RARE DISEASE
Mucopolysaccharidosis type 4A
Mucopolysaccharidosis type 4A
Mucopolysaccharidosis type 4A
Synonyms: GALNS deficiency, Galactosamine-6-sulfatase deficiency, MPS4A, MPSIVA, Morquio disease type A, Mucopolysaccharidosis type IVA, N-acetylgalactosamine-6-sulfate sulfatase deficiency
Synonyms: GALNS deficiency, Galactosamine-6-sulfatase deficiency, MPS4A, MPSIVA, Morquio disease type A, Mucopolysaccharidosis type IVA, N-acetylgalactosamine-6-sulfate sulfatase deficiency
Synonyms: GALNS deficiency, Galactosamine-6-sulfatase deficiency, MPS4A, MPSIVA, Morquio disease type A, Mucopolysaccharidosis type IVA, N-acetylgalactosamine-6-sulfate sulfatase deficiency
Drug discovery
7
drugs
With orphan designations
Overview
Mucopolysaccharidosis type 4A (MPS IVA/Morquio A syndrome) is an autosomal recessive lysosomal storage disorder caused by GALNS gene mutations, leading to deficient N-acetylgalactosamine-6-sulfatase activity. This results in systemic accumulation of keratan sulfate and chondroitin-6-sulfate, causing severe skeletal dysplasia, short stature, spinal instability, respiratory compromise, and corneal clouding. Cognitive function is typically preserved. Disease progression varies, with life expectancy ranging from childhood to >50 years depending on severity and care [1][4][7][10].
Burden
Progressive skeletal deformities cause wheelchair dependency by adolescence in severe cases [1][15]
Major mortality risks: spinal cord compression (odontoid hypoplasia) and respiratory failure [4][10]
High healthcare utilization due to multisystem complications (orthopedic, cardiac, pulmonary) and frequent surgical interventions [1][7]
Therapies
Enzyme replacement therapy: Elosulfase alfa (Vimizim®) improves endurance and reduces keratan sulfate levels but does not reverse skeletal pathology [3][7][15]
Supportive care: Spinal fusion for cervical instability, tracheal reconstruction, joint surgeries, and respiratory support [1][7]
Emerging approaches: Prenatal ERT trials to induce immune tolerance and bone-targeted therapies in preclinical development [7][12]
Categories: rare bone diseases, rare developmental anomalies during embryogenesis, rare genetic diseases, rare inborn errors of metabolism, rare ophthalmic disorders, rare transplant-related disorders
Research Papers
292 drug discovery papers about Mucopolysaccharidosis type 4A, with 3 first-in-class and 3 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
292 drug discovery papers about Mucopolysaccharidosis type 4A, with 3 first-in-class and 3 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-04-28 | Long-Term Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Mucopolysaccharidosis IVA: A 10-Year Follow-Up from a Single-Center Experience in China.
Allogeneic hematopoietic stem cell transplantation (HSCT) is a potential approach for pediatric mucopolysaccharidosis IVA (MPS IVA). However, delayed diagnosis and higher transplant-related complications have limited its broader use. This study investigated treatment-related benefit and up to 10-year outcomes following HSCT in children with MPS IVA. Study Design We retrospectively analyzed 19 pediatric patients with a severe phenotype of MPS IVA who underwent HSCT between January 2015 and July 2025. N-acetylgalactosamine-6-sulfatase (GALNS) enzyme activity, height growth, and organ dysfunction (cardiac, auditory, and visual) was evaluated to analyze the benefit of HSCT. The donor sources include human leukocyte antigen (HLA)-matched sibling donor peripheral blood stem cell transplantation (MSD-PBSCT, n = 5), HLA-matched unrelated donor PBSCT (MUD-PBSCT, n = 7), and single-unit unrelated umbilical cord blood transplantation (UD-UCBT, n = 7). The overall survival rate was 94.7% (18/19), apart from 1 mortality due to pulmonary infection. All surviving patients achieved full donor engraftment and durable restoration of GALNS activity. There is no severe graft-versus-host disease (GVHD) was observed. The majority of patients exhibited no deterioration in auditory, visual, respiratory, or cardiac function. During the long-term follow-up period, our cases showed a continued linear growth post-HSCT. Here we demonstrated the data of our HSCT experience in MPS IVA with the safety and efficacy of HSCT. More data with an expanded patient cohort are imperative to delineate the capacity of HSCT to repair severe skeletal manifestations in MPS IVA.
2026-03-30 | Ultrasound-guided one-point puncture lumbosacral plexus block combined with laryngeal mask airway general anesthesia for thigh amputation in a patient with mucopolysaccharidosis: a case report.
Mucopolysaccharidosis (MPS) is a group of rare inherited lysosomal storage disorders caused by deficiencies of specific enzymes, leading to abnormal accumulation of glycosaminoglycans in tissues throughout the body. It is often associated with a difficult airway, cervical spine instability, restrictive pulmonary dysfunction, and cardiovascular pathologies, which significantly increase perioperative risks. This manuscript reports a case of a 36-year-old male MPS patient (clinical phenotype highly suggestive of type IV) who underwent right mid-to-upper thigh amputation for a pathological fracture of the right femur. Given his potential difficult airway (Mallampati class III, thyromental distance <6 cm), mild kyphosis, and restrictive pulmonary dysfunction, the anesthetic plan consisted of an ultrasound-guided one-point puncture, dual-target lumbosacral plexus block (35 mL of 0.15% ropivacaine) combined with supraglottic airway (laryngeal mask airway, LMA) under general anesthesia. The block successfully provided an L2-S3 sensory level and served as the basis for postoperative multimodal analgesia. The surgery lasted 2 h with 500 mL blood loss, requiring 2 units of red blood cells. Hemodynamics remained stable, and no additional muscle relaxants were administered. The patient regained consciousness and the LMA was removed 10 min postoperatively. The Numerical Rating Scale (NRS) pain scores at 2, 6, 12, and 24 h postoperatively were 2, 3, 2, and 1, respectively. Functional exercise began on postoperative day 1 without major complications. The patient was discharged 15 days after surgery and was hospitalized for a total of 18 days. With strict patient selection and thorough preparation of emergency airway protocols, combining an LMA with an ultrasound-guided one-point puncture lumbosacral plexus block can be a safe and feasible individualized anesthetic strategy for lower limb proximal surgery in MPS patients. This approach helps avoid intubation risks, reduces opioid consumption, and promotes early recovery. However, due to the considerable difficulty of airway management in patients with MPS, elective surgery requires multidisciplinary consultation and comprehensive airway assessment to ensure perioperative safety.
2026-03-05 | P044: First report of GLP-1 agonist use in MCAD deficiency
Case Presentation: A 29-year-old Hispanic female presented with a clinical and biochemical diagnosis of MPSIVA.She has short stature, mild corneal clouding, pectus carinatum, required multiple knee surgeries and her x-ray showed bullet shaped vertebrae.This individual had two affected siblings with MPSIVA who are unavailable for testing.Her mother is mildly affected and presents with corneal clouding and short stature.Diagnostic Workup: This individual initially had an LSD panel which identified one pathogenic variant in the GALNS gene, c.107T>C, which was insufficient to explain the patient's phenotype.ES with RNA-seq was ordered.RNA-seq analysis identified an 11 bp deletion in an alternative transcript (NM_001323544.2), leading to frameshift: p.(Gly43Aspfs*5).This aberrant transcript was a consequence of a single nucleotide change (c.121-210C>T) located in intron 1 and is 210 bp upstream of the splice acceptor site for exon 2 in the MANE transcript (NM_000512.5).As this variant is located at the startproximal nonsense-mediated mRNA decay insensitivity region, re-initiation of translation at the next in-frame start codon (p.47) is possible.This variant was originally classified as likely benign (LB) due to being observed at a frequency of 0.31% (523/166064 alleles) with the highest frequency noted in the African subpopulation at 3.05% in the gnomAD database.However, this variant has also been reported in the compound heterozygous and homozygous state in four individuals with MPSIVA and has been classified as a "Potentially Disease Associated Mutation" in the Human Gene Mutation Database.Based on the RNA-seq analysis and other affected individuals identified with this variant, the lab was able to upgrade the variant from LB to a variant of uncertain significance (VUS) and may represent a hypomorphic allele.Outcome and Follow-Up: The provider was able to provide this individual with a molecular diagnosis of MPSIVA based on the detection of two GALNS variants.Since then, we have tested the mildly affected mother who was found to be homozygous for the c.121-210C>T variant with consistent RNA-seq results to the proband.This strengthens the understanding that this is a hypomorphic allele.Testing the proband's siblings is still recommended. Conclusion:The use of ES with RNA-seq was able to identify a variant that was -210 nucleotides upstream of the splice acceptor site and lead to an upgrade in variant classification from LB to VUS.This highlights the diagnostic advantages of using RNA-seq over standard DNA-only testing methodology.RNAseq can aid in identifying aberrant splicing, mono-allelic expression, and aberrant expression which can increase diagnostic yield.Having a molecular diagnosis can provide individuals with different treatment options, including possible GT enrollment, and family planning options.
2026-03-05 | Development and characterization of a model of mucopolysaccharidosis type IVA for evaluating therapies targeting bone disease.
Mucopolysaccharidosis type IVA (MPSIVA) is a lysosomal storage disease (LSD) caused by deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS), which causes the accumulation of keratan sulphate (KS) and chondroitin sulphate (CS). Patients with MPSIVA typically present with severe skeletal and joint disorders, which are not addressed by conventional therapies. Currently, no animal model accurately replicates the human disease, hindering the development of novel therapeutic interventions. To overcome this limitation, we established, by CRISPR-Cas9 technology, a Galns-/- mouse model that expresses a non-functional enzyme and accumulates CS and KS in the urine, plasma and distinct tissues, and glycosaminoglycans in the spleen. The mice exhibit shortened long bones, trabecular bone alterations and skeletal abnormalities in the growth plate. Additionally, we observed increased levels of inflammatory and oxidative markers in visceral organs and plasma. Our newly developed model of MPSIVA demonstrates clear and quantifiable signs of skeletal alterations, providing novel means of assessment of the safety and efficacy of innovative therapies, including hematopoietic stem and progenitor cell gene therapy, which has recently been shown to provide a beneficial effect on skeletal alterations in Hurler syndrome.
2026-03-02 | Computational Prediction of Deleterious SNPs in the GALNS Gene Implicated in Morquio A Syndrome (MPS IVA).
Morquio syndrome A, also known as mucopolysaccharidosis type IVA (MPS IVA), is a lysosomal storage disorder resulting from mutations in the gene responsible for N-acetylgalactosamine-6-sulfatase. The deficiency of this enzyme impairs the degradation of glycosaminoglycans, particularly chondroitin 6-sulfate and keratan sulfate. This research uses a variety of computational techniques for analyzing the GALNS variants mainly causing child death and to provide better healthcare. The variants were collected from research sources, such as PubMed, ResearchGate, and ScienceDirect, along with databases like HGMD, ClinVar, and UniProt. The analysis of the conservation, pathogenicity, and stability of the variations was conducted utilizing algorithms such as ConSurf, PredictSNP, and iStable. Structural analysis was carried out using the PDB databank and PyMOL software. Molecular docking was used to study the interaction of native and variant GALNS proteins with Ezetimibe. GROMACS was used to simulate the behavior of the GALNS protein with variants and Ezetimibe binding in docked complexes for over 100 ns. A total of 345 SNP variants were retrieved, of which D40H, C79R, and C79L variants were identified to be highly deleterious after conservation (75 SNPs), pathogenicity (5 SNPs), and biophysical and stability (3 SNPs) analysis. During docking, the native protein demonstrated a strong binding affinity of -8.54 kcal/mol for the drug. The C79R variant displayed a binding affinity of -8.41 kcal/mol, while the C79L and D40H variants showed affinities of -7.07 and -7.92 kcal/mol, respectively. MD simulations of the native and variant structures showed similar ligand binding flexibility and stability, confirmed by RMSD, RMSF, H-bond, and gyration plots. The increased binding affinity and stability of both complexes suggest that Ezetimibe has comparable therapeutic effects for both the native and variant forms. This work provides detailed structural and dynamic insights into the GALNS protein, paving the way for further research and new treatments for Morquio syndrome A.
2026-04-28 | Long-Term Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Mucopolysaccharidosis IVA: A 10-Year Follow-Up from a Single-Center Experience in China.
Allogeneic hematopoietic stem cell transplantation (HSCT) is a potential approach for pediatric mucopolysaccharidosis IVA (MPS IVA). However, delayed diagnosis and higher transplant-related complications have limited its broader use. This study investigated treatment-related benefit and up to 10-year outcomes following HSCT in children with MPS IVA. Study Design We retrospectively analyzed 19 pediatric patients with a severe phenotype of MPS IVA who underwent HSCT between January 2015 and July 2025. N-acetylgalactosamine-6-sulfatase (GALNS) enzyme activity, height growth, and organ dysfunction (cardiac, auditory, and visual) was evaluated to analyze the benefit of HSCT. The donor sources include human leukocyte antigen (HLA)-matched sibling donor peripheral blood stem cell transplantation (MSD-PBSCT, n = 5), HLA-matched unrelated donor PBSCT (MUD-PBSCT, n = 7), and single-unit unrelated umbilical cord blood transplantation (UD-UCBT, n = 7). The overall survival rate was 94.7% (18/19), apart from 1 mortality due to pulmonary infection. All surviving patients achieved full donor engraftment and durable restoration of GALNS activity. There is no severe graft-versus-host disease (GVHD) was observed. The majority of patients exhibited no deterioration in auditory, visual, respiratory, or cardiac function. During the long-term follow-up period, our cases showed a continued linear growth post-HSCT. Here we demonstrated the data of our HSCT experience in MPS IVA with the safety and efficacy of HSCT. More data with an expanded patient cohort are imperative to delineate the capacity of HSCT to repair severe skeletal manifestations in MPS IVA.
2026-03-30 | Ultrasound-guided one-point puncture lumbosacral plexus block combined with laryngeal mask airway general anesthesia for thigh amputation in a patient with mucopolysaccharidosis: a case report.
Mucopolysaccharidosis (MPS) is a group of rare inherited lysosomal storage disorders caused by deficiencies of specific enzymes, leading to abnormal accumulation of glycosaminoglycans in tissues throughout the body. It is often associated with a difficult airway, cervical spine instability, restrictive pulmonary dysfunction, and cardiovascular pathologies, which significantly increase perioperative risks. This manuscript reports a case of a 36-year-old male MPS patient (clinical phenotype highly suggestive of type IV) who underwent right mid-to-upper thigh amputation for a pathological fracture of the right femur. Given his potential difficult airway (Mallampati class III, thyromental distance <6 cm), mild kyphosis, and restrictive pulmonary dysfunction, the anesthetic plan consisted of an ultrasound-guided one-point puncture, dual-target lumbosacral plexus block (35 mL of 0.15% ropivacaine) combined with supraglottic airway (laryngeal mask airway, LMA) under general anesthesia. The block successfully provided an L2-S3 sensory level and served as the basis for postoperative multimodal analgesia. The surgery lasted 2 h with 500 mL blood loss, requiring 2 units of red blood cells. Hemodynamics remained stable, and no additional muscle relaxants were administered. The patient regained consciousness and the LMA was removed 10 min postoperatively. The Numerical Rating Scale (NRS) pain scores at 2, 6, 12, and 24 h postoperatively were 2, 3, 2, and 1, respectively. Functional exercise began on postoperative day 1 without major complications. The patient was discharged 15 days after surgery and was hospitalized for a total of 18 days. With strict patient selection and thorough preparation of emergency airway protocols, combining an LMA with an ultrasound-guided one-point puncture lumbosacral plexus block can be a safe and feasible individualized anesthetic strategy for lower limb proximal surgery in MPS patients. This approach helps avoid intubation risks, reduces opioid consumption, and promotes early recovery. However, due to the considerable difficulty of airway management in patients with MPS, elective surgery requires multidisciplinary consultation and comprehensive airway assessment to ensure perioperative safety.
2026-03-05 | P044: First report of GLP-1 agonist use in MCAD deficiency
Case Presentation: A 29-year-old Hispanic female presented with a clinical and biochemical diagnosis of MPSIVA.She has short stature, mild corneal clouding, pectus carinatum, required multiple knee surgeries and her x-ray showed bullet shaped vertebrae.This individual had two affected siblings with MPSIVA who are unavailable for testing.Her mother is mildly affected and presents with corneal clouding and short stature.Diagnostic Workup: This individual initially had an LSD panel which identified one pathogenic variant in the GALNS gene, c.107T>C, which was insufficient to explain the patient's phenotype.ES with RNA-seq was ordered.RNA-seq analysis identified an 11 bp deletion in an alternative transcript (NM_001323544.2), leading to frameshift: p.(Gly43Aspfs*5).This aberrant transcript was a consequence of a single nucleotide change (c.121-210C>T) located in intron 1 and is 210 bp upstream of the splice acceptor site for exon 2 in the MANE transcript (NM_000512.5).As this variant is located at the startproximal nonsense-mediated mRNA decay insensitivity region, re-initiation of translation at the next in-frame start codon (p.47) is possible.This variant was originally classified as likely benign (LB) due to being observed at a frequency of 0.31% (523/166064 alleles) with the highest frequency noted in the African subpopulation at 3.05% in the gnomAD database.However, this variant has also been reported in the compound heterozygous and homozygous state in four individuals with MPSIVA and has been classified as a "Potentially Disease Associated Mutation" in the Human Gene Mutation Database.Based on the RNA-seq analysis and other affected individuals identified with this variant, the lab was able to upgrade the variant from LB to a variant of uncertain significance (VUS) and may represent a hypomorphic allele.Outcome and Follow-Up: The provider was able to provide this individual with a molecular diagnosis of MPSIVA based on the detection of two GALNS variants.Since then, we have tested the mildly affected mother who was found to be homozygous for the c.121-210C>T variant with consistent RNA-seq results to the proband.This strengthens the understanding that this is a hypomorphic allele.Testing the proband's siblings is still recommended. Conclusion:The use of ES with RNA-seq was able to identify a variant that was -210 nucleotides upstream of the splice acceptor site and lead to an upgrade in variant classification from LB to VUS.This highlights the diagnostic advantages of using RNA-seq over standard DNA-only testing methodology.RNAseq can aid in identifying aberrant splicing, mono-allelic expression, and aberrant expression which can increase diagnostic yield.Having a molecular diagnosis can provide individuals with different treatment options, including possible GT enrollment, and family planning options.
2026-03-05 | Development and characterization of a model of mucopolysaccharidosis type IVA for evaluating therapies targeting bone disease.
Mucopolysaccharidosis type IVA (MPSIVA) is a lysosomal storage disease (LSD) caused by deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS), which causes the accumulation of keratan sulphate (KS) and chondroitin sulphate (CS). Patients with MPSIVA typically present with severe skeletal and joint disorders, which are not addressed by conventional therapies. Currently, no animal model accurately replicates the human disease, hindering the development of novel therapeutic interventions. To overcome this limitation, we established, by CRISPR-Cas9 technology, a Galns-/- mouse model that expresses a non-functional enzyme and accumulates CS and KS in the urine, plasma and distinct tissues, and glycosaminoglycans in the spleen. The mice exhibit shortened long bones, trabecular bone alterations and skeletal abnormalities in the growth plate. Additionally, we observed increased levels of inflammatory and oxidative markers in visceral organs and plasma. Our newly developed model of MPSIVA demonstrates clear and quantifiable signs of skeletal alterations, providing novel means of assessment of the safety and efficacy of innovative therapies, including hematopoietic stem and progenitor cell gene therapy, which has recently been shown to provide a beneficial effect on skeletal alterations in Hurler syndrome.
2026-03-02 | Computational Prediction of Deleterious SNPs in the GALNS Gene Implicated in Morquio A Syndrome (MPS IVA).
Morquio syndrome A, also known as mucopolysaccharidosis type IVA (MPS IVA), is a lysosomal storage disorder resulting from mutations in the gene responsible for N-acetylgalactosamine-6-sulfatase. The deficiency of this enzyme impairs the degradation of glycosaminoglycans, particularly chondroitin 6-sulfate and keratan sulfate. This research uses a variety of computational techniques for analyzing the GALNS variants mainly causing child death and to provide better healthcare. The variants were collected from research sources, such as PubMed, ResearchGate, and ScienceDirect, along with databases like HGMD, ClinVar, and UniProt. The analysis of the conservation, pathogenicity, and stability of the variations was conducted utilizing algorithms such as ConSurf, PredictSNP, and iStable. Structural analysis was carried out using the PDB databank and PyMOL software. Molecular docking was used to study the interaction of native and variant GALNS proteins with Ezetimibe. GROMACS was used to simulate the behavior of the GALNS protein with variants and Ezetimibe binding in docked complexes for over 100 ns. A total of 345 SNP variants were retrieved, of which D40H, C79R, and C79L variants were identified to be highly deleterious after conservation (75 SNPs), pathogenicity (5 SNPs), and biophysical and stability (3 SNPs) analysis. During docking, the native protein demonstrated a strong binding affinity of -8.54 kcal/mol for the drug. The C79R variant displayed a binding affinity of -8.41 kcal/mol, while the C79L and D40H variants showed affinities of -7.07 and -7.92 kcal/mol, respectively. MD simulations of the native and variant structures showed similar ligand binding flexibility and stability, confirmed by RMSD, RMSF, H-bond, and gyration plots. The increased binding affinity and stability of both complexes suggest that Ezetimibe has comparable therapeutic effects for both the native and variant forms. This work provides detailed structural and dynamic insights into the GALNS protein, paving the way for further research and new treatments for Morquio syndrome A.
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Drug Discovery Landscape
7 orphan drug designations for Mucopolysaccharidosis type 4A, including 2 approved therapies.
7 orphan drug designations for Mucopolysaccharidosis type 4A, including 2 approved therapies.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
adeno-associated virus 8 vector expressing functional human cDNA encoding the N-acetylgalactosamine-6-sulfate sulfatase | gene therapies | FDA | 2024-09-20 | — | National Center for Advancing Translational Sciences, National Institutes of Health |
Autologous CD34+ haematopoietic stem and progenitor cells genetically modified with a lentiviral vector encoding for the N-acetylgalactosamine 6-sulfatase cDNA | gene therapies | EMA | 2022-08-10 | — | Fondazione Telethon Ets |
Adeno-associated virus serotype 9 vector containing human Nacetylgalactosamine-6-sulfate sulfatase gene | gene therapies | FDA | 2020-01-15 | — | Esteve Pharmaceuticals, S.A. |
Adeno-associated virus serotype 9 vector containing human N-acetylgalactosamine-6-sulfate sulfatase gene | gene therapies | EMA | 2020-01-09 | — | Esteve Pharmaceuticals S.A. |
Elosulfase alfa [Vimizim] | proteins | EMA | 2009-07-24 | 2014-04-30 | Biomarin International Limited |
elosulfase alfa [Vimizim] | proteins | FDA | 2009-05-15 | 2014-02-14 | BioMarin Pharmaceutical Inc. |
N-terminal hexaglutamine-tagged recombinant human N-acetylgalactosamine-6-sulfate sulfatase | proteins | EMA | 2009-02-27 | — | Granzer Regulatory Consulting & Services GmbH |
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