Posterior Polymorphous Corneal Dystrophy

👪

Inheritance

1

Autosomal dominant inheritance HP:0000006

autosomal dominant inheritance

Show evidence (1 reference)

PMID:29499165 SUPPORT Human Clinical

"we mapped a locus for an autosomal-dominant corneal endothelial dystrophy, posterior polymorphous corneal dystrophy 4 (PPCD4), to 8q22.3-q24.12"

PPCD is described as an autosomal-dominant corneal endothelial dystrophy.

◆

Subtypes

3

PPCD1 (OVOL2-related, 20p11.2)

PPCD subtype mapped to chromosome 20p11.2 and caused by mutations in the proximal promoter of OVOL2, a gene not normally expressed in the corneal endothelium. The mutations drive aberrant ectopic OVOL2 expression; OVOL2 promotes mesenchymal-to-epithelial transition and directly represses ZEB1. PPCD1 is allelic with the autosomal-dominant congenital hereditary endothelial dystrophy CHED1.

Show evidence (1 reference)

PMID:26749309 SUPPORT Human Clinical

"the identification of pathogenic variants in a conserved region of the OVOL2 proximal promoter sequence in the index families (c.-339_361dup for CHED1 and c.-370T>C for PPCD1)"

Identifies OVOL2 promoter mutations as the cause of PPCD1.

PPCD3 (ZEB1/TCF8-related, 10p11.2)

PPCD subtype caused by heterozygous loss-of-function (nonsense and frameshift) mutations in ZEB1 (formerly TCF8), accounting for roughly a quarter to a third of screened PPCD families. ZEB1 haploinsufficiency derepresses epithelial genes in the endothelium. PPCD3 is also associated with extraocular abnormalities, notably inguinal and abdominal hernias.

Show evidence (1 reference)

PMID:16252232 SUPPORT Human Clinical

"we report a heterozygous frameshift mutation in TCF8 that segregates with PPCD in the family used to map PPCD3 and four different heterozygous nonsense and frameshift mutations in TCF8 in four other PPCD probands"

Establishes ZEB1 (TCF8) loss-of-function mutations as the cause of PPCD3.

PPCD4 (GRHL2-related, 8q22.3-q24.12)

PPCD subtype caused by non-coding (intronic/regulatory) mutations in GRHL2 that induce ectopic GRHL2 expression in the corneal endothelium. GRHL2 is a transcription factor that suppresses EMT and directly represses ZEB1; its ectopic expression drives the endothelium toward an epithelial-like state.

Show evidence (1 reference)

PMID:29499165 SUPPORT Human Clinical

"Whole-genome sequencing identified a unique variant (c.20+544G>T) in this locus, within an intronic regulatory region of GRHL2."

Identifies non-coding GRHL2 regulatory mutations as the cause of PPCD4.

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Pathophysiology

5

Corneal Endothelial-to-Epithelial Transdifferentiation

The central, convergent mechanism of PPCD. Normal corneal endothelial cells are post-mitotic, neural-crest-derived cells with a hexagonal monolayer morphology. In PPCD, the endothelium undergoes metaplasia toward an epithelial-like phenotype, acquiring epithelial morphology, epithelial gene expression (E-cadherin, cytokeratin 7), microvilli, and an aberrant proliferative/migratory behavior. These cells can overgrow the trabecular meshwork and iris. The cell-state switch reflects dysregulation of the ZEB1 EMT axis: ZEB1 normally maintains the mesenchymal/endothelial state by repressing epithelial genes, while OVOL2 and GRHL2 are EMT-suppressing transcription factors that repress ZEB1 and drive mesenchymal-to-epithelial transition (MET). Loss of ZEB1 (PPCD3) or ectopic activation of OVOL2 (PPCD1) or GRHL2 (PPCD4) all push the endothelium toward the epithelial state, explaining the indistinguishable phenotypes.

Corneal endothelial cell undergoing epithelial-like transdifferentiation CL:0000132 ⚠ ABNORMAL

Aberrant mesenchymal-to-epithelial transition of the endothelium GO:0060231 ⚠ ABNORMAL Dysregulated epithelial-to-mesenchymal transition control GO:0001837 ⚠ ABNORMAL

Downstream

Aberrant Descemet Membrane Deposition

Iridocorneal Adhesion and Anterior Chamber Distortion

Show evidence (4 references)

PMID:16252232 SUPPORT Human Clinical

"a rare disease involving metaplasia and overgrowth of corneal endothelial cells. In patients with PPCD, these cells manifest in an epithelial morphology and gene expression pattern"

Directly describes the endothelial-to-epithelial metaplasia central to PPCD.

PMID:29499165 SUPPORT Human Clinical

"These cells were also positive for epithelial markers E-Cadherin and Cytokeratin 7, indicating they have transitioned to an epithelial-like cell type. We suggest that mutations inducing MET within the corneal endothelium are a convergent pathogenic mechanism"

Demonstrates epithelial-marker expression in PPCD endothelium and the convergent MET mechanism.

PMID:31194824 SUPPORT In Vitro

"Transcriptomic and functional studies support the hypothesis that CEnC undergo a MET-like transition in PPCD, termed endothelial to epithelial transition (EnET)"

A CRISPR ZEB1-knockout corneal endothelial cell model defines the endothelial-to-epithelial transition (EnET) as the cell-state mechanism of PPCD.

+ 1 more reference

ZEB1 EMT-Axis Transcription Factor Dysregulation

PPCD-associated genes encode transcription factors that regulate cell-state transitions and converge on ZEB1. ZEB1 (PPCD3) loss-of-function causes haploinsufficiency that derepresses epithelial genes. OVOL2 (PPCD1) and GRHL2 (PPCD4) are EMT-suppressing factors that directly repress ZEB1 and are normally absent from the corneal endothelium; PPCD mutations cause their ectopic expression. Transcriptomic and immunohistochemical studies of PPCD endothelium show decreased ZEB1, increased OVOL2/GRHL2, and aberrant activation of the Wnt signaling pathway (nuclear accumulation of phospho-beta-catenin), consistent with a shared GRHL2-OVOL2-ZEB1 axis disturbance.

Dysregulated RNA polymerase II transcriptional regulation GO:0006357 ⚠ ABNORMAL Aberrant Wnt signaling activation GO:0016055 ↑ INCREASED

Downstream

Corneal Endothelial-to-Epithelial Transdifferentiation

Show evidence (3 references)

PMID:31233731 SUPPORT Human Clinical

"Each of these genes encodes a transcription factor that regulates cell-state transitions."

Confirms the three PPCD genes are cell-state-transition transcription factors converging on a shared axis.

PMID:31233731 SUPPORT Human Clinical

"indicating aberrant activation of Wnt signaling, which was not observed in control corneal endothelium"

Demonstrates aberrant Wnt signaling activation in PPCD endothelium.

PMID:26749309 SUPPORT Human Clinical

"OVOL2 encodes ovo-like zinc finger 2, a C2H2 zinc-finger transcription factor that regulates mesenchymal-to-epithelial transition and acts as a direct transcriptional repressor of the established PPCD-associated gene ZEB1"

Establishes OVOL2 as a direct repressor of ZEB1, anchoring the convergent axis.

Aberrant Descemet Membrane Deposition

The transdifferentiated, epithelial-like endothelium produces an abnormal, thickened, multilaminar basement membrane (Descemet membrane) with posterior collagenous layers. In ZEB1-related PPCD, loss of ZEB1 transcriptional repression leads to ectopic expression of basement-membrane collagen COL4A3 (collagen type IV alpha 3) by corneal endothelial cells, a target shared with the Alport syndrome COL4A3 gene. This aberrant matrix underlies the characteristic vesicular, band-like, and geographic opacities at the level of Descemet membrane seen clinically.

Corneal endothelial cell CL:0000132

Aberrant basement membrane assembly GO:0070831 ⚠ ABNORMAL

Show evidence (2 references)

PMID:16252232 SUPPORT Human Clinical

"produce an aberrant basement membrane"

PPCD endothelial cells deposit an aberrant basement membrane (Descemet membrane).

PMID:16252232 SUPPORT Human Clinical

"we present immunohistochemical evidence of ectopic expression of COL4A3 in corneal endothelium of the proband of the original PPCD3 family"

Documents ectopic COL4A3 basement-membrane collagen expression in PPCD3 endothelium.

Iridocorneal Adhesion and Anterior Chamber Distortion

The proliferative, migratory epithelial-like endothelium can extend across the iridocorneal angle and over the iris surface, producing iridocorneal/peripheral anterior synechiae, corectopia (pupillary distortion), and pseudopolycoria. Overgrowth and membrane formation across the trabecular meshwork impede aqueous outflow, increasing the risk of secondary glaucoma.

Epithelial-like (transdifferentiated) corneal endothelial cell CL:0000132 ⚠ ABNORMAL

Downstream

Secondary Glaucoma

Show evidence (1 reference)

PMID:16252232 SUPPORT Human Clinical

"sometimes, spread over the iris and nearby structures in a way that increases the risk for glaucoma"

Endothelial overgrowth onto the iris and angle increases glaucoma risk.

Secondary Glaucoma

Obstruction of aqueous humor outflow by the abnormal endothelium and associated iridocorneal adhesions/membranes raises intraocular pressure, leading to secondary (often angle-closure or membrane-associated) glaucoma, a major cause of visual morbidity in PPCD.

Show evidence (1 reference)

PMID:16252232 SUPPORT Human Clinical

"spread over the iris and nearby structures in a way that increases the risk for glaucoma"

Links the endothelial overgrowth mechanism to secondary glaucoma.

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Pathograph

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Phenotypes

9

Digestive 1

Inguinal hernia Inguinal hernia HP:0000023

Show evidence (1 reference)

PMID:17935237 SUPPORT Human Clinical

"the presence of apparently causative TCF8 mutations is associated with abdominal and inguinal hernias"

Establishes increased inguinal/abdominal hernia frequency in ZEB1-related PPCD3.

Eye 2

Corneal opacity Corneal opacity HP:0007957

Show evidence (1 reference)

PMID:26749309 PARTIAL Human Clinical

"CHED1 represents the extreme of what can be considered a disease spectrum"

PPCD1 lies on a spectrum with CHED1, whose severe extreme presents with corneal clouding/opacity.

Glaucoma Glaucoma HP:0000501

Show evidence (1 reference)

PMID:16252232 SUPPORT Human Clinical

"spread over the iris and nearby structures in a way that increases the risk for glaucoma"

Directly links PPCD pathology to increased glaucoma risk.

Other 6

Polymorphous posterior corneal dystrophy Polymorphous posterior corneal dystrophy HP:0007915

Show evidence (1 reference)

PMID:16252232 SUPPORT Human Clinical

"Posterior polymorphous corneal dystrophy (PPCD, also known as PPMD) is a rare disease involving metaplasia and overgrowth of corneal endothelial cells."

Establishes the disease entity defined by the posterior polymorphous corneal lesions.

Abnormal corneal endothelium morphology Abnormal corneal endothelium morphology HP:0011488

Show evidence (1 reference)

PMID:16252232 SUPPORT Human Clinical

"these cells manifest in an epithelial morphology and gene expression pattern"

PPCD endothelial cells show abnormal epithelial-like morphology.

Reduced corneal endothelial cell density Reduced number of corneal endothelial cells HP:0011491

Show evidence (1 reference)

PMID:33608638 SUPPORT Human Clinical

"Patients with PPCD had significantly lower endothelial cell densities (ECD) at recruitment (1918.9 ± 666.3 vs. 3340.1 ± 286.5 cells/mm2, p < 0.007)"

Quantitatively documents reduced corneal endothelial cell density in PPCD versus controls.

Abnormal Descemet membrane morphology Abnormal Descemet membrane morphology HP:0011490

Show evidence (1 reference)

PMID:16252232 SUPPORT Human Clinical

"produce an aberrant basement membrane"

The aberrant basement membrane corresponds to abnormal Descemet membrane.

Corectopia Ectopia pupillae HP:0009918

Show evidence (1 reference)

PMID:16252232 PARTIAL Human Clinical

"spread over the iris and nearby structures"

Endothelial spread over the iris underlies iris distortion/corectopia; the abstract documents the iris involvement that produces this sign.

Iridocorneal adhesions Anterior synechiae of the anterior chamber HP:0011483

Show evidence (1 reference)

PMID:16252232 PARTIAL Human Clinical

"spread over the iris and nearby structures"

Endothelial spread over the iris and angle produces iridocorneal adhesions (anterior synechiae).

🧬

Genetic Associations

3

OVOL2

Gene: OVOL2 hgnc:15804

Show evidence (1 reference)

PMID:26749309 SUPPORT Human Clinical

"we postulate that the mutations identified create cryptic cis-acting regulatory sequence binding sites that drive aberrant OVOL2 expression during endothelial cell development"

OVOL2 promoter mutations drive aberrant endothelial OVOL2 expression, causing PPCD1.

ZEB1

Gene: ZEB1 hgnc:11642

Show evidence (2 references)

PMID:16252232 SUPPORT Human Clinical

"this study has identified TCF8 as the gene responsible for approximately half of the cases of PPCD"

Establishes ZEB1 (TCF8) as a major PPCD (PPCD3) gene.

PMID:33946386 SUPPORT Human Clinical

"ZEB1 loss-of-function (LoF) alleles are known to cause a rare autosomal dominant disorder-posterior polymorphous corneal dystrophy type 3 (PPCD3)."

Confirms ZEB1 loss-of-function alleles as the cause of PPCD3; the study also documents reduced/incomplete penetrance.

GRHL2

Gene: GRHL2 hgnc:2799

Show evidence (1 reference)

PMID:29499165 SUPPORT Human Clinical

"GRHL2 is a transcription factor that suppresses epithelial-to-mesenchymal transition (EMT) and is a direct transcriptional repressor of ZEB1."

Establishes GRHL2 as a PPCD4 gene acting through the EMT/ZEB1 axis.

💊

Medical Actions

4

Observation

Action: watchful waiting Ontology label: supportive care MAXO:0000950

Most individuals with PPCD are asymptomatic and require only periodic monitoring of corneal status and intraocular pressure rather than active intervention.

Show evidence (1 reference)

PMID:33608638 PARTIAL Human Clinical

"children with PPCD were followed with slit-lamp photography and non-contact specular microscopy"

Reflects real-world longitudinal monitoring (slit-lamp and specular microscopy follow-up) of PPCD patients, consistent with observation as the baseline management of mild/asymptomatic disease.

Corneal Transplantation

Action: corneal transplantation MAXO:0010034

For symptomatic PPCD with corneal decompensation/edema, corneal transplantation (endothelial keratoplasty such as DSEK/DMEK, or penetrating keratoplasty) replaces the dysfunctional endothelium and Descemet membrane.

Show evidence (1 reference)

PMID:29499165 PARTIAL Human Clinical

"leading to dysfunction of the endothelial barrier and disease"

PPCD produces endothelial-barrier dysfunction; when this decompensates the cornea, corneal transplantation (endothelial keratoplasty or penetrating keratoplasty) replaces the dysfunctional endothelium and Descemet membrane (clinical-management context).

Antiglaucoma Therapy

Action: antiglaucoma agent therapy MAXO:0000307

Medical and/or surgical management of secondary glaucoma to control intraocular pressure in PPCD patients with angle involvement.

Show evidence (1 reference)

PMID:16252232 PARTIAL Human Clinical

"increases the risk for glaucoma"

Increased glaucoma risk in PPCD motivates antiglaucoma management of affected patients.

Genetic Counseling

Action: Genetic Counseling NCIT:C15240

Genetic counseling for affected families given autosomal-dominant inheritance and the availability of diagnostic gene testing for OVOL2, ZEB1, and GRHL2.

Show evidence (1 reference)

PMID:31201376 SUPPORT Other

"DNA-based testing for variants in theOVOL2, ZEB1andGRHL2gene(s) in a diagnostic setting, predictive and parental settings and for risk assesment in relatives"

The Clinical Utility Gene Card supports diagnostic/predictive gene testing and counseling for PPCD families.

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Source YAML

click to show

name: Posterior Polymorphous Corneal Dystrophy
creation_date: "2026-06-15T00:00:00Z"
category: Mendelian
description: >-
  Posterior polymorphous corneal dystrophy (PPCD) is a rare, usually
  autosomal-dominant, bilateral posterior corneal endothelial dystrophy. Its
  defining pathology is an abnormal transdifferentiation of the corneal
  endothelium toward an epithelial-like phenotype: endothelial cells acquire
  epithelial morphology, gene expression (E-cadherin, cytokeratins), and
  proliferative behavior, and deposit an aberrant, multilaminar Descemet
  membrane. Clinically this produces the characteristic vesicular, band, and
  diffuse opacities at the level of Descemet membrane. Most patients are
  asymptomatic, but a subset develop corneal edema, iridocorneal adhesions,
  corectopia, and secondary glaucoma. PPCD is genetically heterogeneous and the
  recognized subtypes are caused by transcription-factor dysregulation that
  converges on the ZEB1 epithelial-mesenchymal transition (EMT) axis:
  OVOL2 promoter mutations (PPCD1), ZEB1 loss-of-function (PPCD3), and GRHL2
  non-coding regulatory mutations (PPCD4). It is distinct from Fuchs endothelial
  corneal dystrophy, which is an attritional (cell-loss) endothelial dystrophy
  rather than an endothelial-to-epithelial transdifferentiation disorder.
disease_term:
  preferred_term: posterior polymorphous corneal dystrophy
  term:
    id: MONDO:0020364
    label: posterior polymorphous corneal dystrophy
synonyms:
- PPCD
- PPMD
- Schlichting dystrophy
- Posterior polymorphous dystrophy
parents:
- Corneal endothelial dystrophy
- Posterior corneal dystrophy
- Hereditary disease
has_subtypes:
- name: PPCD1
  display_name: PPCD1 (OVOL2-related, 20p11.2)
  description: >-
    PPCD subtype mapped to chromosome 20p11.2 and caused by mutations in the
    proximal promoter of OVOL2, a gene not normally expressed in the corneal
    endothelium. The mutations drive aberrant ectopic OVOL2 expression; OVOL2
    promotes mesenchymal-to-epithelial transition and directly represses ZEB1.
    PPCD1 is allelic with the autosomal-dominant congenital hereditary
    endothelial dystrophy CHED1.
  evidence:
  - reference: PMID:26749309
    reference_title: "Autosomal-Dominant Corneal Endothelial Dystrophies CHED1 and PPCD1 Are Allelic Disorders Caused by Non-coding Mutations in the Promoter of OVOL2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the identification of pathogenic variants in a conserved region of the OVOL2 proximal promoter sequence in the index families (c.-339_361dup for CHED1 and c.-370T>C for PPCD1)"
    explanation: Identifies OVOL2 promoter mutations as the cause of PPCD1.
- name: PPCD3
  display_name: PPCD3 (ZEB1/TCF8-related, 10p11.2)
  description: >-
    PPCD subtype caused by heterozygous loss-of-function (nonsense and
    frameshift) mutations in ZEB1 (formerly TCF8), accounting for roughly a
    quarter to a third of screened PPCD families. ZEB1 haploinsufficiency
    derepresses epithelial genes in the endothelium. PPCD3 is also associated
    with extraocular abnormalities, notably inguinal and abdominal hernias.
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we report a heterozygous frameshift mutation in TCF8 that segregates with PPCD in the family used to map PPCD3 and four different heterozygous nonsense and frameshift mutations in TCF8 in four other PPCD probands"
    explanation: Establishes ZEB1 (TCF8) loss-of-function mutations as the cause of PPCD3.
- name: PPCD4
  display_name: PPCD4 (GRHL2-related, 8q22.3-q24.12)
  description: >-
    PPCD subtype caused by non-coding (intronic/regulatory) mutations in GRHL2
    that induce ectopic GRHL2 expression in the corneal endothelium. GRHL2 is a
    transcription factor that suppresses EMT and directly represses ZEB1; its
    ectopic expression drives the endothelium toward an epithelial-like state.
  evidence:
  - reference: PMID:29499165
    reference_title: "Ectopic GRHL2 Expression Due to Non-coding Mutations Promotes Cell State Transition and Causes Posterior Polymorphous Corneal Dystrophy 4."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Whole-genome sequencing identified a unique variant (c.20+544G>T) in this locus, within an intronic regulatory region of GRHL2."
    explanation: Identifies non-coding GRHL2 regulatory mutations as the cause of PPCD4.
notes: >-
  Subtype-to-gene assignment follows the 2020 Clinical Utility Gene Card (CUGC)
  for PPCD (OVOL2/PPCD1, ZEB1/PPCD3, GRHL2/PPCD4). Historical assignments of
  VSX1 to PPCD1 and COL8A2 to PPCD2 (OMIM 609140) are now regarded as
  unconfirmed or of uncertain significance; evidence-based reviews support a
  segregating causal role only for ZEB1 in PPCD3 among the early candidates.
  Many PPCD pedigrees remain genetically unresolved. PPCD is mechanistically and
  classificationally distinct from Fuchs endothelial corneal dystrophy.
inheritance:
- name: Autosomal dominant inheritance
  inheritance_term:
    preferred_term: autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  evidence:
  - reference: PMID:29499165
    reference_title: "Ectopic GRHL2 Expression Due to Non-coding Mutations Promotes Cell State Transition and Causes Posterior Polymorphous Corneal Dystrophy 4."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we mapped a locus for an autosomal-dominant corneal endothelial dystrophy, posterior polymorphous corneal dystrophy 4 (PPCD4), to 8q22.3-q24.12"
    explanation: PPCD is described as an autosomal-dominant corneal endothelial dystrophy.
pathophysiology:
- name: Corneal Endothelial-to-Epithelial Transdifferentiation
  description: >-
    The central, convergent mechanism of PPCD. Normal corneal endothelial cells
    are post-mitotic, neural-crest-derived cells with a hexagonal monolayer
    morphology. In PPCD, the endothelium undergoes metaplasia toward an
    epithelial-like phenotype, acquiring epithelial morphology, epithelial gene
    expression (E-cadherin, cytokeratin 7), microvilli, and an aberrant
    proliferative/migratory behavior. These cells can overgrow the trabecular
    meshwork and iris. The cell-state switch reflects dysregulation of the
    ZEB1 EMT axis: ZEB1 normally maintains the mesenchymal/endothelial state by
    repressing epithelial genes, while OVOL2 and GRHL2 are EMT-suppressing
    transcription factors that repress ZEB1 and drive
    mesenchymal-to-epithelial transition (MET). Loss of ZEB1 (PPCD3) or ectopic
    activation of OVOL2 (PPCD1) or GRHL2 (PPCD4) all push the endothelium toward
    the epithelial state, explaining the indistinguishable phenotypes.
  cell_types:
  - preferred_term: Corneal endothelial cell undergoing epithelial-like transdifferentiation
    term:
      id: CL:0000132
      label: corneal endothelial cell
    modifier: ABNORMAL
  biological_processes:
  - preferred_term: Aberrant mesenchymal-to-epithelial transition of the endothelium
    term:
      id: GO:0060231
      label: mesenchymal to epithelial transition
    modifier: ABNORMAL
  - preferred_term: Dysregulated epithelial-to-mesenchymal transition control
    term:
      id: GO:0001837
      label: epithelial to mesenchymal transition
    modifier: ABNORMAL
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a rare disease involving metaplasia and overgrowth of corneal endothelial cells. In patients with PPCD, these cells manifest in an epithelial morphology and gene expression pattern"
    explanation: Directly describes the endothelial-to-epithelial metaplasia central to PPCD.
  - reference: PMID:29499165
    reference_title: "Ectopic GRHL2 Expression Due to Non-coding Mutations Promotes Cell State Transition and Causes Posterior Polymorphous Corneal Dystrophy 4."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These cells were also positive for epithelial markers E-Cadherin and Cytokeratin 7, indicating they have transitioned to an epithelial-like cell type. We suggest that mutations inducing MET within the corneal endothelium are a convergent pathogenic mechanism"
    explanation: Demonstrates epithelial-marker expression in PPCD endothelium and the convergent MET mechanism.
  - reference: PMID:31194824
    reference_title: "ZEB1 insufficiency causes corneal endothelial cell state transition and altered cellular processing."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Transcriptomic and functional studies support the hypothesis that CEnC undergo a MET-like transition in PPCD, termed endothelial to epithelial transition (EnET)"
    explanation: A CRISPR ZEB1-knockout corneal endothelial cell model defines the endothelial-to-epithelial transition (EnET) as the cell-state mechanism of PPCD.
  - reference: PMID:31194824
    reference_title: "ZEB1 insufficiency causes corneal endothelial cell state transition and altered cellular processing."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "PPCD is characterized by a cadherin-switch and transition to an epithelial-like transcriptomic and cellular phenotype"
    explanation: Documents the cadherin switch and epithelial-like transcriptomic phenotype underlying PPCD transdifferentiation.
  downstream:
  - target: Aberrant Descemet Membrane Deposition
    causal_link_type: DIRECT
  - target: Iridocorneal Adhesion and Anterior Chamber Distortion
    causal_link_type: DIRECT
- name: ZEB1 EMT-Axis Transcription Factor Dysregulation
  description: >-
    PPCD-associated genes encode transcription factors that regulate
    cell-state transitions and converge on ZEB1. ZEB1 (PPCD3) loss-of-function
    causes haploinsufficiency that derepresses epithelial genes. OVOL2 (PPCD1)
    and GRHL2 (PPCD4) are EMT-suppressing factors that directly repress ZEB1
    and are normally absent from the corneal endothelium; PPCD mutations cause
    their ectopic expression. Transcriptomic and immunohistochemical studies of
    PPCD endothelium show decreased ZEB1, increased OVOL2/GRHL2, and aberrant
    activation of the Wnt signaling pathway (nuclear accumulation of
    phospho-beta-catenin), consistent with a shared GRHL2-OVOL2-ZEB1 axis
    disturbance.
  biological_processes:
  - preferred_term: Dysregulated RNA polymerase II transcriptional regulation
    term:
      id: GO:0006357
      label: regulation of transcription by RNA polymerase II
    modifier: ABNORMAL
  - preferred_term: Aberrant Wnt signaling activation
    term:
      id: GO:0016055
      label: Wnt signaling pathway
    modifier: INCREASED
  evidence:
  - reference: PMID:31233731
    reference_title: "Alterations in GRHL2-OVOL2-ZEB1 axis and aberrant activation of Wnt signaling lead to altered gene transcription in posterior polymorphous corneal dystrophy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Each of these genes encodes a transcription factor that regulates cell-state transitions."
    explanation: Confirms the three PPCD genes are cell-state-transition transcription factors converging on a shared axis.
  - reference: PMID:31233731
    reference_title: "Alterations in GRHL2-OVOL2-ZEB1 axis and aberrant activation of Wnt signaling lead to altered gene transcription in posterior polymorphous corneal dystrophy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "indicating aberrant activation of Wnt signaling, which was not observed in control corneal endothelium"
    explanation: Demonstrates aberrant Wnt signaling activation in PPCD endothelium.
  - reference: PMID:26749309
    reference_title: "Autosomal-Dominant Corneal Endothelial Dystrophies CHED1 and PPCD1 Are Allelic Disorders Caused by Non-coding Mutations in the Promoter of OVOL2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "OVOL2 encodes ovo-like zinc finger 2, a C2H2 zinc-finger transcription factor that regulates mesenchymal-to-epithelial transition and acts as a direct transcriptional repressor of the established PPCD-associated gene ZEB1"
    explanation: Establishes OVOL2 as a direct repressor of ZEB1, anchoring the convergent axis.
  downstream:
  - target: Corneal Endothelial-to-Epithelial Transdifferentiation
    causal_link_type: DIRECT
- name: Aberrant Descemet Membrane Deposition
  description: >-
    The transdifferentiated, epithelial-like endothelium produces an abnormal,
    thickened, multilaminar basement membrane (Descemet membrane) with
    posterior collagenous layers. In ZEB1-related PPCD, loss of ZEB1
    transcriptional repression leads to ectopic expression of basement-membrane
    collagen COL4A3 (collagen type IV alpha 3) by corneal endothelial cells, a
    target shared with the Alport syndrome COL4A3 gene. This aberrant matrix
    underlies the characteristic vesicular, band-like, and geographic opacities
    at the level of Descemet membrane seen clinically.
  cell_types:
  - preferred_term: Corneal endothelial cell
    term:
      id: CL:0000132
      label: corneal endothelial cell
  biological_processes:
  - preferred_term: Aberrant basement membrane assembly
    term:
      id: GO:0070831
      label: basement membrane assembly
    modifier: ABNORMAL
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "produce an aberrant basement membrane"
    explanation: PPCD endothelial cells deposit an aberrant basement membrane (Descemet membrane).
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we present immunohistochemical evidence of ectopic expression of COL4A3 in corneal endothelium of the proband of the original PPCD3 family"
    explanation: Documents ectopic COL4A3 basement-membrane collagen expression in PPCD3 endothelium.
- name: Iridocorneal Adhesion and Anterior Chamber Distortion
  description: >-
    The proliferative, migratory epithelial-like endothelium can extend across
    the iridocorneal angle and over the iris surface, producing
    iridocorneal/peripheral anterior synechiae, corectopia (pupillary
    distortion), and pseudopolycoria. Overgrowth and membrane formation across
    the trabecular meshwork impede aqueous outflow, increasing the risk of
    secondary glaucoma.
  cell_types:
  - preferred_term: Epithelial-like (transdifferentiated) corneal endothelial cell
    term:
      id: CL:0000132
      label: corneal endothelial cell
    modifier: ABNORMAL
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "sometimes, spread over the iris and nearby structures in a way that increases the risk for glaucoma"
    explanation: Endothelial overgrowth onto the iris and angle increases glaucoma risk.
  downstream:
  - target: Secondary Glaucoma
    causal_link_type: DIRECT
- name: Secondary Glaucoma
  description: >-
    Obstruction of aqueous humor outflow by the abnormal endothelium and
    associated iridocorneal adhesions/membranes raises intraocular pressure,
    leading to secondary (often angle-closure or membrane-associated) glaucoma,
    a major cause of visual morbidity in PPCD.
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "spread over the iris and nearby structures in a way that increases the risk for glaucoma"
    explanation: Links the endothelial overgrowth mechanism to secondary glaucoma.
phenotypes:
- name: Polymorphous posterior corneal dystrophy
  category: Ophthalmologic
  description: >-
    The defining clinical sign: polymorphous (vesicular, band-like, and
    geographic/diffuse) opacities at the level of Descemet membrane and the
    posterior cornea, reflecting the abnormal transdifferentiated endothelium
    and aberrant Descemet membrane.
  phenotype_term:
    preferred_term: Polymorphous posterior corneal dystrophy
    term:
      id: HP:0007915
      label: Polymorphous posterior corneal dystrophy
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Posterior polymorphous corneal dystrophy (PPCD, also known as PPMD) is a rare disease involving metaplasia and overgrowth of corneal endothelial cells."
    explanation: Establishes the disease entity defined by the posterior polymorphous corneal lesions.
- name: Abnormal corneal endothelium morphology
  category: Ophthalmologic
  description: >-
    The corneal endothelium shows metaplastic, epithelial-like morphology with
    loss of the normal hexagonal monolayer architecture.
  phenotype_term:
    preferred_term: Abnormal corneal endothelium morphology
    term:
      id: HP:0011488
      label: Abnormal corneal endothelium morphology
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "these cells manifest in an epithelial morphology and gene expression pattern"
    explanation: PPCD endothelial cells show abnormal epithelial-like morphology.
- name: Reduced corneal endothelial cell density
  category: Ophthalmologic
  description: >-
    Quantitative reduction in corneal endothelial cell density (ECD). A
    longitudinal pediatric case-control study found markedly lower ECD in PPCD
    than in age-matched controls, with the lowest densities in diffuse-type
    disease and eyes with many posterior corneal lesions.
  phenotype_term:
    preferred_term: Reduced corneal endothelial cell density
    term:
      id: HP:0011491
      label: Reduced number of corneal endothelial cells
  evidence:
  - reference: PMID:33608638
    reference_title: "Endothelial cell density in children with posterior polymorphous corneal dystrophy: a longitudinal case-control study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with PPCD had significantly lower endothelial cell densities (ECD) at recruitment (1918.9 ± 666.3 vs. 3340.1 ± 286.5 cells/mm2, p < 0.007)"
    explanation: Quantitatively documents reduced corneal endothelial cell density in PPCD versus controls.
- name: Abnormal Descemet membrane morphology
  category: Ophthalmologic
  description: >-
    Aberrant, thickened, multilaminar Descemet membrane produced by the
    transdifferentiated endothelium.
  phenotype_term:
    preferred_term: Abnormal Descemet membrane morphology
    term:
      id: HP:0011490
      label: Abnormal Descemet membrane morphology
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "produce an aberrant basement membrane"
    explanation: The aberrant basement membrane corresponds to abnormal Descemet membrane.
- name: Corneal opacity
  category: Ophthalmologic
  description: >-
    Posterior and, in severe cases, diffuse corneal opacity from the abnormal
    endothelium, Descemet changes, and corneal edema.
  phenotype_term:
    preferred_term: Corneal opacity
    term:
      id: HP:0007957
      label: Corneal opacity
  evidence:
  - reference: PMID:26749309
    reference_title: "Autosomal-Dominant Corneal Endothelial Dystrophies CHED1 and PPCD1 Are Allelic Disorders Caused by Non-coding Mutations in the Promoter of OVOL2."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "CHED1 represents the extreme of what can be considered a disease spectrum"
    explanation: PPCD1 lies on a spectrum with CHED1, whose severe extreme presents with corneal clouding/opacity.
- name: Glaucoma
  category: Ophthalmologic
  description: >-
    Secondary glaucoma arising from endothelial overgrowth across the
    iridocorneal angle and iris with impaired aqueous outflow.
  phenotype_term:
    preferred_term: Glaucoma
    term:
      id: HP:0000501
      label: Glaucoma
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "spread over the iris and nearby structures in a way that increases the risk for glaucoma"
    explanation: Directly links PPCD pathology to increased glaucoma risk.
- name: Corectopia
  category: Ophthalmologic
  description: >-
    Corectopia (displaced/distorted pupil) caused by iridocorneal adhesions and
    iris traction from endothelial overgrowth.
  phenotype_term:
    preferred_term: Corectopia
    term:
      id: HP:0009918
      label: Ectopia pupillae
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "spread over the iris and nearby structures"
    explanation: Endothelial spread over the iris underlies iris distortion/corectopia; the abstract documents the iris involvement that produces this sign.
- name: Iridocorneal adhesions
  category: Ophthalmologic
  description: >-
    Iridocorneal/peripheral anterior synechiae from migration of the abnormal
    endothelium across the angle and onto the iris.
  phenotype_term:
    preferred_term: Iridocorneal adhesions
    term:
      id: HP:0011483
      label: Anterior synechiae of the anterior chamber
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "spread over the iris and nearby structures"
    explanation: Endothelial spread over the iris and angle produces iridocorneal adhesions (anterior synechiae).
- name: Inguinal hernia
  category: Extraocular
  subtype: PPCD3
  description: >-
    Inguinal/abdominal hernias occur at significantly increased frequency in
    individuals with ZEB1 (TCF8)-associated PPCD3, reflecting a role for ZEB1 in
    tissues lining body cavities beyond the eye.
  phenotype_term:
    preferred_term: Inguinal hernia
    term:
      id: HP:0000023
      label: Inguinal hernia
  evidence:
  - reference: PMID:17935237
    reference_title: "Posterior polymorphous corneal dystrophy is associated with TCF8 gene mutations and abdominal hernia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the presence of apparently causative TCF8 mutations is associated with abdominal and inguinal hernias"
    explanation: Establishes increased inguinal/abdominal hernia frequency in ZEB1-related PPCD3.
genetic:
- name: OVOL2
  subtype: PPCD1
  notes: >-
    Mutations in the proximal promoter of OVOL2 cause PPCD1 by driving ectopic
    OVOL2 expression in the corneal endothelium. OVOL2 promotes
    mesenchymal-to-epithelial transition and directly represses ZEB1.
  gene_term:
    preferred_term: OVOL2
    term:
      id: hgnc:15804
      label: OVOL2
  evidence:
  - reference: PMID:26749309
    reference_title: "Autosomal-Dominant Corneal Endothelial Dystrophies CHED1 and PPCD1 Are Allelic Disorders Caused by Non-coding Mutations in the Promoter of OVOL2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "we postulate that the mutations identified create cryptic cis-acting regulatory sequence binding sites that drive aberrant OVOL2 expression during endothelial cell development"
    explanation: OVOL2 promoter mutations drive aberrant endothelial OVOL2 expression, causing PPCD1.
- name: ZEB1
  subtype: PPCD3
  notes: >-
    Heterozygous nonsense/frameshift loss-of-function mutations in ZEB1
    (formerly TCF8) cause PPCD3 via haploinsufficiency, accounting for about a
    quarter to a third of PPCD families and associated with extraocular hernias.
  gene_term:
    preferred_term: ZEB1
    term:
      id: hgnc:11642
      label: ZEB1
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "this study has identified TCF8 as the gene responsible for approximately half of the cases of PPCD"
    explanation: Establishes ZEB1 (TCF8) as a major PPCD (PPCD3) gene.
  - reference: PMID:33946386
    reference_title: "Non-Penetrance for Ocular Phenotype in Two Individuals Carrying Heterozygous Loss-of-Function ZEB1 Alleles."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ZEB1 loss-of-function (LoF) alleles are known to cause a rare autosomal dominant disorder-posterior polymorphous corneal dystrophy type 3 (PPCD3)."
    explanation: Confirms ZEB1 loss-of-function alleles as the cause of PPCD3; the study also documents reduced/incomplete penetrance.
- name: GRHL2
  subtype: PPCD4
  notes: >-
    Non-coding (intronic regulatory) mutations in GRHL2 cause PPCD4 by inducing
    ectopic GRHL2 expression in the corneal endothelium. GRHL2 suppresses EMT
    and is a direct transcriptional repressor of ZEB1.
  gene_term:
    preferred_term: GRHL2
    term:
      id: hgnc:2799
      label: GRHL2
  evidence:
  - reference: PMID:29499165
    reference_title: "Ectopic GRHL2 Expression Due to Non-coding Mutations Promotes Cell State Transition and Causes Posterior Polymorphous Corneal Dystrophy 4."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "GRHL2 is a transcription factor that suppresses epithelial-to-mesenchymal transition (EMT) and is a direct transcriptional repressor of ZEB1."
    explanation: Establishes GRHL2 as a PPCD4 gene acting through the EMT/ZEB1 axis.
treatments:
- name: Observation
  description: >-
    Most individuals with PPCD are asymptomatic and require only periodic
    monitoring of corneal status and intraocular pressure rather than active
    intervention.
  treatment_term:
    preferred_term: watchful waiting
    term:
      id: MAXO:0000950
      label: supportive care
  evidence:
  - reference: PMID:33608638
    reference_title: "Endothelial cell density in children with posterior polymorphous corneal dystrophy: a longitudinal case-control study."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "children with PPCD were followed with slit-lamp photography and non-contact specular microscopy"
    explanation: Reflects real-world longitudinal monitoring (slit-lamp and specular microscopy follow-up) of PPCD patients, consistent with observation as the baseline management of mild/asymptomatic disease.
- name: Corneal Transplantation
  description: >-
    For symptomatic PPCD with corneal decompensation/edema, corneal
    transplantation (endothelial keratoplasty such as DSEK/DMEK, or penetrating
    keratoplasty) replaces the dysfunctional endothelium and Descemet membrane.
  treatment_term:
    preferred_term: corneal transplantation
    term:
      id: MAXO:0010034
      label: corneal transplantation
  evidence:
  - reference: PMID:29499165
    reference_title: "Ectopic GRHL2 Expression Due to Non-coding Mutations Promotes Cell State Transition and Causes Posterior Polymorphous Corneal Dystrophy 4."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "leading to dysfunction of the endothelial barrier and disease"
    explanation: PPCD produces endothelial-barrier dysfunction; when this decompensates the cornea, corneal transplantation (endothelial keratoplasty or penetrating keratoplasty) replaces the dysfunctional endothelium and Descemet membrane (clinical-management context).
- name: Antiglaucoma Therapy
  description: >-
    Medical and/or surgical management of secondary glaucoma to control
    intraocular pressure in PPCD patients with angle involvement.
  treatment_term:
    preferred_term: antiglaucoma agent therapy
    term:
      id: MAXO:0000307
      label: antiglaucoma agent therapy
  evidence:
  - reference: PMID:16252232
    reference_title: "Mutations in TCF8 cause posterior polymorphous corneal dystrophy and ectopic expression of COL4A3 by corneal endothelial cells."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "increases the risk for glaucoma"
    explanation: Increased glaucoma risk in PPCD motivates antiglaucoma management of affected patients.
- name: Genetic Counseling
  description: >-
    Genetic counseling for affected families given autosomal-dominant
    inheritance and the availability of diagnostic gene testing for OVOL2,
    ZEB1, and GRHL2.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:31201376
    reference_title: "CUGC for posterior polymorphous corneal dystrophy (PPCD)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "DNA-based testing for variants in theOVOL2, ZEB1andGRHL2gene(s) in a diagnostic setting, predictive and parental settings and for risk assesment in relatives"
    explanation: The Clinical Utility Gene Card supports diagnostic/predictive gene testing and counseling for PPCD families.

📚

References & Deep Research

Deep Research

1

Falcon ▸

1. Disease Information

Edison Scientific Literature 38 citations 2026-06-15T23:05:10.030880

1. Disease Information

1.1 Concise overview

Posterior polymorphous corneal dystrophy (PPCD) is a rare autosomal dominant corneal endothelial dystrophy characterized by abnormal corneal endothelial cell morphology and posterior corneal/Descemet membrane changes that can be clinically visible as vesicular lesions, band/“snail‑track/rail‑track” changes, and/or diffuse posterior opacities, with variable severity from asymptomatic findings to corneal edema, secondary glaucoma, and need for corneal transplantation. (Human clinical) (fung2021endothelialcelldensity pages 1-2, davidson2016autosomaldominantcornealendothelial pages 1-3, liskova2018ectopicgrhl2expression pages 6-7, davidson2020cugcforposterior pages 1-2)

1.2 Key identifiers

OMIM disease IDs (PPCD subtypes): 122000; 609141; 618031 (davidson2020cugcforposterior pages 1-2)
Genes and OMIM gene IDs: OVOL2 (616441), ZEB1 (189909), GRHL2 (608576) (davidson2020cugcforposterior pages 1-2)
IC3D classification context: IC3D “Edition 3” is a 2024 update that evaluated peer‑reviewed publications from 2014–2023 and provides standardized corneal dystrophy templates and a management table. URL in abstract: https://corneasociety.org/publications/ic3d (Published Feb 2024) (fung2021endothelialcelldensity pages 1-2)

MONDO / MeSH / ICD / Orphanet IDs: Not reliably extractable from the retrieved documents in this session; therefore they are not asserted here.

1.3 Common synonyms / alternative names

Posterior polymorphous corneal dystrophy
Often discussed by genetic subtypes: PPCD1, PPCD3, PPCD4 (davidson2020cugcforposterior pages 1-2)

1.4 Source type (aggregated vs patient-level)

Aggregated resources: IC3D classification (2024) (fung2021endothelialcelldensity pages 1-2)
Aggregated clinical genetics guidance: CUGC for PPCD (2020) (davidson2020cugcforposterior pages 1-2)
Patient-level primary data: OVOL2 families (AJHG 2016), GRHL2 families (AJHG 2018), ZEB1 non‑penetrance family (Genes 2021), pediatric longitudinal cohort (Eye 2021), family case report with variants (Frontiers Genet 2025) (fung2021endothelialcelldensity pages 2-4, davidson2016autosomaldominantcornealendothelial pages 6-8, liskova2018ectopicgrhl2expression pages 6-7, dudakova2021nonpenetranceforocular pages 1-2, lin2025polymorphouscornealdystrophy pages 2-3)

2. Etiology

2.1 Primary causes (genetic)

PPCD is predominantly caused by autosomal dominant variants affecting transcriptional regulators of epithelial/mesenchymal cell state: - PPCD1: non‑coding promoter mutations in OVOL2 (gain of promoter activity) (davidson2016autosomaldominantcornealendothelial pages 1-3, chung2017confirmationofthe pages 5-7) - PPCD3: ZEB1 haploinsufficiency / loss‑of‑function variants (dudakova2021nonpenetranceforocular pages 1-2, siddiqui2016geneticanalysisof pages 42-46) - PPCD4: non‑coding regulatory variants in GRHL2 causing increased transcription and ectopic endothelial expression (liskova2018ectopicgrhl2expression pages 1-2, liskova2018ectopicgrhl2expression pages 8-9)

Historically proposed loci such as COL8A2 have shown inconsistent replication across cohorts, suggesting weaker/uncertain evidence for a general PPCD2 mechanism in many populations. (siddiqui2016geneticanalysisof pages 42-46)

2.2 Risk factors

Genetic risk factors: carrying a pathogenic/likely pathogenic variant in OVOL2 promoter, ZEB1 LoF, or GRHL2 regulatory region (davidson2016autosomaldominantcornealendothelial pages 1-3, liskova2018ectopicgrhl2expression pages 1-2, dudakova2021nonpenetranceforocular pages 1-2)
Iatrogenic/clinical risk context: Reduced endothelial reserve may increase vulnerability to intraocular surgery; pediatric cohort emphasizes lower baseline endothelial cell density (ECD). (Human clinical) (fung2021endothelialcelldensity pages 2-4)
Corneal refractive surgery context: A three‑generation family report describes keratoconus aggravation after SMILE in individuals later diagnosed with PPCD3 and carrying ZEB1/ZNF469 variants, supporting caution and pre‑operative corneal evaluation/genetic screening in suspected familial disease. (Human clinical) (lin2025polymorphouscornealdystrophy pages 2-3)

2.3 Protective factors

No specific genetic or environmental protective factors were identified in the retrieved evidence.

2.4 Gene–environment interactions

No PPCD-specific gene–environment interaction studies were identified in the retrieved evidence.

3. Phenotypes (with suggested HPO terms)

3.1 Core corneal/endothelial phenotypes

Posterior corneal lesions / Descemet abnormalities - Clinical lesion patterns: vesicular, band/snail-track, diffuse posterior corneal opacities (fung2021endothelialcelldensity pages 1-2, fung2021endothelialcelldensity pages 2-4) - Suggested HPO (examples): - Abnormality of the cornea (HP:0000481) - Corneal opacity (HP:0007957) - Corneal dystrophy (HP:0001117)

Reduced corneal endothelial cell density (ECD) (key quantitative phenotype) - Pediatric longitudinal case-control study (mean age 10.5 years; follow-up ~3 years): - Baseline ECD: 1918.9 ± 666.3 cells/mm² (PPCD) vs 3340.1 ± 286.5 cells/mm² (controls) - Final ECD: 1793.1 ± 684.6 (PPCD) vs 3265.2 ± 304.3 (controls) - Annual ECD loss: 1.9 ± 3.7% per year, not significantly different from controls (p=0.95) (Human clinical) (fung2021endothelialcelldensity pages 2-4) - Suggested HPO: - Abnormality of the corneal endothelium (no specific code provided here; map at curation time)

Visual impairment / amblyopia risk - PPCD can be asymmetric in children and may contribute to amblyopia via unilateral/asymmetric involvement. (Human clinical) (fung2021endothelialcelldensity pages 5-6) - Suggested HPO: - Reduced visual acuity (HP:0007663) - Amblyopia (HP:0000649)

3.2 Glaucoma and anterior segment abnormalities

OVOL2-linked families: secondary glaucoma reported at approximately ~30% in one dataset excerpt. (Human clinical) (davidson2016autosomaldominantcornealendothelial pages 6-8)
GRHL2/PPCD4 Czech series: glaucoma in 25.9% (mean diagnosis ~46 years). (Human clinical) (liskova2018ectopicgrhl2expression pages 6-7)
Iris abnormalities/adhesions noted in OVOL2-linked disease descriptions (ectropion uveae/corectopia/adhesions). (Human clinical) (davidson2016autosomaldominantcornealendothelial pages 1-3)
Suggested HPO:
Glaucoma (HP:0000501)
Corectopia (HP:0000579)
Anterior segment dysgenesis (HP:0000591)

3.3 Course, onset, progression

Disease expression ranges from asymptomatic to severe corneal edema requiring transplantation; infants may rarely present with early corneal edema/haze. (Human clinical) (fung2021endothelialcelldensity pages 1-2, liskova2018ectopicgrhl2expression pages 6-7)
In pediatric PPCD, no corneal edema or ectasia occurred during ~3 years follow-up, despite lower ECD. (Human clinical) (fung2021endothelialcelldensity pages 1-2)

3.4 Quality of life impact

A prospective case-control study of non-Fuchs corneal dystrophies (2021–2024 recruitment; included 3 PPCD patients) found significantly worse quality of life scores vs controls using VF-14 and NEI-VFQ, correlated with visual acuity and higher-order aberrations. (Human clinical) (elhardt2025 study retrieval; PPCD-specific subgroup results not extractable in retrieved snippets) (lin2025polymorphouscornealdystrophy pages 5-7)

4. Genetic / Molecular Information

4.1 Causal genes (established)

OVOL2 (PPCD1): promoter mutations (non-coding) (davidson2016autosomaldominantcornealendothelial pages 1-3, chung2017confirmationofthe pages 5-7)
ZEB1 (PPCD3): LoF/haploinsufficiency (dudakova2021nonpenetranceforocular pages 1-2, siddiqui2016geneticanalysisof pages 42-46)
GRHL2 (PPCD4): intronic/5′ regulatory mutations (liskova2018ectopicgrhl2expression pages 1-2, liskova2018ectopicgrhl2expression pages 6-7)

4.2 Pathogenic variant classes and examples

OVOL2 promoter: c.-307T>C segregates in PPCD1-linked family and increases promoter activity in corneal endothelial cells. (Human clinical / in vitro promoter assay) (chung2017confirmationofthe pages 5-7)
GRHL2 intron 1 regulatory: c.20+544G>T; c.20+257delT; c.20+133delA; all associated with increased transcriptional activity in luciferase assays. (Human genetics / in vitro) (liskova2018ectopicgrhl2expression pages 1-2, liskova2018ectopicgrhl2expression pages 8-9)
ZEB1 LoF: example c.1279C>T p.(Glu427) reported in non-penetrant carriers; population data suggest extreme rarity but presence of LoF alleles in gnomAD. (Human genetics*) (dudakova2021nonpenetranceforocular pages 1-2)

4.3 Inheritance, penetrance, expressivity

Inheritance: autosomal dominant (davidson2020cugcforposterior pages 1-2)
Penetrance: Familial studies for ZEB1 LoF suggest ~95% penetrance, but documented non-penetrance indicates true penetrance may be lower. (dudakova2021nonpenetranceforocular pages 1-2)
Expressivity: highly variable, ranging from asymptomatic endothelial findings to corneal edema and transplantation. (davidson2016autosomaldominantcornealendothelial pages 1-3, liskova2018ectopicgrhl2expression pages 6-7)

4.4 Modifier genes

A 2025 family report suggests potential interaction of ZEB1 variants with ZNF469 (ECM regulation; brittle cornea syndrome gene) in a family with PPCD3 and keratoconus aggravation; ZEB1 variant allele frequency noted as ~1e-5 in gnomAD EAS. (Human clinical) (lin2025polymorphouscornealdystrophy pages 3-5, lin2025polymorphouscornealdystrophy pages 2-3)

4.5 Epigenetic / chromosomal abnormalities

No PPCD-specific epigenetic signatures were identified in retrieved evidence; however, disease causality is frequently driven by cis-regulatory non-coding variants (OVOL2, GRHL2) (davidson2016autosomaldominantcornealendothelial pages 1-3, liskova2018ectopicgrhl2expression pages 1-2).

5. Environmental Information

No PPCD-specific environmental, lifestyle, or infectious causal factors were identified in the retrieved evidence.

6. Mechanism / Pathophysiology

6.1 Core concept: endothelial-to-epithelial transition (EnET) as a MET-like process

Frausto et al. developed a CRISPR ZEB1+/- corneal endothelial cell model and concluded that PPCD represents an MET-like transition termed endothelial-to-epithelial transition (EnET).

Direct abstract-supported statement (from retrieved abstract excerpt): PPCD is described as being “characterized by a cadherin-switch and transition to an epithelial-like transcriptomic and cellular phenotype” in the context of ZEB1 insufficiency. (In vitro / transcriptomics) (frausto2019zeb1insufficiencycauses pages 1-2)

6.2 Regulatory network: OVOL2 / GRHL2 repress ZEB1

OVOL2 promoter mutations increase promoter activity and are interpreted as causing ectopic/increased OVOL2 expression; OVOL2 “directly represses ZEB1.” (Human genetics / in vitro promoter assay) (davidson2016autosomaldominantcornealendothelial pages 1-3, davidson2016autosomaldominantcornealendothelial pages 11-13)
GRHL2 regulatory variants cause ectopic endothelial GRHL2 expression; diseased endothelium can express epithelial markers (E-cadherin, CK7) consistent with MET. (Human ex vivo / in vitro) (liskova2018ectopicgrhl2expression pages 8-9, liskova2018ectopicgrhl2expression pages 7-8)

6.3 Causal chain (variant → phenotype)

1) Non-coding promoter/intronic variants (OVOL2/GRHL2) or ZEB1 LoF → 2) Reduced ZEB1 function/expression (direct LoF or repression by OVOL2/GRHL2) → 3) EnET / epithelialization of corneal endothelium (cadherin switch; epithelial gene expression; stratification) → 4) Abnormal Descemet membrane and endothelial morphology, reduced endothelial reserve → 5) Corneal edema/opacification and angle/iris abnormalities, predisposing to secondary glaucoma and sometimes keratoplasty. (davidson2016autosomaldominantcornealendothelial pages 1-3, liskova2018ectopicgrhl2expression pages 6-7, frausto2019zeb1insufficiencycauses pages 1-2)

6.4 Biochemical abnormalities

Aqueous humor study (ELISA) found active TGF‑β2 significantly higher in PPCD patients (mean 386.98 ± 114.88 pg/mL) vs controls (mean 260.95 ± 112.43 pg/mL; P=0.0001). (Human clinical samples) (chung2017confirmationofthe pages 2-4)

6.5 Suggested ontology annotations

Cell types (CL):
Corneal endothelial cell (curation to CL term)
Corneal epithelial cell (curation to CL term)
Anatomy (UBERON):
Corneal endothelium, Descemet membrane, cornea (curation to UBERON terms)
Processes (GO):
Epithelial to mesenchymal transition (GO:0001837)
Mesenchymal to epithelial transition (GO:XXXXXXX; commonly represented as MET/epithelialization processes)
Cell fate commitment / cell differentiation
Cell adhesion

7. Anatomical Structures Affected

Primary: corneal endothelium and Descemet membrane (fung2021endothelialcelldensity pages 1-2, davidson2016autosomaldominantcornealendothelial pages 1-3)
Secondary/complications: iridocorneal angle/iris (adhesions/corectopia) and glaucoma risk (davidson2016autosomaldominantcornealendothelial pages 1-3, liskova2018ectopicgrhl2expression pages 6-7)

8. Temporal Development

Onset: can be recognized in childhood; rare infantile onset with edema/haze reported in PPCD4 series; OVOL2 allelic CHED1/PPCD1 can present from infancy with haze. (liskova2018ectopicgrhl2expression pages 6-7, davidson2016autosomaldominantcornealendothelial pages 5-6)
Progression: variable; pediatric ECD decline similar to controls over ~3 years suggests slow change in childhood despite low baseline ECD. (fung2021endothelialcelldensity pages 2-4)

9. Inheritance and Population

9.1 Epidemiology

Prevalence estimate: Czech prevalence reported as ~1 per 80,000. (davidson2020cugcforposterior pages 1-2)
Broader prevalence is poorly defined; PPCD is consistently described as rare. (davidson2020cugcforposterior pages 1-2)

9.2 Population genetics and founder effects

Founder effects are noted in the CUGC context (details not fully extractable here). (davidson2020cugcforposterior pages 1-2)
Example allele frequency (illustrative, not definitive for PPCD causality): ZEB1 p.P5A variant reported with gnomAD EAS frequency ~0.00001 in a family study. (lin2025polymorphouscornealdystrophy pages 3-5)

10. Diagnostics

10.1 Clinical and imaging tests used in practice

Slit-lamp biomicroscopy for posterior corneal lesions (chung2017confirmationofthe pages 5-7)
Specular microscopy for rail-track/snail-track and endothelial morphology; ECD quantification (fung2021endothelialcelldensity pages 2-4, fernandezgutierrez2022posteriorpolymorphouscorneal pages 1-2)
In vivo confocal microscopy (posterior lesions; abnormal/absent endothelial cells; hyperreflective deposits) (fung2021endothelialcelldensity pages 5-6)
OCT / anterior segment imaging including SD‑OCT (posterior reflectivity, Descemet protrusion) (liskova2018ectopicgrhl2expression pages 6-7)
Corneal tomography (Pentacam) used in complex/overlap phenotypes (e.g., keratoconus) (lin2025polymorphouscornealdystrophy pages 2-3)

10.2 Genetic testing approach (authoritative guidance)

CUGC recommends genome sequencing as the most comprehensive approach because PPCD includes structural and non-coding variants across OVOL2, ZEB1, and GRHL2; Sanger validation and CNV methods may be required to confirm ZEB1 haploinsufficiency and define breakpoints. (davidson2020cugcforposterior pages 1-2)

10.3 Differential diagnosis

Not systematically extractable from retrieved documents; however, PPCD overlaps clinically with other corneal endothelial dystrophies and with anterior segment dysgenesis entities.

11. Outcome / Prognosis

Many patients remain mildly affected; however, substantial minorities require surgery.
Keratoplasty proportion:
OVOL2-linked cohorts: about one-third underwent keratoplasty in an excerpted dataset (davidson2016autosomaldominantcornealendothelial pages 6-8)
GRHL2/PPCD4 Czech series: 25.9% underwent corneal transplantation (mean first surgery ~35 years) (liskova2018ectopicgrhl2expression pages 6-7)
Glaucoma: GRHL2/PPCD4 Czech series: 25.9% (liskova2018ectopicgrhl2expression pages 6-7)

12. Treatment

12.1 Current standard management (real-world)

Observation/monitoring: visual acuity, endothelial reserve, glaucoma surveillance, amblyopia/strabismus monitoring in children. (davidson2020cugcforposterior pages 4-5)
Glaucoma management: medical drops and/or drainage surgery when needed. (davidson2020cugcforposterior pages 4-5)
Corneal transplantation: performed for corneal edema/endothelial failure; includes penetrating keratoplasty historically and increasing use of endothelial keratoplasty in endothelial diseases broadly (PPCD infant endothelial keratoplasty reported). (davidson2016autosomaldominantcornealendothelial pages 5-6, fung2021endothelialcelldensity pages 5-6)

12.2 MAXO suggestions

Corneal transplantation (MAXO: term for keratoplasty)
Endothelial keratoplasty (MAXO: term for lamellar endothelial keratoplasty)
Topical intraocular pressure-lowering therapy (MAXO: term for glaucoma medication)
Glaucoma surgery (MAXO: term for aqueous shunt/trabeculectomy procedures)

12.3 Clinical trials

ClinicalTrials.gov search performed within this session did not retrieve PPCD-specific therapeutic trials among the returned set. (trial search results not PPCD-relevant) (fung2021endothelialcelldensity pages 1-2)

13. Prevention

No primary prevention strategies exist for Mendelian PPCD.
Secondary/tertiary prevention: family screening, genetic counseling, monitoring for glaucoma/amblyopia; avoidance of high-risk elective corneal procedures without adequate endothelial evaluation in suspected familial disease. (davidson2020cugcforposterior pages 4-5, lin2025polymorphouscornealdystrophy pages 2-3)

14. Other Species / Natural Disease

No naturally occurring PPCD in non-human species was identified in retrieved evidence.

15. Model Organisms and Experimental Systems

15.1 In vitro models

CRISPR ZEB1+/- corneal endothelial cell model recapitulates epithelial-like shift, EnET concept, and transcriptomic PPCD signatures; ZEB1 reconstitution rescues phenotype, suggesting therapeutic plausibility in principle. (In vitro) (frausto2019zeb1insufficiencycauses pages 2-3, frausto2019zeb1insufficiencycauses pages 14-16)

15.2 Mouse models

PPCD1 mouse model (DBA/2J background; D2.Ppcd1): enlarged anterior chamber due to endothelial epithelialization/proliferation and angle blockage; increased IOP and downstream retinal pathology were reported. (Model organism) (shen2017retinalpathologyin pages 11-12)

Key quantitative data highlights (for knowledge base ingestion)

Pediatric PPCD ECD baseline: 1918.9 ± 666.3 cells/mm² vs controls 3340.1 ± 286.5 (fung2021endothelialcelldensity pages 2-4)
Pediatric PPCD annual ECD loss: ~1.9 ± 3.7%/year, similar to controls (fung2021endothelialcelldensity pages 2-4)
GRHL2/PPCD4 series: 25.9% keratoplasty; 25.9% glaucoma (liskova2018ectopicgrhl2expression pages 6-7)
OVOL2-linked cohorts excerpt: ~30% secondary glaucoma; ~one-third keratoplasty (davidson2016autosomaldominantcornealendothelial pages 6-8)
Aqueous humor active TGF‑β2: 386.98 ± 114.88 pg/mL (PPCD) vs 260.95 ± 112.43 pg/mL (controls), P=0.0001 (chung2017confirmationofthe pages 2-4)

Visual evidence (ECD by lesion subtype)

Cropped tables/figures from the pediatric longitudinal cohort show ECD stratification by lesion subtype and longitudinal trends. (fung2021endothelialcelldensity media 4fa8c68b, fung2021endothelialcelldensity media 5637544d)

Genetics summary artifact

The following table compares PPCD subtypes, variant classes, mechanisms, and complication frequencies.

Subtype / OMIM disease ID	Gene (OMIM gene ID)	Variant types / hotspots (example)	Molecular mechanism	Key clinical features / complications	Key supporting citations
PPCD1 / OMIM 122000	OVOL2 (OMIM 616441)	Non-coding promoter variants in a conserved proximal promoter region; examples: c.-307T>C, c.-274T>G, c.-370T>C; related severe allelic CHED1 family with c.-339_361dup	Promoter variants increase OVOL2 transcriptional activity, causing ectopic/increased OVOL2 expression in corneal endothelium; OVOL2 is a MET-promoting transcription factor that represses ZEB1, driving endothelial cell-state transition toward epithelial-like phenotype	Typical PPCD posterior corneal lesions (vesicles/bands/gray-white opacities), endothelial dysfunction, corneal edema/haze, iris abnormalities/adhesions, secondary glaucoma risk; ~20–25% of affected individuals may require corneal transplantation in PPCD overall; in OVOL2-linked families, ~30% secondary glaucoma and about one-third underwent keratoplasty; severe early-onset/founder families may present from infancy and need repeated grafting. Czech prevalence estimate for PPCD overall: ~1 per 80,000	(davidson2016autosomaldominantcornealendothelial pages 1-3, davidson2016autosomaldominantcornealendothelial pages 11-13, davidson2016autosomaldominantcornealendothelial pages 6-8, chung2017confirmationofthe pages 1-2, davidson2020cugcforposterior pages 1-2)
PPCD3 / OMIM 609141	ZEB1 (OMIM 189909)	Predominantly heterozygous loss-of-function variants: nonsense, frameshift, splice, whole-gene/partial deletions; example: c.1279C>T p.Glu427*; rare missense variants also reported in some families	ZEB1 haploinsufficiency causes a MET-like endothelial-to-epithelial transition (EnET) with a cadherin switch (↓CDH2, ↑CDH1), epithelial-like transcriptome, altered adhesion/proliferation/migration, and endothelial stratification	Bilateral often asymmetric PPCD lesions, reduced endothelial cell density, occasional corectopia/iridocorneal synechiae, association with corneal steepening/ectasia in some cases; PPCD3 is often milder than OVOL2-linked disease but variable. Familial studies suggest ~95% penetrance, yet documented non-penetrance exists, so true penetrance may be lower. ZEB1 LoF alleles are extremely rare in population databases	(frausto2019zeb1insufficiencycauses pages 1-2, frausto2019zeb1insufficiencycauses pages 13-14, frausto2019zeb1insufficiencycauses pages 2-3, dudakova2021nonpenetranceforocular pages 1-2, dudakova2021nonpenetranceforocular pages 2-4)
PPCD4 / OMIM 618031	GRHL2 (OMIM 608576)	Non-coding regulatory / intron 1 variants; examples: c.20+544G>T, c.20+257delT, c.20+133delA	Regulatory variants increase GRHL2 transcription, causing ectopic GRHL2 expression in corneal endothelium; GRHL2 promotes epithelial identity and represses/acts upstream of ZEB1, producing MET-like transition with epithelial markers (e.g., E-cadherin, CK7)	Typical PPCD lesions with irregular posterior corneal surface, endothelial multilayering, corneal edema (including infantile onset in some), reduced endothelial cell density, corectopia/band keratopathy; in the large Czech series with recurrent variant, 25.9% underwent corneal transplantation and 25.9% developed glaucoma; mean first keratoplasty ~35 years, mean glaucoma diagnosis ~46 years	(liskova2018ectopicgrhl2expression pages 1-2, liskova2018ectopicgrhl2expression pages 6-7, liskova2018ectopicgrhl2expression pages 9-10, liskova2018ectopicgrhl2expression pages 8-9, davidson2020cugcforposterior pages 1-2)

Table: This table summarizes the main genetically supported PPCD subtypes—OVOL2/PPCD1, ZEB1/PPCD3, and GRHL2/PPCD4—covering variant classes, mechanisms, clinical complications, and the strongest available evidence. It is useful for quickly comparing subtype-specific diagnostic and counseling implications.

URLs and publication dates (where available in retrieved texts)

Weiss et al. IC3D Classification of Corneal Dystrophies—Edition 3. Cornea. Feb 2024. https://doi.org/10.1097/ICO.0000000000003420 and online resource: https://corneasociety.org/publications/ic3d (fung2021endothelialcelldensity pages 1-2)
Davidson et al. Autosomal-Dominant Corneal Endothelial Dystrophies CHED1 and PPCD1… OVOL2 promoter. Am J Hum Genet. Jan 2016. https://doi.org/10.1016/j.ajhg.2015.11.018 (davidson2016autosomaldominantcornealendothelial pages 1-3)
Liskova et al. Ectopic GRHL2 expression… PPCD4. Am J Hum Genet. Mar 2018. https://doi.org/10.1016/j.ajhg.2018.02.002 (liskova2018ectopicgrhl2expression pages 1-2)
Frausto et al. ZEB1 insufficiency… EnET. PLoS ONE. Feb 2019. https://doi.org/10.1371/journal.pone.0218279 (frausto2019zeb1insufficiencycauses pages 1-2)
Davidson et al. CUGC for PPCD. Eur J Hum Genet. Jun 2020. https://doi.org/10.1038/s41431-019-0448-8 (davidson2020cugcforposterior pages 1-2)
Fung et al. Endothelial cell density in children with PPCD. Eye. Feb 2021. https://doi.org/10.1038/s41433-021-01451-y (fung2021endothelialcelldensity pages 2-4)
Dudakova et al. Non-penetrance… ZEB1 LoF. Genes. Apr 2021. https://doi.org/10.3390/genes12050677 (dudakova2021nonpenetranceforocular pages 1-2)

Limitations and gaps (explicit)

MONDO/Orphanet/ICD/MeSH identifiers were not retrieved in the available evidence and are therefore not provided.
2023–2024 PPCD-specific primary studies were not prominently retrievable in this run beyond the IC3D 2024 classification update; consequently, “latest” advances are described using the best-available primary mechanistic/genetic sources (2016–2019) plus later clinical genetics guidance.
Differential diagnosis and formal diagnostic criteria for PPCD (as distinct from FECD/ICE syndrome/anterior segment dysgenesis) require additional targeted retrieval beyond the current evidence set.

References

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(davidson2016autosomaldominantcornealendothelial pages 1-3): Alice E. Davidson, Petra Liskova, Cerys J. Evans, Lubica Dudakova, Lenka Nosková, Nikolas Pontikos, Hana Hartmannová, Kateřina Hodaňová, Viktor Stránecký, Zbyněk Kozmík, Hannah J. Levis, Nwamaka Idigo, Noriaki Sasai, Geoffrey J. Maher, James Bellingham, Neyme Veli, Neil D. Ebenezer, Michael E. Cheetham, Julie T. Daniels, Caroline M.H. Thaung, Katerina Jirsova, Vincent Plagnol, Martin Filipec, Stanislav Kmoch, Stephen J. Tuft, and Alison J. Hardcastle. Autosomal-dominant corneal endothelial dystrophies ched1 and ppcd1 are allelic disorders caused by non-coding mutations in the promoter of ovol2. The American Journal of Human Genetics, 98:75-89, Jan 2016. URL: https://doi.org/10.1016/j.ajhg.2015.11.018, doi:10.1016/j.ajhg.2015.11.018. This article has 94 citations.
(liskova2018ectopicgrhl2expression pages 6-7): Petra Liskova, Lubica Dudakova, Cerys J. Evans, Karla E. Rojas Lopez, Nikolas Pontikos, Dimitra Athanasiou, Hodan Jama, Josef Sach, Pavlina Skalicka, Viktor Stranecky, Stanislav Kmoch, Caroline Thaung, Martin Filipec, Michael E. Cheetham, Alice E. Davidson, Stephen J. Tuft, and Alison J. Hardcastle. Ectopic grhl2 expression due to non-coding mutations promotes cell state transition and causes posterior polymorphous corneal dystrophy 4. American Journal of Human Genetics, 102:447-459, Mar 2018. URL: https://doi.org/10.1016/j.ajhg.2018.02.002, doi:10.1016/j.ajhg.2018.02.002. This article has 59 citations and is from a highest quality peer-reviewed journal.
(davidson2020cugcforposterior pages 1-2): Alice E. Davidson, Nathaniel J. Hafford-Tear, Lubica Dudakova, Amanda N. Sadan, Nikolas Pontikos, Alison J. Hardcastle, Stephen J. Tuft, and Petra Liskova. Cugc for posterior polymorphous corneal dystrophy (ppcd). European Journal of Human Genetics, 28:126-131, Jun 2020. URL: https://doi.org/10.1038/s41431-019-0448-8, doi:10.1038/s41431-019-0448-8. This article has 7 citations and is from a domain leading peer-reviewed journal.
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(lin2025polymorphouscornealdystrophy pages 5-7): Qinghong Lin, Xuejun Wang, Xiaoliao Peng, Xiaosong Han, Xiaoyu Zhang, Ling Sun, Yan Wang, Shengtao Liu, and Xingtao Zhou. Polymorphous corneal dystrophy subtype 3 and keratoconus aggravation after corneal refractive surgery in a three-generation family carrying both zeb1 and znf469 pathogenic variant. Frontiers in Genetics, Jun 2025. URL: https://doi.org/10.3389/fgene.2025.1603019, doi:10.3389/fgene.2025.1603019. This article has 0 citations and is from a peer-reviewed journal.
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(davidson2016autosomaldominantcornealendothelial pages 11-13): Alice E. Davidson, Petra Liskova, Cerys J. Evans, Lubica Dudakova, Lenka Nosková, Nikolas Pontikos, Hana Hartmannová, Kateřina Hodaňová, Viktor Stránecký, Zbyněk Kozmík, Hannah J. Levis, Nwamaka Idigo, Noriaki Sasai, Geoffrey J. Maher, James Bellingham, Neyme Veli, Neil D. Ebenezer, Michael E. Cheetham, Julie T. Daniels, Caroline M.H. Thaung, Katerina Jirsova, Vincent Plagnol, Martin Filipec, Stanislav Kmoch, Stephen J. Tuft, and Alison J. Hardcastle. Autosomal-dominant corneal endothelial dystrophies ched1 and ppcd1 are allelic disorders caused by non-coding mutations in the promoter of ovol2. The American Journal of Human Genetics, 98:75-89, Jan 2016. URL: https://doi.org/10.1016/j.ajhg.2015.11.018, doi:10.1016/j.ajhg.2015.11.018. This article has 94 citations.
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(chung2017confirmationofthe pages 2-4): Doug D. Chung, Ricardo F. Frausto, Aleck E. Cervantes, Katherine M. Gee, Marina Zakharevich, Evelyn M. Hanser, Edwin M. Stone, Elise Heon, and Anthony J. Aldave. Confirmation of the ovol2 promoter mutation c.-307t>c in posterior polymorphous corneal dystrophy 1. PLoS ONE, 12:e0169215, Jan 2017. URL: https://doi.org/10.1371/journal.pone.0169215, doi:10.1371/journal.pone.0169215. This article has 26 citations and is from a peer-reviewed journal.
(davidson2016autosomaldominantcornealendothelial pages 5-6): Alice E. Davidson, Petra Liskova, Cerys J. Evans, Lubica Dudakova, Lenka Nosková, Nikolas Pontikos, Hana Hartmannová, Kateřina Hodaňová, Viktor Stránecký, Zbyněk Kozmík, Hannah J. Levis, Nwamaka Idigo, Noriaki Sasai, Geoffrey J. Maher, James Bellingham, Neyme Veli, Neil D. Ebenezer, Michael E. Cheetham, Julie T. Daniels, Caroline M.H. Thaung, Katerina Jirsova, Vincent Plagnol, Martin Filipec, Stanislav Kmoch, Stephen J. Tuft, and Alison J. Hardcastle. Autosomal-dominant corneal endothelial dystrophies ched1 and ppcd1 are allelic disorders caused by non-coding mutations in the promoter of ovol2. The American Journal of Human Genetics, 98:75-89, Jan 2016. URL: https://doi.org/10.1016/j.ajhg.2015.11.018, doi:10.1016/j.ajhg.2015.11.018. This article has 94 citations.
(fernandezgutierrez2022posteriorpolymorphouscorneal pages 1-2): Eva Fernández-Gutiérrez, Pedro Fernández-Pérez, Ana Boto-De-Los-Bueis, Laura García-Fernández, Patricia Rodríguez-Solana, Mario Solís, and Elena Vallespín. Posterior polymorphous corneal dystrophy in a patient with a novel zeb1 gene mutation. International Journal of Molecular Sciences, 24:209, Dec 2022. URL: https://doi.org/10.3390/ijms24010209, doi:10.3390/ijms24010209. This article has 9 citations.
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(frausto2019zeb1insufficiencycauses pages 14-16): Ricardo F. Frausto, Doug D. Chung, Payton M. Boere, Vinay S. Swamy, Huong N.V. Duong, Liyo Kao, Rustam Azimov, Wenlin Zhang, Liam Carrigan, Davey Wong, Marco Morselli, Marina Zakharevich, E. Maryam Hanser, Austin C. Kassels, Ira Kurtz, Matteo Pellegrini, and Anthony J. Aldave. Zeb1 insufficiency causes corneal endothelial cell state transition and altered cellular processing. PLoS ONE, Feb 2019. URL: https://doi.org/10.1371/journal.pone.0218279, doi:10.1371/journal.pone.0218279. This article has 31 citations and is from a peer-reviewed journal.
(shen2017retinalpathologyin pages 11-12): Anna L. Shen, Susan M. Moran, Edward A. Glover, Leandro B. Teixeira, and Christopher A. Bradfield. Retinal pathology in the ppcd1 mouse. PLoS ONE, 12:e0185094, Oct 2017. URL: https://doi.org/10.1371/journal.pone.0185094, doi:10.1371/journal.pone.0185094. This article has 3 citations and is from a peer-reviewed journal.
(fung2021endothelialcelldensity media 4fa8c68b): Simon Sheung Man Fung, Hamza Sami, Ali El Hamouly, Dishay Jiandani, Sara Williams, Kamiar Mireskandari, and Asim Ali. Endothelial cell density in children with posterior polymorphous corneal dystrophy: a longitudinal case-control study. Eye, 35:3397-3403, Feb 2021. URL: https://doi.org/10.1038/s41433-021-01451-y, doi:10.1038/s41433-021-01451-y. This article has 6 citations and is from a peer-reviewed journal.
(fung2021endothelialcelldensity media 5637544d): Simon Sheung Man Fung, Hamza Sami, Ali El Hamouly, Dishay Jiandani, Sara Williams, Kamiar Mireskandari, and Asim Ali. Endothelial cell density in children with posterior polymorphous corneal dystrophy: a longitudinal case-control study. Eye, 35:3397-3403, Feb 2021. URL: https://doi.org/10.1038/s41433-021-01451-y, doi:10.1038/s41433-021-01451-y. This article has 6 citations and is from a peer-reviewed journal.
(chung2017confirmationofthe pages 1-2): Doug D. Chung, Ricardo F. Frausto, Aleck E. Cervantes, Katherine M. Gee, Marina Zakharevich, Evelyn M. Hanser, Edwin M. Stone, Elise Heon, and Anthony J. Aldave. Confirmation of the ovol2 promoter mutation c.-307t>c in posterior polymorphous corneal dystrophy 1. PLoS ONE, 12:e0169215, Jan 2017. URL: https://doi.org/10.1371/journal.pone.0169215, doi:10.1371/journal.pone.0169215. This article has 26 citations and is from a peer-reviewed journal.
(frausto2019zeb1insufficiencycauses pages 13-14): Ricardo F. Frausto, Doug D. Chung, Payton M. Boere, Vinay S. Swamy, Huong N.V. Duong, Liyo Kao, Rustam Azimov, Wenlin Zhang, Liam Carrigan, Davey Wong, Marco Morselli, Marina Zakharevich, E. Maryam Hanser, Austin C. Kassels, Ira Kurtz, Matteo Pellegrini, and Anthony J. Aldave. Zeb1 insufficiency causes corneal endothelial cell state transition and altered cellular processing. PLoS ONE, Feb 2019. URL: https://doi.org/10.1371/journal.pone.0218279, doi:10.1371/journal.pone.0218279. This article has 31 citations and is from a peer-reviewed journal.
(dudakova2021nonpenetranceforocular pages 2-4): Lubica Dudakova, Viktor Stranecky, Lenka Piherova, Tomas Palecek, Nikolas Pontikos, Stanislav Kmoch, Pavlina Skalicka, Manuela Vaneckova, Alice E. Davidson, and Petra Liskova. Non-penetrance for ocular phenotype in two individuals carrying heterozygous loss-of-function zeb1 alleles. Genes, 12:677, Apr 2021. URL: https://doi.org/10.3390/genes12050677, doi:10.3390/genes12050677. This article has 4 citations.
(liskova2018ectopicgrhl2expression pages 9-10): Petra Liskova, Lubica Dudakova, Cerys J. Evans, Karla E. Rojas Lopez, Nikolas Pontikos, Dimitra Athanasiou, Hodan Jama, Josef Sach, Pavlina Skalicka, Viktor Stranecky, Stanislav Kmoch, Caroline Thaung, Martin Filipec, Michael E. Cheetham, Alice E. Davidson, Stephen J. Tuft, and Alison J. Hardcastle. Ectopic grhl2 expression due to non-coding mutations promotes cell state transition and causes posterior polymorphous corneal dystrophy 4. American Journal of Human Genetics, 102:447-459, Mar 2018. URL: https://doi.org/10.1016/j.ajhg.2018.02.002, doi:10.1016/j.ajhg.2018.02.002. This article has 59 citations and is from a highest quality peer-reviewed journal.

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Inheritance

Subtypes

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Source YAML

References & Deep Research

Deep Research

1. Disease Information

1.1 Concise overview

1.2 Key identifiers

1.3 Common synonyms / alternative names

1.4 Source type (aggregated vs patient-level)

2. Etiology

2.1 Primary causes (genetic)

2.2 Risk factors

2.3 Protective factors

2.4 Gene–environment interactions

3. Phenotypes (with suggested HPO terms)

3.1 Core corneal/endothelial phenotypes

3.2 Glaucoma and anterior segment abnormalities

3.3 Course, onset, progression

3.4 Quality of life impact

4. Genetic / Molecular Information

4.1 Causal genes (established)

4.2 Pathogenic variant classes and examples

4.3 Inheritance, penetrance, expressivity

4.4 Modifier genes

4.5 Epigenetic / chromosomal abnormalities

5. Environmental Information

6. Mechanism / Pathophysiology

6.1 Core concept: endothelial-to-epithelial transition (EnET) as a MET-like process

6.2 Regulatory network: OVOL2 / GRHL2 repress ZEB1

6.3 Causal chain (variant → phenotype)

6.4 Biochemical abnormalities

6.5 Suggested ontology annotations

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

9.1 Epidemiology

9.2 Population genetics and founder effects

10. Diagnostics

10.1 Clinical and imaging tests used in practice

10.2 Genetic testing approach (authoritative guidance)

10.3 Differential diagnosis

11. Outcome / Prognosis

12. Treatment

12.1 Current standard management (real-world)

12.2 MAXO suggestions

12.3 Clinical trials

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms and Experimental Systems

15.1 In vitro models

15.2 Mouse models

Key quantitative data highlights (for knowledge base ingestion)

Visual evidence (ECD by lesion subtype)

Genetics summary artifact

URLs and publication dates (where available in retrieved texts)

Limitations and gaps (explicit)

Artifacts