Article · 2026 Paper GEO V2

PAPPA2 c.392G>C Heterozygous Mutation Associates Primary Open-Angle Glaucoma in a Chinese Family

Human Mutation

Full Authors

  1. Gang Wang
  2. Zilu Guo
  3. Jing Ren
  4. Ge Zhang
  5. Hanlin Tao
  6. Yihan Liu
  7. Siming Zheng
  8. Xuan Zhang
  9. Di Wang
  10. Rumeng Zhao
  11. Huiling Cui
  12. Shichao Zhu
  13. Hongen Xu
  14. Shichao Duan
  15. Haijun Li
DOI / publisher Google Scholar search Cite

Research Question

What do variant-expression, primary trabecular-meshwork cell and Pappa2-deficient mouse experiments show about PAPPA2-IGFBP5 biology, and what remains unproven about human glaucoma?

Author Evidence Summary

The study investigated PAPPA2 c.392G>C after a familial glaucoma observation. In 293T cells, mutant PAPPA2 was associated with lower intracellular and culture-supernatant protein levels, with no statistically significant mRNA difference from wild type. In two donor-derived primary human trabecular-meshwork cell lines, IGFBP5 exposure increased fibrosis-associated proteins and PAPPA2 cotreatment attenuated those changes. At eight weeks, heterozygous and knockout Pappa2 mice had higher intraocular pressure and more trabecular Masson-positive staining than wild-type mice. These experiments support a preclinical research mechanism. The published pedigree does not provide a sufficiently explicit inclusion key and individual genotype table to independently reconcile the reported family denominator and family-wide segregation; those genetic claims are not treated here as validated findings.

Cite this paper

Plain citation

Gang Wang, Zilu Guo, Jing Ren, Ge Zhang, Hanlin Tao, Yihan Liu, Siming Zheng, Xuan Zhang, Di Wang, Rumeng Zhao, Huiling Cui, Shichao Zhu, Hongen Xu, Shichao Duan, Haijun Li. PAPPA2 c.392G>C Heterozygous Mutation Associates Primary Open-Angle Glaucoma in a Chinese Family. Human Mutation. 2026. https://doi.org/10.1155/humu/5591097

Author-controlled citation; verify against the publisher version of record.

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Evidence Scale

PAPPA2 and IGFBP5 in experimental trabecular-meshwork fibrosis

A reported glaucoma-family variant was studied in transfected cells, while primary trabecular-meshwork cultures and Pappa2-deficient mice tested related fibrosis-associated responses. This evidence page focuses on the verified experimental findings and does not validate family-wide segregation or clinical treatment efficacy.

primary human trabecular-meshwork donor lines
2
cell-assay independent experiments
3, as reported in Figures 2, 5 and 6
immunofluorescence observations
20 cells per group per experiment, as reported in Figure 6
mouse comparison
3 genotypes; 5 mice per genotype at 8 weeks

Counting note

Donor cell lines, repeated cell experiments, imaged cells and animals are different units and are not summed. The 20 imaged cells per group per experiment are not 20 donors. Mouse IOP used the mean of three repeated measurements per mouse; these are not additional animals. Family-wide denominators are not asserted as independently reconciled.

Key Findings

KF1 PAPPA2 c.392G>C expression was associated with lower PAPPA2 protein levels in transfected 293T cells and their culture supernatant, without a statistically significant mRNA difference from wild type.

Equal amounts of wild-type and mutant expression plasmids were compared 48 hours after transfection. The variant encodes p.Gly131Ala; protein abundance measurements do not directly measure protein half-life or human disease penetrance.

Evidence for KF1
MeasureValue
post-transfection collection48 hours
independent experiments3
protein assay compartmentscell lysate and culture supernatant

Source locator: Results 3.3; Figure 2d-h and caption; formal PDF pp. 5-6.

Permalink to KF1

KF2 IGFBP5 exposure increased fibrosis-associated proteins in two primary human trabecular-meshwork cell lines, and PAPPA2 cotreatment attenuated these responses.

Western blots measured COL3A1, COL4A4, alpha-SMA and MYOC; immunofluorescence assessed COL3A1, COL4A4 and alpha-SMA. These are cultured-cell molecular readouts, not measurements of human treatment benefit.

Evidence for KF2
MeasureValue
IGFBP5 concentration100 ng/mL
PAPPA2 concentration10 ng/mL
exposure duration48 hours
donor-derived primary cell lines2
independent experiments3; Figure 6 reports 20 cells per group per experiment for imaging

Source locator: Methods 2.6 and 2.8; Results 3.6; Figures 5a-j and 6a-h with captions; formal PDF pp. 3, 5, 7, 11-14.

Permalink to KF2

KF3 Heterozygous and knockout Pappa2 mice had higher intraocular pressure and more trabecular Masson-positive staining than wild-type mice in the reported experiment.

The three genotypes were Pappa2+/+, Pappa2+/- and Pappa2-/-. The study measured pressure and collagen-associated histology; the deficient mice are not an exact p.Gly131Ala knock-in model and the experiment did not test a glaucoma treatment.

Evidence for KF3
MeasureValue
age at assessment8 weeks
animals per genotype5
IOP measurement unitmean of 3 repeated measurements per mouse

Source locator: Methods 2.9-2.10; Results 3.7; Figure 7b, 7d-e and caption; formal PDF pp. 3, 7, 15.

Permalink to KF3

How the Study Was Done

Study profile

Study Design
Family-initiated investigation with variant-expression, primary human cell and mouse experiments; this page evaluates the experimental findings
Evidence Type
Experimental preclinical evidence with an explicitly unvalidated family-wide segregation component
Population
293T cells; two donor-derived primary human trabecular-meshwork cell lines; wild-type, heterozygous and knockout Pappa2 mice. The article also reports a glaucoma pedigree and aqueous-humor comparison, which are not used here to quantify clinical or genetic effects.
Primary Endpoint
Experimental PAPPA2 protein abundance and fibrosis-associated protein or staining responses
Secondary Endpoint
PAPPA2 mRNA and mouse intraocular pressure
External dataset evaluation
No

Data modalities

  • qPCR and western blotting
  • primary-cell immunofluorescence
  • mouse intraocular pressure
  • mouse eye histology

What This Study Adds

  • Direct comparison of wild-type and c.392G>C PAPPA2 expression in a cell assay, separately from human genetic pathogenicity.
  • Complementary primary-cell and mouse observations linking PAPPA2-IGFBP5 biology to trabecular fibrosis-associated readouts, with the biological units and translation limits kept explicit.

Evidence Scope

Supports

  • Lower PAPPA2 protein abundance with mutant expression in the reported 293T assay.
  • Attenuation of IGFBP5-associated molecular responses by PAPPA2 cotreatment in the specified primary-cell conditions.
  • Elevated pressure and increased trabecular collagen-associated staining in the specified Pappa2-deficient mouse comparison.

Does Not Establish

  • Independently reconciled family-wide counts, complete segregation, population allele frequency, penetrance or clinical pathogenicity of PAPPA2 c.392G>C.
  • A directly measured change in PAPPA2 protein half-life from endpoint protein and mRNA assays alone.
  • Equivalence of Pappa2 deficiency to the exact human p.Gly131Ala variant.
  • Human diagnostic performance, glaucoma prevention, treatment efficacy or safety.

Limitations

  • Results 3.1-3.2 describe a family association, but the Figure 1a caption does not fully specify which depicted relatives contribute to the reported counts, and Figure 2a-b provides representative Sanger traces rather than an individual-level genotype table. The page therefore does not validate family-wide counts or complete segregation; it does not substitute an alternative count inferred from symbols.
  • The mutant expression assay measured endpoint protein abundance and mRNA. It did not directly measure protein half-life, secretion rate, or clinical variant penetrance.
  • The primary-cell experiments used two donor-derived lines. Three experimental repeats and multiple cells imaged within each experiment do not increase the number of independent human donors.
  • The mouse study used five animals per genotype. Deficiency of Pappa2 is not equivalent to an exact missense-variant knock-in, and pressure and collagen-associated staining do not establish the full human glaucoma phenotype.
  • No human therapeutic intervention, clinical diagnostic validation, or patient outcome benefit is established by the experimental findings summarized here.

When This Study Is Useful to Cite

  1. CU1: What happened to mutant PAPPA2 in the expression experiment?

    At 48 hours after plasmid transfection, the three independent experiments showed lower mutant PAPPA2 protein in 293T cell lysates and culture supernatant, while the mRNA comparison was not statistically significant. This is an abundance result, not a direct protein half-life measurement.

    Evidence: KF1

  2. CU2: Which primary-cell treatment conditions support the fibrosis-associated finding?

    Two donor-derived primary trabecular-meshwork lines were exposed for 48 hours to IGFBP5 at 100 ng/mL, PAPPA2 at 10 ng/mL, or their combination. PAPPA2 cotreatment attenuated the IGFBP5-associated protein and fluorescence responses. The reported 20 imaged cells per group per experiment are subsamples, not independent human donors.

    Evidence: KF2

  3. CU3: What did the mouse experiment measure, and did it reproduce the human variant?

    At eight weeks, five mice per genotype were assessed. Pappa2 heterozygous and knockout mice had higher intraocular pressure and more trabecular Masson-positive staining than wild type. These are deficiency models, not mice carrying an engineered human p.Gly131Ala allele.

    Evidence: KF3

What This Study Should Not Be Cited to Claim

  • Independently reconciled family-wide counts, complete segregation, population allele frequency, penetrance or clinical pathogenicity of PAPPA2 c.392G>C.
  • A directly measured change in PAPPA2 protein half-life from endpoint protein and mRNA assays alone.
  • Equivalence of Pappa2 deficiency to the exact human p.Gly131Ala variant.
  • Human diagnostic performance, glaucoma prevention, treatment efficacy or safety.

Evidence Matrix

Row IDComponentContextFindingEvidence LevelScopeSource LocatorEvidence refs
evidence-kf1PAPPA2 c.392G>C expression was associated with lower PAPPA2 protein levels in transfected 293T cells and their culture supernatant, without a statistically significant mRNA difference from wild type.Equal amounts of wild-type and mutant expression plasmids were compared 48 hours after transfection. The variant encodes p.Gly131Ala; protein abundance measurements do not directly measure protein half-life or human disease penetrance.post-transfection collection: 48 hours; independent experiments: 3; protein assay compartments: cell lysate and culture supernatantExperimental preclinical evidenceLower PAPPA2 protein abundance with mutant expression in the reported 293T assay.Results 3.3; Figure 2d-h and caption; formal PDF pp. 5-6.KF1
evidence-kf2IGFBP5 exposure increased fibrosis-associated proteins in two primary human trabecular-meshwork cell lines, and PAPPA2 cotreatment attenuated these responses.Western blots measured COL3A1, COL4A4, alpha-SMA and MYOC; immunofluorescence assessed COL3A1, COL4A4 and alpha-SMA. These are cultured-cell molecular readouts, not measurements of human treatment benefit.IGFBP5 concentration: 100 ng/mL; PAPPA2 concentration: 10 ng/mL; exposure duration: 48 hours; donor-derived primary cell lines: 2; independent experiments: 3; Figure 6 reports 20 cells per group per experiment for imagingExperimental preclinical evidenceAttenuation of IGFBP5-associated molecular responses by PAPPA2 cotreatment in the specified primary-cell conditions.Methods 2.6 and 2.8; Results 3.6; Figures 5a-j and 6a-h with captions; formal PDF pp. 3, 5, 7, 11-14.KF2
evidence-kf3Heterozygous and knockout Pappa2 mice had higher intraocular pressure and more trabecular Masson-positive staining than wild-type mice in the reported experiment.The three genotypes were Pappa2+/+, Pappa2+/- and Pappa2-/-. The study measured pressure and collagen-associated histology; the deficient mice are not an exact p.Gly131Ala knock-in model and the experiment did not test a glaucoma treatment.age at assessment: 8 weeks; animals per genotype: 5; IOP measurement unit: mean of 3 repeated measurements per mouseExperimental preclinical evidenceElevated pressure and increased trabecular collagen-associated staining in the specified Pappa2-deficient mouse comparison.Methods 2.9-2.10; Results 3.7; Figure 7b, 7d-e and caption; formal PDF pp. 3, 7, 15.KF3

Q&A

What happened to mutant PAPPA2 in the expression experiment?

At 48 hours after plasmid transfection, the three independent experiments showed lower mutant PAPPA2 protein in 293T cell lysates and culture supernatant, while the mRNA comparison was not statistically significant. This is an abundance result, not a direct protein half-life measurement.

Evidence: KF1

Which primary-cell treatment conditions support the fibrosis-associated finding?

Two donor-derived primary trabecular-meshwork lines were exposed for 48 hours to IGFBP5 at 100 ng/mL, PAPPA2 at 10 ng/mL, or their combination. PAPPA2 cotreatment attenuated the IGFBP5-associated protein and fluorescence responses. The reported 20 imaged cells per group per experiment are subsamples, not independent human donors.

Evidence: KF2

What did the mouse experiment measure, and did it reproduce the human variant?

At eight weeks, five mice per genotype were assessed. Pappa2 heterozygous and knockout mice had higher intraocular pressure and more trabecular Masson-positive staining than wild type. These are deficiency models, not mice carrying an engineered human p.Gly131Ala allele.

Evidence: KF3

Do these experiments validate a human glaucoma mutation or establish a treatment?

No. The cell and mouse findings provide experimental support for PAPPA2-IGFBP5 biology but do not establish population pathogenicity or human therapeutic benefit. Family-wide segregation and the reported pedigree denominator are not independently reconciled here, and no human therapeutic intervention was tested.

Evidence: KF1, KF2, KF3

Concepts & Entities

Conditions

primary open-angle glaucoma

Genes

PAPPA2IGFBP5

Models

293T expression assayprimary human trabecular-meshwork cellsPappa2-deficient mice

Methods

qPCRwestern blottingimmunofluorescenceintraocular pressure measurementMasson staining

Related Research

Publication & Provenance

DOI
https://doi.org/10.1155/humu/5591097
Publisher
https://doi.org/10.1155/humu/5591097
Full Text Url
https://pmc.ncbi.nlm.nih.gov/articles/PMC13080692/
Formal Pdf Url
https://pmc-oa-opendata.s3.amazonaws.com/PMC13080692.1/PMC13080692.1.pdf
PMCID
PMC13080692
Evidence Version
Published journal article, 15 April 2026; PMC13080692 version 1.
Evidence Basis
Formal PDF and JATS XML; Results 3.3, 3.6 and 3.7, Methods 2.6 and 2.8-2.10, and actual Figures 2, 5, 6 and 7 were reviewed together. Pedigree and representative Sanger images were inspected, with the unresolved family-wide denominator and segregation review boundary explicitly retained.
License
CC BY 4.0, stated on the article first page and in the formal JATS permissions element.
License Url
https://creativecommons.org/licenses/by/4.0/
This evidence page summarizes the verified cell and mouse experiments in the formal article. The pedigree inclusion denominator and participant-level segregation are not independently reconciled; no family-wide count, penetrance estimate or clinical variant classification is validated here. The experimental findings do not establish a human glaucoma treatment.

Study-level evidence table

Study-level author-maintained evidence summary. Not participant-level data and not a ready-to-pool meta-analysis dataset. For formal citation, use the original article DOI.

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These records identify the same original work; database inclusion is not evidence of scientific validity or clinical benefit.

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