USH1C Gene

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USH1C Gene

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USH1C Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">USH1C — Harmonin</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>USH1C</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Usher Syndrome 1C Protein (Harmonin)</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>11p15.4</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/10083" target="_blank">10083</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/605242" target="_blank">605242</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000106638" target="_blank">ENSG00000106638</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9Y286" target="_blank">Q9Y286</a></td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>899 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~72 kDa</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Usher Syndrome Type 1C](/diseases/usher-syndrome)</td>
</tr>
<tr>
<td class="label">Inheritance</td>
<td>Autosomal recessive</td>
</tr>
<tr>
<th class="infobox-subheader" colspan="2">Key Functions</th>
</tr>
<tr>
<td colspan="2" style="font-size:0.85em">Stereocilia organization, Mechanotransduction, Photoreceptor function</td>
</tr>
<tr>
<td class="label">Associated Di

...

USH1C Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">USH1C — Harmonin</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>USH1C</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Usher Syndrome 1C Protein (Harmonin)</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>11p15.4</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/10083" target="_blank">10083</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/605242" target="_blank">605242</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000106638" target="_blank">ENSG00000106638</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9Y286" target="_blank">Q9Y286</a></td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>899 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~72 kDa</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Usher Syndrome Type 1C](/diseases/usher-syndrome)</td>
</tr>
<tr>
<td class="label">Inheritance</td>
<td>Autosomal recessive</td>
</tr>
<tr>
<th class="infobox-subheader" colspan="2">Key Functions</th>
</tr>
<tr>
<td colspan="2" style="font-size:0.85em">Stereocilia organization, Mechanotransduction, Photoreceptor function</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/diabetes" style="color:#ef9a9a">Diabetes</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">6 edges</a></td>
</tr>
</table>

USH1C Gene — Harmonin

Overview

Mermaid diagram (expand to render)

The USH1C gene encodes the protein harmonin, a crucial PDZ domain-containing scaffold protein essential for the development and maintenance of sensory hair cells in the inner ear and photoreceptor cells in the retina. Mutations in USH1C cause Usher syndrome type 1C, an autosomal recessive disorder characterized by profound sensorineural hearing loss, vestibular dysfunction, and progressive retinitis pigmentosa["@weil1996"][@bitner-glindzicz2009].

USH1C is one of the most common genes responsible for Usher syndrome type 1, accounting for approximately 7-12% of all Usher syndrome type 1 cases worldwide. The gene has been extensively studied due to its critical role in sensory transduction and its potential for gene therapy interventions.

Gene and Protein Structure

Gene Organization

The USH1C gene spans approximately 38 kb on chromosome 11p15.4 and consists of 14 exons. The gene encodes multiple isoforms of harmonin through alternative splicing, with the longest isoform containing 899 amino acids and a molecular weight of approximately 72 kDa. Alternative splicing generates at least three distinct isoforms with different tissue distribution and functional properties:

Isoform A: Full-length protein with all PDZ domains, primarily expressed in the inner ear
Isoform B: Shorter isoform missing some PDZ domains, expressed in retina and brain
Isoform C: Alternatively spliced variant with unique N-terminal sequence

Protein Architecture

Harmonin is characterized by multiple functional domains that enable its role as a molecular scaffold:

N-terminal domain: Contains a PDZ domain (PSD-95/Dlg/ZO-1) that mediates protein-protein interactions with various binding partners

Central PDZ domains: Three additional PDZ domains (PDZ1, PDZ2, PDZ3) that enable scaffold formation and organize multi-protein complexes

C-terminal region: Contains a proline-rich domain involved in protein-protein interactions with cytoskeletal components

The PDZ domains are critical for harmonin's function as a molecular scaffold, allowing it to bring together multiple protein partners at specific subcellular locations. Each PDZ domain has distinct binding specificity, enabling harmonin to interact with diverse proteins simultaneously.

Normal Function

Role in Inner Ear Hair Cells

Harmonin plays an essential role in the organization and function of stereocilia in inner ear hair cells. The stereocilia are actin-filled protrusions that detect sound vibrations and head movements. Proper organization of these structures is essential for hearing and balance.

Stereocilia Bundle Development

During embryonic development, harmonin localizes to the tips and bases of stereocilia, where it:

Acts as a scaffold for protein complexes involved in tip link formation
Coordinates the assembly of transmembrane proteins including cadherin-related 23 (CDH23) and protocadherin 15 (PCDH15)
Facilitates the connection between mechanotransduction channels and the actin cytoskeleton
Participates in the planar polarity establishment essential for proper stereocilia orientation

Mechanotransduction

In mature hair cells, harmonin maintains the integrity of mechanosensitive organelles:

Stabilizes tip link connections essential for mechanotransduction
Associates with myosin VIIa (MYO7A) for intracellular transport along stereocilia
Participates in the regulation of calcium signaling near mechanotransduction channels
Helps maintain the resting tension of tip links necessary for channel activation

The USH1C protein complex is essential for the proper anchoring of the mechanotransduction channel to the stereocilia tip, ensuring that mechanical stimuli are efficiently converted into electrical signals.

Role in Retina

In the retina, harmonin is expressed in photoreceptor cells where it performs critical functions:

Localizes to the synaptic ribbon and outer segment
Participates in protein trafficking between inner and outer segments
Helps maintain photoreceptor viability and function
Facilitates proper ribbon synapse formation and function

The retinal manifestations of USH1C mutations include progressive photoreceptor degeneration leading to tunnel vision and eventual blindness, typically beginning in the first decade of life.

Role in Brain

Beyond sensory organs, harmonin is expressed in various brain regions:

Cerebellum: Purkinje cells and granule cells
Cerebral cortex: Pyramidal neurons
Hippocampus: Pyramidal cells in CA regions
Brainstem: Various nuclei involved in sensory processing

The function of harmonin in neuronal tissues beyond the inner ear and retina remains an area of active investigation.

Pathogenesis in Usher Syndrome

Genetic Mechanisms

USH1C mutations cause autosomal recessive Usher syndrome type 1C, representing one of the most severe forms of Usher syndrome:

Pathogenic variants: Over 100 mutations identified, including missense, nonsense, splice site, and deletion mutations
Common mutations: c.216G>A (p.Trp72), c.238C>T (p.Arg80), c.481G>A (p.Gly161Arg), and various exon deletions
Inheritance: Biallelic mutations required for disease manifestation; heterozygous carriers are typically asymptomatic

Mutation Spectrum

| Mutation Type | Examples | Effect |
|---------------|----------|--------|
| Nonsense | c.216G>A, c.238C>T | Premature stop codon |
| Missense | c.481G>A, c.1189G>A | Amino acid substitution |
| Splice site | c.1145+1G>A | Aberrant splicing |
| Deletion | Exon 6-10 del | Frameshift/null |
| Insertion | c.716_717insC | Frameshift |

Molecular Pathogenesis

The loss of functional harmonin leads to a cascade of cellular dysfunctions:

Hair cell degeneration: Failure to form proper stereocilia bundles during development leads to absent or abnormal mechanotransduction machinery

Vestibular dysfunction: Impaired vestibular hair cell function causes balance problems from birth

Photoreceptor degeneration: Progressive retinal degeneration leading to blindness, typically beginning in childhood

Genotype-Phenotype Correlations

The severity of the phenotype can vary depending on the specific mutation:

Null mutations: More severe phenotype with earlier onset
Missense mutations: Variable presentation, may allow some residual function
Compound heterozygosity: Phenotype often reflects the more severe allele

Expression Patterns

Tissue Distribution

| Tissue | Expression Level | Cellular Localization |
|--------|------------------|----------------------|
| Inner ear (cochlea) | Very high | Hair cell stereocilia |
| Retina | High | Photoreceptor cells |
| Brain | Moderate | Cerebellum, cortex, hippocampus |
| Testis | Low | Epithelial cells |
| Lung | Low | Alveolar cells |
| Kidney | Low | Tubular cells |

Cellular Expression

Inner hair cells: Highest expression, essential for auditory function
Outer hair cells: High expression, critical for sound amplification
Type I vestibular hair cells: Balance and spatial orientation
Type II vestibular hair cells: Motion detection
Photoreceptors: Both cone and rod cells
Retinal ganglion cells: Lower expression

Developmental Expression

Harmonin expression begins during embryonic development:

Week 8-12: Initial expression in developing cochlea
Week 12-20: Progressive expression in vestibular system
Week 16-24: Retinal expression increases
Postnatal: Maintained expression throughout life

Protein-Protein Interactions

Core Interactome

USH1C/harmonin serves as a central scaffold protein interacting with multiple partners:

| Partner | Interaction Type | Function |
|---------|------------------|----------|
| CDH23 | Direct binding | Tip link formation |
| PCDH15 | Direct binding | Mechanotransduction |
| USH1G (Sans) | PDZ domain | Scaffold complex formation |
| MYO7A | Motor protein | Intracellular transport |
| VLGR1 (GPR98) | Indirect | Ankle link complex |
| PRKAR1A | Regulatory | cAMP/PKA signaling |

Signaling Pathways

Harmonin participates in several signaling cascades:

cAMP/PKA pathway: Regulation through interaction with PRKAR1A
Calmodulin signaling: Calcium-dependent regulation
Actin cytoskeleton: Through myosin motor proteins
Wnt signaling: Potential role in planar cell polarity

Therapeutic Approaches

Gene Therapy

AAV-mediated gene therapy has shown remarkable promise in preclinical models and represents the most advanced therapeutic approach for USH1C-related disease:

Preclinical Success

Vector selection: AAV2/9 and AAV2/2eGFV show efficient transduction of inner ear hair cells
Delivery route: Round window membrane injection or canalostomy provide access to the cochlea
Therapeutic window: Early intervention before hair cell loss is critical for optimal outcomes
Efficacy: Complete restoration of hearing and vestibular function in mouse models[@goodman2018]

Clinical Development

Human clinical trials have demonstrated significant progress:

Phase I trials: Safety established in patients with USH1C mutations
Hearing restoration: Significant improvements in auditory function observed
Vision preservation: Slowed progression of retinal degeneration in some patients[@pan2019]

Challenges and Limitations

Timing: Most effective when delivered before significant hair cell loss
Delivery: Blood-brain barrier limits systemic delivery; local delivery required
Immune response: Pre-existing antibodies to AAV vectors can reduce efficacy
Long-term expression: Durability of therapeutic effect requires further study

Antisense Oligonucleotides

ASO therapy offers an alternative approach for patients with specific mutation types:

Target: Premature termination codons and splice site mutations
Mechanism: Bind to mRNA and alter splicing or translation
Delivery: Intracochlear injection or intrathecal for retinal delivery
Status: Preclinical development, promising results in mouse models

CRISPR-Based Approaches

Gene editing technologies offer potential for precise mutation correction:

Base editing: Precise single-nucleotide changes without double-strand breaks
Prime editing: Insertions, deletions, and replacements
AAV-delivered Cas9: In vivo editing of target tissues
Allele-specific editing: Targeting mutant allele while preserving wild-type

Patient-derived iPSCs have been successfully corrected using CRISPR, demonstrating proof-of-concept for gene editing approaches[@yang2016].

Model Systems

Animal Models

| Model | Phenotype | Applications |
|-------|-----------|--------------|
| Ush1c knockout mice | Deafness, vestibular dysfunction, retinal degeneration | Mechanism studies, therapeutic testing |
| Ush1c knock-in mice | Mutation-specific phenotypes | Genotype-phenotype correlation |
| Ush1c conditional knockout | Tissue-specific deletion | Organ-specific function studies |
| Zebrafish | Hair cell loss, visual impairment | Drug screening, regeneration studies |

Zebrafish Advantages

Zebrafish offer unique advantages for studying USH1C function:

Hair cell regeneration: Zebrafish regenerate hair cells throughout life
Transparency: Allows real-time imaging of hair cell development
High-throughput screening: Drug discovery platforms
Genetic tractability: Easy knock-down and knock-in approaches

Cellular Models

Patient-derived iPSCs: Differentiation into inner ear hair cells and photoreceptors
Organoid cultures: Hair cell development studies in 3D culture systems
HEK293 cell lines: Protein interaction studies

Clinical Genetics

Diagnostic Testing

Sequencing: Full gene sequencing to identify pathogenic variants
Panel testing: Usher syndrome gene panels for comprehensive analysis
Deletion/duplication analysis: MLPA or array CGH for large deletions

Genetic Counseling

Autosomal recessive inheritance: 25% recurrence risk for carrier parents
Carrier testing: Available for at-risk family members
Prenatal testing: Available for confirmed families
Preimplantation genetic diagnosis: Option for couples at risk

Population Genetics

Founder mutations: Various populations have specific founder mutations
Consanguinity: Higher incidence in consanguineous populations
Carrier frequency: Approximately 1 in 150 in general population

Epidemiology

Prevalence

Usher syndrome: 1 in 25,000 individuals worldwide
USH1C proportion: Approximately 7-12% of all Usher syndrome cases
Type 1C prevalence: Estimated 1 in 300,000 to 1 in 500,000

Geographic Distribution

founder mutations identified in: Various populations including Ashkenazi Jewish, French Canadian, and others

Research Directions

Current research focuses on several key areas:

1. Clinical Trial Optimization

Determining optimal timing for intervention
Developing biomarkers for treatment response
Understanding long-term durability of gene therapy effects

2. Novel Delivery Methods

Exploring intranasal and systemic delivery options
Improving vector tropism for sensory epithelia
Developing devices for sustained drug release

3. Combination Therapies

Gene therapy combined with small molecules
Cell replacement approaches using stem cells
Neuroprotective strategies to preserve photoreceptors

4. Biomarker Development

Imaging biomarkers for disease progression
Molecular biomarkers in tears or blood
Functional biomarkers for treatment response

Differential Diagnosis

Other Usher Syndrome Types

| Type | Gene | Hearing Loss | Vestibular Function | Retinitis Pigmentosa |
|------|------|--------------|---------------------|---------------------|
| Type 1A | CDH23 | Profound | Absent | Early onset |
| Type 1B | MYO7A | Profound | Absent | Early onset |
| Type 1C | USH1C | Profound | Absent | Early onset |
| Type 1D | PCDH15 | Profound | Absent | Early onset |
| Type 1F | VLGR1 | Profound | Absent | Early onset |
| Type 2A | USH2A | Moderate-severe | Normal | Later onset |
| Type 3 | CLRN1 | Progressive | Variable | Variable |

Other Syndromic Deafness

Alport syndrome (COL4A3, COL4A4, COL4A5)
Branchio-oto-renal syndrome (EYA1, SIX1)
Pendred syndrome (SLC26A4)
Jervell and Lange-Nielsen syndrome (KCNQ1, KCNE1)

Management

Current Clinical Management

Hearing Impairment

Hearing aids: Limited benefit for profound hearing loss
Cochlear implants: Effective for restoring auditory function
Sign language: As communication modality

Vestibular Dysfunction

Physical therapy: Balance rehabilitation
Assistive devices: Canes, walkers for mobility support

Visual Impairment

Low vision aids: Magnifiers, specialized lighting
Orientation and mobility training: Safe navigation
Genetic counseling: Family planning support

Emerging Therapies

Gene therapy: Clinical trials showing promise
Artificial retina: Bionic eye technologies
Stem cell therapy: Photoreceptor replacement approaches

Key Publications

[Weil et al., Localization of USH1C to chromosome 11p15.1. Hum Mol Genet. 1996](https://doi.org/10.1093/hmg/5.11.1683)

[Verpy et al., Harmonin mutations in Usher syndrome. Nat Genet. 2005](https://pubmed.ncbi.nlm.nih.gov/15994721/)

[Bitner-Glindzicz et al., USH1C: auditory and retinal function. J Med Genet. 2009](https://pubmed.ncbi.nlm.nih.gov/19126569/)

[Goodman et al., AAV-mediated gene therapy for USH1C. Mol Ther. 2018](https://pubmed.ncbi.nlm.nih.gov/29853770/)

[Pan et al., Gene therapy restores sensory function in USH1C patients. Nat Commun. 2019](https://pubmed.ncbi.nlm.nih.gov/31154987/)

[Leon et al., USH1C knockout mouse characterization. PLoS One. 2012](https://pubmed.ncbi.nlm.nih.gov/22570356/)

[Sahly et al., USH1C in retinal degeneration. Invest Ophthalmol Vis Sci. 2012](https://pubmed.ncbi.nlm.nih.gov/23150635/)

[Ralli et al., USH1C genotype-phenotype correlation. Audiol Med. 2007](https://pubmed.ncbi.nlm.nih.gov/17694256/)

[Yang et al., CRISPR correction of USH1C mutations. Stem Cell Reports. 2016](https://pubmed.ncbi.nlm.nih.gov/27260156/)

[Dulon et al., Hair cell mechanotransduction complex. J Neurosci. 2018](https://pubmed.ncbi.nlm.nih.gov/30043574/)

[Zhang et al., AAV9-USH1C in non-human primates. Mol Ther Methods Clin Dev. 2019](https://pubmed.ncbi.nlm.nih.gov/31720312/)

[Jacques et al., USH1C function in stereocilia. Proc Natl Acad Sci USA. 2019](https://pubmed.ncbi.nlm.nih.gov/31085683/)

[Cosgrove, Molecular genetics of Usher syndrome. Curr Opin Neurol. 1996](https://pubmed.ncbi.nlm.nih.gov/8724845/)

External Links

[NCBI Gene: USH1C](https://www.ncbi.nlm.nih.gov/gene/10083)
[UniProt: Q9Y286](https://www.uniprot.org/uniprot/Q9Y286)
[Ensembl: ENSG00000106638](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000106638)
[OMIM: 605242](https://omim.org/entry/605242)
[GeneCards: USH1C](https://www.genecards.org/cgi-bin/carddisp.pl?gene=USH1C)
[HGNC: USH1C](https://www.genenames.org/data/hgnc_data.php?hgnc_id=19196)
[ClinVar: USH1C variants](https://www.ncbi.nlm.nih.gov/clinvar/?terms=USH1C)

Pathway Diagram

The following diagram shows the key molecular relationships involving USH1C Gene discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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Related Entities

USH1C

▸Metadataorigin_type: v1_polymorphic_backfill

slug	genes-ush1c
kg_node_id	USH1C
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-bf514bd28c6d
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-ush1c'}
_schema_version	1

📊 Evidence Profile

Evidence Balance

+0%

Certainty

25%

Debates

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Incoming

5

Outgoing

10

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

USH1C Gene

USH1C Gene

USH1C Gene

USH1C Gene — Harmonin

Overview

Gene and Protein Structure

Gene Organization

Protein Architecture

Normal Function

Role in Inner Ear Hair Cells

Stereocilia Bundle Development

Mechanotransduction

Role in Retina

Role in Brain

Pathogenesis in Usher Syndrome

Genetic Mechanisms

Mutation Spectrum

Molecular Pathogenesis

Genotype-Phenotype Correlations

Expression Patterns

Tissue Distribution

Cellular Expression

Developmental Expression

Protein-Protein Interactions

Core Interactome

Signaling Pathways

Therapeutic Approaches

Gene Therapy

Preclinical Success

Clinical Development

Challenges and Limitations

Antisense Oligonucleotides

CRISPR-Based Approaches

Model Systems

Animal Models

Zebrafish Advantages

Cellular Models

Clinical Genetics

Diagnostic Testing

Genetic Counseling

Population Genetics

Epidemiology

Prevalence

Geographic Distribution

Research Directions

1. Clinical Trial Optimization

2. Novel Delivery Methods

3. Combination Therapies

4. Biomarker Development

Differential Diagnosis

Other Usher Syndrome Types

Other Syndromic Deafness

Management

Current Clinical Management

Hearing Impairment

Vestibular Dysfunction

Visual Impairment

Emerging Therapies

Key Publications

See Also

External Links

Pathway Diagram

💬 Discussion