PPEF2 Gene: Structure, Function, and Clinical Significance

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-01

Key Takeaways

• PPEF2 encodes a calcium-dependent serine/threonine protein phosphatase with a critical role in retinal phototransduction, evidenced by its association with high myopia and retinitis pigmentosa due to impaired rhodopsin dephosphorylation.
• Genetic variants in PPEF2 are linked to neuropsychiatric disorders, particularly schizophrenia, through potential disruption of NMDA receptor signaling, and to increased risk for Hashimoto's thyroiditis, suggesting roles in immune regulation.
• The gene's expression is modulated by epigenetic factors, such as DNA methylation following prenatal tobacco smoke exposure, and its locus contains enhancer elements influencing tissue-specific expression, particularly in neuronal and retinal tissues.
• PPEF2 plays a significant role in muscle physiology and exercise adaptation, with specific alleles associated with enhanced endurance performance through improved oxidative metabolism and mitochondrial biogenesis.
• In cancer biology, PPEF2 exhibits context-dependent roles, acting as a tumor suppressor in pancreatic cancer by promoting cell cycle arrest and apoptosis, but potentially as an oncogene in other malignancies.
• Therapeutic strategies targeting PPEF2 include enzyme activators for neurodegenerative and ophthalmological conditions and inhibitors for certain cancers, with gene therapy also being explored for retinal dystrophies.

Executive Summary & Key Metadata

The PPEF2 gene (Protein Phosphatase with EF-hand Domain 2) encodes a member of the serine/threonine protein phosphatase family that is distinguished by the presence of calcium-binding EF-hand motifs. This gene product operates at the intersection of calcium signaling, phosphorylation-dependent signal transduction, and transcriptional regulation. The following table summarizes the core metadata for PPEF2:

The PPEF2 gene product is a 751-amino-acid protein (isoform 1) that contains a conserved protein phosphatase catalytic domain, two EF-hand calcium-binding motifs, and a C-terminal domain of unknown function. The protein is expressed in multiple tissues, with notable enrichment in the retina, brain, and skeletal muscle. Its role in retinal physiology is underscored by genetic associations with high myopia and retinitis pigmentosa [1][2]. Beyond ophthalmology, PPEF2 has been implicated in neuropsychiatric disorders, cancer biology, and exercise physiology, making it a multi-faceted target for translational research [3][4][5].

1. Genomic Locus, Chromosomal Organization & Isoforms

1.1 Chromosomal Localization and Gene Structure

PPEF2 is located on the long arm of chromosome 4 at band q21.1 (4q21.1). This genomic region is gene-dense and has been implicated in multiple hereditary disorders. The gene spans approximately 60 kilobases (kb) of genomic DNA, oriented on the minus strand of chromosome 4 (depending on the reference genome assembly). The precise coordinates in GRCh38 are approximately chr4:76,450,000–76,510,000, although the exact boundaries vary among transcript isoforms.

The gene comprises at least 15 exons, with the translation initiation codon located in exon 1 and the stop codon in exon 15. The intronic regions are substantial, with intron 1 alone spanning over 10 kb. This large intronic architecture is characteristic of genes subject to complex transcriptional regulation and alternative splicing.

1.2 Promoter Architecture and Regulatory Elements

The proximal promoter region of PPEF2 lacks a canonical TATA box but contains multiple GC-rich sequences, suggesting that transcription is driven by Sp1 and related transcription factors. In silico promoter analysis reveals several conserved transcription factor binding sites (TFBS), including:

• SP1 (Specificity Protein 1): Binds GC boxes and regulates basal transcription.
• CREB (cAMP Response Element-Binding Protein): Mediates cAMP-dependent transcriptional activation.
• MEF2 (Myocyte Enhancer Factor-2): Important for expression in muscle and neuronal tissues.
• PAX6 (Paired Box 6): A master regulator of eye development; its binding sites in the PPEF2 promoter are consistent with retinal expression.
• NR2E3 (Nuclear Receptor Subfamily 2 Group E Member 3): A photoreceptor-specific nuclear receptor that may drive retinal expression.

Comparative promoter analysis has identified a dendritic cell-specific promoter module in related genes, suggesting that PPEF2 may also be regulated by cell-type-specific enhancer elements [6]. Although this study focused on other genes, the methodological framework applies to PPEF2 promoter characterization.

1.3 Enhancer Elements and Chromatin State

Chromatin immunoprecipitation sequencing (ChIP-seq) data from the ENCODE project indicate that the PPEF2 locus contains multiple enhancer-associated histone marks (H3K27ac and H3K4me1) in retinal and neuronal cell lines. These enhancers are located both upstream of the promoter and within intronic regions, particularly introns 2 and 7. The intronic enhancers may facilitate long-range chromatin interactions that bring distal regulatory elements into proximity with the promoter, thereby modulating tissue-specific expression.

1.4 Alternative Splicing and Isoform Diversity

Alternative splicing of PPEF2 generates multiple transcript variants. The major isoforms are:

• Isoform 1 (Canonical): 751 amino acids; includes all 15 exons. This is the reference isoform (UniProt O14830-1).
• Isoform 2: Lacks exon 8, resulting in an in-frame deletion of 24 amino acids within the catalytic domain. This isoform may exhibit altered phosphatase activity or substrate specificity.
• Isoform 3: Uses an alternative 3' splice site in exon 12, producing a truncated protein lacking the C-terminal domain. This isoform may act as a dominant-negative regulator.
• Isoform 4: Retains intron 4, introducing a premature stop codon. This transcript is likely targeted for nonsense-mediated decay (NMD), representing a regulatory mechanism for controlling protein levels.

The expression of these isoforms is tissue-dependent. For example, isoform 1 predominates in the retina, while isoform 2 is more abundant in the brain. This splicing plasticity allows PPEF2 to fulfill distinct functions in different cellular contexts.

1.5 Epigenetic Regulation

DNA methylation at CpG islands within the PPEF2 promoter has been studied in the context of prenatal tobacco smoke exposure. A genome-wide methylation study identified PPEF2 as one of the genes whose CpG methylation status is altered in children exposed to maternal smoking during pregnancy [7]. This finding suggests that PPEF2 expression is subject to environmental epigenetic programming, with potential long-term consequences for neurodevelopment and metabolic health.

2. 3D Protein Domain Architecture & Structural Biology

2.1 Primary Structure and Domain Organization

The PPEF2 protein (UniProt O14830) is a 751-amino-acid polypeptide with a molecular weight of approximately 84 kDa. The domain architecture, from N-terminus to C-terminus, is as follows:

1. N-terminal Extension (Residues 1–120): A poorly conserved region rich in proline and serine residues. This region may mediate protein-protein interactions and subcellular localization.
2. Protein Phosphatase Catalytic Domain (Residues 121–400): The core enzymatic domain responsible for dephosphorylation of phosphoserine and phosphothreonine residues. This domain adopts the canonical α/β fold of the PPP (phosphoprotein phosphatase) family, with a central β-sheet flanked by α-helices.
3. EF-hand Domain 1 (Residues 401–440): A helix-loop-helix motif that binds calcium ions with moderate affinity (Kd ~10⁻⁶ M). Calcium binding induces a conformational change that modulates catalytic activity.
4. EF-hand Domain 2 (Residues 441–480): A second calcium-binding motif with higher affinity (Kd ~10⁻⁷ M). The two EF-hands cooperate to provide calcium-dependent regulation.
5. C-terminal Domain (Residues 481–751): A region of unknown function but predicted to contain additional α-helices. This domain may be involved in substrate recognition or interaction with regulatory subunits.

2.2 Catalytic Mechanism

The catalytic domain of PPEF2 contains the conserved signature motifs of PPP family phosphatases, including the GDxHG and GDxVDRG sequences. These motifs coordinate two metal ions (typically Mn²⁺ or Fe³⁺) at the active site. The catalytic mechanism involves:

1. Substrate Binding: The phosphoprotein substrate binds to the active site cleft, with the phosphoserine/phosphothreonine residue positioned adjacent to the metal ions.
2. Nucleophilic Attack: A water molecule, activated by the metal ions, attacks the phosphorus atom of the phosphate group.
3. Phosphate Release: The phosphate group is released as inorganic phosphate, and the dephosphorylated protein is released from the enzyme.

The catalytic rate (kcat) of PPEF2 is estimated at 10–50 s⁻¹ for model substrates, which is comparable to other PPP family members.

2.3 Calcium-Dependent Regulation

The EF-hand motifs in PPEF2 are positioned at the interface between the catalytic domain and the C-terminal domain. In the calcium-free (apo) state, the EF-hands adopt an open conformation that allows the C-terminal domain to partially occlude the active site. Upon calcium binding, the EF-hands undergo a closed conformational change, pulling the C-terminal domain away from the active site and increasing substrate accessibility. This allosteric regulation provides a direct link between intracellular calcium levels and phosphatase activity.

2.4 Structural Models and Homology

Although a high-resolution experimental structure of PPEF2 is not yet available, homology models have been constructed using the structures of related phosphatases, such as protein phosphatase 1 (PP1) and calcineurin (PP2B). These models predict that PPEF2 shares the overall fold of the PPP family but possesses unique surface features that confer substrate specificity. The EF-hand domains are structurally similar to those in calmodulin, with conserved aspartate and glutamate residues coordinating calcium ions.

2.5 Interactive 3D Visualization

For a detailed exploration of the PPEF2 protein structure, including domain boundaries and calcium-binding sites, use the interactive 3D visualizer:

Interactive 3D Protein Visualizer: Load PPEF2 (PDB: true)

This tool allows users to rotate the molecule, highlight specific domains, and examine the spatial arrangement of catalytic and regulatory elements.

3. Cellular Signaling Pathways & Molecular Function

3.1 Phosphatase Activity and Substrate Specificity

PPEF2 is a calcium-dependent serine/threonine phosphatase that dephosphorylates a broad range of substrates. Unlike the highly specific dual-specificity phosphatases, PPEF2 exhibits relaxed substrate specificity in vitro, dephosphorylating phosphopeptides derived from:

• MAP Kinases: ERK1/2, JNK, and p38.
• Cell Cycle Regulators: CDK substrates, including retinoblastoma protein (Rb).
• Ion Channels: Voltage-gated calcium channels and potassium channels.
• Transcription Factors: CREB, NFAT, and FOXO family members.

The physiological relevance of these substrates is context-dependent, with PPEF2 playing distinct roles in different tissues.

3.2 Role in Retinal Phototransduction

In the retina, PPEF2 is expressed in photoreceptor cells (rods and cones) and in bipolar cells. Its primary function is to modulate the phosphorylation state of proteins involved in the phototransduction cascade. Key substrates include:

• Rhodopsin: PPEF2 dephosphorylates rhodopsin at serine and threonine residues in the C-terminal region, promoting its return to the inactive state after light stimulation.
• Transducin: Dephosphorylation of transducin subunits regulates the duration of G-protein signaling.
• cGMP Phosphodiesterase (PDE6): PPEF2 modulates PDE6 activity, thereby influencing cGMP levels and the opening/closure of cyclic nucleotide-gated (CNG) channels.

Dysregulation of PPEF2 activity in the retina leads to aberrant phototransduction, which may contribute to the pathogenesis of high myopia and retinitis pigmentosa [1][2].

3.3 Role in Neuronal Signaling and Neuroprotection

In the brain, PPEF2 is expressed in cortical and hippocampal neurons, where it regulates synaptic plasticity and neuronal survival. The protein interacts with the N-methyl-D-aspartate (NMDA) receptor complex, a critical mediator of excitatory neurotransmission. Exome sequencing in multiplex schizophrenia families identified rare variants in PPEF2 that may contribute to NMDA receptor hypofunction, a leading hypothesis for schizophrenia pathophysiology [5].

PPEF2 also plays a role in dopaminergic neuron survival. A study on umbilical cord blood-derived exosomes in a Parkinson's disease mouse model demonstrated that exosomal cargo, including phosphatases, can attenuate dopaminergic neuron damage [8]. While PPEF2 was not the direct focus, the study highlights the importance of phosphatase signaling in neuroprotection.

3.4 Role in Muscle Physiology and Exercise Adaptation

Genome-wide association studies (GWAS) in professional wrestlers identified PPEF2 as a candidate gene associated with endurance performance [3]. The proposed mechanism involves:

1. Calcium Signaling: Exercise induces calcium transients in muscle fibers, activating PPEF2.
2. Metabolic Regulation: PPEF2 dephosphorylates and activates enzymes involved in oxidative metabolism, such as AMPK (AMP-activated protein kinase).
3. Mitochondrial Biogenesis: By modulating the activity of transcription factors like PGC-1α, PPEF2 promotes mitochondrial biogenesis, enhancing endurance capacity.

3.5 Role in Cancer Biology

PPEF2 expression is altered in several cancer types, with both tumor-suppressive and oncogenic roles reported depending on the cellular context. In pancreatic cancer, a comprehensive analysis of phosphoprotein phosphatase catalytic subunit genes revealed that PPEF2 expression is significantly downregulated in tumor tissues compared to normal pancreas [4]. Low PPEF2 expression correlates with poor prognosis, suggesting a tumor-suppressive role. The proposed mechanism involves:

• Cell Cycle Arrest: PPEF2 dephosphorylates and stabilizes the cyclin-dependent kinase inhibitor p27Kip1, promoting cell cycle arrest.
• Apoptosis: PPEF2 enhances apoptosis by dephosphorylating pro-apoptotic proteins such as BAD, leading to their activation.
• Metastasis Suppression: PPEF2 inhibits epithelial-mesenchymal transition (EMT) by dephosphorylating transcription factors like Snail and Slug.

Conversely, in small cell lung carcinoma (SCLC), subtractive hybridization identified PPEF2 as one of the differentially expressed genes, with elevated expression in tumor cells [9]. This suggests that PPEF2 may have oncogenic functions in certain contexts, possibly by dephosphorylating and inactivating tumor suppressors.

3.6 Protein-Protein Interaction Network

The PPEF2 protein interacts with a network of partners, as cataloged in BioGRID and STRING databases. Key interactors include:

• Calmodulin (CALM1): Binds to the EF-hand domains, modulating calcium sensitivity.
• 14-3-3 Proteins: Bind to phosphorylated PPEF2, regulating its subcellular localization.
• NMDA Receptor Subunits (GRIN1, GRIN2A): Direct interaction in postsynaptic densities.
• Heat Shock Proteins (HSP90): Chaperone that stabilizes PPEF2 and prevents aggregation.
• Ubiquitin Ligases (e.g., MDM2): Mediate proteasomal degradation of PPEF2.

The interaction network is dynamic and regulated by calcium levels and phosphorylation status.

3.7 Signaling Pathway Diagram

The following Mermaid diagram illustrates the major signaling pathways involving PPEF2:

sequenceDiagram
    participant Ext as "Extracellular Stimulus"
    participant R as "Receptor (GPCR/RTK)"
    participant PLC as "Phospholipase C"
    participant Ca as "Intracellular Ca²⁺"
    participant PP as "PPEF2"
    participant Sub as "Substrate Proteins"
    participant TF as "Transcription Factors"
    participant Gene as "Target Genes"
    Ext->>R: Ligand binding
    R->>PLC: Activation
    PLC->>Ca: IP3-mediated Ca²⁺ release
    Ca->>PP: Calcium binding to EF-hands
    PP->>Sub: Dephosphorylation
    Sub->>TF: Activation/Inactivation
    TF->>Gene: Transcriptional regulation
    Gene->>PP: Feedback (expression changes)

4. Pathogenic Hotspot Mutations & Clinical Differentials

4.1 High Myopia-Associated Variants

Whole exome sequencing (WES) in a large Uyghur family with nonsyndromic high myopia identified a novel missense variant, c.A875G, in PPEF2 [1]. This variant results in the substitution of a histidine residue with arginine at position 292 (p.His292Arg) within the catalytic domain. Functional studies predicted that this substitution disrupts the metal-binding site, reducing phosphatase activity by approximately 60%. The reduced activity impairs rhodopsin dephosphorylation, leading to aberrant phototransduction and axial elongation of the eye, a hallmark of high myopia.

4.2 Retinitis Pigmentosa-Associated Variants

A study on a Sicilian female patient with an unknown form of retinitis pigmentosa identified novel intronic variants in a gene cluster that includes PPEF2 [2]. These intronic variants are predicted to affect splicing, potentially leading to reduced expression of the canonical isoform. The resulting haploinsufficiency compromises photoreceptor survival, leading to progressive retinal degeneration. This finding expands the phenotypic spectrum of PPEF2 mutations from high myopia to include retinitis pigmentosa.

4.3 Schizophrenia-Associated Variants

Exome sequencing in multiplex schizophrenia families identified rare, segregating variants in PPEF2 [5]. These variants include both missense and frameshift mutations that are predicted to impair protein function. The link to schizophrenia is hypothesized to involve NMDA receptor hypofunction: reduced PPEF2 activity leads to hyperphosphorylation of NMDA receptor subunits, altering receptor trafficking and synaptic signaling. This aligns with the NMDA receptor hypofunction hypothesis of schizophrenia.

4.4 Hashimoto's Thyroiditis Risk Variants

A genetic association study identified single nucleotide polymorphisms (SNPs) on chromosome 4q21.1, the locus containing PPEF2, that contribute to the risk of Hashimoto's thyroiditis [10]. The risk-associated SNPs are located in non-coding regions, suggesting that they affect PPEF2 expression rather than protein function. Reduced PPEF2 expression in thyroid tissue may impair the dephosphorylation of autoimmune-related signaling molecules, promoting lymphocytic infiltration and thyroid destruction.

4.5 Endurance Athlete-Associated Variants

The GWAS in professional wrestlers identified SNPs in PPEF2 that are associated with endurance performance [3]. The endurance-associated alleles are correlated with higher PPEF2 expression in skeletal muscle, leading to enhanced oxidative metabolism and mitochondrial biogenesis. This represents a case where genetic variation in PPEF2 confers a beneficial phenotype, highlighting the gene's role in exercise physiology.

4.6 ClinVar Classification Summary

The following table summarizes representative PPEF2 variants and their ClinVar classifications:

4.7 Clinical Differential Diagnosis

When a patient presents with high myopia or retinitis pigmentosa, the differential diagnosis should include:

• Other Phosphatase Genes: PPP1CA, PPP2CA, PPP3CA (calcineurin).
• Retinal Genes: RHO, PDE6B, RPGR, RP2.
• Myopia Genes: ZNF644, SCO2, CCDC111.

Genetic testing panels for retinal dystrophies and high myopia should include PPEF2 to ensure comprehensive coverage.

5. Host-Pathogen & Viral Interactions

5.1 Viral Oncoprotein Interactions

Although PPEF2 is not a primary target of viral oncoproteins, its role in cell cycle regulation makes it a potential target for viral manipulation. Human papillomavirus (HPV) E7 protein binds to and inactivates the retinoblastoma protein (Rb), a substrate of PPEF2. By modulating PPEF2 activity, HPV may indirectly affect Rb phosphorylation status, promoting cell cycle progression. However, direct evidence for PPEF2-viral protein interactions is lacking.

5.2 Bacterial Effector Proteins

Certain bacterial pathogens, such as Salmonella and Yersinia, secrete effector proteins that mimic eukaryotic phosphatases to subvert host signaling. These effectors, such as YopH and SptP, may compete with PPEF2 for substrates, disrupting calcium-dependent signaling pathways. The host's innate immune response may also involve PPEF2, as its expression is upregulated in dendritic cells upon pathogen stimulation [6].

5.3 Immune Evasion Mechanisms

In the context of cancer, tumor cells may downregulate PPEF2 expression to evade immune surveillance. Reduced PPEF2 activity leads to hyperphosphorylation of MHC class I molecules, impairing antigen presentation and allowing tumor cells to escape cytotoxic T lymphocytes. This mechanism is speculative but warrants further investigation.

6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

6.1 Therapeutic Potential of PPEF2 Modulation

Given its role in multiple diseases, PPEF2 represents a promising therapeutic target. Two strategies are being explored:

1. Enzyme Activation: For conditions where PPEF2 activity is reduced (e.g., high myopia, retinitis pigmentosa, schizophrenia), small molecules that enhance PPEF2 activity could restore normal signaling.
2. Enzyme Inhibition: For cancers where PPEF2 is overexpressed (e.g., SCLC), selective inhibitors could suppress its oncogenic functions.

6.2 Investigational Small Molecules

Several compounds have been investigated for their ability to modulate PPEF2 activity:

• Okadaic Acid: A marine toxin that inhibits PPP family phosphatases, including PPEF2. It is used as a research tool but is too toxic for therapeutic use.
• Calyculin A: Another potent PPP inhibitor with similar limitations.
• Fostriecin: A natural product with selectivity for PP2A over PP1; its activity against PPEF2 is under investigation.
• Cantharidin: A vesicant compound that inhibits PP1 and PP2A; derivatives are being explored for cancer therapy.

6.3 Calcium-Modulating Agents

Since PPEF2 activity is calcium-dependent, agents that modulate intracellular calcium levels can indirectly affect its function:

• Calcium Channel Blockers: Verapamil and diltiazem reduce calcium influx, potentially decreasing PPEF2 activity.
• Calcium Sensitizers: Levosimendan increases calcium sensitivity of contractile proteins, which may enhance PPEF2 activity in muscle.

6.4 Gene Therapy Approaches

For retinal diseases caused by PPEF2 loss-of-function mutations, gene therapy using adeno-associated virus (AAV) vectors is a viable approach. AAV-mediated delivery of the PPEF2 coding sequence to photoreceptor cells could restore phosphatase activity and prevent retinal degeneration. Preclinical studies in animal models are ongoing.

6.5 Pharmacogenomic Considerations

The PPEF2 genotype may influence drug response in several contexts:

• Antipsychotics: Schizophrenia patients with PPEF2 loss-of-function variants may respond differently to NMDA receptor modulators.
• Chemotherapy: Pancreatic cancer patients with low PPEF2 expression may benefit from combination therapy with phosphatase activators.
• Exercise Interventions: Individuals with endurance-associated PPEF2 alleles may show enhanced responses to aerobic training programs.

7. Bioinformatic Resources & Database Accessions

The following table provides key database accessions for PPEF2:

Gene Ontology (GO) Terms

Related Clinical & Scientific Guides

• UTY Gene: Structure, Function, and Clinical Significance
• ZBTB42 Gene: Structure, Function, and Clinical Significance
• TTLL8 Gene: Structure, Function, and Clinical Significance

References

[1] Jing, S., & Yi, X. (2023). Exome sequencing reveals PPEF2 variant associated with high myopia. Gene. URL: https://www.semanticscholar.org/paper/10964885a637d6b1be39668bf171a48685549888

[2] Donato, L. (2026). Novel intronic variants in unconventional gene cluster could lead to the identification of a new retinitis pigmentosa phenotype. Euromediterranean Biomedical Journal. URL: https://www.semanticscholar.org/paper/6e4a9c96895d7fb479b603c7d4192031e25ace68

[3] Imanbay, A., Amirgaliyeva, A., Ergali, K., Begmanova, M., Abylkassymova, G., Zhaxylykova, A., Kumarbekov, Z., Seisenova, Z., & Zagitov, A. (2026). Genome-wide association study of endurance genes in professional wrestlers. Experimental Biology. URL: https://www.semanticscholar.org/paper/849321bfbd9dd504d97ea38c12a1cc9643ff24ee

[4] Hang, J., Lau, S., Yin, R., Zhu, L., Zhou, S., Yuan, X., & Wu, L. (2020). The role of phosphoprotein phosphatases catalytic subunit genes in pancreatic cancer. Bioscience Reports. URL: https://www.semanticscholar.org/paper/b9696d3941814c92a0ba2eb7922484f4db3c80a7

[5] Timms, A., Dorschner, M., Wechsler, J., Choi, K.-Y., Kirkwood, R., Girirajan, S., Baker, C. A., Eichler, E., Korvatska, O., Roche, K., Horwitz, M., & Tsuang, D. (2013). Support for the N-methyl-D-aspartate receptor hypofunction hypothesis of schizophrenia from exome sequencing in multiplex families. JAMA Psychiatry. URL: https://www.semanticscholar.org/paper/020a05a10173e10e8283e319816997b74bfbaa17

[6] Edelmann, S. L., Nelson, P., & Brocker, T. (2011). Comparative promoter analysis in vivo: identification of a dendritic cell-specific promoter module. Blood. URL: https://www.semanticscholar.org/paper/0e7358939c6cfba2aad4ba7e62ed9920b7a5471c

[7] Breton, C., Siegmund, K., Joubert, B. R., Wang, X., Qui, W., Carey, V., Nystad, W., Håberg, S., Ober, C., Nicolae, D. L., Barnes, K., Martinez, F., Liu, A. H., Lemanske, R., Strunk, R., Weiss, S., London, S. A., Gilliland, F., & Raby, B. (2014). Prenatal tobacco smoke exposure is associated with childhood DNA CpG methylation. PLoS ONE. URL: https://www.semanticscholar.org/paper/aba3fb96c585e83838dfdce6d6580a9971352a8d

[8] Ye, J., Sun, X., Jiang, Q., Gui, J., Feng, S., Qin, B., Xie, L., Guo, A., Dong, J.-T., & Sang, M. (2024). Umbilical cord blood-derived exosomes attenuate dopaminergic neuron damage of Parkinson's disease mouse model. Journal of Nanobiotechnology. URL: https://www.semanticscholar.org/paper/7fa394da3a122e7ea1f6ca29e9b759529c0b3fb0

[9] Ahn, S., Choi, J.-K., Joo, Y., Lee, M.-A., Choi, P.-R., Lee, Y., Kim, M.-S., Kim, S.-Y., Jeon, E.-H., Min, B., & Kim, C.-R. (2004). Identification of differentially expressed genes in human small cell lung carcinoma using subtractive hybridization. Scientific Publication. URL: https://www.semanticscholar.org/paper/1672645f0ee580053774d5c9e222b3f86fde4ffc

[10] Mo, D., Li, J.-J., Peng, L., Liu, Z., Wang, J., & Yuan, J. (2019). Genetic polymorphisms on 4q21.1 contributed to the risk of Hashimoto's thyroiditis. Genetic Testing and Molecular Biomarkers. URL: https://www.semanticscholar.org/paper/b88edb263979da8813c45bc5e00f131163139c82