SNCA — Alpha-Synuclein Gene Entity Page

SNCA — Alpha-Synuclein Gene Entity Page

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">SNCA — Alpha-Synuclein</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>SNCA</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Synuclein Alpha</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>4q22.1</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/6622" target="_blank">6622</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000145335" target="_blank">ENSG00000145335</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/163890" target="_blank">163890</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P37840" target="_blank">P37840</a></td>
</tr>
<tr>
<td class="label">Diseases</td>
<td><a href="/diseases/parkinsons-disease">Parkinson's Disease</a>, <a href="/diseases/dementia-with-lewy-bodies">Dementia with Lewy Bodies</a>, <a href="/diseases/multiple-system-atrophy">Multiple System Atrophy</a></td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Substantia nigra, Cerebral cortex, Presynaptic terminals</td>
</tr>
<tr>
<th class="infobox-subheader" colspan="2">Key Mutations</th>
</tr>
<tr>
<td colspan="2" style="font-size:0.85em">A53T, A30P, E46K, H50Q, G51D</td>
</tr>
</table>

SNCA — Alpha-Synuclein Gene Entity Page

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">SNCA — Alpha-Synuclein</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>SNCA</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Synuclein Alpha</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>4q22.1</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/6622" target="_blank">6622</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000145335" target="_blank">ENSG00000145335</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/163890" target="_blank">163890</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P37840" target="_blank">P37840</a></td>
</tr>
<tr>
<td class="label">Diseases</td>
<td><a href="/diseases/parkinsons-disease">Parkinson's Disease</a>, <a href="/diseases/dementia-with-lewy-bodies">Dementia with Lewy Bodies</a>, <a href="/diseases/multiple-system-atrophy">Multiple System Atrophy</a></td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Substantia nigra, Cerebral cortex, Presynaptic terminals</td>
</tr>
<tr>
<th class="infobox-subheader" colspan="2">Key Mutations</th>
</tr>
<tr>
<td colspan="2" style="font-size:0.85em">A53T, A30P, E46K, H50Q, G51D</td>
</tr>
</table>

SNCA — Alpha-Synuclein Gene Entity

Overview

SNCA (Synuclein Alpha) is a gene located on chromosome 4q22.1 that encodes the alpha-synuclein (α-Syn) protein — the central pathological player in Parkinson's disease and related synucleinopathies. Discovered in 1997 when the A53T mutation was identified in the Contursi kindred[@mutation1997], SNCA is now recognized as the gene whose protein product forms the hallmark [Lewy bodies](/mechanisms/lewy-body-formation) found in [Parkinson's disease](/diseases/parkinsons-disease), [Dementia with Lewy Bodies](/diseases/dementia-with-lewy-bodies), and [Multiple System Atrophy](/diseases/multiple-system-atrophy)[@alphasynuclein1997].

SNCA is one of the most extensively studied genes in neurodegeneration research. Its discovery transformed our understanding of Parkinson's disease pathogenesis, establishing α-synuclein aggregation as the unifying mechanism across both familial and sporadic forms of the disease. The gene encodes a 140-amino acid protein that is predominantly expressed in presynaptic terminals of [neurons](/entities/neurons) throughout the brain, particularly in dopaminergic neurons of the [substantia nigra pars compacta](/cell-types/dopaminergic-neurons)[@physiological2019].

Gene Structure and Genomic Organization

Chromosomal Location

The SNCA gene spans approximately 417 kb on chromosome 4 at position 4q22.1. It consists of 6 exons, with the coding sequence distributed across exons 3-6. The gene structure is compact relative to its regulatory complexity, with extensive upstream and intronic regulatory elements influencing expression.

Transcript Variants

Multiple SNCA transcript variants have been identified:

• SNCA-140 (full-length isoform): 140 amino acids, the predominant transcript in adult brain
• SNCA-126: Lacks exon 5 (NAC domain), less aggregation-prone
• SNCA-112: Lacks exon 3, has neuroprotective properties relative to full-length

Regulatory Elements

The SNCA promoter contains binding sites for numerous transcription factors:

• Nurr1 (NR4A2): Critical for dopaminergic neuron expression
• AP-1: Jun/Fos binding site responsive to oxidative stress
• CREB: Activity-dependent transcriptional regulation
• Sp1: Basal transcription factor
• Nrf2: Responds to oxidative stress and may upregulate SNCA

Protein Structure and Conformational States

Alpha-Synuclein Protein Architecture

The α-synuclein protein consists of three distinct structural regions[@membrane2020]:

N-terminal Region (residues 1-60): Adopts an amphipathic alpha-helical conformation upon binding to lipid membranes. Contains 7 imperfect KTKEGV repeat motifs that mediate lipid interaction and membrane curvature sensing. This region is highly conserved across species and contains all known pathogenic mutations (A30P, E46K, A53T, G51D, H50Q).

NAC Domain (residues 61-95): The Non-Amyloid Component (NAC) is hydrophobic and central to aggregation propensity. Residues 71-82 form the core of the beta-sheet structure in amyloid fibrils. This domain is absent in some splice variants, and its length correlates with aggregation tendency.

C-terminal Region (residues 96-140): Highly acidic and unstructured in solution. The C-terminus mediates protein-protein interactions, chaperone activity, and regulatory post-translational modifications including phosphorylation at Ser129 — the major pathological modification found in >90% of Lewy body pathology[@phosphorylation2021].

Conformational States

α-Synuclein exists in multiple conformational states[@membrane2020]:

Cryo-EM studies have revealed distinct fibril conformations in different synucleinopathies, with [MSA fibrils showing different structures from PD/DLB](/diseases/multiple-system-atrophy) fibrils, supporting the "strain" hypothesis[@alphasynuclein2019a].

Normal Biological Function

Synaptic Vesicle Trafficking

α-Synuclein is predominantly expressed in presynaptic terminals, comprising up to 1% of total cytosolic protein[@physiological2019]. Under normal physiological conditions:

• Synaptic vesicle pool maintenance: Regulates the size and dynamics of the readily releasable pool (RRP)
• Dopamine synthesis and release: In [dopaminergic neurons](/cell-types/dopaminergic-neurons), modulates tyrosine hydroxylase activity
• Molecular chaperone activity: C-terminal region prevents aggregation under cellular stress
• Lipid binding: N-terminal domain binds synaptic vesicles enriched in polyunsaturated fatty acids[@membrane2020]

Expression Pattern

High expression in:

• Substantia nigra pars compacta (dopaminergic neurons)
• Cerebral cortex (pyramidal neurons)
• [Hippocampus](/brain-regions/hippocampus)
• Amygdala
• Locus coeruleus (noradrenergic neurons)
• Presynaptic terminals throughout the CNS

Pathogenic Mechanisms

Alpha-Synuclein Aggregation Cascade

The central pathogenic event in synucleinopathies is the misfolding and aggregation of α-Syn[@alphasynuclein2019]:

Post-translational modifications influencing aggregation include phosphorylation at Ser129, ubiquitination, truncation, and oxidation[@phosphorylation2021].

Prion-Like Propagation

A critical breakthrough in understanding PD progression is the discovery that α-Syn propagates between neurons in a prion-like manner[@prionlike2014]:

Toxicity Mechanisms

α-Syn aggregates cause neuronal death through[@mitochondrial2014][@neuroinflammation2017]:

• Mitochondrial dysfunction: α-Syn localizes to mitochondria, impairing complex I activity
• ER stress and [unfolded protein response](/entities/unfolded-protein-response): Triggers maladaptive UPR
• Lysosomal dysfunction: Impairs [autophagy](/entities/autophagy)-lysosomal pathway
• Neuroinflammation: Activated [microglia](/cell-types/microglia) release pro-inflammatory cytokines
• Synaptic dysfunction: Disrupts neurotransmitter release and vesicle cycling

Disease Associations

Parkinson's Disease (PD)

SNCA was the first gene linked to familial PD (Contursi kindred, A53T mutation, 1997)[@mutation1997]:

• Familial PD: Point mutations (A53T, A30P, E46K, H50Q, G51D) cause autosomal dominant PD
• Sporadic PD: SNCA polymorphisms are the strongest genetic risk factor for idiopathic PD

Dementia with Lewy Bodies (DLB)

Characterized by diffuse [Lewy body](/mechanisms/lewy-body-formation) pathology with cortical and limbic involvement. SNCA mutations/duplications contribute to DLB pathogenesis.

Multiple System Atrophy (MSA)

Features predominantly oligodendroglial inclusions (GCIs) containing α-Syn fibrils with distinct strain properties from PD/DLB, suggesting different fibril conformations determine cell-type vulnerability[@alphasynuclein2019a].

Key Mutations and Variants

Disease-Causing Mutations

| Mutation | Location | Effect |
|----------|----------|--------|
| A53T | Residue 53 | Enhanced aggregation, earlier onset (~46 years) |
| A30P | Residue 30 | Reduced membrane binding, enhanced oligomerization |
| E46K | Residue 46 | Increased aggregation, Lewy body formation |
| H50Q | Residue 50 | Moderate aggregation risk, later onset |
| G51D | Residue 51 | Reduced neuronal viability, earlier onset |

Copy Number Variations

Gene duplications and triplications cause autosomal dominant PD with dose-dependent severity[@snca2013]. Even wild-type α-Syn overexpression is sufficient to cause neurodegeneration — aggregation is dose-dependent.

REP1 Promoter Risk Variants

The NACP-REP1 microsatellite polymorphism (upstream of transcription start site) affects transcriptional activity. The 263bp allele increases PD risk ~1.5-2x, while the 261bp allele shows protective effects.

Alpha-Synuclein Interactome

Protein-Protein Interactions[@proteinprotein2024]

Synaptic Proteins: Synapsin I, synaptophysin, VAMP2 (regulates SNCA phase separation), CSPalpha.

Chaperones: Hsp70, Hsp90, Hsp40/DNAJB6, CHIP/STUB1 (E3 ubiquitin ligase for degradation).

Trafficking Proteins: Rab proteins (Rab3, Rab5, Rab8), NSF, complexin.

Membrane Receptors: PrPC (receptor for extracellular α-Syn), transferrin receptor (mediates uptake), LRP1.

Kinases and Phosphatases: LRRK2 (phosphorylates Ser129), GSK3-beta, casein kinases.

Key Interactors in Neurodegeneration

| Interactor | Role | Effect on Pathology |
|-----------|------|---------------------|
| [LRRK2](/entities/lrrk2) | Kinase | Phosphorylates alpha-syn at Ser129, accelerating aggregation |
| [GBA1](/genes/gba1) | Lysosomal enzyme | Deficiency increases glucosylceramide, promotes aggregation |
| [Parkin](/genes/park2) | E3 ligase | Ubiquitinates alpha-syn for degradation |
| TMEM106B | Lysosomal protein | Deficiency exacerbates aggregation (2026)[@tmemb2026] |
| VAMP2 | SNARE protein | Regulates phase separation of alpha-syn[@proteinprotein2024] |
| Fibrinogen | Coagulation factor | Exacerbates aggregation via alpha5beta3 integrin (2026)[@fibrinogen2026] |

Therapeutic Targets

SNCA is a major therapeutic target for disease modification in synucleinopathies[@alphasynucleintargeting2021]:

Gene Silencing

• ASO therapy targeting SNCA mRNA
• miRNA-based approaches (miR-7, miR-153 targeting 3'UTR)
• [CRISPRi approaches](/ideas/payload-crispri-snca-silencing)

Immunotherapy[@immunotherapy2021]

• Active immunization (PD01A, PD03A)
• Passive immunization (cinamerene/BIIB054, UB-312, REGN-PGN9)

Aggregation Inhibitors[@aggregation2021]

• Small molecules preventing/reversing aggregation
• Examples: dopamine analogs, curcumin analogs, NPT100-18A

Propagation Blockers

• Receptor blockers (PrPC antagonists)
• Endocytosis inhibitors

Chaperone-Based Therapies

• Hsp70/Hsp90 modulators to enhance protein clearance

Biomarkers

SNCA-related biomarkers are critical for diagnosis and clinical trials[@biological2024][@neuronally2024]:

• [Total Alpha-Synuclein](/biomarkers/total-alpha-synuclein): CSF and blood markers; typically decreased in PD
• [Phosphorylated Alpha-Synuclein (pSer129](/biomarkers/phosphorylated-alpha-synuclein-pser129): Elevated in PD/DLB
• [Alpha-Synuclein Oligomers](/biomarkers/alpha-synuclein-oligomers): Toxic intermediate species
• [Alpha-Synuclein Seeding Assays](/biomarkers/alpha-synuclein-seeding-assay): RT-QuIC and PMCA for prion-like activity
• Neuronally-derived EV α-Syn: Serum biomarker for at-risk individuals[@neuronally2024]

Clinical Trials

Multiple clinical trials are targeting α-synuclein[@alphasynucleintargeting2021][@immunotherapy2021]:

| Agent | Company | Mechanism | Phase |
|-------|---------|-----------|-------|
| Cinamerene (BIIB054) | Biogen | Passive antibody | Phase 2 |
| UB-312 | UCB | Oligomer-targeting antibody | Phase 1 |
| REGN-PGN9 | Regeneron | Monoclonal antibody | Phase 1 |
| PR001A/PDA03A | AFFiRiS | Active immunotherapy | Phase 1 |
| Anle138b | MODAG | Aggregation inhibitor | Phase 1/2 |
| DNL310 | Denali | ASO therapy | Phase 1/2 |

Mechanistic Pathway: Alpha-Synuclein in Synucleinopathies

Recent Research (2025-2026)

• 2026: α-Syn strain dynamics correlate with cognitive shifts in PD, providing insights into disease heterogeneity[@alphasynuclein2026]
• 2026: TMEM106B deficiency exacerbates α-Syn aggregation via novel lysosomal regulatory mechanism[@tmemb2026]
• 2026: Fibrinogen promotes α-Syn aggregation through α5β3 integrin interaction, revealing vascular contributions to PD[@fibrinogen2026]
• 2025: Glymphatic system clearance of α-Syn highlights therapeutic strategies targeting protein clearance pathways
• 2025: Glucosylceramide-induced ectosomes propagate pathogenic α-Syn, revealing lipid-mediated propagation[@glucosylceramide2025]
• 2024: VAMP2 regulates phase separation of α-Syn[@proteinprotein2024]
• 2024: Neuronally-derived extracellular vesicle α-Syn serves as a serum biomarker for at-risk individuals[@neuronally2024]

See Also

• [SNCA Gene Page](/genes/snca) — Comprehensive gene-level page
• [Alpha-Synuclein Protein](/proteins/alpha-synuclein) — Protein-level page
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Dementia with Lewy Bodies](/diseases/dementia-with-lewy-bodies)
• [Multiple System Atrophy](/diseases/multiple-system-atrophy)
• [LRRK2 Gene](/entities/lrrk2) — Key interacting gene
• [GBA1 Gene](/genes/gba1) — Lysosomal interactor
• [Parkin Gene](/genes/park2) — E3 ligase for α-Syn degradation
• [Alpha-Synuclein Prion-Like Spreading](/mechanisms/alpha-synuclein-prion-like-spreading)
• [Lewy Body Formation](/mechanisms/lewy-body-formation)

External Links

• NCBI Gene: [6622](https://www.ncbi.nlm.nih.gov/gene/6622)
• Ensembl: [ENSG00000145335](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000145335)
• OMIM: [163890](https://omim.org/entry/163890)
• UniProt: [P37840](https://www.uniprot.org/uniprot/P37840)
• Allen Human Brain Atlas: [SNCA expression](https://human.brain-map.org/microarray/search/show?search_term=SNCA)
• Michael J. Fox Foundation: [Research funding](https://www.michaeljfox.org/)