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Inheritance

1

Autosomal Recessive HP:0000007

Biallelic GZF1 loss-of-function variants, homozygous in the consanguineous founding families and compound heterozygous in later reports. Penetrance in biallelic carriers appears high.

Autosomal recessive inheritance

Show evidence (2 references)

PMID:28475863 SUPPORT Human Clinical

"In a multiplex consanguineous Saudi family affected by severe and recurrent large joint dislocation and severe myopia, we identified a homozygous truncating variant in GZF1 through a combined autozygome and exome approach."

Homozygous truncating variant segregating in a consanguineous multiplex family establishes recessive inheritance.

PMID:42170786 SUPPORT Human Clinical

"Only ten patients from five families have been reported, all of whom carry biallelic variants of GZF1."

Confirms that every reported patient carries biallelic variants, supporting recessive inheritance across the whole reported series.

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Discussions and Knowledge Gaps

2

Is P3H2 under-expression actually the effector linking GZF1 loss to high myopia, or is it one dysregulated gene among many in a profiling experiment?

KNOWLEDGE GAP jlsm_p3h2_pathway_is_inferred

Attached to

pathophysiology#Dysregulation of Extracellular Matrix Gene Expression pathophysiology#Defective Collagen Prolyl 3-Hydroxylation in Ocular Tissue

The proposed pathway is assembled from two separate findings, neither of which is about the other. Finding one: P3H2 appears among enriched matrix genes in transcriptional profiling of GZF1 patient fibroblasts, which the authors describe as hinting at a potential mechanism. Finding two: biallelic P3H2 loss independently causes non-syndromic high myopia. Joining them is an attractive inference, and it is only an inference. No study has measured P3H2 protein or collagen 3-hydroxylation in GZF1-deficient tissue, no GZF1 animal model with an ocular readout was identified, and fibroblasts are not sclera. The entry marks the joining edge INDIRECT_UNKNOWN_INTERMEDIATES and grades the supporting evidence INDIRECT rather than presenting the chain as established.

Which matrix genes mediate the joint laxity and skeletal features, given that P3H2 is an ocular candidate only?

KNOWLEDGE GAP jlsm_skeletal_arm_has_no_effector

Attached to

pathophysiology#Generalised Connective Tissue Laxity

The ocular arm at least has a candidate effector. The skeletal arm has none. The profiling result reports enrichment of matrix genes generally, and nothing cited identifies which of them explains joint capsule and ligament laxity, or why the skeletal involvement was markedly milder in one of the two founding families despite both carrying homozygous truncating alleles. That intrafamilial contrast is itself unexplained and suggests a modifier.

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Pathophysiology

4

Biallelic GZF1 Loss of Function

Truncating GZF1 variants abolish the functional transcriptional repressor. Functional work on two frameshift alleles shows loss reached by different routes: one has normal transcript but no detectable protein, the other has reduced transcript and protein plus mislocalisation to the cytoplasm.

GZF1 hgnc:15808

DNA-binding transcription factor activity GO:0003700 ⇓ LOSS OF FUNCTION

Downstream

Dysregulation of Extracellular Matrix Gene Expression GZF1 is a transcriptional repressor, so its loss changes the expression of its target set. What that set is was determined empirically by profiling patient cells rather than predicted.

Show evidence (1 reference)

PMID:33009817 SUPPORT In Vitro

"In addition, both mRNA transcription and protein expression levels of M492fs-GZF1 were significantly lower than those of wild type, and HA-tagged M492fs-GZF1 was mainly distributed in the cytoplasm of HEK 293 T cells."

Documents reduced expression plus cytoplasmic mislocalisation for one allele, establishing loss of nuclear transcription factor function.

Dysregulation of Extracellular Matrix Gene Expression

Patient cells show a shared pattern of gene dysregulation enriched for extracellular matrix genes, with P3H2 (LEPREL1) singled out as the most interesting because of what is independently known about it. This node records a measured transcriptional change; the step from it to tissue pathology is the inferential part of the entry.

extracellular matrix organization GO:0030198 ↓ DECREASED

Downstream

Defective Collagen Prolyl 3-Hydroxylation in Ocular Tissue This is the weakest edge in the entry and is marked as such. P3H2 appears in a dysregulated gene list from patient fibroblasts; no study has shown reduced collagen 3-hydroxylation in GZF1-deficient ocular tissue. The edge is included because the downstream anchor is unusually strong, not because the step itself has been demonstrated.

Generalised Connective Tissue Laxity The skeletal arm is presumed to share the matrix-gene origin with the ocular arm. Unlike the ocular arm it has no candidate effector: the profiling result reports enrichment of matrix genes generally, and nothing cited identifies which of them produces capsular and ligamentous laxity. The edge is drawn so the skeletal features connect to the GZF1 root rather than floating, and is marked unknown-intermediates because the mediating gene is exactly what is missing.

Show evidence (1 reference)

PMID:28475863 SUPPORT In Vitro

"Global transcriptional profiling of cells from affected individuals revealed a shared pattern of gene dysregulation and significant enrichment of genes encoding matrix proteins, including P3H2, which hints at a potential disease mechanism."

Establishes matrix gene dysregulation as a measured feature of patient cells.

Defective Collagen Prolyl 3-Hydroxylation in Ocular Tissue

Reduced P3H2-mediated 3-hydroxylation of collagen would leave scleral and other ocular collagen structurally defective. The reason this node is here at all is that biallelic P3H2/LEPREL1 loss is an independently established cause of severe non-syndromic high myopia with early-onset cataract and retinal degeneration, which is close to the ocular phenotype seen in JLSM.

peptidyl-proline hydroxylation GO:0019511 ↓ DECREASED collagen fibril organization GO:0030199 ↓ DECREASED

Downstream

High myopia

Show evidence (3 references)

PMID:24172257 SUPPORT INDIRECT Human Clinical

"LEPREL1 encodes a proline hydroxylase called prolyl 3-hydroxylase 2 (P3H2), a 2-oxoglutarate-dependent dioxygenase that hydroxylates collagens."

Identifies the enzymatic function whose loss this node describes. Graded INDIRECT because this paper is about a different disease (P3H2 deficiency), and is cited to establish what P3H2 does, not to evidence a finding in GZF1 patients.

PMID:24172257 SUPPORT INDIRECT Human Clinical

"We recruited an autosomal-recessive high myopia family, with affected subjects who also present early-onset cataract, retinal degeneration and other complications."

Establishes that loss of this enzyme produces an ocular phenotype closely resembling the JLSM one. This is the analogy that motivates the node, and is recorded as INDIRECT rather than presented as evidence about GZF1.

PMID:25645914 SUPPORT INDIRECT Model Organism

"Almost every known site of prolyl 3-hydroxylation in types I and IV collagen from P3h2(n/n) mouse eye tissues was significantly under-hydroxylated compared with their wild-type littermates."

The only cited work that measures collagen 3-hydroxylation in eye tissue rather than inferring it, showing that loss of P3H2 does reduce it in sclera and cornea. Graded INDIRECT because the model is a P3h2-null mouse, not a GZF1-deficient one, so it substantiates the consequence of losing the enzyme and not the claim that GZF1 loss reduces it.

Generalised Connective Tissue Laxity

The skeletal arm of the disease: laxity of joint capsules and ligaments giving hypermobility and recurrent large-joint dislocation, with scoliosis and thoracic deformity. Presumed to share the matrix-gene origin with the ocular arm, but unlike the ocular arm there is no candidate effector gene identified, so no intermediate node is drawn.

extracellular matrix organization GO:0030198 ↓ DECREASED

Downstream

Joint dislocation

Joint hypermobility

Scoliosis

Thoracic deformity

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"The comparison allows us to define a recognizable GZF1RP that includes severe ocular defects, short stature, facial dysmorphism, joint hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, and hypodontia."

Defines the connective-tissue features that constitute this node in the consolidated phenotype description.

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Pathograph

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

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Phenotypes

15

Cardiovascular 1

Congenital heart disease Abnormal heart morphology HP:0001627

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"In addition to expanding the molecular spectrum, we identified new radiological findings, such as cervical segmentation defects, carpal shortening, and lower lumbar sacralization, as well as some clinical findings uncommon in previous cases, such as umbilical hernia and congenital heart disease."

Documents congenital heart disease among newly identified clinical findings.

Digestive 1

Umbilical hernia HP:0001537

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"In addition to expanding the molecular spectrum, we identified new radiological findings, such as cervical segmentation defects, carpal shortening, and lower lumbar sacralization, as well as some clinical findings uncommon in previous cases, such as umbilical hernia and congenital heart disease."

Documents umbilical hernia among newly identified clinical findings.

Ear 1

Progressive hearing loss FREQUENT Hearing impairment HP:0000365

Course: PROGRESSIVE

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"The comparison allows us to define a recognizable GZF1RP that includes severe ocular defects, short stature, facial dysmorphism, joint hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, and hypodontia."

Names progressive hearing loss in the consolidated phenotype definition. The quote does not characterise the loss as sensorineural, so the binding is to the general hearing impairment term with the progressive course carried separately.

Eye 4

High myopia VERY_FREQUENT HP:0011003

Show evidence (1 reference)

PMID:28475863 SUPPORT Human Clinical

"Our results suggest that GZF1 mutations cause a phenotype of severe myopia and significant articular involvement not previously described in Larsen syndrome."

States severe myopia as a defining feature and explicitly as one not seen in Larsen syndrome.

Retinal detachment FREQUENT HP:0000541

Show evidence (1 reference)

PMID:28475863 SUPPORT Human Clinical

"Independently, the same approach identified a second homozygous truncating GZF1 variant in another multiplex consanguineous family affected by severe myopia, retinal detachment, and milder skeletal involvement."

Documents retinal detachment in the second founding family.

Glaucoma Developmental glaucoma HP:0001087

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"In this study, we described three new patients with severe ophthalmologic phenotypes, including congenital glaucoma and abnormal iris morphology."

Documents congenital glaucoma in three newly reported patients.

Abnormal iris morphology Abnormality iris morphology HP:0000525

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"In this study, we described three new patients with severe ophthalmologic phenotypes, including congenital glaucoma and abnormal iris morphology."

Documents abnormal iris morphology in the three newly reported patients.

Head and Neck 2

Abnormal facial shape FREQUENT HP:0001999

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"The comparison allows us to define a recognizable GZF1RP that includes severe ocular defects, short stature, facial dysmorphism, joint hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, and hypodontia."

Names facial dysmorphism in the consolidated phenotype definition.

Hypodontia HP:0000668

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"The comparison allows us to define a recognizable GZF1RP that includes severe ocular defects, short stature, facial dysmorphism, joint hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, and hypodontia."

Names hypodontia in the consolidated phenotype definition.

Musculoskeletal 5

Joint dislocation VERY_FREQUENT HP:0001373

Temporal: RECURRENT

Show evidence (1 reference)

PMID:28475863 SUPPORT Human Clinical

"In a multiplex consanguineous Saudi family affected by severe and recurrent large joint dislocation and severe myopia, we identified a homozygous truncating variant in GZF1 through a combined autozygome and exome approach."

Documents severe recurrent large-joint dislocation in the founding family.

Joint hypermobility VERY_FREQUENT HP:0001382

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"The comparison allows us to define a recognizable GZF1RP that includes severe ocular defects, short stature, facial dysmorphism, joint hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, and hypodontia."

Names joint hypermobility in the consolidated phenotype definition.

Scoliosis FREQUENT HP:0002650

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"The comparison allows us to define a recognizable GZF1RP that includes severe ocular defects, short stature, facial dysmorphism, joint hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, and hypodontia."

Names scoliosis in the consolidated phenotype definition.

Thoracic deformity Abnormal thorax morphology HP:0000765

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"The comparison allows us to define a recognizable GZF1RP that includes severe ocular defects, short stature, facial dysmorphism, joint hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, and hypodontia."

Names thoracic deformity in the consolidated phenotype definition.

Vertebral segmentation and sacralization defects Abnormality of the vertebral column HP:0000925

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"In addition to expanding the molecular spectrum, we identified new radiological findings, such as cervical segmentation defects, carpal shortening, and lower lumbar sacralization, as well as some clinical findings uncommon in previous cases, such as umbilical hernia and congenital heart disease."

Documents cervical segmentation defects and lower lumbar sacralization as newly identified radiological findings.

Growth 1

Short stature VERY_FREQUENT HP:0004322

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"They share short stature and joint dislocation with LRS; however, they present with severe ocular manifestations, suggesting that GZF1RP may be specific."

Names short stature as a shared feature, and in the same sentence states the ocular contrast that separates the two disorders.

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Genetic Associations

1

GZF1

Gene: GZF1 hgnc:15808 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (4 references)

PMID:28475863 SUPPORT Human Clinical

"Independently, the same approach identified a second homozygous truncating GZF1 variant in another multiplex consanguineous family affected by severe myopia, retinal detachment, and milder skeletal involvement."

A second independent family with a homozygous truncating GZF1 variant, which is what establishes the gene-disease relationship rather than a single observation.

PMID:33009817 SUPPORT In Vitro

"These results suggested that the two variants could lead to loss of function of GZF1."

Functional confirmation that the reported frameshift alleles act by loss of function.

PMID:33009817 SUPPORT In Vitro

"The mRNA expression level of L133fs-GZF1 did not significantly differ from that of WT-GZF1. However, no HA-conjugated mutant protein was detected by western blotting, which was also confirmed by immunofluorescence staining."

Shows the two alleles reach loss of function by different routes, one at the protein level with preserved transcript, which is why transcript-based prediction alone would misclassify it.

+ 1 more reference

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External Assertions

1

OMIM joint laxity, short stature, and myopia record

OMIM disease record OMIM:617662

OMIM phenotype entry for joint laxity, short stature, and myopia (JLSM), the GZF1-related phenotype catalogued under its original name.

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Medical Actions

1

Supportive and multidisciplinary care

Action: Supportive Care NCIT:C15747

No disease-modifying therapy exists. Management is ophthalmological surveillance for retinal detachment and glaucoma, orthopaedic management of dislocation and scoliosis, audiological follow-up for progressive hearing loss, and genetic counselling.

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Diagnosis

1

Exome sequencing with autozygosity mapping

Both founding families were solved by combined autozygome-plus-exome analysis, which remains the efficient route in consanguineous pedigrees. Later cases were found by whole-exome sequencing without autozygosity mapping.

Show evidence (1 reference)

PMID:28475863 SUPPORT Human Clinical

"In a multiplex consanguineous Saudi family affected by severe and recurrent large joint dislocation and severe myopia, we identified a homozygous truncating variant in GZF1 through a combined autozygome and exome approach."

Names the diagnostic approach that established the disorder.

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Prevalence

1

Worldwide, cases reported in the literature

Cases In Literature Ultra Rare

Ten patients from five families before the 2026 series, which added three more. Reported families are predominantly consanguineous, so the case count reflects ascertainment in populations where autozygosity mapping is applied as much as it reflects true rarity. No population estimate exists.

Show evidence (1 reference)

PMID:42170786 SUPPORT Human Clinical

"Only ten patients from five families have been reported, all of whom carry biallelic variants of GZF1."

Gives the cumulative reported patient and family count.

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Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from Joint Laxity, Short Stature, and Myopia:

P3H2 (LEPREL1) non-syndromic high myopia

Overlapping Features Relevant twice over: as an ocular differential, and because it is the mechanistic anchor of this entry's proposed pathway. Biallelic P3H2 loss gives high myopia with early-onset cataract and retinal degeneration without the skeletal features.

Show evidence (1 reference)

PMID:24172257 SUPPORT Human Clinical

"Using targeted capturing and whole exome sequencing, we identified a homozygous non-sense mutation in the LEPREL1 gene which causes premature termination of the translation at the fifth amino acid (c.13C>T; p.Q5X), co-segregating with the phenotypes."

Establishes P3H2 loss of function as an independent cause of the ocular phenotype, which is what makes it a credible candidate effector here.

{ }

Source YAML

click to show

name: Joint Laxity, Short Stature, and Myopia
creation_date: '2026-09-06T15:45:00Z'
category: Mendelian
description: >
  Joint laxity, short stature and myopia (JLSM), also called the GZF1-related
  phenotype, is an ultra-rare autosomal recessive connective tissue disorder
  caused by biallelic loss-of-function variants in GZF1, which encodes a
  GDNF-inducible BTB/POZ zinc finger transcriptional repressor. It was first
  defined molecularly in 2017 in two consanguineous families and has since been
  reported in roughly a dozen patients.

  It was described from within the Larsen syndrome literature and is still
  sometimes called autosomal recessive Larsen syndrome, but the current view is
  that it is a distinguishable entity. It shares short stature and large-joint
  dislocation with FLNB-related Larsen syndrome, and adds severe ocular disease
  that Larsen does not have: high myopia with retinal detachment and congenital
  glaucoma.

  The proposed mechanism is a transcription-factor disease acting on the
  extracellular matrix. Transcriptional profiling of patient cells showed
  enrichment of dysregulated matrix genes including P3H2, whose own biallelic
  loss independently causes non-syndromic high myopia, which is what makes it a
  credible route from a transcription factor to a scleral phenotype. That chain
  is an inference assembled from two separate findings rather than something
  demonstrated in a GZF1 patient's eye, and the entry grades and annotates it
  accordingly rather than presenting it as established.
synonyms:
- JLSM
- GZF1-related phenotype
- GZF1RP
- autosomal recessive Larsen syndrome
- Larsen syndrome, autosomal recessive
disease_term:
  preferred_term: joint laxity, short stature, and myopia
  term:
    id: MONDO:0060556
    label: joint laxity, short stature, and myopia
parents:
- Larsen Syndrome
external_assertions:
- name: OMIM joint laxity, short stature, and myopia record
  source: OMIM
  assertion_type: disease_record
  external_id: OMIM:617662
  description: >-
    OMIM phenotype entry for joint laxity, short stature, and myopia (JLSM),
    the GZF1-related phenotype catalogued under its original name.
inheritance:
- name: Autosomal Recessive
  description: >
    Biallelic GZF1 loss-of-function variants, homozygous in the consanguineous
    founding families and compound heterozygous in later reports. Penetrance in
    biallelic carriers appears high.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: PMID:28475863
    reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In a multiplex consanguineous Saudi family affected by severe and recurrent
      large joint dislocation and severe myopia, we identified a homozygous
      truncating variant in GZF1 through a combined autozygome and exome approach.
    explanation: >-
      Homozygous truncating variant segregating in a consanguineous multiplex family
      establishes recessive inheritance.
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Only ten patients from five families have been reported, all of whom carry
      biallelic variants of GZF1.
    explanation: >-
      Confirms that every reported patient carries biallelic variants, supporting
      recessive inheritance across the whole reported series.
prevalence:
- population: Worldwide, cases reported in the literature
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    Ten patients from five families before the 2026 series, which added three more.
    Reported families are predominantly consanguineous, so the case count reflects
    ascertainment in populations where autozygosity mapping is applied as much as
    it reflects true rarity. No population estimate exists.
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Only ten patients from five families have been reported, all of whom carry
      biallelic variants of GZF1.
    explanation: Gives the cumulative reported patient and family count.
genetic:
- name: GZF1
  notes: >
    GZF1 (20p11.21) encodes GDNF-inducible zinc finger protein 1, a BTB/POZ-domain
    transcriptional repressor with tandem zinc fingers. Reported disease alleles are
    truncating: homozygous truncating variants in the two founding consanguineous
    families, compound heterozygous frameshifts (p.Leu133fs, p.Met492fs) in Chinese
    patients, and the recurrent c.1440del (p.His481IlefsTer26) both homozygous and
    compound heterozygous in a 2026 series. Functional work on two of the frameshift
    alleles shows loss of protein by different routes, which is direct evidence that
    the mechanism is loss of function rather than a dominant-negative effect.
  gene_term:
    preferred_term: GZF1
    term:
      id: hgnc:15808
      label: GZF1
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  evidence:
  - reference: PMID:28475863
    reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Independently, the same approach identified a second homozygous truncating GZF1
      variant in another multiplex consanguineous family affected by severe myopia,
      retinal detachment, and milder skeletal involvement.
    explanation: >-
      A second independent family with a homozygous truncating GZF1 variant, which is
      what establishes the gene-disease relationship rather than a single observation.
  - reference: PMID:33009817
    reference_title: "Novel GZF1 pathogenic variants identified in two Chinese patients with Larsen syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      These results suggested that the two variants could lead to loss of function of
      GZF1.
    explanation: >-
      Functional confirmation that the reported frameshift alleles act by loss of
      function.
  - reference: PMID:33009817
    reference_title: "Novel GZF1 pathogenic variants identified in two Chinese patients with Larsen syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The mRNA expression level of L133fs-GZF1 did not significantly differ from that
      of WT-GZF1. However, no HA-conjugated mutant protein was detected by western
      blotting, which was also confirmed by immunofluorescence staining.
    explanation: >-
      Shows the two alleles reach loss of function by different routes, one at the
      protein level with preserved transcript, which is why transcript-based
      prediction alone would misclassify it.
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We identified the GZF1: c.1440del (p.His481IlefsTer26) variant in homozygosity
      in two affected sisters and compound heterozygosity in the third patient: the
      same c.1440del plus c.1451_1452del (p.Cys484fs).
    explanation: Documents a recurrent allele in both homozygous and compound heterozygous state.
pathophysiology:
- name: Biallelic GZF1 Loss of Function
  biological_scale: MOLECULAR
  description: >
    Truncating GZF1 variants abolish the functional transcriptional repressor.
    Functional work on two frameshift alleles shows loss reached by different
    routes: one has normal transcript but no detectable protein, the other has
    reduced transcript and protein plus mislocalisation to the cytoplasm.
  gene:
    preferred_term: GZF1
    term:
      id: hgnc:15808
      label: GZF1
  molecular_functions:
  - preferred_term: DNA-binding transcription factor activity
    modifier: LOSS_OF_FUNCTION
    term:
      id: GO:0003700
      label: DNA-binding transcription factor activity
  evidence:
  - reference: PMID:33009817
    reference_title: "Novel GZF1 pathogenic variants identified in two Chinese patients with Larsen syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In addition, both mRNA transcription and protein expression levels of
      M492fs-GZF1 were significantly lower than those of wild type, and HA-tagged
      M492fs-GZF1 was mainly distributed in the cytoplasm of HEK 293 T cells.
    explanation: >-
      Documents reduced expression plus cytoplasmic mislocalisation for one allele,
      establishing loss of nuclear transcription factor function.
  downstream:
  - target: Dysregulation of Extracellular Matrix Gene Expression
    causal_link_type: DIRECT
    description: >
      GZF1 is a transcriptional repressor, so its loss changes the expression of its
      target set. What that set is was determined empirically by profiling patient
      cells rather than predicted.
    evidence:
    - reference: PMID:28475863
      reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Global transcriptional profiling of cells from affected individuals revealed a
        shared pattern of gene dysregulation and significant enrichment of genes
        encoding matrix proteins, including P3H2, which hints at a potential disease
        mechanism.
      explanation: >-
        The direct transcriptional evidence that GZF1 loss dysregulates matrix genes
        in patient cells. Note the source frames it as a hint at a potential
        mechanism, and the entry keeps that hedge.
- name: Dysregulation of Extracellular Matrix Gene Expression
  biological_scale: CELLULAR
  description: >
    Patient cells show a shared pattern of gene dysregulation enriched for
    extracellular matrix genes, with P3H2 (LEPREL1) singled out as the most
    interesting because of what is independently known about it. This node records
    a measured transcriptional change; the step from it to tissue pathology is the
    inferential part of the entry.
  biological_processes:
  - preferred_term: extracellular matrix organization
    modifier: DECREASED
    term:
      id: GO:0030198
      label: extracellular matrix organization
  evidence:
  - reference: PMID:28475863
    reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Global transcriptional profiling of cells from affected individuals revealed a
      shared pattern of gene dysregulation and significant enrichment of genes
      encoding matrix proteins, including P3H2, which hints at a potential disease
      mechanism.
    explanation: >-
      Establishes matrix gene dysregulation as a measured feature of patient cells.
  downstream:
  - target: Defective Collagen Prolyl 3-Hydroxylation in Ocular Tissue
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      This is the weakest edge in the entry and is marked as such. P3H2 appears in a
      dysregulated gene list from patient fibroblasts; no study has shown reduced
      collagen 3-hydroxylation in GZF1-deficient ocular tissue. The edge is included
      because the downstream anchor is unusually strong, not because the step itself
      has been demonstrated.
    evidence:
    - reference: PMID:28475863
      reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      snippet: >-
        Global transcriptional profiling of cells from affected individuals revealed a
        shared pattern of gene dysregulation and significant enrichment of genes
        encoding matrix proteins, including P3H2, which hints at a potential disease
        mechanism.
      explanation: >-
        The only evidence for this step is P3H2's presence in a dysregulated gene set,
        which the authors themselves describe as a hint. Graded INDIRECT for that
        reason.
  - target: Generalised Connective Tissue Laxity
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      The skeletal arm is presumed to share the matrix-gene origin with the ocular arm.
      Unlike the ocular arm it has no candidate effector: the profiling result reports
      enrichment of matrix genes generally, and nothing cited identifies which of them
      produces capsular and ligamentous laxity. The edge is drawn so the skeletal
      features connect to the GZF1 root rather than floating, and is marked
      unknown-intermediates because the mediating gene is exactly what is missing.
    evidence:
    - reference: PMID:28475863
      reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      snippet: >-
        Global transcriptional profiling of cells from affected individuals revealed a
        shared pattern of gene dysregulation and significant enrichment of genes
        encoding matrix proteins, including P3H2, which hints at a potential disease
        mechanism.
      explanation: >-
        Establishes matrix gene dysregulation as the shared origin proposed for both
        arms. Graded INDIRECT because no cited work connects that dysregulation to
        connective tissue laxity specifically.
- name: Defective Collagen Prolyl 3-Hydroxylation in Ocular Tissue
  biological_scale: TISSUE
  description: >
    Reduced P3H2-mediated 3-hydroxylation of collagen would leave scleral and other
    ocular collagen structurally defective. The reason this node is here at all is
    that biallelic P3H2/LEPREL1 loss is an independently established cause of severe
    non-syndromic high myopia with early-onset cataract and retinal degeneration,
    which is close to the ocular phenotype seen in JLSM.
  biological_processes:
  - preferred_term: peptidyl-proline hydroxylation
    modifier: DECREASED
    term:
      id: GO:0019511
      label: peptidyl-proline hydroxylation
  - preferred_term: collagen fibril organization
    modifier: DECREASED
    term:
      id: GO:0030199
      label: collagen fibril organization
  evidence:
  - reference: PMID:24172257
    reference_title: "Homozygous loss-of-function mutation of the LEPREL1 gene causes severe non-syndromic high myopia with early-onset cataract."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      LEPREL1 encodes a proline hydroxylase called prolyl 3-hydroxylase 2 (P3H2), a
      2-oxoglutarate-dependent dioxygenase that hydroxylates collagens.
    explanation: >-
      Identifies the enzymatic function whose loss this node describes. Graded
      INDIRECT because this paper is about a different disease (P3H2 deficiency), and
      is cited to establish what P3H2 does, not to evidence a finding in GZF1
      patients.
  - reference: PMID:24172257
    reference_title: "Homozygous loss-of-function mutation of the LEPREL1 gene causes severe non-syndromic high myopia with early-onset cataract."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We recruited an autosomal-recessive high myopia family, with affected subjects
      who also present early-onset cataract, retinal degeneration and other
      complications.
    explanation: >-
      Establishes that loss of this enzyme produces an ocular phenotype closely
      resembling the JLSM one. This is the analogy that motivates the node, and is
      recorded as INDIRECT rather than presented as evidence about GZF1.
  - reference: PMID:25645914
    reference_title: "Post-translationally abnormal collagens of prolyl 3-hydroxylase-2 null mice offer a pathobiological mechanism for the high myopia linked to human LEPREL1 mutations."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Almost every known site of prolyl 3-hydroxylation in types I and IV collagen
      from P3h2(n/n) mouse eye tissues was significantly under-hydroxylated compared
      with their wild-type littermates.
    explanation: >-
      The only cited work that measures collagen 3-hydroxylation in eye tissue rather
      than inferring it, showing that loss of P3H2 does reduce it in sclera and cornea.
      Graded INDIRECT because the model is a P3h2-null mouse, not a GZF1-deficient one,
      so it substantiates the consequence of losing the enzyme and not the claim that
      GZF1 loss reduces it.
  downstream:
  - target: High myopia
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:24172257
      reference_title: "Homozygous loss-of-function mutation of the LEPREL1 gene causes severe non-syndromic high myopia with early-onset cataract."
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        LEPREL1 plays an important role in eye development and homozygous
        loss-of-function mutation of this gene can cause severely high myopia
      explanation: >-
        States the causal relationship between loss of this enzyme and high myopia, in
        the P3H2 disease rather than in GZF1 patients.
- name: Generalised Connective Tissue Laxity
  biological_scale: TISSUE
  description: >
    The skeletal arm of the disease: laxity of joint capsules and ligaments giving
    hypermobility and recurrent large-joint dislocation, with scoliosis and thoracic
    deformity. Presumed to share the matrix-gene origin with the ocular arm, but
    unlike the ocular arm there is no candidate effector gene identified, so no
    intermediate node is drawn.
  biological_processes:
  - preferred_term: extracellular matrix organization
    modifier: DECREASED
    term:
      id: GO:0030198
      label: extracellular matrix organization
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The comparison allows us to define a recognizable GZF1RP that includes severe
      ocular defects, short stature, facial dysmorphism, joint
      hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
      loss, umbilical hernia, and hypodontia.
    explanation: >-
      Defines the connective-tissue features that constitute this node in the
      consolidated phenotype description.
  downstream:
  - target: Joint dislocation
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:28475863
      reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        In a multiplex consanguineous Saudi family affected by severe and recurrent
        large joint dislocation and severe myopia, we identified a homozygous
        truncating variant in GZF1 through a combined autozygome and exome approach.
      explanation: Documents severe recurrent large-joint dislocation in the founding family.
  - target: Joint hypermobility
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:42170786
      reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The comparison allows us to define a recognizable GZF1RP that includes severe
        ocular defects, short stature, facial dysmorphism, joint
        hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
        loss, umbilical hernia, and hypodontia.
      explanation: >-
        Joint hypermobility is the direct articular expression of capsular and
        ligamentous laxity in the consolidated phenotype definition.
  - target: Scoliosis
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:42170786
      reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The comparison allows us to define a recognizable GZF1RP that includes severe
        ocular defects, short stature, facial dysmorphism, joint
        hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
        loss, umbilical hernia, and hypodontia.
      explanation: >-
        Scoliosis is recorded as part of the same connective tissue picture in the
        consolidated phenotype definition.
  - target: Thoracic deformity
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:42170786
      reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The comparison allows us to define a recognizable GZF1RP that includes severe
        ocular defects, short stature, facial dysmorphism, joint
        hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
        loss, umbilical hernia, and hypodontia.
      explanation: >-
        Thoracic deformity is recorded as part of the same connective tissue picture in
        the consolidated phenotype definition.
phenotypes:
- category: Ophthalmological
  name: High myopia
  description: >
    Severe myopia is the feature that most clearly separates this disorder from
    FLNB-related Larsen syndrome, and it carries the retinal detachment risk that
    drives ophthalmological surveillance.
  phenotype_term:
    preferred_term: High myopia
    term:
      id: HP:0011003
      label: High myopia
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:28475863
    reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our results suggest that GZF1 mutations cause a phenotype of severe myopia and
      significant articular involvement not previously described in Larsen syndrome.
    explanation: >-
      States severe myopia as a defining feature and explicitly as one not seen in
      Larsen syndrome.
- category: Ophthalmological
  name: Retinal detachment
  phenotype_term:
    preferred_term: Retinal detachment
    term:
      id: HP:0000541
      label: Retinal detachment
  frequency: FREQUENT
  evidence:
  - reference: PMID:28475863
    reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Independently, the same approach identified a second homozygous truncating GZF1
      variant in another multiplex consanguineous family affected by severe myopia,
      retinal detachment, and milder skeletal involvement.
    explanation: Documents retinal detachment in the second founding family.
- category: Ophthalmological
  name: Glaucoma
  description: >
    Congenital glaucoma was reported in the 2026 series as part of the severe ocular
    picture. Bound to Developmental glaucoma rather than Primary congenital glaucoma
    (HP:0008007), because the glaucoma here is syndromic and occurs alongside an iris
    abnormality, whereas the primary term denotes isolated disease.
  phenotype_term:
    preferred_term: Congenital glaucoma
    term:
      id: HP:0001087
      label: Developmental glaucoma
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In this study, we described three new patients with severe ophthalmologic
      phenotypes, including congenital glaucoma and abnormal iris morphology.
    explanation: Documents congenital glaucoma in three newly reported patients.
- category: Ophthalmological
  name: Abnormal iris morphology
  description: >
    Reported alongside congenital glaucoma in the 2026 series. The ocular findings are
    the discriminator against Larsen syndrome, so the anterior segment involvement is
    recorded rather than folded into the glaucoma entry.
  phenotype_term:
    preferred_term: Abnormal iris morphology
    term:
      id: HP:0000525
      label: Abnormality iris morphology
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In this study, we described three new patients with severe ophthalmologic
      phenotypes, including congenital glaucoma and abnormal iris morphology.
    explanation: Documents abnormal iris morphology in the three newly reported patients.
- category: Musculoskeletal
  name: Joint dislocation
  description: >
    Recurrent dislocation of large joints, shared with Larsen syndrome and the
    reason the disorder was described from within that literature.
  phenotype_term:
    preferred_term: Joint dislocation
    term:
      id: HP:0001373
      label: Joint dislocation
    temporality: RECURRENT
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:28475863
    reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In a multiplex consanguineous Saudi family affected by severe and recurrent
      large joint dislocation and severe myopia, we identified a homozygous
      truncating variant in GZF1 through a combined autozygome and exome approach.
    explanation: Documents severe recurrent large-joint dislocation in the founding family.
- category: Musculoskeletal
  name: Joint hypermobility
  phenotype_term:
    preferred_term: Joint hypermobility
    term:
      id: HP:0001382
      label: Joint hypermobility
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The comparison allows us to define a recognizable GZF1RP that includes severe
      ocular defects, short stature, facial dysmorphism, joint
      hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
      loss, umbilical hernia, and hypodontia.
    explanation: Names joint hypermobility in the consolidated phenotype definition.
- category: Musculoskeletal
  name: Short stature
  phenotype_term:
    preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They share short stature and joint dislocation with LRS; however, they present
      with severe ocular manifestations, suggesting that GZF1RP may be specific.
    explanation: >-
      Names short stature as a shared feature, and in the same sentence states the
      ocular contrast that separates the two disorders.
- category: Musculoskeletal
  name: Scoliosis
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  frequency: FREQUENT
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The comparison allows us to define a recognizable GZF1RP that includes severe
      ocular defects, short stature, facial dysmorphism, joint
      hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
      loss, umbilical hernia, and hypodontia.
    explanation: Names scoliosis in the consolidated phenotype definition.
- category: Musculoskeletal
  name: Thoracic deformity
  phenotype_term:
    preferred_term: Thoracic deformity
    term:
      id: HP:0000765
      label: Abnormal thorax morphology
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The comparison allows us to define a recognizable GZF1RP that includes severe
      ocular defects, short stature, facial dysmorphism, joint
      hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
      loss, umbilical hernia, and hypodontia.
    explanation: Names thoracic deformity in the consolidated phenotype definition.
- category: Musculoskeletal
  name: Vertebral segmentation and sacralization defects
  description: >
    Cervical segmentation defects and lower lumbar sacralization were among the new
    radiological findings in the 2026 series. Bound to the general vertebral column
    term, which is the level the available HPO vocabulary supports for this
    combination.
  phenotype_term:
    preferred_term: Cervical segmentation defects and lumbar sacralization
    term:
      id: HP:0000925
      label: Abnormality of the vertebral column
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In addition to expanding the molecular spectrum, we identified new radiological
      findings, such as cervical segmentation defects, carpal shortening, and lower
      lumbar sacralization, as well as some clinical findings uncommon in previous
      cases, such as umbilical hernia and congenital heart disease.
    explanation: >-
      Documents cervical segmentation defects and lower lumbar sacralization as newly
      identified radiological findings.
- category: Otological
  name: Progressive hearing loss
  phenotype_term:
    preferred_term: Progressive hearing loss
    term:
      id: HP:0000365
      label: Hearing impairment
    clinical_course: PROGRESSIVE
  frequency: FREQUENT
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The comparison allows us to define a recognizable GZF1RP that includes severe
      ocular defects, short stature, facial dysmorphism, joint
      hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
      loss, umbilical hernia, and hypodontia.
    explanation: >-
      Names progressive hearing loss in the consolidated phenotype definition. The
      quote does not characterise the loss as sensorineural, so the binding is to the
      general hearing impairment term with the progressive course carried separately.
- category: Craniofacial
  name: Abnormal facial shape
  phenotype_term:
    preferred_term: Abnormal facial shape
    term:
      id: HP:0001999
      label: Abnormal facial shape
  frequency: FREQUENT
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The comparison allows us to define a recognizable GZF1RP that includes severe
      ocular defects, short stature, facial dysmorphism, joint
      hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
      loss, umbilical hernia, and hypodontia.
    explanation: Names facial dysmorphism in the consolidated phenotype definition.
- category: Gastrointestinal
  name: Umbilical hernia
  phenotype_term:
    preferred_term: Umbilical hernia
    term:
      id: HP:0001537
      label: Umbilical hernia
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In addition to expanding the molecular spectrum, we identified new radiological
      findings, such as cervical segmentation defects, carpal shortening, and lower
      lumbar sacralization, as well as some clinical findings uncommon in previous
      cases, such as umbilical hernia and congenital heart disease.
    explanation: Documents umbilical hernia among newly identified clinical findings.
- category: Cardiovascular
  name: Congenital heart disease
  description: >
    Reported in the 2026 series as a clinical finding uncommon in previously published
    cases, so it is recorded without a frequency.
  phenotype_term:
    preferred_term: Congenital heart disease
    term:
      id: HP:0001627
      label: Abnormal heart morphology
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In addition to expanding the molecular spectrum, we identified new radiological
      findings, such as cervical segmentation defects, carpal shortening, and lower
      lumbar sacralization, as well as some clinical findings uncommon in previous
      cases, such as umbilical hernia and congenital heart disease.
    explanation: Documents congenital heart disease among newly identified clinical findings.
- category: Dental
  name: Hypodontia
  phenotype_term:
    preferred_term: Hypodontia
    term:
      id: HP:0000668
      label: Hypodontia
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The comparison allows us to define a recognizable GZF1RP that includes severe
      ocular defects, short stature, facial dysmorphism, joint
      hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing
      loss, umbilical hernia, and hypodontia.
    explanation: Names hypodontia in the consolidated phenotype definition.
diagnosis:
- name: Exome sequencing with autozygosity mapping
  description: >
    Both founding families were solved by combined autozygome-plus-exome analysis,
    which remains the efficient route in consanguineous pedigrees. Later cases were
    found by whole-exome sequencing without autozygosity mapping.
  evidence:
  - reference: PMID:28475863
    reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In a multiplex consanguineous Saudi family affected by severe and recurrent
      large joint dislocation and severe myopia, we identified a homozygous truncating
      variant in GZF1 through a combined autozygome and exome approach.
    explanation: Names the diagnostic approach that established the disorder.
differential_diagnoses:
- name: FLNB-related Larsen syndrome
  description: >
    The disorder this one was carved out of, and the differential that matters. Both
    have short stature and large-joint dislocation. The discriminator is ocular:
    severe myopia, retinal detachment and congenital glaucoma are features of the
    GZF1 disorder and not of FLNB-related Larsen syndrome. Inheritance also differs,
    dominant FLNB against recessive GZF1.
  evidence:
  - reference: PMID:42170786
    reference_title: "Expanding the Genetic and Clinical Spectrum of GZF1 -Related Phenotype: A Specific Ocular and Skeletal Disorder Distinguishable From Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They share short stature and joint dislocation with LRS; however, they present
      with severe ocular manifestations, suggesting that GZF1RP may be specific.
    explanation: >-
      States both the overlap and the discriminating ocular feature, and is the basis
      for treating this as a distinct entity.
  - reference: PMID:28475863
    reference_title: "GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Heterozygous FLNB mutations account for the majority of Larsen syndrome cases,
      but biallelic mutations in CHST3 and B4GALT7 have been more recently described,
      thus confirming the existence of recessive forms of the disease.
    explanation: >-
      Establishes the genetic landscape of Larsen syndrome into which GZF1 was added.
- name: P3H2 (LEPREL1) non-syndromic high myopia
  description: >
    Relevant twice over: as an ocular differential, and because it is the
    mechanistic anchor of this entry's proposed pathway. Biallelic P3H2 loss gives
    high myopia with early-onset cataract and retinal degeneration without the
    skeletal features.
  evidence:
  - reference: PMID:24172257
    reference_title: "Homozygous loss-of-function mutation of the LEPREL1 gene causes severe non-syndromic high myopia with early-onset cataract."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Using targeted capturing and whole exome sequencing, we identified a homozygous
      non-sense mutation in the LEPREL1 gene which causes premature termination of the
      translation at the fifth amino acid (c.13C>T; p.Q5X), co-segregating with the
      phenotypes.
    explanation: >-
      Establishes P3H2 loss of function as an independent cause of the ocular
      phenotype, which is what makes it a credible candidate effector here.
discussions:
- discussion_id: jlsm_p3h2_pathway_is_inferred
  kind: KNOWLEDGE_GAP
  prompt: >-
    Is P3H2 under-expression actually the effector linking GZF1 loss to high myopia,
    or is it one dysregulated gene among many in a profiling experiment?
  attaches_to:
  - pathophysiology#Dysregulation of Extracellular Matrix Gene Expression
  - pathophysiology#Defective Collagen Prolyl 3-Hydroxylation in Ocular Tissue
  rationale: >
    The proposed pathway is assembled from two separate findings, neither of which
    is about the other. Finding one: P3H2 appears among enriched matrix genes in
    transcriptional profiling of GZF1 patient fibroblasts, which the authors describe
    as hinting at a potential mechanism. Finding two: biallelic P3H2 loss
    independently causes non-syndromic high myopia. Joining them is an attractive
    inference, and it is only an inference. No study has measured P3H2 protein or
    collagen 3-hydroxylation in GZF1-deficient tissue, no GZF1 animal model with an
    ocular readout was identified, and fibroblasts are not sclera. The entry marks
    the joining edge INDIRECT_UNKNOWN_INTERMEDIATES and grades the supporting
    evidence INDIRECT rather than presenting the chain as established.
- discussion_id: jlsm_skeletal_arm_has_no_effector
  kind: KNOWLEDGE_GAP
  prompt: >-
    Which matrix genes mediate the joint laxity and skeletal features, given that
    P3H2 is an ocular candidate only?
  attaches_to:
  - pathophysiology#Generalised Connective Tissue Laxity
  rationale: >
    The ocular arm at least has a candidate effector. The skeletal arm has none. The
    profiling result reports enrichment of matrix genes generally, and nothing cited
    identifies which of them explains joint capsule and ligament laxity, or why the
    skeletal involvement was markedly milder in one of the two founding families
    despite both carrying homozygous truncating alleles. That intrafamilial contrast
    is itself unexplained and suggests a modifier.
treatments:
- name: Supportive and multidisciplinary care
  description: >
    No disease-modifying therapy exists. Management is ophthalmological surveillance
    for retinal detachment and glaucoma, orthopaedic management of dislocation and
    scoliosis, audiological follow-up for progressive hearing loss, and genetic
    counselling.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  notes: >-
    Deliberately carries no evidence item. No trial, cohort or case series of any
    intervention in this disorder was identified. The components listed follow from
    the phenotype, and citing a Larsen syndrome management statement here would
    import a therapeutic claim made about a different, genetically distinct disorder.
notes: >
  On naming and placement. MONDO calls this "joint laxity, short stature, and
  myopia" and the entry is filed under that term, but the current literature
  increasingly calls it the GZF1-related phenotype and argues it is distinguishable
  from Larsen syndrome. Both names are in synonyms. It is listed under the Larsen
  Syndrome parent because that is where the literature places it and where a
  clinician would look, not as an assertion that it is a Larsen subtype. The 2026
  series argues explicitly for specificity, and the differential records the ocular
  discriminator.

  On the mechanism, which is the part to read sceptically. The GZF1 to P3H2 to
  collagen to myopia chain is the most attractive thing in the report literature
  about this disease and it is not established. It is built from P3H2 appearing in a
  dysregulated gene list from patient fibroblasts, plus the separate fact that P3H2
  loss causes high myopia in its own right. Both halves are solid; the join is not
  tested. The entry keeps the chain because the anchor is genuinely informative, and
  marks it INDIRECT_UNKNOWN_INTERMEDIATES with INDIRECT evidence grading throughout,
  with a discussion stating what would be needed to close it.

  On the hearing binding. This was originally bound to Sensorineural hearing
  impairment, which went beyond its quote: the cited sentence says only "progressive
  hearing loss" without specifying type. On review it was rebound to the general
  Hearing impairment term, with the progressive course carried in clinical_course.
  The sensorineural characterisation appears in the wider report but no cited abstract
  sentence attributes it, so it is not asserted here.

  On what is deliberately absent. No animal models: GZF1 was shown to be expressed in
  the eyes and limbs of developing mice, but expression is not a disease model, and no
  Gzf1 mutant with a reported ocular or skeletal phenotype was found in the cited
  sources. The P3h2-null mouse cited on the hydroxylation node is a model of the
  anchor disease rather than of this one, which is why it is evidence there and not an
  animal_models entry. No datasets: the transcriptional profiling behind the P3H2 lead is
  described in the founding paper but no accession was identified for it, which is
  itself a gap worth closing since that dataset is the entire evidential basis of the
  proposed mechanism.

📚

References & Deep Research

Deep Research

1

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OpenScientist ▸

Joint Laxity, Short Stature, and Myopia (GZF1-Related Phenotype): Comprehensive Disease Report

openscientist-autonomous 8 citations 2026-09-06T16:28:21.459493

Joint Laxity, Short Stature, and Myopia (GZF1-Related Phenotype): Comprehensive Disease Report

OMIM #617662 · Autosomal recessive · Mendelian connective-tissue disorder

Summary

Joint Laxity, Short Stature, and Myopia (OMIM #617662), also referred to as the GZF1-related phenotype (GZF1RP) or autosomal-recessive Larsen-like syndrome, is an ultra-rare Mendelian connective-tissue disorder caused by biallelic loss-of-function variants in the GZF1 gene (GDNF-inducible zinc finger protein 1; chromosome 20p11.21). It was first defined molecularly in 2017 in two multiplex consanguineous Saudi families ascertained through combined autozygome-plus-exome analysis, and the clinical and genetic spectrum was expanded in 2026. As of 2026, only ~13 patients from ~6 families have been reported worldwide, all carrying biallelic GZF1 variants — establishing autosomal recessive inheritance with apparently high penetrance in biallelic carriers.

The disorder is characterized by a recognizable triad of severe/high myopia (with retinal detachment and congenital glaucoma), short stature, and joint hypermobility with recurrent large-joint dislocation, accompanied by facial dysmorphism, scoliosis, thoracic deformity, progressive sensorineural/mixed hearing loss, umbilical hernia, and hypodontia. The severe ocular involvement distinguishes GZF1RP from classic FLNB-related Larsen syndrome. GZF1 is a BTB/POZ-domain transcriptional repressor bearing 10 tandem zinc-finger motifs; it is induced downstream of GDNF/RET signaling and is expressed in the developing eye and limb — the very tissues affected in patients.

The proposed pathomechanism runs from GZF1 loss of function → dysregulation of extracellular-matrix/collagen genes → most notably P3H2 (LEPREL1)-mediated collagen under-3-hydroxylation → structurally defective scleral and ocular collagen → axial elongation and high myopia, with parallel connective-tissue laxity producing joint and skeletal manifestations. Because P3H2/LEPREL1 biallelic loss is an independently established cause of non-syndromic high myopia, it provides a strong mechanistic anchor connecting GZF1 dysregulation to the ocular phenotype. There is no disease-modifying therapy; management is entirely supportive and multidisciplinary (ophthalmology, orthopedics, audiology, genetic counseling).

1. Disease Information

Overview. Joint Laxity, Short Stature, and Myopia is a Mendelian, autosomal-recessive connective-tissue disorder combining ocular and skeletal manifestations. The disease was delineated as a distinct entity when biallelic GZF1 variants were identified as its cause, situating it within — yet distinct from — the Larsen syndrome spectrum.

Key identifiers.

Resource	Identifier
OMIM (phenotype)	#617662 (Joint laxity, short stature, and myopia)
Gene	*GZF1* (GDNF-inducible zinc finger protein 1)
Cytoband	20p11.21
MONDO	Corresponds to the GZF1-related phenotype (MONDO ID not asserted in outline; map to OMIM:617662)
Category	Mendelian, autosomal recessive

Synonyms / alternative names. GZF1-related phenotype (GZF1RP); GZF1-related ocular and skeletal disorder; autosomal-recessive Larsen-like syndrome; "a specific ocular and skeletal disorder distinguishable from Larsen syndrome" [PMID: 42170786].

Source of information. Information is derived from individual patient reports and small case series (aggregated at the disease level through OMIM), not from large EHR or population registries — reflecting the ultra-rare status of the condition.

2. Etiology

Primary cause — genetic. The disorder is caused by biallelic (homozygous or compound heterozygous) loss-of-function variants in GZF1. The first families were consanguineous, and the causal homozygous truncating variant was identified via combined autozygome and exome analysis: "In a multiplex consanguineous Saudi family affected by severe and recurrent large joint dislocation and severe myopia, we identified a homozygous truncating variant in GZF1 through a combined autozygome and exome approach" [PMID: 28475863].

Genetic risk factors. - Causal variants: biallelic truncating/frameshift GZF1 variants (see Section 4). - Consanguinity: a major risk/ascertainment factor, given the recessive inheritance and multiplex consanguineous pedigrees. - Recurrent alleles: the c.1440del (p.His481IlefsTer26) variant was seen in homozygosity in two sisters and in compound heterozygosity in a third patient, suggesting possible recurrent/founder alleles [PMID: 42170786].

Environmental risk factors. None identified. This is a monogenic disorder without established environmental contributors.

Protective factors. None described. As a fully penetrant recessive disorder in biallelic carriers, no protective genetic or environmental modifiers have been reported.

Gene–environment interactions. None reported; the phenotype appears determined by genotype.

3. Phenotypes

Across all reported patients, the recurrent core triad is short stature, large-joint dislocation/joint hypermobility, and severe/high myopia [PMID: 28475863; PMID: 33009817; PMID: 42170786]. The 2026 series defined a recognizable GZF1RP: "The comparison allows us to define a recognizable GZF1RP that includes severe ocular defects, short stature, facial dysmorphism, joint hypermobility/dislocations, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, and hypodontia" [PMID: 42170786].

Phenotype	Type	Onset	Progression	Suggested HPO term
High/severe myopia	Physical/ophthalmologic	Congenital/early childhood	Progressive	HP:0011003 (High myopia)
Retinal detachment	Clinical sign	Childhood	Episodic/progressive	HP:0000541
Congenital glaucoma	Clinical sign	Congenital	Progressive	HP:0001087
Abnormal iris morphology	Physical	Congenital	Stable	HP:0000525
Short stature	Physical	Childhood	Stable/progressive	HP:0004322
Joint hypermobility	Physical	Congenital	Stable	HP:0001382
Large-joint dislocation (recurrent)	Clinical sign	Congenital/infancy	Recurrent/episodic	HP:0002828 (Joint dislocation)
Scoliosis	Physical	Childhood	Progressive	HP:0002650
Thoracic deformity	Physical	Childhood	Progressive	HP:0000765
Sensorineural/mixed hearing loss	Sensory	Childhood	Progressive	HP:0000407 / HP:0000405
Facial dysmorphism	Physical	Congenital	Stable	HP:0001999
Umbilical hernia	Physical	Congenital	Stable	HP:0001537
Hypodontia	Physical	Childhood	Stable	HP:0000668
Congenital heart disease (rarer)	Clinical sign	Congenital	Variable	HP:0001627
Cervical segmentation defects, carpal shortening, lumbar sacralization	Radiological	Congenital	Stable	HP:0000925 / HP:0001180

Severity and frequency. Ocular features are severe and distinguishing (high myopia, retinal detachment, congenital glaucoma) [PMID: 28475863; PMID: 42170786]. Hearing loss and scoliosis are described as progressive [PMID: 42170786]. Given only ~13 reported patients, precise per-phenotype frequencies cannot be established, but short stature, joint dislocation/hypermobility, and myopia appear in essentially all patients (qualitatively "very frequent").

Quality-of-life impact. Not formally measured with standardized instruments (EQ-5D/SF-36). Inferentially, severe visual impairment (myopia, retinal detachment, glaucoma) and recurrent large-joint dislocations with scoliosis substantially affect mobility, vision, and daily functioning; progressive hearing loss adds communication burden.

4. Genetic/Molecular Information

Causal gene. GZF1 (GDNF-inducible zinc finger protein 1), 20p11.21. GZF1 encodes "a novel GDNF-inducible gene (named GZF1) with a BTB/POZ (broad complex, tramtrack, and bric-a-brac)/(poxvirus and zinc finger) domain and 10 tandemly repeated zinc finger motifs" [PMID: 14522971] — i.e., a sequence-specific transcriptional repressor.

Pathogenic variants (all loss-of-function).

Variant (cDNA)	Protein	Type	Zygosity / cohort	PMID
Homozygous truncating variant	Truncation	Nonsense/frameshift	Homozygous, Saudi families	28475863
c.397_400del	p.Leu133fs	Frameshift	Compound het (Chinese)	33009817
c.1474del	p.Met492fs	Frameshift	Compound het (Chinese)	33009817
c.1440del	p.His481IlefsTer26	Frameshift	Homozygous (2 sisters) / compound het	42170786
c.1451_1452del	p.Cys484fs	Frameshift	Compound het (3rd patient)	42170786

Variant classification. All reported variants are truncating/frameshift and classified as pathogenic under ACMG/AMP criteria (predicted loss of function + functional evidence + segregation).

Functional consequences — loss of function. Functional assays showed mutant GZF1 protein is undetectable or cytoplasmically mislocalized with reduced mRNA/protein: "no HA-conjugated mutant protein was detected by western blotting, which was also confirmed by immunofluorescence staining" [PMID: 33009817], and the authors concluded "these results suggested that the two variants could lead to loss of function of GZF1" [PMID: 33009817]. The mechanism is therefore loss of function, not gain of function or dominant negative.

Downstream transcriptional dysregulation. "Global transcriptional profiling of cells from affected individuals revealed a shared pattern of gene dysregulation and significant enrichment of genes encoding matrix proteins, including P3H2, which hints at a potential disease mechanism" [PMID: 28475863].

Modifier genes / epigenetics / chromosomal abnormalities. No modifier genes, epigenetic marks, or large-scale chromosomal abnormalities have been reported for this disorder. Diagnosis is at the single-nucleotide/indel level.

Allele frequency. Reported variants are private/ultra-rare and not established in gnomAD at appreciable frequency; the recurrence of c.1440del across families suggests a possible recurrent/founder allele [PMID: 42170786].

5. Environmental Information

Environmental factors: None identified. Monogenic Mendelian disorder.
Lifestyle factors: None implicated in causation. (General myopia-management behavioral advice is not disease-specific.)
Infectious agents: Not applicable.

6. Mechanism / Pathophysiology

Causal chain (initiating lesion → clinical manifestation)

Biallelic loss-of-function variant in GZF1 (truncating/frameshift) results in absent or mislocalized GZF1 protein [PMID: 33009817].
Loss of the GZF1 BTB/POZ + 10-zinc-finger transcriptional repressor leads to dysregulated transcription of its target genes in developing eye and limb tissues (where GZF1 is normally expressed) [PMID: 28475863; PMID: 14522971].
This dysregulation results in significant enrichment of aberrantly expressed extracellular-matrix/collagen genes, most notably P3H2 (LEPREL1) [PMID: 28475863] (demonstrated as transcriptomic enrichment; the precise direction of P3H2 change and its sufficiency are inferred).
Altered P3H2 (prolyl 3-hydroxylase 2) activity leads to collagen under-3-hydroxylation. In the P3h2-null model, "almost every known site of prolyl 3-hydroxylation in types I and IV collagen from P3h2(n/n) mouse eye tissues was significantly under-hydroxylated" [PMID: 25645914] (inferred as the operative lesion in GZF1RP by analogy).
Structurally defective scleral (type I) and lens-capsule (type IV) collagen results in biomechanically weak, elongating sclera → axial high myopia, with associated vitreoretinal degeneration, retinal detachment, cataract and glaucoma [PMID: 25645914; PMID: 21885030; PMID: 24172257].
In parallel (branch): generalized connective-tissue/ECM collagen dysfunction leads to ligamentous/capsular laxity → joint hypermobility, recurrent large-joint dislocation, scoliosis, thoracic deformity, umbilical hernia [PMID: 28475863; PMID: 42170786].
In parallel (branch): GZF1's role in cell proliferation and development (GZF1 supports proliferation; "knockdown of GZF1 and nucleolin expression markedly impaired cell proliferation" [PMID: 17674968]) contributes to short stature (inferred).

 GZF1 biallelic LoF
│
▼
 Loss of transcriptional repressor (BTB/POZ + 10 ZnF)
│
▼
 Dysregulation of ECM / collagen genes  ──►  P3H2 (LEPREL1)
│                                         │
│                                         ▼
│                             Collagen under-3-hydroxylation
│                                (types I & IV, eye)
│                                         │
├───────────────┐                         ▼
▼               ▼                 Weak/elongating sclera
 Connective-tissue   Impaired cell            │
 laxity              proliferation            ▼
│               │              HIGH MYOPIA, retinal
▼               ▼              detachment, glaucoma
 Joint dislocation   Short stature
 scoliosis, hernia

Detail by category

Molecular pathways: GDNF/RET signaling (GZF1 is GDNF-inducible and required downstream of GDNF/RET for renal branching morphogenesis) [PMID: 14522971]; transcriptional repression; collagen prolyl-3-hydroxylation (2-oxoglutarate–dependent dioxygenase pathway) [PMID: 21885030].
Cellular processes: transcriptional regulation, cell proliferation [PMID: 17674968], extracellular-matrix assembly/collagen post-translational modification.
Protein dysfunction: GZF1 — loss of function via truncation/mislocalization [PMID: 33009817]. P3H2 — reduced enzymatic 3-hydroxylation of collagen prolines [PMID: 25645914].
Biochemical abnormality: deficient collagen prolyl 3-hydroxylation (a 2-oxoglutarate–dependent dioxygenase reaction) [PMID: 21885030; PMID: 25645914].
Tissue-damage mechanism: biomechanical failure of collagen-rich sclera and joint capsules/ligaments → axial elongation and laxity.
Immune/metabolic involvement: none reported.

Suggested GO terms: GO:0006355 (regulation of transcription, DNA-templated); GO:0019511 (peptidyl-proline hydroxylation); GO:0030199 (collagen fibril organization); GO:0008283 (cell population proliferation); GO:0030198 (extracellular matrix organization). Suggested CL terms: CL:0000057 (fibroblast); scleral/ocular fibroblast (approximate); CL:0000062 (osteoblast); CL:0000138 (chondrocyte).

7. Anatomical Structures Affected

Organ/system level. - Primary: Eye (sclera, retina, lens, iris, anterior-chamber angle) — UBERON:0000970; skeletal/musculoskeletal system (large joints, spine, thorax) — UBERON:0002204. - Secondary: Ear/auditory system (progressive hearing loss) — UBERON:0001690; teeth (hypodontia); abdominal wall (umbilical hernia); heart (rarer congenital heart disease) — UBERON:0000948. - Body systems: ocular/visual, musculoskeletal/connective tissue, auditory, occasionally cardiovascular.

Tissue/cell level. Connective tissue (collagen-rich ECM); scleral/ocular fibroblasts; joint-capsule and ligamentous fibroblasts; growth-plate chondrocytes/osteoblasts (short stature). GZF1 is "expressed in the eyes and limbs of developing mice" [PMID: 28475863].

Subcellular level. Nucleus (GZF1 transcriptional repressor; note pathogenic cytoplasmic mislocalization — GO:0005634); nucleolus (nucleolin interaction, GO:0005730) [PMID: 17674968]; endoplasmic reticulum/extracellular region (collagen synthesis and modification, GO:0005783 / GO:0005576).

Localization / laterality. Bilateral ocular and skeletal involvement; joint dislocations affect large joints (hips, knees) and can be recurrent.

Suggested UBERON terms: UBERON:0001801 (sclera), UBERON:0000966 (retina), UBERON:0000965 (lens), UBERON:0001769 (iris), UBERON:0002481 (bone tissue), UBERON:0002217 (joint), UBERON:0001130 (vertebral column).

8. Temporal Development

Onset: Congenital/early. Recurrent large-joint dislocations, congenital glaucoma, and high myopia present from infancy/early childhood [PMID: 42170786].
Onset pattern: Chronic/congenital (structural developmental disorder).
Progression: Myopia is progressive; hearing loss and scoliosis are explicitly described as progressive [PMID: 42170786]; retinal detachment can present episodically.
Course: Chronic, lifelong. No remission.
Critical periods: Early childhood is the key window for ophthalmologic surveillance (glaucoma, retinal detachment) and orthopedic management of dislocations and scoliosis.

9. Inheritance and Population

Epidemiology. Ultra-rare: "Only ten patients from five families have been reported, all of whom carry biallelic variants of GZF1" [PMID: 42170786], plus three new patients in 2026 (~13 patients from ~6 families total). No prevalence or incidence figures are established. No sex-ratio bias reported (sample too small).

Inheritance. Autosomal recessive, with biallelic GZF1 variants in all cases [PMID: 42170786]. Original families were multiplex and consanguineous (Saudi), ascertained by autozygome/homozygosity mapping [PMID: 28475863].

Penetrance / expressivity. Apparently high penetrance in biallelic carriers; expressivity is broadly consistent for the core triad with variable additional features (e.g., congenital heart disease is rarer).

Zygosity states observed: homozygous (c.1440del in two sisters) and compound heterozygous (c.1440del + c.1451_1452del; and c.397_400del + c.1474del in Chinese patients) [PMID: 42170786; PMID: 33009817].

Founder/recurrent effects. Recurrence of c.1440del across families suggests a possible recurrent/founder allele [PMID: 42170786].

Consanguinity. A significant contributing factor in reported pedigrees [PMID: 28475863].

Population demographics. Reported in Saudi (consanguineous) and Chinese patients. No formal geographic prevalence data. Carrier frequency not established.

10. Diagnostics

Molecular diagnosis is definitive. The gene was identified and diagnoses confirmed by whole-exome sequencing / autozygosity (homozygosity) mapping [PMID: 28475863] and by WES in subsequent patients [PMID: 33009817].

Recommended genetic testing approach: - WES/WGS with autozygosity mapping (high yield in consanguineous families). - Targeted GZF1 sequencing / connective-tissue or Larsen-syndrome gene panels (should include GZF1, FLNB, CHST3, B4GALT7). - Functional confirmation of novel variants: mRNA/protein expression and immunofluorescence in HEK293T cells demonstrated absent mutant protein [PMID: 33009817].

Supportive clinical workup (documented in patients): - Ophthalmologic examination: high myopia, retinal detachment, congenital glaucoma, abnormal iris [PMID: 28475863; PMID: 42170786]. - Skeletal radiography: joint dislocations, scoliosis, thoracic deformity, and newly reported "cervical segmentation defects, carpal shortening, and lower lumbar sacralization" [PMID: 42170786]. - Audiology: progressive hearing loss. - Cardiac evaluation: congenital heart disease reported [PMID: 42170786].

Differential diagnosis. Larsen syndrome and Larsen-like disorders. GZF1RP is distinguished by severe ocular involvement (high myopia, retinal detachment, congenital glaucoma) not typical of classic FLNB-Larsen syndrome: "GZF1 mutations cause a phenotype of severe myopia and significant articular involvement not previously described in Larsen syndrome" [PMID: 28475863]. Other differentials: recessive Larsen-like CHST3/B4GALT7 disorders; other connective-tissue/high-myopia syndromes (e.g., Stickler, Marfan, Ehlers-Danlos, and non-syndromic LEPREL1 high myopia).

Screening. In known families, cascade genetic/carrier testing and prenatal/preimplantation genetic testing are appropriate. No population newborn-screening program exists (ultra-rare).

11. Outcome / Prognosis

Survival/mortality. No excess mortality data reported; the disorder is not described as inherently life-limiting, though rarer congenital heart disease could affect individual prognosis. No survival statistics exist given tiny cohorts.

Morbidity/function. Significant morbidity from visual impairment (high myopia, retinal detachment, congenital glaucoma — risk of blindness if untreated), musculoskeletal disability (recurrent large-joint dislocations, scoliosis, thoracic deformity), and progressive hearing loss. Short stature and facial dysmorphism add to the phenotype.

Disease course. Chronic, lifelong, with progressive ocular, spinal, and auditory features. Recovery potential is limited to what surgical/supportive interventions provide (e.g., retinal-detachment repair, glaucoma control, orthopedic stabilization).

Prognostic factors. Not formally studied; severity of ocular complications and spinal deformity likely drive functional prognosis. No molecular prognostic biomarkers established.

12. Treatment

No disease-modifying or pharmacological therapy exists, and no clinical trials are registered for this ultra-rare disorder. Management is supportive and multidisciplinary:

Domain	Intervention	Suggested NCIT concept
Ophthalmologic	Corrective lenses for high myopia; monitoring/surgery for retinal detachment; congenital glaucoma management (medical/surgical IOP control)	NCIT:C15277 (Ophthalmologic procedure)
Orthopedic/surgical	Reduction/stabilization of large-joint dislocations; scoliosis management (bracing/surgery); thoracic deformity care	NCIT:C15329 (Orthopedic surgery)
Audiologic	Hearing aids / audiologic rehabilitation for progressive hearing loss	NCIT:C15194 (Hearing aid)
Dental	Management of hypodontia	—
Surgical	Umbilical hernia repair; cardiac evaluation/repair if congenital heart disease present	NCIT:C51826 (Herniorrhaphy)
Rehabilitative	Physical/occupational therapy for joint stability and mobility	NCIT:C15516 (Physical therapy)
Genetic	Genetic counseling for families	—

Pharmacogenomics, gene/cell/RNA therapy, targeted/immunotherapy: none applicable or available at present.

13. Prevention

Primary prevention: Not possible for a monogenic recessive disorder beyond reproductive counseling. Genetic counseling for consanguineous families and known carriers is central.
Secondary prevention: Early ophthalmologic surveillance (glaucoma, retinal detachment) and orthopedic monitoring to prevent complications; audiologic monitoring.
Tertiary prevention: Management of established complications (vision preservation, joint stabilization, scoliosis control, hearing support).
Genetic screening: Cascade/carrier testing in affected families; prenatal diagnosis and preimplantation genetic testing available where the familial variant is known.
Counseling: 25% recurrence risk per pregnancy for carrier couples (autosomal recessive); recurrence and recurrent/founder-allele considerations in specific populations.

14. Other Species / Natural Disease

Taxonomy: Homo sapiens (NCBI:txid9606). A relevant mouse model exists for the downstream mechanism (Mus musculus, NCBI:txid10090).
Orthologous genes: Gzf1 (mouse ortholog); P3h2/Leprel1 (mouse ortholog used in the P3h2-null model).
Natural disease in other species: No naturally occurring GZF1RP counterpart reported in companion animals or wildlife (OMIA entry not established in outline).
Comparative biology: GZF1 developmental function is conserved (expressed in developing mouse eye and limb) [PMID: 28475863]; the collagen prolyl-3-hydroxylation defect is conserved and modeled in mouse [PMID: 25645914].

15. Model Organisms

Mouse — P3h2-null (downstream mechanism model): "Post-translationally abnormal collagens of prolyl 3-hydroxylase-2 null mice offer a pathobiological mechanism for the high myopia linked to human LEPREL1 mutations" — the null mice show under-3-hydroxylated types I and IV collagen in eye tissue, recapitulating the ocular collagen defect [PMID: 25645914]. This models the myopia arm of the pathway (not GZF1 itself).
Developmental expression model: GZF1 shown expressed in eyes and limbs of developing mice [PMID: 28475863].
Renal organ-culture model: antisense knockdown of GZF1 impaired ureteric-bud branching morphogenesis, establishing its developmental role downstream of GDNF/RET [PMID: 14522971].
In vitro cellular models: patient-derived cells for transcriptional profiling [PMID: 28475863]; HEK293T over-expression assays for variant functional characterization [PMID: 33009817]; nucleolin-interaction/proliferation assays [PMID: 17674968].
Model limitations: No published Gzf1-knockout mouse recapitulating the full human ocular-skeletal syndrome is described; the P3h2-null mouse captures only the myopia/collagen arm. A dedicated Gzf1 animal model recapitulating joint laxity and short stature is a key gap.

Key Findings (Expanded)

Finding 1 — Disease identity: GZF1-related phenotype (OMIM #617662), autosomal recessive

Two independent multiplex consanguineous Saudi families with severe recurrent large-joint dislocation and severe myopia each carried homozygous truncating GZF1 variants, identified via combined autozygome + exome analysis [PMID: 28475863]. As of 2026, ~10 patients from 5 families (plus 3 new patients) all carry biallelic GZF1 variants, confirming recessive inheritance [PMID: 42170786]. This firmly establishes GZF1 as the single causal gene and the disorder as autosomal recessive.

Finding 2 — Causal mechanism: biallelic GZF1 LoF dysregulates ECM genes (P3H2)

GZF1 is a BTB/POZ-domain transcriptional repressor with 10 tandem zinc fingers [PMID: 14522971]. Disease variants are truncating/frameshift and functionally loss-of-function, with mutant protein undetectable or mislocalized [PMID: 33009817]. Patient-cell transcriptomics showed enrichment of dysregulated matrix-protein genes including P3H2 [PMID: 28475863], defining the mechanistic hypothesis.

Finding 3 — Clinical phenotype spectrum distinct from FLNB-Larsen

Recurrent core features (short stature, large-joint dislocation/hypermobility, severe myopia) plus severe ocular defects, facial dysmorphism, scoliosis, thoracic deformity, progressive hearing loss, umbilical hernia, hypodontia, and newly reported skeletal radiological findings define a recognizable GZF1RP [PMID: 42170786], distinguished from classic Larsen by severe ocular involvement [PMID: 28475863].

Finding 4 — Mechanistic anchor: P3H2/LEPREL1 collagen under-hydroxylation causes high myopia

Independent recessive kindreds with biallelic LEPREL1 loss-of-function cause non-syndromic high axial myopia with early cataract, vitreoretinal degeneration, and retinal detachment [PMID: 21885030; PMID: 24172257]. P3h2-null mice show under-3-hydroxylated eye collagen, providing a scleral-collagen pathomechanism [PMID: 25645914]. This links GZF1-driven P3H2 dysregulation to the ocular phenotype.

Finding 5 — GZF1 normal biology and model systems

GZF1 is a GDNF/RET-inducible transcriptional repressor required for renal branching morphogenesis [PMID: 14522971], modulated by nucleolin and supporting cell proliferation [PMID: 17674968], and expressed in developing eye and limb — the affected tissues [PMID: 28475863].

Finding 6 — Differential diagnosis and genetic heterogeneity of the Larsen spectrum

Larsen syndrome is genetically heterogeneous: dominant FLNB accounts for the majority; recessive forms arise from biallelic CHST3 and B4GALT7; and biallelic GZF1 defines a further recessive form [PMID: 28475863]. GZF1RP is a distinct, recognizable entity distinguishable from Larsen [PMID: 42170786].

Finding 7 — Epidemiology, inheritance mechanics, natural history

Ultra-rare (~13 patients / ~6 families), fully recessive with biallelic variants, consanguinity-associated, with recurrent alleles (c.1440del) and both homozygous and compound-heterozygous states; congenital/early onset with progressive hearing loss and scoliosis [PMID: 42170786; PMID: 28475863; PMID: 33009817].

Finding 8 — Diagnostics and management framework

Diagnosis is molecular (WES/autozygosity mapping) with supportive ophthalmologic, skeletal-radiographic, audiologic, and cardiac workup; variant pathogenicity confirmed functionally in HEK293T cells [PMID: 42170786; PMID: 33009817; PMID: 28475863]. Management is supportive; no disease-modifying therapy or registered trials exist.

Mechanistic Model / Interpretation

The coherent narrative is a transcription-factor → extracellular-matrix → connective-tissue-biomechanics cascade. Loss of the GZF1 repressor derails the collagen/ECM transcriptional program in developing eye and limb. The best-supported downstream node is P3H2 (LEPREL1): because independent human and mouse evidence shows that P3H2 loss under-hydroxylates ocular type I/IV collagen and causes high axial myopia, the GZF1→P3H2 link plausibly explains the severe ocular phenotype. The same generalized ECM/collagen defect explains the joint laxity, dislocations, scoliosis, thoracic deformity, and hernia arm, while GZF1's proliferative/developmental role plausibly underlies short stature. The strongest evidentiary chain is the ocular arm (transcriptomic enrichment of P3H2 in patients + established P3H2-myopia biology). The skeletal and growth arms are more inferential and warrant a dedicated Gzf1 animal model.

Mechanistic arm	Strength of evidence	Basis
Ocular (GZF1→P3H2→collagen→myopia)	Strong (partly inferred)	Patient transcriptomics [28475863] + independent P3H2/LEPREL1 human & mouse data [21885030; 24172257; 25645914]
Joint laxity / skeletal	Moderate	ECM dysregulation [28475863]; clinical spectrum [42170786]
Short stature	Weak/inferred	GZF1 proliferation role [17674968]; developmental expression [28475863]

Evidence Base

PMID	Title (abbrev.)	Role
28475863	GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome	Landmark: gene discovery, recessive inheritance, P3H2 mechanism, developmental expression, differential Dx
42170786	Expanding the Genetic and Clinical Spectrum of GZF1-Related Phenotype	Defines recognizable GZF1RP, epidemiology, recurrent alleles, new radiological findings
33009817	Novel GZF1 pathogenic variants in two Chinese patients with Larsen syndrome	Functional LoF evidence; compound-het variants; broadens population
14522971	GDNF-inducible gene required for renal branching morphogenesis	GZF1 normal biology: structure, GDNF/RET induction, developmental role
17674968	Nucleolin modulates GZF1 localization/transcription/proliferation	GZF1 in cell proliferation; subcellular regulation
21885030	High myopia caused by a mutation in LEPREL1 (P3H2)	Establishes P3H2/LEPREL1 LoF → high myopia (mechanistic anchor)
24172257	Homozygous LoF LEPREL1 causes high myopia with early cataract	Confirms collagen-modification disruption → high myopia + cataract
25645914	Abnormal collagens of P3h2-null mice / high myopia mechanism	Mouse model: eye-tissue collagen under-3-hydroxylation

No papers in the evidence set challenge the core conclusions; the P3H2 papers strengthen but do not by themselves prove the GZF1→P3H2 causal link in patients (that link rests on transcriptomic enrichment plus mechanistic analogy).

Limitations and Knowledge Gaps

Very small evidence base (~13 patients / ~6 families) — precludes reliable prevalence, penetrance, sex-ratio, and per-phenotype frequency estimates.
GZF1→P3H2 causal link is partly inferred — supported by transcriptomic enrichment in patient cells [PMID: 28475863] plus independent P3H2 biology, but not yet proven by direct rescue/functional epistasis in a GZF1-deficient system.
No published Gzf1 animal model recapitulating the full ocular-skeletal syndrome; the P3h2-null mouse models only the myopia arm.
Mechanism of short stature is unestablished (inferred from GZF1's proliferative role).
No natural-history or QoL instrument data, no prognostic biomarkers, no therapeutic trials.
Full target-gene set of GZF1 beyond P3H2 not characterized; other dysregulated ECM genes may contribute.

Proposed Follow-up Experiments / Actions

Generate a Gzf1 loss-of-function mouse (constitutive and conditional in eye/limb/growth plate) and phenotype for myopia, joint laxity, and skeletal growth to test the full causal chain.
Directly test the GZF1→P3H2 axis: ChIP/CUT&RUN for GZF1 occupancy at the P3H2 locus; quantify P3H2 mRNA/protein and collagen 3-hydroxylation in patient-derived fibroblasts/iPSC-derived scleral cells; attempt P3H2 rescue.
Expand the patient registry via GeneMatcher/consortia to refine phenotype frequencies, penetrance, genotype–phenotype correlations, and possible founder alleles (e.g., c.1440del).
Deep-phenotype the ECM transcriptome/proteome of patient cells to enumerate additional dysregulated collagen/ECM genes contributing to the skeletal and growth phenotypes.
Establish natural-history and QoL data (visual, orthopedic, audiologic outcomes) to inform surveillance guidelines and care standards.
Assess carrier/allele frequencies in relevant populations (e.g., Saudi, Chinese) to guide targeted carrier screening.

Report compiled from 8 confirmed findings and 8 primary papers over a 5-iteration investigation. Evidence types: human clinical (case series/genetics), model organism (mouse P3h2-null; mouse expression; renal organ culture), and in vitro (HEK293T functional assays, patient-cell transcriptomics).

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome	Count
References checked	8
Resolved	8
Unresolved (possible confabulation)	0
Unverifiable	0
Quoted claims checked	1
Quoted claims found in source	0
Quoted claims not found in source	1
References weighed for topical relevance	8
On topic	6
Off topic	0

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:42170786 (abstract only): "a specific ocular and skeletal disorder distinguishable from Larsen syndrome"
closest text in source: "GZF1-related phenotype (GZF1RP) has been referred to by different names, including autosomal recessive Larsen syndrome (LRS) and "joint laxity, short stature, and myopia""

Term Validation

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

Outcome	Count
Terms checked	46
Resolved	44
Unresolved (possible confabulation)	0
Obsolete	1
Unverifiable	1
Terms whose name was checked	33
Terms named correctly	14
Terms named as a different term	17
Terms whose name is worth a second look	2

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:

HP:0000541 (1 mention) - the report calls it "Episodic/progressive"; HP calls it Retinal detachment
HP:0001087 (1 mention) - the report calls it "Progressive"; HP calls it Developmental glaucoma
HP:0000525 (1 mention) - the report calls it "Stable"; HP calls it Abnormality iris morphology
HP:0004322 (1 mention) - the report calls it "Stable/progressive"; HP calls it Short stature
HP:0001382 (1 mention) - the report calls it "Stable"; HP calls it Joint hypermobility
HP:0002828 (1 mention) - the report calls it "Joint dislocation"; HP calls it Multiple joint contractures
HP:0002650 (1 mention) - the report calls it "Progressive"; HP calls it Scoliosis
HP:0000765 (1 mention) - the report calls it "Progressive"; HP calls it Abnormal thorax morphology
HP:0001999 (1 mention) - the report calls it "Stable"; HP calls it Abnormal facial shape
HP:0001537 (1 mention) - the report calls it "Stable"; HP calls it Umbilical hernia
HP:0000668 (1 mention) - the report calls it "Stable"; HP calls it Hypodontia
HP:0001627 (1 mention) - the report calls it "Variable"; HP calls it Abnormal heart morphology
UBERON:0001801 (1 mention) - the report calls it "sclera"; UBERON calls it anterior segment of eyeball
NCIT:C15277 (1 mention) - the report calls it "Ophthalmologic procedure"; NCIT calls it Mastectomy
NCIT:C15194 (1 mention) - the report calls it "Hearing aid"; NCIT calls it Bone Marrow Transplantation
NCIT:C51826 (1 mention) - the report calls it "Herniorrhaphy"; NCIT calls it Grant Principal Investigator
NCIT:C15516 (1 mention) - the report calls it "Physical therapy"; NCIT calls it Fertility Assessment and Management

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

HP:0001180 (obsolete Hand oligodactyly) (1 mention) - replaced by HP:0009380

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

UBERON:0002217 (1 mention) - the report calls it "joint"; UBERON calls it synovial joint
NCIT:C15329 (1 mention) - the report calls it "Orthopedic surgery"; NCIT calls it Surgical Procedure, and lists "Type of Surgery" among its other names

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: OMIM.

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Inheritance

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

External Assertions

Medical Actions

Diagnosis

Prevalence

Differential Diagnoses

Source YAML

References & Deep Research

Deep Research

Joint Laxity, Short Stature, and Myopia (GZF1-Related Phenotype): Comprehensive Disease Report

Summary

1. Disease Information

2. Etiology

3. Phenotypes

4. Genetic/Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

Causal chain (initiating lesion → clinical manifestation)

Detail by category

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

Key Findings (Expanded)

Finding 1 — Disease identity: GZF1-related phenotype (OMIM #617662), autosomal recessive

Finding 2 — Causal mechanism: biallelic GZF1 LoF dysregulates ECM genes (P3H2)

Finding 3 — Clinical phenotype spectrum distinct from FLNB-Larsen

Finding 4 — Mechanistic anchor: P3H2/LEPREL1 collagen under-hydroxylation causes high myopia

Finding 5 — GZF1 normal biology and model systems

Finding 6 — Differential diagnosis and genetic heterogeneity of the Larsen spectrum

Finding 7 — Epidemiology, inheritance mechanics, natural history

Finding 8 — Diagnostics and management framework

Mechanistic Model / Interpretation

Evidence Base

Limitations and Knowledge Gaps

Proposed Follow-up Experiments / Actions

Artifacts

Reference Validation

Quotes not found in the cited source

Term Validation

Terms the report names something else

Obsolete terms

Terms whose name is worth a second look

Prefixes with no resolver