 20/20 references with 2 unsupported quotes (PMID:31922594, PMID:28212375) and 2 off-topic ENaC papers; none of those four is cited here. preflight-dr returned WARN only because it counted the PVNH7 abbreviation as a gene; the report is about NEDD4L and OMIM 617201. The report's remaining extra citations (generic PVNH epilepsy cohort, FLNA, DEPDC5/NPRL3 mTORopathy models) are not PVNH7-specific and were not used. Validated with just validate (48/48 snippets verified), validate-terms, check-entity-refs, check-causal-targets, check-gene-activity-grounding and the other whole-repo gates. Only 1 of 13 phenotypes is causally connected; the others lack a sourced mechanism. Claim issue #16776.

OpenScientist ▸

Periventricular Nodular Heterotopia 7 (PVNH7, NEDD4L): Comprehensive Disease Report

openscientist-autonomous 20 citations 2026-11-07T02:22:34.921792

Periventricular Nodular Heterotopia 7 (PVNH7, NEDD4L): Comprehensive Disease Report

Disease: Periventricular Nodular Heterotopia 7 (PVNH7) Causal gene: NEDD4L (NEDD4-2; HECT-type E3 ubiquitin–protein ligase; chromosome 18q21; HGNC:7728; NCBI Gene 23327; UniProt Q96PU5) OMIM: 617201 | MONDO: MONDO:0014966 Category: Mendelian, autosomal dominant malformation of cortical development

Summary

Periventricular Nodular Heterotopia 7 (PVNH7) is an ultra-rare, autosomal-dominant malformation of cortical development caused by mostly de novo heterozygous missense variants in NEDD4L, the gene encoding the HECT-type E3 ubiquitin–protein ligase NEDD4-2 on chromosome 18q21. The disease was defined by Broix et al. in 2016, who showed that missense mutations clustering in the catalytic HECT domain of NEDD4L cause periventricular nodular heterotopia (PNH) accompanied by a distinctive syndromic constellation. The causal gene is NEDD4L — this is important to state up front because "periventricular nodular heterotopia" is a genetically heterogeneous radiological entity, and the far more common classic form is X-linked and caused by FLNA, a different gene with a different clinical and inheritance profile.

Mechanistically, PVNH7 arises when mutant NEDD4-2 protein — which is sensitive to proteasomal degradation — deregulates AKT–mTORC1 signaling and the Dab1/Reelin pathway, impairing neurogenesis, neuronal positioning, and the terminal translocation of migrating neurons. Neurons that fail to migrate are retained as bilateral periventricular nodules lining the lateral ventricles. The condition is not a simple loss-of-function/haploinsufficiency disorder: both mutant protein and excess wild-type NEDD4L perturb cortical development, pointing to dosage/activity sensitivity. Clinically, PVNH7 presents as a recognizable syndrome of bilateral PNH, perisylvian polymicrogyria, cleft palate, 2–3 toe syndactyly, seizures (including infantile spasms), hypotonia, and variable global developmental delay/intellectual disability.

As of 2023, only eight pathogenic NEDD4L variants across ~15 cases worldwide had been reported, so population-level epidemiology, penetrance estimates, and natural-history data remain largely undefined. Inheritance is autosomal dominant with documented parental mosaicism and marked intra-familial variability. There is no disease-specific or curative therapy; management is symptomatic and multidisciplinary (antiseizure medication, cleft-palate repair, developmental/rehabilitative therapy, and genetic counseling). Because the disorder deregulates mTORC1/AKT, mTOR inhibition (rapamycin/sirolimus) is a mechanistic/theoretical target, supported by rescue experiments in other mTORopathy models, but no clinical trials exist for PVNH7.

1. Disease Information

Overview. PVNH7 is a Mendelian malformation of cortical development (MCD) in the periventricular nodular heterotopia family. On brain MRI it is defined by nodules of gray-matter-isointense neurons that are ectopically retained along the walls of the lateral ventricles. PVNH7 specifically denotes the form caused by NEDD4L and is distinguished by a syndromic pattern that includes cortical malformation beyond the nodules themselves (typically perisylvian polymicrogyria), orofacial clefting, and distal limb anomalies.

Key identifiers.

Resource	Identifier
OMIM	617201
MONDO	MONDO:0014966
Gene (HGNC)	NEDD4L / HGNC:7728
NCBI Gene / UniProt	23327 / Q96PU5
Chromosomal locus	18q21
Inheritance	Autosomal dominant (mostly de novo)

ICD-10/ICD-11, Orphanet, and MeSH do not maintain a dedicated code that cleanly separates PVNH7 from the broader "periventricular nodular heterotopia" grouping; PNH overall maps to the malformations-of-cortical-development/neuronal-migration-disorder categories (ICD-10 Q04.8 "other congenital malformations of brain" is used pragmatically).

Synonyms: periventricular nodular heterotopia 7; PVNH7; periventricular nodular heterotopia type 7; NEDD4L periventricular nodular heterotopia; periventricular nodular heterotopia caused by mutation in NEDD4L.

Source of information. The knowledge base here is derived from aggregated disease-level resources (OMIM, MONDO) plus individual patient case reports and small case series in the primary literature — not from a large EHR cohort, because the disease is ultra-rare.

2. Etiology

Primary cause — genetic. PVNH7 is caused by heterozygous pathogenic missense variants in NEDD4L. The overwhelming majority are de novo, though inherited/familial transmission and parental somatic/germline mosaicism are documented. There is no known infectious or primary environmental cause.

Genetic risk factors. The causal variants themselves are the risk factor; they cluster in the catalytic HECT domain (with at least one recurrent WW-domain variant, p.Arg208Gln). No susceptibility loci or modifier genes have been formally established for PVNH7, given the tiny case count.

Environmental risk factors / protective factors. None established. No toxin, lifestyle, occupational exposure, dietary, or protective allele has been linked to PVNH7. Because the disorder is caused by highly penetrant de novo dominant variants, environmental contribution is expected to be minimal.

Gene–environment interactions. None described. This is a monogenic developmental malformation; GxE data are not available.

3. Phenotypes

Across the reported cases, PVNH7 produces a recurrent multi-system constellation. The table below summarizes the core phenotypes with suggested HPO terms and qualitative frequency.

Phenotype	Type	HPO suggestion	Onset	Frequency (qualitative)
Bilateral periventricular nodular heterotopia	Imaging/structural sign	HP:0032388 (periventricular nodular heterotopia)	Congenital	~All cases
Perisylvian polymicrogyria	Imaging/structural sign	HP:0002126 (polymicrogyria)	Congenital	Frequent
Seizures / infantile spasms	Clinical sign	HP:0001250 (seizure); HP:0012469 (infantile spasms)	Infancy–childhood	Most cases
Global developmental delay / intellectual disability	Clinical sign	HP:0001263; HP:0001249	Infancy onward	Frequent, variable
Cleft palate	Physical malformation	HP:0000175 (cleft palate)	Congenital	Frequent
2–3 toe syndactyly	Physical malformation	HP:0001770 (toe syndactyly)	Congenital	Frequent
Hypotonia	Clinical sign	HP:0001252	Infancy	Common
Absent/delayed speech & walking	Developmental	HP:0001344; HP:0002540	Childhood	Common
Microretrognathia	Physical malformation	HP:0000308	Congenital	Reported
Strabismus	Clinical sign	HP:0000486	Childhood	Reported
Hypospadias	Physical malformation	HP:0000047	Congenital	Reported (males)

"All patients reported with NEDD4L HECT domain mutations showed periventricular nodular heterotopia, and most had seizures, cortex anomalies, cleft palate and syndactyly" (PMID: 28515470).

Severity and progression. The structural brain malformation is static (non-progressive), but its clinical consequences — epilepsy and developmental impairment — evolve over time. Severity is highly variable, even within a single family: a familial case carrying p.Arg208Gln spanned the range from isolated bilateral PNH to severe neurodevelopmental delay with refractory seizures — "Phenotypic features in the proband consisted of severe neurodevelopmental delay, refractory seizures, bilateral PNH, and perisylvian polymicrogyria" (PMID: 32117442). A mosaic-carrier father had an affected prior fetus with hypokinesia and flexion contractures, suggesting the prenatal spectrum extends to a severe fetal akinesia-like presentation (PMID: 30393983).

Quality-of-life impact. No formal EQ-5D/SF-36/PROMIS data exist for PVNH7. Qualitatively, QoL is driven by seizure burden (which may be drug-resistant) and by intellectual disability/motor impairment that affect speech, ambulation, and independence. Cleft palate adds feeding/speech burden early in life.

4. Genetic / Molecular Information

Causal gene. NEDD4L (neural precursor cell expressed, developmentally down-regulated 4-like), encoding NEDD4-2, a HECT-type E3 ubiquitin–protein ligase (HGNC:7728; NCBI Gene 23327; UniProt Q96PU5; chromosome 18q21). "Missense mutations in NEDD4L mapping to the HECT domain of the encoded E3 ubiquitin ligase lead to PNH associated with toe syndactyly, cleft palate and neurodevelopmental delay" (PMID: 27694961).

Protein architecture. NEDD4-2 contains an N-terminal C2 domain (membrane/calcium binding), four WW domains that bind PY/L-PxY motifs in substrates, and a C-terminal catalytic HECT domain that transfers ubiquitin (PMID: 12698368; PMID: 18498246).

Pathogenic variants. PVNH7 variants are predominantly missense and cluster in the HECT domain, with a recurrent WW-domain variant also reported:

Variant (protein)	cDNA / notes	Domain	Classification
p.Glu893Lys (= p.Glu873Lys)	NM_001144967.2 c.2677G>A (= NM_015277 c.2617G>A) — recurrent	HECT	Pathogenic
p.Leu706Pro	c.2117T>C — de novo	HECT	Likely pathogenic (ACMG)
p.Tyr679His	—	HECT	Pathogenic
p.Gln900Arg	—	HECT	Pathogenic
p.Arg208Gln	familial, variable expressivity	WW domain	Pathogenic

A de novo heterozygous missense mechanism is documented: "de novo heterozygous missense mutation in the NEDD4L gene (NM_015277: c.2617G>A; p.Glu873Lys)" (PMID: 28515470). Note the nomenclature caveat: the variant initially described as "novel" p.Glu873Lys (NM_015277) is identical to p.Glu893Lys (NM_001144967) reported by Broix et al.; a published Author Correction clarified it is recurrent, not novel (PMID: 31028281). The p.Leu706Pro variant was reported as "a heterozygous c.2117T>C (p.Leu706Pro) variant… a de novo variant… predicted to be likely pathogenic according to the American College of Medical Genetics Guidelines" (PMID: 31922594).

Allele frequency. These are private/de novo disease alleles essentially absent from population databases (gnomAD); no appreciable population allele frequency.

Somatic vs germline. Germline (constitutional) in affected individuals; parental mosaicism (somatic/germline) has been documented — "Molecular testing from peripheral blood identified the healthy father to carry the NEDD4L variant in mosaic state" (PMID: 30393983).

Functional consequences. PVNH7 is not a simple loss-of-function disorder. PNH-associated mutants are sensitive to proteasomal degradation — "Cellular and expression data showed sensitivity of PNH-associated mutants to proteasome degradation" (PMID: 27694961) — and both mutant protein and excess wild-type NEDD4L disrupt neurodevelopment, indicating dosage/activity sensitivity rather than haploinsufficiency. A functional case study of p.Gln900Arg found the variant "did not affect mRNA expression, whereas WB and IF results indicated that the level of muta[nt protein]…" was altered, consistent with protein-level destabilization (PMID: 36934385). The net downstream effect is deregulation of mTORC1 and AKT activities.

Modifier genes / epigenetics / chromosomal abnormalities. No specific modifier genes or epigenetic marks are established for PVNH7. In the broader PNH population, array-CGH detects causative copy-number variants in a substantial subset (~35.7% of PNH vs 9.1% of polymicrogyria), underscoring extreme genetic heterogeneity of the PNH phenotype generally (PMID: 30683929) — but PVNH7 proper is defined by the point mutations in NEDD4L, not CNVs.

5. Environmental Information

No environmental factors, lifestyle factors, toxins, radiation exposures, or infectious agents have been implicated in PVNH7. It is a monogenic developmental disorder. This section is not applicable beyond noting the absence of evidence.

6. Mechanism / Pathophysiology

Ordered causal chain (initiating lesion → clinical manifestation)

A de novo (or mosaic-inherited) heterozygous missense mutation in NEDD4L, clustering in the catalytic HECT domain (or a WW domain), arises in the germline → produces a structurally altered, proteasome-sensitive NEDD4-2 protein (demonstrated: proteasome sensitivity; PMID: 27694961).
The altered NEDD4-2 deregulates its E3 ubiquitin-ligase activity and substrate handling → abnormal signaling output, specifically "deregulation of mTORC1 and AKT activities" (demonstrated in overexpression systems; PMID: 27694961).
In parallel, excess/dysregulated NEDD4L activity disrupts Dab1, a key node of the Reelin pathway that guides neuronal migration — "Excess wild-type NEDD4L leads to disruption of Dab1 and mTORC1 pathways" (PMID: 27694961).
Deregulated AKT–mTORC1 and Dab1/Reelin signaling impairs neurogenesis, neuronal positioning, and terminal translocation of migrating cortical neurons — "PNH-related mutants and excess wild-type NEDD4L affect neurogenesis, neuronal positioning and terminal translocation" (demonstrated by in utero electroporation; PMID: 27694961).
Neurons that fail to complete radial migration are retained ectopically along the lateral ventricles → bilateral periventricular nodular heterotopia; cortical organization is further disturbed → perisylvian polymicrogyria (inferred from imaging + migration defect).
The abnormal cortical circuitry, combined with NEDD4-2's physiological role in down-regulating the AMPA receptor GluA1 subunit (loss of this regulation elevates neuronal activity), lowers seizure threshold → epilepsy/infantile spasms — "Nedd4-2 mediates neuronal activity and seizure susceptibility through ubiquitination of GluA1 subunit of the… AMPA receptor" (demonstrated in Nedd4-2-deficient mice; PMID: 28212375; mechanistic bridge to PVNH7 inferred).
Disrupted cortical development and NEDD4-2's broader developmental roles manifest systemically as developmental delay/intellectual disability, hypotonia, and non-CNS malformations (cleft palate, toe syndactyly) (inferred from consistent clinical co-occurrence).

NEDD4L HECT/WW missense (de novo)
│  (proteasome-sensitive mutant NEDD4-2)
▼
 Deregulated E3 ligase activity
├──────────────► ↑/dysreg AKT–mTORC1 ──┐
└──────────────► disrupted Dab1/Reelin ─┤
                                ▼
       Impaired neurogenesis, positioning,
             terminal translocation
                                ▼
 Bilateral periventricular nodules + polymicrogyria
                                │
        (abnormal circuits + loss of GluA1 control)
                                ▼
     Epilepsy / infantile spasms, DD/ID, hypotonia
     + syndromic: cleft palate, 2–3 toe syndactyly

Supporting detail

Molecular pathways. PI3K–AKT–mTORC1 is the central deregulated axis (PMID: 27694961). NEDD4-family ligases act downstream of PI3K/PTEN–mTORC1 signaling and promote neurite/axonal growth; PTEN controls Nedd4-1 expression by modulating mTORC1 activity — "PTEN controls neurite growth by regulating Nedd4-1 expression" (PMID: 25157163). The Reelin–Dab1 migration pathway is the second affected arm (PMID: 27694961).

Cellular processes. Neurogenesis, radial neuronal migration, neuronal positioning, and terminal translocation are the core affected processes. Suggested GO terms: GO:0001764 (neuron migration), GO:0022008 (neurogenesis), GO:0021799 (cerebral cortex radially oriented cell migration), GO:0016567 (protein ubiquitination), GO:0032008 (positive regulation of TOR signaling).

Protein dysfunction. Mutant NEDD4-2 is destabilized/proteasome-sensitive with altered catalytic/substrate behavior — a complex, non-simple loss-of-function effect with evidence of dosage sensitivity (PMID: 27694961; PMID: 36934385). Nedd4-2 stability is itself regulated by an intramolecular WW–HECT PY-motif interaction and by SGK1/PKA phosphorylation with 14-3-3 binding (PMID: 18498246; PMID: 16716084).

Cell types involved. Cortical neural progenitors and migrating projection (pyramidal) neurons. Suggested CL terms: CL:0000047 (neural stem cell / neural progenitor), CL:0000679 (glutamatergic neuron), CL:0000598 (pyramidal neuron).

Ion channel / receptor links. NEDD4-2's canonical substrate is the epithelial Na⁺ channel ENaC — "The epithelial Na(+) channel ENaC is the best studied example of a Nedd4/Nedd4-like substrate" (PMID: 12698368) — whose dysregulation causes the unrelated Liddle syndrome hypertension phenotype (PMID: 20675381). In brain, NEDD4-2 ubiquitinates the AMPA receptor GluA1 subunit; Nedd4-2-deficient mice show elevated neuronal activity and increased kainic-acid seizure susceptibility, normalized by genetically reducing GluA1 (PMID: 28212375).

Context-dependence caveat. Not all systems show the same magnitude of signaling change: Kato et al. (2017) found only subtle AKT–mTOR deregulation in patient lymphoblastoid cell lines, versus the robust effects in forced-overexpression/in-utero electroporation systems — a reminder that the quantitative mechanism is context-dependent.

7. Anatomical Structures Affected

Organ / system level. Primary organ: the brain (central nervous system). The disorder also affects craniofacial structures (palate → cleft palate; jaw → microretrognathia) and distal limbs (toes → 2–3 syndactyly), with occasional genitourinary involvement (hypospadias) and reported strabismus (ocular motility).

Tissue and cell level. Nervous tissue — specifically the developing cerebral cortex. Affected cell populations: neural progenitors and migrating cortical neurons (CL:0000047; CL:0000598).

Subcellular level. The pathology centers on the ubiquitin–proteasome system (cytoplasmic; mutant protein degraded by the proteasome) and on mTORC1 signaling at the lysosomal surface/cytoplasm. Suggested GO cellular component terms: GO:0005737 (cytoplasm), GO:0000502 (proteasome complex).

Localization. Nodules line the walls of the lateral ventricles (UBERON:0002285, lateral ventricle of the brain; periventricular region). Associated polymicrogyria is perisylvian (around the Sylvian fissure / insular cortex). Lateralization is characteristically bilateral in PVNH7 — a feature of diagnostic and prognostic importance. Suggested UBERON terms: UBERON:0002285 (lateral ventricle), UBERON:0000956 (cerebral cortex).

8. Temporal Development

Onset. The structural malformation is congenital (established during fetal corticogenesis). Clinical onset: seizures typically emerge in infancy to childhood (infantile spasms can be an early manifestation); developmental delay becomes apparent across infancy and early childhood. In the broader PNH-epilepsy population, "Mean seizure onset age was 7.9 years" (PMID: 37119372), though PVNH7's syndromic, bilateral pattern tends toward earlier and more severe presentations.

Progression. The brain malformation itself is static/non-progressive. The clinical course is dominated by epilepsy, which may be self-limited, pharmacoresponsive, or drug-resistant depending on malformation pattern, and by a chronic, lifelong developmental disability. Disease duration is lifelong.

Patterns / critical periods. The critical period is fetal cortical neurogenesis and migration (second trimester), when the malformation is laid down — the only true window for primary prevention would be preconception/prenatal. Post-natally there is no remission of the structural lesion; "remission" applies only to seizure control achieved with medication or, in selected drug-resistant focal cases, surgery.

9. Inheritance and Population

Epidemiology. PVNH7 is ultra-rare: "only eight NEDD4L pathogenic variants have been identified across 15 cases of PVNH7 worldwide" as of 2023 (PMID: 36934385). No reliable prevalence or incidence figures exist, and no separate Orphanet prevalence class is defined for PVNH7.

Inheritance. Autosomal dominant. The majority of cases are de novo heterozygous missense variants, but familial transmission occurs, and parental somatic/germline mosaicism is documented (PMID: 30393983).

Penetrance and expressivity. Penetrance appears high for carriers of a constitutional pathogenic variant, but expressivity is strikingly variable — the familial p.Arg208Gln pedigree ranged from isolated bilateral PNH to severe neurodevelopmental delay (PMID: 32117442). Formal penetrance estimates are not possible with so few cases.

Anticipation / founder effects / consanguinity / carrier frequency. No genetic anticipation (not a repeat-expansion disorder). No founder effect, ethnic clustering, or consanguinity role established. Carrier frequency is effectively nil in the general population (de novo dominant disease).

Population demographics. No sex predilection established. No geographic/ethnic clustering of the disease or of specific variants. The recurrent p.Glu893Lys/p.Glu873Lys variant is the most frequently reported allele but reflects a mutational hotspot rather than a population founder.

10. Diagnostics

Imaging (first-line). Brain MRI is the primary diagnostic modality: it demonstrates nodules of gray-matter-isointense neurons lining the lateral ventricles; in PVNH7 the nodules are bilateral, frequently with perisylvian polymicrogyria.

Molecular confirmation. Diagnosis is confirmed by trio whole-exome sequencing (proband + parents) with Sanger confirmation of a de novo NEDD4L variant — the standard approach "verified the genetic etiology using Trio-whole-exome and Sanger sequencing" (PMID: 36934385). WES is high-yield because it establishes de novo status and distinguishes PVNH7 from other genetic PNH forms. Gene panels for malformations of cortical development / neuronal migration disorders should include NEDD4L alongside FLNA, ARFGEF2, and others. Chromosomal microarray (array-CGH) is recommended as a first-line test in PNH generally (especially sporadic, non-classical cases) because CNVs are a cumulatively frequent cause (~35.7% in one PNH series; PMID: 30683929) — though PVNH7 itself is a point-mutation disorder.

Differential diagnosis. The principal genetic differentials are:

Gene	Inheritance	Distinguishing features
FLNA (classic PNH)	X-linked dominant	Predominantly females; male prenatal lethality; cardiovascular, pulmonary (childhood interstitial lung disease), skeletal, GI involvement; no cleft palate + toe syndactyly constellation (PMID: 37422633; PMID: 30547349)
ARFGEF2	Autosomal recessive	Microcephaly, severe DD
NEDD4L (PVNH7)	Autosomal dominant (de novo)	Bilateral PNH + polymicrogyria + cleft palate + 2–3 toe syndactyly — a unique constellation

"The unique constellation of clinical features in patients with NEDD4L mutations might help clinically distinguish them from patients with other genetic mutations including FLNA" (PMID: 28515470).

Laboratory / biomarkers / electrophysiology. No specific blood/urine biomarker exists. EEG is used to characterize seizures (and may show hypsarrhythmia in infantile spasms). No omics-based or liquid-biopsy diagnostic is established.

Screening. Because most cases are de novo, there is no population carrier-screening program. For families with an identified variant (including mosaic parents), cascade testing and prenatal/preimplantation genetic testing are feasible.

11. Outcome / Prognosis

Survival/mortality. PVNH7 is not primarily a lethal disorder postnatally; no specific survival or mortality statistics are published. The severe end of the prenatal spectrum (fetal hypokinesia/flexion contractures in an affected fetus; PMID: 30393983) indicates the possibility of a severe/lethal fetal presentation in some pregnancies.

Morbidity and function. The dominant morbidity is epilepsy (potentially drug-resistant) and neurodevelopmental disability (intellectual disability, motor delay, speech impairment). Epilepsy prognosis is stratified by nodule distribution:

PNH pattern	Drug-resistance
Isolated single-nodule PNH	No drug-resistant seizures
PVNH-Plus, bilateral nodules (the PVNH7 pattern)	Highest drug resistance (39%)

In a retrospective cohort of 100 PVNH patients with seizures, mean onset was 7.9 years; 10 had self-limited epilepsy, 35 more were pharmacoresponsive, 55 had ongoing seizures, and 23 met drug-resistance criteria; "PVNH-Plus with bilateral nodules demonstrated the highest proportion of drug resistance (39%)" (PMID: 37119372). Because PVNH7 characteristically presents as bilateral PNH plus an additional malformation (polymicrogyria), affected individuals fall into this higher-severity stratum.

Complications and recovery. Complications include refractory seizures, feeding/speech difficulty from cleft palate, and functional impairment. The structural brain lesion does not resolve; recovery is limited to seizure control and developmental gains with therapy.

Prognostic factors. Bilateral + syndromic malformation pattern (worse epilepsy prognosis), seizure burden, and degree of developmental delay are the main prognostic indicators. No molecular prognostic biomarker is validated; intra-familial variability (PMID: 32117442) limits genotype-based prediction.

12. Treatment

No disease-modifying or NEDD4L-specific therapy exists. Management is symptomatic and multidisciplinary (NCIT suggestions in parentheses):

Antiseizure medication for epilepsy — e.g., valproate (Convulex): "The patient was treated with Convulex 300 mg/mL for the successful seizure control" (PMID: 34087865). (NCIT: Anticonvulsant Agent; Valproic Acid.)
Surgical repair of cleft palate (NCIT: Cleft Palate Repair / Palatoplasty).
Treatment of associated anomalies, e.g., levothyroxine for thyroid dysfunction where present (NCIT: Levothyroxine).
Developmental / rehabilitative therapy — physical, occupational, and speech therapy (NCIT: Physical Therapy; Occupational Therapy; Speech Therapy).
Epilepsy surgery may be considered for selected drug-resistant focal cases (NCIT: Epilepsy Surgery).

Mechanistic/experimental target. Because PVNH7 deregulates mTORC1/AKT, mTOR inhibitors (rapamycin/sirolimus) are a theoretical disease-mechanism target. This rationale is supported by rescue of mTORopathy phenotypes by rapamycin in animal models — "prenatal treatment with mTORC1 inhibitor rapamycin rescued the phenotype" in a Depdc5 mTORopathy model (PMID: 26873552) — and rapamycin reversed mTOR-dependent morphological/localization defects from GATOR1-subunit knockdown in neurons (PMID: 29481864). No clinical trials of mTOR inhibition exist for PVNH7, and the structural malformation is established prenatally, limiting postnatal disease modification.

Pharmacogenomics / advanced therapeutics. No PVNH7-specific pharmacogenomic guidance. No gene, cell, RNA-based, targeted, or immunotherapy is available or in trial for this indication.

13. Prevention

Primary prevention: Not possible postnatally (malformation is congenital). For families with a known variant, options are preconception counseling, preimplantation genetic testing (PGT), and prenatal diagnosis.
Secondary prevention: Early MRI and genetic diagnosis enable early seizure management and developmental intervention.
Tertiary prevention: Optimizing antiseizure therapy to prevent status epilepticus and developmental regression; multidisciplinary care to manage complications.
Genetic counseling: Essential. Counseling must address the predominantly de novo origin, the documented parental mosaicism (which affects recurrence risk for apparently de novo cases; PMID: 30393983), and the variable expressivity that complicates prognostic prediction within families (PMID: 32117442).
Immunization / public health / environmental interventions: Not applicable.

14. Other Species / Natural Disease

No naturally occurring animal disease equivalent to PVNH7 is cataloged (e.g., in OMIA). The gene is evolutionarily conserved: Nedd4l/Nedd4-2 orthologs exist in mouse (NCBI Gene: Nedd4l; Mus musculus, NCBI Taxon txid10090), rat (Rattus norvegicus, txid10116), and other vertebrates. Comparative mechanistic conservation is strong — mouse studies of Nedd4-2 (AMPA/GluA1 regulation and seizure susceptibility; ENaC regulation) directly inform the human mechanism. No zoonotic potential or cross-species transmission (not applicable — genetic developmental disorder).

15. Model Organisms

Mouse models [model organism]. The most informative is the Nedd4-2-deficient mouse (e.g., Nedd4-2^andi^), which shows elevated neuronal activity and increased kainic-acid seizure susceptibility, normalized by genetically reducing GluA1 — modeling the epilepsy arm of NEDD4L dysfunction (PMID: 28212375). Conditional Nedd4-1/Nedd4-2 knockout mice demonstrate that these ligases are required for axonal growth/branching in CNS neurons (PMID: 25157163).
In utero electroporation (mouse) [model organism]. The landmark functional system for PVNH7: expression of PNH-related mutants or excess wild-type NEDD4L in the developing mouse cortex reproduced defective neurogenesis, neuronal positioning, and terminal translocation, and revealed the AKT–mTORC1 and Dab1 mechanisms (PMID: 27694961). This is the best recapitulation of the migration defect underlying the nodules.
In vitro / cellular models [in vitro]. Patient-derived lymphoblastoid cell lines (showed only subtle AKT–mTOR changes — a model limitation highlighting context-dependence; Kato 2017) and expression constructs demonstrating proteasome sensitivity of mutants (PMID: 27694961) and protein-level destabilization (PMID: 36934385). Neuroblastoma (N2a) and neural progenitor cell systems are used to study mTORC1-dependent morphology in related mTORopathies (PMID: 29481864).
Related mTORopathy models [model organism]. The Depdc5 knockout rat (PMID: 26873552) and DEPDC5/NPRL3 knockdown neuronal models (PMID: 29481864) are not NEDD4L models but validate the mTORC1-rescue-by-rapamycin logic relevant to PVNH7's pathway.

Recapitulation and limitations. In utero electroporation recapitulates the core neuronal migration/heterotopia phenotype and the signaling deregulation well. Limitations: no single published model reproduces the full human syndrome (bilateral PNH + polymicrogyria + cleft palate + toe syndactyly) simultaneously; lymphoblastoid cells underrepresent the signaling phenotype; and dosage-sensitivity effects are hard to model precisely.

Resources: MGI (Nedd4l), IMPC/KOMP for knockout alleles, and standard mouse repositories.

Mechanistic Model / Interpretation

PVNH7 is best understood as a ubiquitin-ligase/mTOR-pathway "corticogenesis" disorder with dosage sensitivity. The unifying model: a destabilizing, proteasome-sensitive HECT-domain missense change in NEDD4-2 perturbs the ligase's normal control over the AKT–mTORC1 growth-signaling axis and over Dab1/Reelin migration signaling. Because both mutant protein and excess wild-type protein are deleterious, the system is exquisitely sensitive to the level and activity of NEDD4-2 during a narrow fetal window of neurogenesis and radial migration. The consequence is twofold: (1) a structural failure of neurons to reach the cortex, producing bilateral periventricular nodules and polymicrogyria; and (2) an excitability liability, because NEDD4-2 normally throttles the AMPA-receptor GluA1 subunit, and its dysfunction lowers seizure threshold. The syndromic non-CNS features (cleft palate, toe syndactyly) reflect NEDD4-2's broader developmental roles. This model explains the clinical stratification — bilateral "PVNH-Plus" portends the worst epilepsy — and identifies mTOR inhibition as the only rational, if currently unproven and likely prenatal-window-limited, disease-mechanism target.

Evidence Base

PMID	Title (abbrev.)	Role
PMID: 27694961	Mutations in the HECT domain of NEDD4L lead to AKT-mTOR pathway deregulation and cause PNH	Landmark: defines gene, HECT clustering, proteasome sensitivity, AKT-mTORC1/Dab1 mechanism, migration defect
PMID: 28515470	Missense mutation in HECT domain of NEDD4L… PNH, polymicrogyria, cleft palate	De novo heterozygous inheritance; core phenotype; FLNA differential
PMID: 31028281	Author Correction	Clarifies p.Glu873Lys = p.Glu893Lys is recurrent, not novel
PMID: 32117442	Recurrent NEDD4L Variant in PNH, Polymicrogyria and Syndactyly	Familial p.Arg208Gln; variable expressivity; bilateral PNH + polymicrogyria
PMID: 30393983	Familial NEDD4L variant… and a fetus with hypokinesia	Parental mosaicism; severe fetal spectrum
PMID: 36934385	Genetic analysis of PVNH7… Case and literature summary	Trio-WES diagnosis; 8 variants/15 cases; protein (not mRNA) destabilization
PMID: 34087865	Admixed phenotype of NEDD4L-associated PNH	Symptomatic valproate seizure control
PMID: 31922594	PVNH7 caused by NEDD4L variant	p.Leu706Pro de novo, likely pathogenic (ACMG)
PMID: 28212375	Nedd4-2 mediates neuronal activity and seizure susceptibility through AMPA receptors	Links NEDD4L to seizures via GluA1 (mouse)
PMID: 12698368	Nedd4/Nedd4-like ubiquitylation in epithelial transport	Domain architecture; ENaC substrate
PMID: 18498246	Regulation of Nedd4-2 self-ubiquitination via HECT PY motif	Protein stability regulation
PMID: 16716084	14-3-3 / SGK1 phosphorylation regulation of Nedd4-2	Regulatory control of the ligase
PMID: 20675381	Hrs controls ENaC sorting (Nedd4-2)	Canonical trafficking substrate biology; Liddle syndrome
PMID: 25157163	Nedd4-1 downstream of PI3K/PTEN-mTORC1 to promote neurite growth	Places NEDD4 in mTOR network; axon growth
PMID: 30683929	Genomic CNVs in PNH — extreme heterogeneity	Array-CGH as first-line test in PNH
PMID: 37119372	Phenotypic spectrum of epilepsy with PNH	Epilepsy prognosis stratification; onset 7.9 y; 39% drug resistance in bilateral PVNH-Plus
PMID: 37422633	PNH associated with FLNA	FLNA differential diagnosis
PMID: 30547349	FLNA mutations and interstitial lung disease	FLNA phenotype distinction
PMID: 26873552	Depdc5 knockout rat: mTORopathy model	Rapamycin rescue rationale
PMID: 29481864	DEPDC5/NPRL3 modulate mTOR in neurons	Rapamycin-reversible mTOR phenotype

Limitations and Knowledge Gaps

Ultra-rarity. With only ~15 reported cases and 8 variants, all frequency estimates are qualitative; prevalence, incidence, penetrance, and sex ratio are unquantified.
Mechanism context-dependence. Robust AKT–mTORC1 deregulation is seen in overexpression/in-utero electroporation systems but is only subtle in patient lymphoblastoid cells (Kato 2017) — the quantitative in vivo mechanism remains uncertain, and whether gain-of-function, loss-of-function, or dominant-negative best describes individual variants is unresolved.
No full-syndrome animal model. Existing models capture either the migration defect or the seizure phenotype, not the complete human syndrome including cleft palate and syndactyly.
No therapeutic evidence. mTOR inhibition is purely theoretical for PVNH7; the structural lesion is prenatal, so postnatal disease modification may be inherently limited.
Weak genotype–phenotype correlation, confounded by marked intra-familial variability (p.Arg208Gln pedigree).
No natural-history, QoL, or long-term outcome data specific to PVNH7.

Proposed Follow-up Experiments / Actions

Establish an international PVNH7 registry (GeneMatcher-based) to aggregate cases, variants, imaging, and outcomes — the single highest-value action given rarity.
Variant-specific functional dissection using isogenic human iPSC-derived cortical organoids/neurons carrying each recurrent variant (p.Glu893Lys, p.Leu706Pro, p.Tyr679His, p.Gln900Arg, p.Arg208Gln) to quantify effects on NEDD4-2 stability, ubiquitin-ligase activity, AKT–mTORC1 output, and Dab1/Reelin signaling in a human, non-overexpression context.
Humanized/knock-in mouse models of recurrent HECT variants to test whether the full syndrome is recapitulated and to perform prenatal rapamycin rescue experiments.
GluA1/AMPA-receptor characterization in patient-derived neurons to determine whether seizure susceptibility maps to the same GluA1 mechanism shown in Nedd4-2-deficient mice, which could nominate AMPA-receptor modulators (e.g., perampanel) as a mechanism-matched antiseizure choice.
Systematic parental mosaicism screening (deep sequencing of multiple tissues) in apparently de novo cases to refine recurrence-risk counseling.
Prospective natural-history and QoL study capturing seizure trajectory, developmental outcomes, and drug-resistance predictors across nodule distribution patterns.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.5.1.

Outcome	Count
References checked	20
Resolved	20
Unresolved (possible confabulation)	0
Unverifiable	0
Quoted claims checked	18
Quoted claims found in source	16
Quoted claims not found in source	2
References weighed for topical relevance	20
On topic	8
Off topic	2

Quotes not found in the cited source

Searched the abstract, any retrieved full text, and the title. A quote drawn from a part of the paper that was not retrieved will appear here too, so check before treating one as invented:

Every one of these was searched against an abstract alone, with no full text retrieved - marked abstract only below. Where full text can be fetched, re-running with it will settle them; where the source publishes only a summary to PubMed, as GeneReviews chapters do, it will not, and the quote has to be checked by hand against the chapter itself.

PMID:31922594 (abstract only): "a heterozygous c.2117T>C (p.Leu706Pro) variant… a de novo variant… predicted to be likely pathogenic according to the American College of Medical Genetics Guidelines"
closest text in source: "RESULTS: The proband was found to carry a heterozygous c.2117T>C (p.Leu706Pro) variant of the NEDD4L gene, which was a de novo variant validated by Sanger sequencing and predicted to be likely pathogenic according to the American College of Medical Genetics Guidelines"
PMID:28212375 (abstract only): "Nedd4-2 mediates neuronal activity and seizure susceptibility through ubiquitination of GluA1 subunit of the… AMPA receptor"
closest text in source: "In this study, we provide evidence to show that Nedd4-2 mediates neuronal activity and seizure susceptibility through ubiquitination of GluA1 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, (AMPAR)"

References that may not be about this subject

These identifiers resolve, so they are not fabrications, but the records they resolve to share almost none of this report's vocabulary. That is a clue and not a verdict - a paper can be relevant in ways its title and abstract do not spell out - so read them before deciding:

PMID:18498246 (5 mentions) - Regulation of Nedd4-2 self-ubiquitination and stability by a PY motif located within its HECT-domain.
shared terms: nedd4-2
PMID:20675381 (4 mentions) - Hrs controls sorting of the epithelial Na+ channel between endosomal degradation and recycling pathways.
shared terms: nedd4-2

Weighed against this report's own most characteristic terms: pvnh7, seizure, nedd4l, developmental, palate, cleft, malformation, bilateral, neuron, nedd4-2, polymicrogyria, disease, novo, variant, mtorc1, pnh, syndactyly, disorder, gene, cortical.

Term Validation

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

Outcome	Count
Terms checked	28
Resolved	27
Unresolved (possible confabulation)	0
Obsolete	0
Unverifiable	1
Terms whose name was checked	9
Terms named correctly	4
Terms named as a different term	5

Terms the report names something else

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

MONDO:0014966 (2 mentions) - the report calls it "MONDO"; MONDO calls it periventricular nodular heterotopia 7
HP:0001252 (1 mention) - the report calls it "Clinical sign"; HP calls it Hypotonia
HP:0000308 (1 mention) - the report calls it "Physical malformation"; HP calls it Microretrognathia
HP:0000486 (1 mention) - the report calls it "Clinical sign"; HP calls it Strabismus
HP:0000047 (1 mention) - the report calls it "Physical malformation"; HP calls it Hypospadias

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Periventricular Nodular Heterotopia 7 (PVNH7, NEDD4L): Comprehensive Disease Report

Summary

1. Disease Information

2. Etiology

3. Phenotypes

4. Genetic / Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

Ordered causal chain (initiating lesion → clinical manifestation)

Supporting detail

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

10. Diagnostics

11. Outcome / Prognosis

12. Treatment

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Mechanistic Model / Interpretation

Evidence Base

Limitations and Knowledge Gaps

Proposed Follow-up Experiments / Actions

Artifacts

Reference Validation

Quotes not found in the cited source

References that may not be about this subject

Term Validation

Terms the report names something else