DRPLA Gene
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">DRPLA Gene</th>
</tr>
<tr> [@nagafuchi1994]
<td class="label">Full Name</td>
<td>Dentatorubral-Pallidoluysian Atrophy</td>
</tr>
<tr>
<td class="label">Symbol</td>
<td>DRPLA</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P55072" target="_blank">P55072</a></td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/1785" target="_blank">1785</a></td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>12p13.31</td>
</tr>
<tr>
<td class="label">Exons</td>
<td>10</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Atrophin-1 (ATN1)</td>
</tr>
<tr>
<td class="label">Protein Size</td>
<td>1,190 amino acids</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Ubiquitous, highest in brain (cerebellum, basal ganglia)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>[Dentatorubral-Pallidoluysian Atrophy](/diseases/dentatorubral-pallidoluysian-atrophy), [Huntington's Disease](/diseases/huntingtons-disease)</td>
</tr>
</table>
DRPLA Gene
Introduction
The DRPLA gene (Dentatorubral-Pallidoluysian Atrophy) encodes the protein atrophin-1 (ATN1), a transcriptional co-repressor involved in neuronal development and function. Expansion of a CAG trinucleotide repeat within the DRPLA gene causes the neurodegenerative disorder DRPLA, characterized by cerebellar ataxia, choreoathetosis, and progressive dementia.
Overview
Mermaid diagram (expand to render)
The [DRPLA](/diseases/dentatorubral-pallidoluysian-atrophy) gene is located on chromosome 12p13.31 and contains 10 exons spanning approximately 11 kb of genomic DNA [1]. The gene encodes atrophin-1, a 1,190 amino acid protein that is ubiquitously expressed but shows highest levels in the cerebellum and basal ganglia—brain regions most affected in DRPLA patients.
DRPLA is classified as a polyglutamine (polyQ) disease, joining Huntington's disease (HD), several spinocerebellar ataxias (SCAs), and spinal bulbar muscular atrophy (SBMA) in this group of inherited neurodegenerative disorders.
Gene Structure
Genomic Organization
- Chromosomal location: 12p13.31
- Genomic span: ~11 kb
- Exons: 10
- Transcript length: ~4.5 kb mRNA
- Coding sequence: 3,570 bp
Mutation Spectrum
The pathogenic mutation in DRPLA is an expansion of a CAG trinucleotide repeat in exon 5:
- Normal range: 6-35 CAG repeats
- Intermediate (premutation): 36-48 repeats (may expand in offspring)
- Pathogenic: 49-88 repeats (adult onset), >88 repeats (juvenile onset)
The CAG repeat is unstable during meiosis, particularly in paternal transmission, showing anticipation (earlier onset in successive generations).
Protein: Atrophin-1 (ATN1)
Structure
Atrophin-1 is a nuclear protein with several functional domains:
- PolyQ tract: Length varies with repeat expansion
- Polyproline tract: Mediates protein-protein interactions
- N-terminal domain: Transcription repression activity
- C-terminal domain: Nuclear localization and localization signals
Normal Function
Atrophin-1 functions as a transcriptional co-repressor:
- Interacts with histone deacetylases (HDACs)
- Represses transcription through histone hypoacetylation
- Modulates nuclear receptor signaling
- Participates in Notch and Wnt pathways
Normal Physiological Roles
In the healthy brain, atrophin-1 is involved in:
- Cerebellar development and Purkinje cell function
- Striatal medium spiny neuron survival
- Synaptic plasticity
- Neuronal migration during development
Pathogenesis
Gain-of-Function Mechanism
Like other polyQ diseases, DRPLA is caused by a toxic gain-of-function in the mutant protein:
- Expanded polyQ tract forms abnormal protein conformations
- Leads to aggregation and formation of nuclear inclusions
- Disrupts normal transcriptional regulation
- Impairs mitochondrial function
- Causes progressive neuronal dysfunction and death
Transcriptional Dysregulation
Atrophin-1 with expanded polyQ alters transcription of:
- Neurotrophic factors (BDNF, NGF)
- Dopamine signaling components
- Mitochondrial function genes
- Cell cycle regulators
Nuclear Inclusions
DRPLA [neurons](/entities/neurons) contain:
- Ubiquitin-positive nuclear aggregates
- Co-localization with transcription factors
- Presence of insoluble, aggregation-prone protein
- Correlation with disease severity
Clinical Features
DRPLA Disease
| Feature | Description |
|---------|-------------|
| Age of onset | 20-50 years (adult), <20 years (juvenile) |
| Core symptoms | Ataxia, choreoathetosis, myoclonus, dementia |
| Additional features | Seizures (especially juvenile onset), psychiatric symptoms |
| Progression | Progressive over 10-30 years |
| Neuropathology | Cerebellar atrophy, pallidal degeneration, neuronal loss |
Juvenile-onset DRPLA
- Earlier onset correlates with longer CAG repeats
- More severe phenotype
- Prominent myoclonus and seizures
- Rapid progression
Animal Models
Transgenic Mouse Models
- DRPLA transgenic mice: Express mutant DRPLA with expanded CAG repeats
- Conditional models: Enable temporal control of expression
- Knock-in models: Human DRPLA with pathological repeat
Phenotypic Findings
- Motor coordination deficits
- Cognitive impairment
- Nuclear inclusions in neurons
- Transcriptional changes
- [Neurodegeneration](/diseases/neurodegeneration)
Therapeutic Approaches
Gene Therapy
- RNAi targeting mutant DRPLA
- Antisense oligonucleotides (ASOs)
- CRISPR-based approaches
Small Molecule Therapies
- [HDAC](/entities/hdac-enzymes) inhibitors (reduce transcriptional dysregulation)
- Aggregation inhibitors
- Neurotrophic factor enhancers
Symptomatic Treatments
- Antichoreatic medications (tetrabenazine, deutetrabenazine)
- Antiepileptic drugs for seizures
- Physical and occupational therapy
Genetics
Inheritance
- Pattern: Autosomal dominant
- Anticipation: Earlier onset in successive generations (especially paternal)
- Penetrance: Complete when CAG > 48
Genetic Testing
- Direct CAG repeat counting
- Predictive testing available
- Prenatal diagnosis possible
Research Directions
Current research focuses on:
- Understanding polyQ toxicity mechanisms
- Identifying genetic modifiers
- Developing biomarkers
- Clinical trials for ASO therapies
Background
The study of Drpla Gene has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
External Links
- [PubMed](https://pubmed.ncbi.nlm.nih.gov/) - Biomedical literature
- [Alzheimer's Disease Neuroimaging Initiative](https://adni.loni.usc.edu/) - Research data
- [Allen Brain Atlas](https://brain-map.org/) - Brain gene expression data
See Also
- [Dentatorubral-Pallidoluysian Atrophy (DRPLA) Disease](/diseases/drpla)
- [Atrophin-1 Protein](/entities/atrophin-1)
- [Huntington's Disease Gene (HTT)](/diseases/huntingtons-disease)
- [Polyglutamine Diseases](/content/diseases)
- [Spinocerebellar Ataxias](/diseases/cerebellar-ataxia)
- Trinucleotide Repeat Disorders
References
[Nucifora et al., Brain Res Bull (2017) (2017)](PMID: 28215576(https://pubmed.ncbi.nlm.nih.gov/28215576/))
[Yamada et al., Brain (2001) (2001)](PMID: 11222429(https://pubmed.ncbi.nlm.nih.gov/11222429/))
[Sakai et al., Brain (2006) (2006)](PMID: 16399806(https://pubmed.ncbi.nlm.nih.gov/16399806/))
[Koide et al., Nat Genet (1994) (1994)](PMID: 7926340(https://pubmed.ncbi.nlm.nih.gov/7926340/))
[Nagafuchi et al., Nat Genet (1994) (1994)](PMID: 7951317(https://pubmed.ncbi.nlm.nih.gov/7951317/))Pathway Diagram
The following diagram shows the key molecular relationships involving DRPLA Gene discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)