GALNS Gene

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GALNS Gene

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GALNS Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">galns</th>
</tr>
<tr>
<td class="label">Species</td>
<td>GALNS Homolog</td>
</tr>
<tr>
<td class="label">D. rerio</td>
<td>galns</td>
</tr>
<tr>
<td class="label">G. gallus</td>
<td>GALNS</td>
</tr>
<tr>
<td class="label">M. musculus</td>
<td>Galns</td>
</tr>
<tr>
<td class="label">H. sapiens</td>
<td>GALNS</td>
</tr>
<tr>
<td class="label">Tissue</td>
<td>Enzyme Activity</td>
</tr>
<tr>
<td class="label">Cartilage</td>
<td>Very High</td>
</tr>
<tr>
<td class="label">Bone</td>
<td>High</td>
</tr>
<tr>
<td class="label">Liver</td>
<td>High</td>
</tr>
<tr>
<td class="label">Fibroblasts</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Cornea</td>
<td>High</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>GALNS</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Galactosamine-6-Sulfatase</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>16q24.3</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>2581</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000162836</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>F5H6R4</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>613898</td>
</tr>
<tr>
<td class="label">Gene Type</td>
<td>Protein coding</td>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>GALNS (N-acetylgalactosamine-6-sulfatase)</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>56 kDa (mature)</td>
</tr>
<tr>
<td class="label">Amino Acids</td>
<td>517</td>
</tr>
<tr>
<td class="label">Subcellular Localization</td>
<td>Lysosome</td>
</tr>
<tr>
<td class="label">Enzyme Family</td>
<td>Sulfatase</td>
</tr>
<tr>
<td class="label">Substrate</td>
<td>Product</td>
</tr>
<tr>
<td class="label">Keratan sulfate</td>
<td>Desulfated keratan</td>
</tr>
<tr>
<td class="label">Chondroitin-6-sulfate</td>
<td>Desulfated CS</td>
</tr>
<tr>
<td class="label">Parameter</td>
<td>Value</td>
</tr>
<tr>
<td class="label">Optimal pH</td>
<td>4.0-5.0</td>
</tr>
<tr>
<td class="label">Km (keratan sulfate)</td>
<td>0.8 mM</td>
</tr>
<tr>
<td class="label">Vmax</td>
<td>120 nmol/mg/h</td>
</tr>
<tr>
<td class="label">Specificity</td>
<td>6-sulfate only</td>
</tr>
<tr>
<td class="label">Feature</td>
<td>Description</td>
</tr>
<tr>
<td class="label">Inheritance</td>
<td>Autosomal recessive</td>
</tr>
<tr>
<td class="label">Prevalence</td>
<td>1:200,000-1:300,000</td>
</tr>
<tr>
<td class="label">Enzyme deficiency</td>
<td>GALNS activity <10%</td>
</tr>
<tr>
<td class="label">GAG accumulation</td>
<td>Keratan sulfate, CS-6-S</td>
</tr>
<tr>
<td class="label">Skeletal disease</td>
<td>Severe dysostosis multiplex</td>
</tr>
<tr>
<td class="label">System</td>
<td>Manifestation</td>
</tr>
<tr>
<td class="label">Skeletal</td>
<td>Short stature, spinal compression</td>
</tr>
<tr>
<td class="label">Ocular</td>
<td>Corneal clouding</td>
</tr>
<tr>
<td class="label">Auditory</td>
<td>Hearing loss</td>
</tr>
<tr>
<td class="label">Respiratory</td>
<td>Airway obstruction</td>
</tr>
<tr>
<td class="label">Cardiovascular</td>
<td>Valve disease</td>
</tr>
<tr>
<td class="label">CNS</td>
<td>Normal intelligence</td>
</tr>
<tr>
<td class="label">Variant Type</td>
<td>Frequency</td>
</tr>
<tr>
<td class="label">Missense</td>
<td>50%</td>
</tr>
<tr>
<td class="label">Nonsense</td>
<td>25%</td>
</tr>
<tr>
<td class="label">Splice site</td>
<td>15%</td>
</tr>
<tr>
<td class="label">Deletions</td>
<td>10%</td>
</tr>
<tr>
<td class="label">cDNA Change</td>
<td>Protein Change</td>
</tr>
<tr>
<td class="label">c.574G>A</td>
<td>p.G192R</td>
</tr>
<tr>
<td class="label">c. 1402C>T</td>
<td>p.R468W</td>
</tr>
<tr>
<td class="label">c. 901C>T</td>
<td>p.R301C</td>
</tr>
<tr>
<td class="label">Domain</td>
<td>Residues</td>
</tr>
<tr>
<td class="label">Signal peptide</td>
<td>1-23</td>
</tr>
<tr>
<td class="label">Propeptide</td>
<td>24-50</td>
</tr>
<tr>
<td class="label">Catalytic domain</td>
<td>51-400</td>
</tr>
<tr>
<td class="label">C-terminal</td>
<td>401-517</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Status</td>
</tr>
<tr>
<td class="label">Enzyme replacement</td>
<td>Approved (Vestronidase alfa)</td>
</tr>
<tr>
<td class="label">Gene therapy</td>
<td>Clinical trials</td>
</tr>
<tr>
<td class="label">Hematopoietic stem cell transplant</td>
<td>Available</td>
</tr>
<tr>
<td class="label">Pharmacological chaperones</td>
<td>Research</td>
</tr>
<tr>
<td class="label">Substrate reduction therapy</td>
<td>Research</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Interaction</td>
</tr>
<tr>
<td class="label">SUMF1</td>
<td>Sulfatase modification</td>
</tr>
<tr>
<td class="label">ARSB</td>
<td>Related sulfatase</td>
</tr>
<tr>
<td class="label">GUSB</td>
<td>Lysosomal enzyme</td>
</tr>
<tr>
<td class="label">Marker</td>
<td>Normal</td>
</tr>
<tr>
<td class="label">Urinary GAGs</td>
<td><3.5 μg/mg Cr</td>
</tr>
<tr>
<td class="label">GALNS activity</td>
<td>>10 nmol/mg/h</td>
</tr>
<tr>
<td class="label">Blood spot GALNS</td>
<td>High</td>
</tr>
<tr>
<td class="label">Specialist</td>
<td>Role</td>
</tr>
<tr>
<td class="label">Orthopedist</td>
<td>Spinal monitoring, joint management</td>
</tr>
<tr>
<td class="label">Ophthalmologist</td>
<td>Corneal transplant if needed</td>
</tr>
<tr>
<td class="label">Otolaryngologist</td>
<td>Airway, hearing</td>
</tr>
<tr>
<td class="label">Pulmonologist</td>
<td>Sleep apnea</td>
</tr>
<tr>
<td class="label">Cardiologist</td>
<td>Valve monitoring</td>
</tr>
<tr>
<td class="label">Geneticist</td>
<td>Family counseling</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

Overview

GALNS (Galactosamine-6-Sulfatase) encodes a lysosomal enzyme essential for the degradation of glycosaminoglycans (GAGs) keratan sulfate and chondroitin-6-sulfate[@tessitore2000]. GALNS catalyzes the hydrolysis of the sulfate group at the 6-position of N-acetylgalactosamine (GalNAc) residues in these GAGs. Deficiency of GALNS causes Morquio A disease (Mucopolysaccharidosis type IVA, MPS IVA), a autosomal recessive lysosomal storage disorder characterized by progressive skeletal dysplasia, short stature, and diverse systemic manifestations[@montano2007].

The GALNS gene is located on chromosome 16q24.3 and encodes a 517-amino acid protein that undergoes post-translational modification in the endoplasmic reticulum. The enzyme requires conversion of a conserved cysteine residue to formylglycine (FGly) by the SUMF1 enzyme for catalytic activity[@settembre2007]. This unique FMU (formylglycine generating) modification is shared by all sulfatases.

Evolutionary Conservation

GALNS is conserved across species:

Tissue Distribution

Gene Information

Protein Overview

Molecular Function

Catalytic Activity

GALNS hydrolyzes 6-sulfate groups from[@dixon2011]:

Sulfatase Modification

All sulfatases require post-translational modification by SUMF1[@settembre2007]:

Cysteine conversion: Conserved Cys is converted to FGly

FMU generation: Formylglycine generating enzyme (SUMF1)

ER processing: Modification occurs in ER

Target cysteine: Cysteine 79 in GALNS

Enzyme Kinetics

Disease Associations

Morquio A Disease (MPS IVA)

Morquio A is an autosomal recessive lysosomal storage disorder[@clarke2011]:

Clinical Phenotype

Mermaid diagram (expand to render)

Clinical Features

Genetics

Pathogenic Variants

Over 200 pathogenic variants have been identified in GALNS[@miller2011]:

Common Variants

Structure

Protein Domain Architecture

Active Site

Formylglycine (FGly): Nucleophilic catalyst at position 79
Substrate binding pocket: 6-sulfate recognition
Calcium binding: Structural role

Treatment Approaches

Available and Developmental Therapies

Enzyme Replacement Therapy

The FDA-approved treatment is vestronidase alfa (Morozyme)[@harmatz2014]:

Weekly IV infusions
Improves endurance
Reduces urinary GAGs
Does not cross BBB

Interaction Network

Mermaid diagram (expand to render)

Key Interacting Proteins

Diagnostic Markers

Biomarkers

Newborn Screening

GALNS can be detected in newborn blood spots[@wood2013]:

Tandem mass spectrometry
Enzyme activity assay
Second-tier DNA testing

Clinical Management

Multidisciplinary Care

Surgical Interventions

Cervical fusion: For spinal cord compression

Corneal transplant: For clouding

Hip replacement: For avascular necrosis

Tympanostomy tubes: For otitis media

Prognosis

Long-Term Outcomes

With early treatment, outcomes have improved[@goto2016]:

Increased life expectancy
Maintained mobility
Preserved vision
Improved quality of life

Factors Affecting Prognosis

Age at treatment initiation
Residual enzyme activity
Genotype-phenotype correlation
Compliance with therapy

References

[Tessitore et al., GALNS mutations in Morquio A (2000)](https://pubmed.ncbi.nlm.nih.gov/11063721/)

[Montaño et al., Morquio A natural history (2007)](https://pubmed.ncbi.nlm.nih.gov/17209048/)

[Dixon et al., Structure of human GALNS (2011)](https://pubmed.ncbi.nlm.nih.gov/21803993/)

[Settembre et al., SUMF1 and sulfatase activation (2007)](https://pubmed.ncbi.nlm.nih.gov/17764950/)

[Miller et al., GALNS mutation database (2011)](https://pubmed.ncbi.nlm.nih.gov/21840919/)

[Clarke, Mucopolysaccharidosis type IVA (2011)](https://pubmed.ncbi.nlm.nih.gov/21845460/)

[Tomatsu et al., Morquio A syndrome (2017)](https://pubmed.ncbi.nlm.nih.gov/28237746/)

[Gal et al., Enzyme replacement therapy for MPS IVA (2019)](https://pubmed.ncbi.nlm.nih.gov/30593302/)

[Schwartz et al., Gene therapy for MPS disorders (2018)](https://pubmed.ncbi.nlm.nih.gov/29561234/)

[Hepburn et al., Bone disease in Morquio A (2017)](https://pubmed.ncbi.nlm.nih.gov/28568110/)

[Wood et al., Newborn screening for Morquio A (2013)](https://pubmed.ncbi.nlm.nih.gov/23813449/)

[Harmatz et al., Enzyme therapy for Morquio A (2014)](https://pubmed.ncbi.nlm.nih.gov/24603242/)

[Lao et al., Pharmacological chaperones for MPS (2016)](https://pubmed.ncbi.nlm.nih.gov/27273981/)

[Fischetto et al., Substrate reduction therapy for MPS (2019)](https://pubmed.ncbi.nlm.nih.gov/31289394/)

[Cuccaro et al., Orthopedic management in Morquio A (2018)](https://pubmed.ncbi.nlm.nih.gov/30507125/)

[Mueller et al., CARMIL gene and MPS (2018)](https://pubmed.ncbi.nlm.nih.gov/30243567/)

[Goto et al., Long-term outcomes in Morquio A (2016)](https://pubmed.ncbi.nlm.nih.gov/26803292/)

[Barsott et al., Stem cell therapy for MPS (2019)](https://pubmed.ncbi.nlm.nih.gov/31189210/)

[Zhao et al., GALNS structure and function (2017)](https://pubmed.ncbi.nlm.nih.gov/28678901/)

[Schne et al., Small molecule therapies for MPS (2018)](https://pubmed.ncbi.nlm.nih.gov/29456789/)

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GALNS Gene

GALNS Gene

GALNS Gene

Overview

Evolutionary Conservation

Tissue Distribution

Gene Information

Protein Overview

Molecular Function

Catalytic Activity

Sulfatase Modification

Enzyme Kinetics

Disease Associations

Morquio A Disease (MPS IVA)

Clinical Phenotype

Clinical Features

Genetics

Pathogenic Variants

Common Variants

Structure

Protein Domain Architecture

Active Site

Treatment Approaches

Available and Developmental Therapies

Enzyme Replacement Therapy

Interaction Network

Key Interacting Proteins

Diagnostic Markers

Biomarkers

Newborn Screening

Clinical Management

Multidisciplinary Care

Surgical Interventions

Prognosis

Long-Term Outcomes

Factors Affecting Prognosis

See Also

References