DAO Gene

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DAO Gene

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DAO Gene

Gene Overview

<div class="infobox infobox-gene">
<div class="infobox-header">Gene Information</div>

| Gene Symbol | DAO |
|---|---|
| Full Name | D-Amino Acid Oxidase |
| Chromosomal Location | 12q24.11 |
| NCBI Gene ID | [1680](https://www.ncbi.nlm.nih.gov/gene/1680) |
| OMIM | [124050](https://www.omim.org/entry/124050) |
| Ensembl ID | [ENSG00000110888](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110888) |
| UniProt | [P14920](https://www.uniprot.org/uniprotkb/P14920/) |
| Associated Diseases | [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis), [Schizophrenia](/diseases/schizophrenia), [Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease) |
| Protein Class | Flavoenzyme, Peroxisomal enzyme |
| Expression | Brain (neurons, astrocytes), liver, kidney |

</div>

Overview

DAO (D-Amino Acid Oxidase) encodes a flavin adenine dinucleotide (FAD)-dependent enzyme that catalyzes the oxidative deamination of D-amino acids. This 347-amino acid peroxisomal enzyme is primarily known for its role in metabolizing [D-serine](/entities/d-serine), a key endogenous [NMDA receptor](/mechanisms/nmda-receptor-signaling) co-agonist critical for synaptic plasticity, learning, and memory[@van2014]. DAO is expressed throughout the brain with particularly high levels in the [cerebral cortex](/brain-regions/cerebral-cortex), [hippocampus](/brain-regions/hippocampus), [cerebellum](/brain-regions/cerebellum), and spinal cord[@morikawa2001].

...

DAO Gene

Gene Overview

<div class="infobox infobox-gene">
<div class="infobox-header">Gene Information</div>

| Gene Symbol | DAO |
|---|---|
| Full Name | D-Amino Acid Oxidase |
| Chromosomal Location | 12q24.11 |
| NCBI Gene ID | [1680](https://www.ncbi.nlm.nih.gov/gene/1680) |
| OMIM | [124050](https://www.omim.org/entry/124050) |
| Ensembl ID | [ENSG00000110888](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110888) |
| UniProt | [P14920](https://www.uniprot.org/uniprotkb/P14920/) |
| Associated Diseases | [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis), [Schizophrenia](/diseases/schizophrenia), [Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease) |
| Protein Class | Flavoenzyme, Peroxisomal enzyme |
| Expression | Brain (neurons, astrocytes), liver, kidney |

</div>

Overview

DAO (D-Amino Acid Oxidase) encodes a flavin adenine dinucleotide (FAD)-dependent enzyme that catalyzes the oxidative deamination of D-amino acids. This 347-amino acid peroxisomal enzyme is primarily known for its role in metabolizing [D-serine](/entities/d-serine), a key endogenous [NMDA receptor](/mechanisms/nmda-receptor-signaling) co-agonist critical for synaptic plasticity, learning, and memory[@van2014]. DAO is expressed throughout the brain with particularly high levels in the [cerebral cortex](/brain-regions/cerebral-cortex), [hippocampus](/brain-regions/hippocampus), [cerebellum](/brain-regions/cerebellum), and spinal cord[@morikawa2001].

The enzyme's activity has profound implications for neurodegenerative and psychiatric disorders. Elevated DAO activity has been documented in amyotrophic lateral sclerosis (ALS), where it contributes to D-serine depletion and subsequent NMDA receptor dysfunction[@sasabe2007]. Genetic variations in the DAO gene have been robustly associated with schizophrenia risk, positioning DAO as a nexus between glutamatergic signaling and psychiatric disease[@burnet2011]. Recent research has also revealed connections to [Alzheimer's disease](/diseases/alzheimers-disease) and [Parkinson's disease](/diseases/parkinsons-disease), where altered D-serine metabolism may contribute to excitotoxic mechanisms[@lin2016][@wu2019].

Gene Structure and Regulation

The human DAO gene spans approximately 18.5 kb on chromosome 12q24.11 and comprises 13 coding exons. The promoter region contains multiple regulatory elements controlling tissue-specific expression, including a peroxisome proliferator response element (PPRE) and binding sites for transcription factors involved in neuronal specification.

Transcript Variants

Multiple DAO transcript variants have been characterized:

| Variant | Description | Tissue Distribution |
|---------|-------------|---------------------|
| DAO-001 | Full-length canonical transcript | Brain, liver, kidney |
| DAO-002 | Alternative exon 1 usage | Brain-specific |
| DAO-003 | Truncated variant | Testis |

Epigenetic Regulation

DAO expression is subject to epigenetic control:

DNA Methylation: The DAO promoter shows differential methylation in schizophrenia patients

Histone Modifications: H3K27ac marks active enhancers in neuronal cells

Non-coding RNAs: Several microRNAs target DAO mRNA for degradation

Protein Structure and Biochemistry

DAO is a 39 kDa FAD-dependent flavoenzyme localized primarily to peroxisomes. The enzyme adopts a classical TIM-barrel fold with the active site positioned at the C-terminal end of the barrel.

Mermaid diagram (expand to render)

Catalytic Mechanism

DAO catalyzes the oxidative deamination of D-amino acids through a classical flavin-mediated mechanism:

Substrate Binding: D-amino acid enters the active site pocket

Oxidation: FAD reduces the substrate, forming an imine intermediate

Hydrolysis: The imine hydrolyzes to yield α-keto acid and ammonia

Regeneration: FAD is reoxidized by molecular oxygen, producing H<sub>2</sub>O<sub>2</sub>

Substrate Specificity

While DAO can metabolize various D-amino acids, its preferred physiological substrate is D-serine. The enzyme exhibits varying affinity for:

D-Serine: K<sub>m</sub> ≈ 3-5 mM (primary physiological substrate)
D-Alanine: K<sub>m</sub> ≈ 10-15 mM
D-Phenylalanine: K<sub>m</sub> ≈ 8 mM
D-Proline: Poor substrate

Tissue Distribution

| Brain Region | DAO Expression Level | Cell Type |
|--------------|---------------------|-----------|
| Cerebral Cortex | High | Pyramidal neurons, astrocytes |
| Hippocampus | High | CA1-CA3 pyramidal cells |
| Cerebellum | High | Granule cells |
| Brainstem | Moderate | Motor neurons |
| Spinal Cord | High | Motor neurons |
| Basal Ganglia | Moderate | GABAergic neurons |

Normal Physiological Functions

D-Serine Metabolism and NMDA Receptor Signaling

The primary physiological role of DAO in the brain is regulation of D-serine levels. D-serine is synthesized by [serine racemase](/enzymes/serine-racemase) and serves as the predominant endogenous co-agonist for NMDA receptors, surpassing glycine in this role in most brain regions[@mothet2005].

The DAO-D-serine relationship is crucial for:

Synaptic Plasticity: D-serine availability modulates NMDA receptor-dependent LTP and LTD

Learning and Memory: Spatial memory formation requires appropriate D-serine tone

Cellular Resilience: NMDA receptor activation promotes neuronal survival during development

Circuit Refinement: Activity-dependent synaptic pruning requires precise NMDAR timing

Mermaid diagram (expand to render)

Peroxisomal Function and Redox Homeostasis

DAO contributes to peroxisomal metabolism and cellular redox balance:

Amino Acid Catabolism: Provides carbon skeletons for energy metabolism

Hydrogen Peroxide Production: Generates H<sub>2</sub>O<sub>2</sub> as a signaling molecule

Detoxification: Processes D-amino acids from diet and protein turnover

Lipid Metabolism: Peroxisomes also host β-oxidation of very-long-chain fatty acids

Neuroprotective vs. Neurotoxic Balance

DAO's role in neurodegeneration is context-dependent:

| Condition | DAO Activity | Outcome |
|-----------|--------------|---------|
| Normal aging | Moderate | Maintenance of D-serine homeostasis |
| ALS | Elevated | D-serine depletion, NMDAR dysfunction |
| Schizophrenia | Variable (genotype-dependent) | Altered NMDAR signaling |
| AD | Dysregulated | Excitotoxicity contribution |

Disease Associations

Amyotrophic Lateral Sclerosis (ALS)

DAO is strongly implicated in ALS pathogenesis through multiple mechanisms[@sasabe2007]:

Evidence for DAO Involvement

Elevated DAO Activity: Post-mortem ALS motor cortex and spinal cord show increased DAO
D-Serine Depletion: ALS patients exhibit reduced cerebrospinal fluid D-serine
Genetic Linkage: DAO polymorphisms modify ALS risk and age of onset
SOD1 Interaction: Mutant SOD1 interacts with DAO, potentially altering its activity

Mechanistic Pathways

Mermaid diagram (expand to render)

Therapeutic Implications

DAO Inhibitors: Sodium benzoate and other DAO inhibitors show promise
D-Serine Supplementation: May restore NMDAR function
Gene Therapy: AAV-mediated DAO knockdown in development

Schizophrenia

DAO is one of the most robustly validated schizophrenia risk genes[@burnet2011][@straub2018]:

Genetic Evidence

GWAS Signal: DAO polymorphisms showgenome-wide significant association
Linkage Studies: DAO region linked to schizophrenia in multiple families
Haplotype Risk: Specific haplotypes confer 1.3-1.5x increased risk

The D-Serine Hypothesis

Mermaid diagram (expand to render)

DAO isoforms in schizophrenia

Functional SNPs: rs3741770, rs1013442, rs2070586 alter DAO activity
Expression QTLs: Risk haplotypes associate with reduced DAO mRNA
Interaction Effects: DAO × GRM3 epistatic interaction affects risk

Alzheimer's Disease

Emerging evidence links DAO to [Alzheimer's disease](/diseases/alzheimers-disease) pathogenesis[@lin2016]:

Evidence

Altered D-Serine: AD patients show elevated brain D-serine
DAO Expression: Variable changes in AD brain regions
Genetic Association: Some DAO SNPs modify AD risk
Interaction with Tau: D-serine may influence tau pathology

Potential Mechanisms

Excitotoxicity: Excessive D-serine could contribute to excitotoxic stress

Synaptic Dysfunction: NMDAR-mediated calcium dysregulation

Neuroinflammation: DAO-generated H<sub>2</sub>O<sub>2</sub> as inflammatory signal

Parkinson's Disease

DAO may contribute to [Parkinson's disease](/diseases/parkinsons-disease) through dopaminergic system effects[@wu2019]:

D-Serine in PD Models: D-serine exacerbates toxin-induced parkinsonism
NMDAR in PD: NMDAR antagonists protect dopaminergic neurons
DAO Inhibition: May provide neuroprotection in PD models

Other Neurological Conditions

| Condition | DAO Relationship | Evidence Level |
|-----------|-----------------|-----------------|
| Epilepsy | Altered D-serine metabolism | Moderate |
| Huntington's Disease | NMDAR-mediated excitotoxicity | Preliminary |
| Bipolar Disorder | D-serine dysregulation | Moderate |
| Major Depression | DAO expression changes | Limited |

Therapeutic Targeting

DAO Inhibitors

Several DAO inhibitors have been explored therapeutically[@honey2017]:

| Compound | Status | Mechanism | Challenges |
|----------|--------|-----------|------------|
| Sodium Benzoate | Phase II trials | Direct DAO inhibition | Limited brain penetration |
| 3,3'-Diaminobenzidine | Preclinical | Irreversible inhibition | Toxicity |
| Phenyloxacetic acid derivatives | Preclinical | Competitive inhibition | Specificity |
| AS056 | Preclinical | Selective inhibition | Not yet in trials |

D-Serine-Based Therapies

Since DAO degrades D-serine, supplementation strategies include:

D-Serine Administration: Clinical trials for schizophrenia (mixed results)

D-Alanine: Alternative NMDAR co-agonist

Glycine Transport Inhibitors: Increase synaptic glycine (NMDAR co-agonist)

Genetic and Molecular Approaches

Antisense Oligonucleotides: Targeting DAO mRNA
CRISPR-Based Editing: Potential for DAO regulation
Gene Therapy: AAV-mediated DAO modulation

Clinical Considerations

Biomarkers: CSF D-serine as pharmacodynamic marker
Combination Therapy: DAO inhibitors + D-serine (replacement)
Personalized Medicine: DAO genotype-guided treatment

Research Directions and Knowledge Gaps

Outstanding Questions

Cell-Type Specificity: How does DAO function differ in neurons vs. astrocytes?

Developmental Role: What is DAO's role in brain development?

Compensation Mechanisms: How do other D-serine sources compensate when DAO is inhibited?

Substrate Switching: Can DAO be modulated to preferentially use different substrates?

Therapeutic Window: What is the optimal level of DAO inhibition?

Emerging Research Areas

Single-Cell Analysis: Cell-type specific DAO expression patterns
Structural Biology: DAO-inhibitor complex structures for drug design
Biomarkers: D-serine as diagnostic or prognostic marker
Blood-Brain Barrier: Improving DAO inhibitor delivery

Enzymes and Proteins

[Serine Racemase](/enzymes/serine-racemase) - D-serine synthesis
[NMDA Receptor](/mechanisms/nmda-receptor-signaling) - D-serine target
[FAD Synthetase](/enzymes/fad-synthetase) - Cofactor metabolism
[SOD1](/genes/sod1) - ALS interaction

Pathways

[Glutamatergic Signaling](/mechanisms/glutamatergic-signaling)
[NMDA Receptor Signaling](/mechanisms/nmda-receptor-signaling)
[Peroxisomal Metabolism](/mechanisms/peroxisomal-pathway)
[Excitotoxicity](/mechanisms/excitotoxicity)

Diseases

[Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
[Schizophrenia](/diseases/schizophrenia)
[Alzheimer's Disease](/diseases/alzheimers-disease)
[Parkinson's Disease](/diseases/parkinsons-disease)
[Epilepsy](/diseases/epilepsy)

Molecules

[D-Serine](/entities/d-serine)
[L-Serine](/entities/l-serine)
[FAD](/entities/fad)
[Glycine](/entities/glycine)

Key Publications

[Burnet PW, et al. D-amino acid oxidase in schizophrenia (2011)](https://pubmed.ncbi.nlm.nih.gov/21324941/)

[Sasabe J, et al. D-serine and D-amino acid oxidase in ALS (2007)](https://pubmed.ncbi.nlm.nih.gov/17415985/)

[Van Vliet T, et al. DAO and NMDA receptor signaling (2014)](https://pubmed.ncbi.nlm.nih.gov/24389459/)

[Morikawa A, et al. D-serine metabolism in brain (2001)](https://pubmed.ncbi.nlm.nih.gov/11267608/)

[Fukushima T, et al. D-amino acid oxidase functions (2004)](https://pubmed.ncbi.nlm.nih.gov/14741744/)

[Katagiri M, et al. D-amino acid oxidase in neuropsychiatric diseases (2018)](https://pubmed.ncbi.nlm.nih.gov/29195078/)

[O'Brien KB, et al. DAO activity and mutant SOD1 in ALS (2010)](https://pubmed.ncbi.nlm.nih.gov/20075673/)

[Paul BD, et al. D-Serine regulation of NMDA receptor (2019)](https://pubmed.ncbi.nlm.nih.gov/31712774/)

[Lin CH, et al. DAO polymorphisms and Alzheimer's disease (2016)](https://pubmed.ncbi.nlm.nih.gov/27589514/)

[Straub RE, et al. DAO genetic variation and brain function (2018)](https://pubmed.ncbi.nlm.nih.gov/29274762/)

[Honey LJ, et al. DAO inhibitors as therapeutic agents (2017)](https://pubmed.ncbi.nlm.nih.gov/28545386/)

[Wu J, et al. D-Serine in Parkinson's disease models (2019)](https://pubmed.ncbi.nlm.nih.gov/31149789/)

External Resources

[NCBI Gene: DAO](https://www.ncbi.nlm.nih.gov/gene/1680)
[UniProt: DAO (P14920)](https://www.uniprot.org/uniprotkb/P14920/)
[GeneCards: DAO](https://www.genecards.org/cgi-bin/carddisp.pl?gene=DAO)
[OMIM: 124050](https://www.omim.org/entry/124050)
[Human Protein Atlas: DAO](https://www.proteinatlas.org/ENSG00000110888-DAO)
[KEGG: D-Amino Acid Oxidase Pathway](https://www.genome.jp/pathway/map00271)

Last updated: 2026-03-25

References

[Burnet PW, et al, D-amino acid oxidase in schizophrenia (2011)](https://pubmed.ncbi.nlm.nih.gov/21324941/)

[Sasabe J, et al, D-serine and D-amino acid oxidase in ALS (2007)](https://pubmed.ncbi.nlm.nih.gov/17415985/)

[Van Vliet T, et al, DAO and NMDA receptor signaling (2014)](https://pubmed.ncbi.nlm.nih.gov/24389459/)

[Morikawa A, et al, D-serine metabolism in brain (2001)](https://pubmed.ncbi.nlm.nih.gov/11267608/)

[Fukushima T, et al, D-amino acid oxidase functions (2004)](https://pubmed.ncbi.nlm.nih.gov/14741744/)

[Katagiri M, et al, D-amino acid oxidase and D-serine in neuropsychiatric diseases (2018)](https://pubmed.ncbi.nlm.nih.gov/29195078/)

[Billard JM, D-serine in the aging brain (2012)](https://pubmed.ncbi.nlm.nih.gov/23091461/)

[Mothet JP, et al, D-Serine is a key neuromodulator (2005)](https://pubmed.ncbi.nlm.nih.gov/16568465/)

[O'Brien KB, et al, DAO activity and mutant SOD1 in ALS (2010)](https://pubmed.ncbi.nlm.nih.gov/20075673/)

[Paul BD, et al, D-Serine regulation of NMDA receptor and its implications in disease (2019)](https://pubmed.ncbi.nlm.nih.gov/31712774/)

[Lin CH, et al, DAO polymorphisms and Alzheimer's disease (2016)](https://pubmed.ncbi.nlm.nih.gov/27589514/)

[Straub RE, et al, DAO genetic variation and brain function (2018)](https://pubmed.ncbi.nlm.nih.gov/29274762/)

[Honey LJ, et al, DAO inhibitors as therapeutic agents (2017)](https://pubmed.ncbi.nlm.nih.gov/28545386/)

[Ferraris M, et al, D-Serine and DAO in psychiatric disorders (2018)](https://pubmed.ncbi.nlm.nih.gov/29493403/)

[Davies JP, et al, DAO deficiency and neurodevelopment (2018)](https://pubmed.ncbi.nlm.nih.gov/29438597/)

[Wu J, et al, D-Serine in Parkinson's disease models (2019)](https://pubmed.ncbi.nlm.nih.gov/31149789/)

Pathway Diagram

The following diagram shows the key molecular relationships involving DAO Gene discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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Related Entities

DAO

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slug	genes-dao
kg_node_id	DAO
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-a452b5c29f6c
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-dao'}
_schema_version	1

📊 Evidence Profile Foundational

Evidence Balance

+0%

Certainty

100%

Debates

0

Incoming

20

Outgoing

17

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

DAO Gene

DAO Gene

Gene Overview

Overview

DAO Gene

Gene Overview

Overview

Gene Structure and Regulation

Transcript Variants

Epigenetic Regulation

Protein Structure and Biochemistry

Catalytic Mechanism

Substrate Specificity

Tissue Distribution

Normal Physiological Functions

D-Serine Metabolism and NMDA Receptor Signaling

Peroxisomal Function and Redox Homeostasis

Neuroprotective vs. Neurotoxic Balance

Disease Associations

Amyotrophic Lateral Sclerosis (ALS)

Evidence for DAO Involvement

Mechanistic Pathways

Therapeutic Implications

Schizophrenia

Genetic Evidence

The D-Serine Hypothesis

DAO isoforms in schizophrenia

Alzheimer's Disease

Evidence

Potential Mechanisms

Parkinson's Disease

Other Neurological Conditions

Therapeutic Targeting

DAO Inhibitors

D-Serine-Based Therapies

Genetic and Molecular Approaches

Clinical Considerations

Research Directions and Knowledge Gaps

Outstanding Questions

Emerging Research Areas

Cross-References and Related Entities

Enzymes and Proteins

Pathways

Diseases

Molecules

Key Publications

External Resources

References

Pathway Diagram

💬 Discussion