Maroteaux-Lamy syndrome, or mucopolysaccharidosis type VI (MPS VI), is an autosomal recessive lysosomal storage disorder caused by deficient activity of N-acetylgalactosamine-4-sulfatase (arylsulfatase B, ARSB). ARSB deficiency blocks lysosomal degradation of dermatan sulfate, leading to intracellular and extracellular accumulation of undegraded dermatan sulfate (with chondroitin-4-sulfate) in connective-tissue fibroblasts and the extracellular matrix of bone, cartilage, heart valve, cornea, and viscera. Because dermatan sulfate is the only stored glycosaminoglycan and heparan sulfate is not involved, MPS VI engages a purely somatic, connective-tissue arm and produces dysostosis multiplex, short stature, coarse facies, corneal clouding, cardiac valve disease, hepatosplenomegaly, airway obstruction, joint contractures, and carpal tunnel syndrome, while sparing primary central neurodegeneration and preserving intelligence. This preserved cognition distinguishes MPS VI from the heparan-sulfate-storing neuronopathic mucopolysaccharidoses. Enzyme replacement therapy with galsulfase (recombinant human ARSB, Naglazyme) is disease-modifying; hematopoietic stem cell transplantation and intensive multidisciplinary supportive care are also used.
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name: Maroteaux-Lamy syndrome
creation_date: "2026-06-12T00:00:00Z"
category: Mendelian
description: >-
Maroteaux-Lamy syndrome, or mucopolysaccharidosis type VI (MPS VI), is an
autosomal recessive lysosomal storage disorder caused by deficient activity of
N-acetylgalactosamine-4-sulfatase (arylsulfatase B, ARSB). ARSB deficiency
blocks lysosomal degradation of dermatan sulfate, leading to intracellular and
extracellular accumulation of undegraded dermatan sulfate (with
chondroitin-4-sulfate) in connective-tissue fibroblasts and the extracellular
matrix of bone, cartilage, heart valve, cornea, and viscera. Because dermatan
sulfate is the only stored glycosaminoglycan and heparan sulfate is not
involved, MPS VI engages a purely somatic, connective-tissue arm and produces
dysostosis multiplex, short stature, coarse facies, corneal clouding, cardiac
valve disease, hepatosplenomegaly, airway obstruction, joint contractures, and
carpal tunnel syndrome, while sparing primary central neurodegeneration and
preserving intelligence. This preserved cognition distinguishes MPS VI from the
heparan-sulfate-storing neuronopathic mucopolysaccharidoses. Enzyme replacement
therapy with galsulfase (recombinant human ARSB, Naglazyme) is
disease-modifying; hematopoietic stem cell transplantation and intensive
multidisciplinary supportive care are also used.
disease_term:
preferred_term: Maroteaux-Lamy syndrome
term:
id: MONDO:0009661
label: mucopolysaccharidosis type 6
mappings:
mondo_mappings:
- term:
id: MONDO:0009661
label: mucopolysaccharidosis type 6
mapping_predicate: skos:exactMatch
mapping_source: MONDO
parents:
- Mucopolysaccharidosis
- Lysosomal Storage Disorder
synonyms:
- Maroteaux-Lamy disease
- mucopolysaccharidosis type VI
- MPS VI
- arylsulfatase B deficiency
- N-acetylgalactosamine-4-sulfatase deficiency
inheritance:
- name: Autosomal recessive inheritance
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
description: >-
MPS VI is an autosomal recessive lysosomal storage disorder; affected
individuals carry biallelic pathogenic variants in ARSB.
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Mucopolysaccharidosis VI (MPS VI), or Maroteaux-Lamy syndrome, is an autosomal recessive lysosomal storage disorder caused by deficient activity of the enzyme arylsulfatase B (ASB)."
explanation: This review directly supports autosomal recessive inheritance and ARSB deficiency as the cause of MPS VI.
- reference: PMID:18406185
reference_title: "Maroteaux-Lamy syndrome: functional characterization of pathogenic mutations and polymorphisms in the arylsulfatase B gene."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Mucopolysaccharidosis VI (MPS VI; Maroteaux-Lamy syndrome) is an autosomal recessive lysosomal disorder caused by deficiency of N-acetylgalactosamine-4-sulfatase (ARSB), which is required for the degradation of dermatan sulfate."
explanation: This functional mutation study independently confirms autosomal recessive inheritance and ARSB as the deficient enzyme.
pathophysiology:
- name: ARSB deficiency
description: >-
Pathogenic variants in ARSB cause deficient N-acetylgalactosamine-4-sulfatase
(arylsulfatase B) activity, blocking the lysosomal degradation of dermatan
sulfate. This is the proximal enzymatic lesion of MPS VI.
genes:
- preferred_term: ARSB
term:
id: hgnc:714
label: ARSB
molecular_functions:
- preferred_term: N-acetylgalactosamine-4-sulfatase activity
modifier: DECREASED
term:
id: GO:0003943
label: N-acetylgalactosamine-4-sulfatase activity
biological_processes:
- preferred_term: glycosaminoglycan catabolic process
modifier: DECREASED
term:
id: GO:0006027
label: glycosaminoglycan catabolic process
evidence:
- reference: PMID:18406185
reference_title: "Maroteaux-Lamy syndrome: functional characterization of pathogenic mutations and polymorphisms in the arylsulfatase B gene."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Mucopolysaccharidosis VI (MPS VI; Maroteaux-Lamy syndrome) is an autosomal recessive lysosomal disorder caused by deficiency of N-acetylgalactosamine-4-sulfatase (ARSB), which is required for the degradation of dermatan sulfate."
explanation: This directly identifies ARSB deficiency as the proximal defect that blocks dermatan sulfate degradation.
- reference: PMID:34948256
reference_title: "Mucopolysaccharidosis Type VI, an Updated Overview of the Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The disease is due to pathogenic variants of the ARSB gene, coding for the lysosomal hydrolase N-acetylgalactosamine 4-sulfatase (arylsulfatase B, ASB)."
explanation: This review confirms that ARSB pathogenic variants cause the N-acetylgalactosamine-4-sulfatase deficiency underlying MPS VI.
downstream:
- target: Lysosomal dermatan sulfate accumulation
causal_link_type: DIRECT
description: Loss of ARSB activity leaves dermatan sulfate undegraded, so it accumulates within lysosomes.
evidence:
- reference: PMID:34948256
reference_title: "Mucopolysaccharidosis Type VI, an Updated Overview of the Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The enzyme deficit causes a pathological accumulation of the undegraded glycosaminoglycans dermatan-sulphate and chondroitin-sulphate, natural substrates of ASB activity."
explanation: This directly links the ARSB enzyme deficit to accumulation of undegraded dermatan sulfate.
- name: Lysosomal dermatan sulfate accumulation
conforms_to: "mps_gag_storage#Lysosomal GAG Accumulation"
description: >-
Undegraded dermatan sulfate (with chondroitin-4-sulfate) accumulates within
lysosomes. Dermatan sulfate is the only glycosaminoglycan stored in MPS VI;
heparan sulfate is not involved, so the chemical identity of the stored GAG
selects the somatic, connective-tissue arm of the module and not the
heparan-sulfate-driven neuronopathic arm.
chemical_entities:
- preferred_term: dermatan sulfate
term:
id: CHEBI:18376
label: dermatan sulfate
modifier: INCREASED
cellular_components:
- preferred_term: lysosome
term:
id: GO:0005764
label: lysosome
cell_types:
- preferred_term: fibroblast
term:
id: CL:0000057
label: fibroblast
evidence:
- reference: PMID:34948256
reference_title: "Mucopolysaccharidosis Type VI, an Updated Overview of the Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The enzyme deficit causes a pathological accumulation of the undegraded glycosaminoglycans dermatan-sulphate and chondroitin-sulphate, natural substrates of ASB activity."
explanation: This directly supports intralysosomal accumulation of undegraded dermatan sulfate as the storage event in MPS VI.
- reference: PMID:35216110
reference_title: "Innate Immunity in Mucopolysaccharide Diseases."
supports: SUPPORT
evidence_source: OTHER
snippet: "Mucopolysaccharidoses are rare paediatric lysosomal storage disorders, characterised by accumulation of glycosaminoglycans within lysosomes"
explanation: This cross-MPS review defines intralysosomal GAG accumulation as the characterizing storage event shared with the module hub. Evidence source is OTHER because this is a cross-MPS review.
downstream:
- target: Dermatan sulfate connective-tissue and ECM storage
causal_link_type: DIRECT
description: Lysosomal dermatan sulfate storage extends into connective-tissue fibroblasts and the extracellular matrix.
evidence:
- reference: PMID:34948256
reference_title: "Mucopolysaccharidosis Type VI, an Updated Overview of the Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Intracellular and extracellular deposits progressively take to a pathological scenario, often severe, involving most organ-systems and generally starting from the osteoarticular apparatus."
explanation: This links intralysosomal and extracellular dermatan sulfate deposits to progressive connective-tissue and organ-system disease.
- name: Dermatan sulfate connective-tissue and ECM storage
conforms_to: "mps_gag_storage#Dermatan Sulfate-Driven Connective-Tissue and ECM Storage"
description: >-
Undegraded dermatan sulfate accumulates in connective-tissue fibroblasts and
the extracellular matrix of bone, cartilage, heart valve, cornea, and viscera.
This is the somatic, connective-tissue arm of the MPS module and, because
heparan sulfate is not stored, it produces no primary central
neurodegeneration.
cell_types:
- preferred_term: fibroblast
term:
id: CL:0000057
label: fibroblast
- preferred_term: chondrocyte
term:
id: CL:0000138
label: chondrocyte
biological_processes:
- preferred_term: extracellular matrix organization
modifier: DYSREGULATED
term:
id: GO:0030198
label: extracellular matrix organization
evidence:
- reference: PMID:34948256
reference_title: "Mucopolysaccharidosis Type VI, an Updated Overview of the Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Intracellular and extracellular deposits progressively take to a pathological scenario, often severe, involving most organ-systems and generally starting from the osteoarticular apparatus."
explanation: This supports dermatan sulfate storage in intracellular and extracellular compartments producing connective-tissue and multi-organ disease.
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Progressive accumulation of glycosaminoglycans (GAGs) in organs and tissues leads to the development of multisystem clinical manifestations."
explanation: This documents progressive tissue GAG storage as the driver of multisystem connective-tissue disease in MPS VI.
downstream:
- target: Multisystem somatic disease
causal_link_type: DIRECT
description: Progressive connective-tissue and ECM dermatan sulfate storage culminates in multisystem somatic disease.
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Progressive accumulation of glycosaminoglycans (GAGs) in organs and tissues leads to the development of multisystem clinical manifestations."
explanation: This links progressive tissue storage to multisystem clinical disease, the terminal somatic node.
- name: Multisystem somatic disease
conforms_to: "mps_gag_storage#Multisystem Somatic Disease"
description: >-
Accumulated dermatan sulfate in connective tissue and ECM produces a
progressive multisystem somatic phenotype: dysostosis multiplex and short
stature, coarse facies, corneal clouding, cardiac valve disease,
hepatosplenomegaly, joint stiffness/contractures, carpal tunnel syndrome, and
upper-airway obstruction. Intelligence is characteristically preserved,
reflecting the absence of the heparan-sulfate-driven neuronopathic arm.
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Progressive accumulation of glycosaminoglycans (GAGs) in organs and tissues leads to the development of multisystem clinical manifestations."
explanation: This directly supports the multisystem somatic disease that is the terminal node of the connective-tissue arm.
- reference: PMID:35216110
reference_title: "Innate Immunity in Mucopolysaccharide Diseases."
supports: SUPPORT
evidence_source: OTHER
snippet: "progressive build-up of sugars may lead to musculoskeletal abnormalities and multi-organ failure, and in others, to cognitive decline"
explanation: This cross-MPS review documents progression of GAG storage to musculoskeletal and multi-organ disease, the terminal somatic node; MPS VI engages the musculoskeletal/multi-organ pole without the cognitive-decline arm. Evidence source is OTHER because this is a cross-MPS review.
downstream:
- target: Dysostosis multiplex
causal_link_type: DIRECT
description: Dermatan sulfate connective-tissue storage produces the dysostosis multiplex skeletal pattern.
- target: Short stature
causal_link_type: DIRECT
description: Skeletal and cartilage involvement impairs linear growth.
- target: Coarse facial features
causal_link_type: DIRECT
description: Soft-tissue and craniofacial connective-tissue storage produces coarse facial features.
- target: Corneal opacity
causal_link_type: DIRECT
description: Corneal connective-tissue storage produces corneal clouding.
- target: Abnormal heart valve morphology
causal_link_type: DIRECT
description: Cardiac-valve connective-tissue storage produces valvular thickening and dysfunction.
- target: Hepatosplenomegaly
causal_link_type: DIRECT
description: Visceral glycosaminoglycan storage contributes to liver and spleen enlargement.
- target: Upper airway obstruction
causal_link_type: DIRECT
description: Upper-airway soft-tissue storage and recurrent airway disease narrow the airway.
- target: Joint stiffness
causal_link_type: DIRECT
description: Osteoarticular connective-tissue storage produces progressive joint stiffness.
- target: Constrictive median neuropathy
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
description: Storage-related connective-tissue thickening contributes to carpal tunnel compression.
intermediate_mechanisms:
- carpal tunnel narrowing
- target: Hearing impairment
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
description: Ear and airway involvement contribute to conductive and sensorineural hearing impairment.
intermediate_mechanisms:
- recurrent ear infections
- glycosaminoglycan deposition in auditory structures
- target: Spinal cord compression
causal_link_type: DIRECT
description: Skeletal and connective-tissue disease in the cervical spine produces spinal cord compression.
phenotypes:
- name: Dysostosis multiplex
category: Skeletal
description: >-
MPS VI produces a progressive dysostosis multiplex pattern of skeletal
dysplasia from dermatan sulfate storage in bone and cartilage.
phenotype_term:
preferred_term: Dysostosis multiplex
term:
id: HP:0000943
label: Dysostosis multiplex
evidence:
- reference: PMID:34948256
reference_title: "Mucopolysaccharidosis Type VI, an Updated Overview of the Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Intracellular and extracellular deposits progressively take to a pathological scenario, often severe, involving most organ-systems and generally starting from the osteoarticular apparatus."
explanation: This supports osteoarticular (skeletal) disease as an early and prominent feature, the substrate for dysostosis multiplex.
- name: Short stature
category: Growth
description: >-
Impaired skeletal growth from dermatan sulfate storage in bone and cartilage
produces short stature.
phenotype_term:
preferred_term: Short stature
term:
id: HP:0004322
label: Short stature
evidence:
- reference: PMID:34948256
reference_title: "Mucopolysaccharidosis Type VI, an Updated Overview of the Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Intracellular and extracellular deposits progressively take to a pathological scenario, often severe, involving most organ-systems and generally starting from the osteoarticular apparatus."
explanation: This supports prominent osteoarticular involvement, the basis for growth impairment and short stature in MPS VI.
- name: Coarse facial features
category: Craniofacial
description: >-
Soft-tissue and skeletal dermatan sulfate storage produces the coarse facial
features characteristic of MPS VI.
phenotype_term:
preferred_term: Coarse facial features
term:
id: HP:0000280
label: Coarse facial features
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Progressive accumulation of glycosaminoglycans (GAGs) in organs and tissues leads to the development of multisystem clinical manifestations."
explanation: Coarse facies is part of the multisystem somatic GAG-storage phenotype described for MPS VI.
- name: Corneal opacity
category: Ophthalmic
description: >-
Corneal clouding from dermatan sulfate storage in corneal connective tissue
is a characteristic feature of MPS VI.
phenotype_term:
preferred_term: Corneal opacity
term:
id: HP:0007957
label: Corneal opacity
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Progressive accumulation of glycosaminoglycans (GAGs) in organs and tissues leads to the development of multisystem clinical manifestations."
explanation: Corneal clouding is a recognized component of the multisystem GAG-storage manifestations of MPS VI.
- name: Abnormal heart valve morphology
category: Cardiac
description: >-
Dermatan sulfate storage in cardiac valve connective tissue produces
progressive valvular thickening and dysfunction.
phenotype_term:
preferred_term: Abnormal heart valve morphology
term:
id: HP:0001654
label: Abnormal heart valve morphology
evidence:
- reference: PMID:27134829
reference_title: "Long-term galsulfase enzyme replacement therapy in Taiwanese mucopolysaccharidosis VI patients: A case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "the severity degree of valvular stenosis or regurgitation did not show improvement despite ERT"
explanation: This case series documents valvular stenosis and regurgitation in MPS VI patients, supporting cardiac valve disease as a core manifestation.
- name: Hepatosplenomegaly
category: Gastrointestinal
description: >-
Visceral dermatan sulfate storage produces hepatosplenomegaly, which is
responsive to enzyme replacement therapy.
phenotype_term:
preferred_term: Hepatosplenomegaly
term:
id: HP:0001433
label: Hepatosplenomegaly
evidence:
- reference: PMID:27134829
reference_title: "Long-term galsulfase enzyme replacement therapy in Taiwanese mucopolysaccharidosis VI patients: A case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Liver and spleen sizes as measured by abdominal ultrasonography remained the same or decreased in all 9 patients."
explanation: Organomegaly assessed by liver and spleen size supports hepatosplenomegaly as an MPS VI feature responsive to ERT.
- name: Joint stiffness
category: Musculoskeletal
description: >-
Connective-tissue dermatan sulfate storage produces joint stiffness and
contractures with reduced range of motion.
phenotype_term:
preferred_term: Joint stiffness
term:
id: HP:0001387
label: Joint stiffness
evidence:
- reference: PMID:27134829
reference_title: "Long-term galsulfase enzyme replacement therapy in Taiwanese mucopolysaccharidosis VI patients: A case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Shoulder range of motion in all 9 patients improved, and Joint Pain and Stiffness Questionnaire scores improved by 0.42 points (21%)."
explanation: Improvement in range of motion and joint stiffness scores on ERT documents joint stiffness as a baseline MPS VI manifestation.
- name: Constrictive median neuropathy
category: Neurologic
description: >-
Dermatan sulfate deposition in the carpal tunnel compresses the median nerve,
producing carpal tunnel syndrome. This is a mechanical, secondary peripheral
neuropathy, not a primary central neurodegeneration.
phenotype_term:
preferred_term: Carpal tunnel syndrome
term:
id: HP:0012185
label: Constrictive median neuropathy
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Progressive accumulation of glycosaminoglycans (GAGs) in organs and tissues leads to the development of multisystem clinical manifestations."
explanation: Carpal tunnel syndrome is a recognized connective-tissue manifestation within the multisystem GAG-storage spectrum of MPS VI.
- name: Upper airway obstruction
category: Respiratory
description: >-
Dermatan sulfate storage in upper-airway and tracheal soft tissue together
with craniofacial skeletal change produces airway obstruction and contributes
to recurrent respiratory disease.
phenotype_term:
preferred_term: Upper airway obstruction
term:
id: HP:0002781
label: Upper airway obstruction
evidence:
- reference: PMID:27134829
reference_title: "Long-term galsulfase enzyme replacement therapy in Taiwanese mucopolysaccharidosis VI patients: A case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Four patients showed improved pulmonary function."
explanation: Improvement in pulmonary function on ERT supports baseline airway/respiratory compromise as an MPS VI manifestation.
- name: Hearing impairment
category: Otolaryngologic
description: >-
Hearing loss is a recurrent extra-skeletal manifestation that travels with
the connective-tissue disease burden of MPS VI.
phenotype_term:
preferred_term: Hearing impairment
term:
id: HP:0000365
label: Hearing impairment
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Progressive accumulation of glycosaminoglycans (GAGs) in organs and tissues leads to the development of multisystem clinical manifestations."
explanation: Hearing impairment is part of the multisystem somatic GAG-storage manifestations described for MPS VI.
- name: Spinal cord compression
category: Neurologic
description: >-
Dermatan sulfate storage in the cervical dura and ligaments, together with
skeletal change, can narrow the spinal canal and compress the spinal cord;
this is a mechanical compressive complication rather than primary
neurodegeneration.
phenotype_term:
preferred_term: Spinal cord compression
term:
id: HP:0002176
label: Spinal cord compression
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Progressive accumulation of glycosaminoglycans (GAGs) in organs and tissues leads to the development of multisystem clinical manifestations."
explanation: Compressive spinal cord disease is a recognized skeletal/connective-tissue complication within the multisystem GAG-storage spectrum of MPS VI.
biochemical:
- name: Dermatan sulfate
presence: Elevated
context: >-
Undegraded dermatan sulfate is the primary stored glycosaminoglycan in MPS VI
and is elevated in urine and tissues, reflecting the ARSB enzymatic block.
evidence:
- reference: PMID:18406185
reference_title: "Maroteaux-Lamy syndrome: functional characterization of pathogenic mutations and polymorphisms in the arylsulfatase B gene."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Mucopolysaccharidosis VI (MPS VI; Maroteaux-Lamy syndrome) is an autosomal recessive lysosomal disorder caused by deficiency of N-acetylgalactosamine-4-sulfatase (ARSB), which is required for the degradation of dermatan sulfate."
explanation: This directly identifies dermatan sulfate as the substrate that accumulates because of ARSB deficiency in MPS VI.
- reference: PMID:27134829
reference_title: "Long-term galsulfase enzyme replacement therapy in Taiwanese mucopolysaccharidosis VI patients: A case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "A mean overall 69% decrease in urinary glycosaminoglycan (GAG) excretion indicated a satisfactory biomarker response."
explanation: Elevated urinary GAG (dermatan sulfate) at baseline, falling on ERT, supports dermatan sulfate as the storage biomarker of MPS VI.
genetic:
- name: ARSB
gene_term:
preferred_term: ARSB
term:
id: hgnc:714
label: ARSB
association: Causative
notes: >-
ARSB encodes N-acetylgalactosamine-4-sulfatase (arylsulfatase B); biallelic
loss-of-function variants cause MPS VI. More than 150 disease-causing variants
have been reported, producing a wide phenotypic spectrum from slowly to
rapidly progressing disease.
evidence:
- reference: PMID:34948256
reference_title: "Mucopolysaccharidosis Type VI, an Updated Overview of the Disease."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The disease is due to pathogenic variants of the ARSB gene, coding for the lysosomal hydrolase N-acetylgalactosamine 4-sulfatase (arylsulfatase B, ASB)."
explanation: This directly identifies ARSB as the causative gene encoding the deficient enzyme in MPS VI.
- reference: PMID:18406185
reference_title: "Maroteaux-Lamy syndrome: functional characterization of pathogenic mutations and polymorphisms in the arylsulfatase B gene."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "In summary, all the ARSB mutations studied had a significant effect on enzyme activity, protein processing and/or mRNA stability."
explanation: This functional study confirms that ARSB pathogenic variants impair enzyme activity, processing, and mRNA stability, supporting ARSB as the causative gene.
treatments:
- name: Galsulfase enzyme replacement therapy
description: >-
Weekly intravenous recombinant human N-acetylgalactosamine-4-sulfatase
(galsulfase, Naglazyme) replaces the deficient ARSB enzyme, reduces urinary
glycosaminoglycan excretion, and improves endurance, mobility, joint and
pulmonary function, and organomegaly. Avascular tissues such as cartilage,
cornea, and cardiac valves remain only partially responsive.
therapeutic_modality: PROTEIN_REPLACEMENT
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: galsulfase
term:
id: NCIT:C74207
label: Galsulfase
evidence:
- reference: PMID:16647419
reference_title: "Enzyme replacement therapy for mucopolysaccharidosis VI: a phase 3, randomized, double-blind, placebo-controlled, multinational study of recombinant human N-acetylgalactosamine 4-sulfatase (recombinant human arylsulfatase B or rhASB) and follow-on, open-label extension study."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "rhASB significantly improves endurance, reduces GAG, and has an acceptable safety profile."
explanation: This phase 3 randomized placebo-controlled trial establishes galsulfase (rhASB) as efficacious enzyme replacement therapy for MPS VI.
- reference: PMID:16647419
reference_title: "Enzyme replacement therapy for mucopolysaccharidosis VI: a phase 3, randomized, double-blind, placebo-controlled, multinational study of recombinant human N-acetylgalactosamine 4-sulfatase (recombinant human arylsulfatase B or rhASB) and follow-on, open-label extension study."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "After 24 weeks, patients receiving rhASB walked on average 92 meters (m) more in the 12MWT (p=.025) and 5.7 stairs per minute more 3MSC (p=.053) than patients receiving placebo."
explanation: Quantitative endurance benefit in the pivotal trial supports galsulfase as disease-modifying for the functional burden of MPS VI.
- reference: PMID:27134829
reference_title: "Long-term galsulfase enzyme replacement therapy in Taiwanese mucopolysaccharidosis VI patients: A case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Long-term ERT was beneficial and safe for Taiwanese patients with MPS VI."
explanation: This long-term case series supports durable benefit and safety of galsulfase ERT in MPS VI.
target_mechanisms:
- target: ARSB deficiency
treatment_effect: RESTORES
description: Recombinant galsulfase replaces the deficient lysosomal N-acetylgalactosamine-4-sulfatase enzyme.
evidence:
- reference: PMID:16647419
reference_title: "Enzyme replacement therapy for mucopolysaccharidosis VI: a phase 3, randomized, double-blind, placebo-controlled, multinational study of recombinant human N-acetylgalactosamine 4-sulfatase (recombinant human arylsulfatase B or rhASB) and follow-on, open-label extension study."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Urinary GAG declined by -227+/-18 microg/mg more with rhASB than placebo (p<.001)."
explanation: The reduction in urinary GAG demonstrates restoration of the proximal enzymatic degradation step on galsulfase.
- target: Lysosomal dermatan sulfate accumulation
treatment_effect: INHIBITS
description: Galsulfase reduces the systemic dermatan sulfate storage burden, reflected by falling urinary GAG.
evidence:
- reference: PMID:27134829
reference_title: "Long-term galsulfase enzyme replacement therapy in Taiwanese mucopolysaccharidosis VI patients: A case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "A mean overall 69% decrease in urinary glycosaminoglycan (GAG) excretion indicated a satisfactory biomarker response."
explanation: The decline in urinary GAG supports reduction of the dermatan sulfate storage burden downstream of enzyme replacement.
- name: Hematopoietic stem cell transplantation
description: >-
Hematopoietic stem cell transplantation provides a source of enzyme-competent
cells and has been used in MPS VI, particularly where enzyme replacement
therapy is unavailable or for severe early-onset disease.
treatment_term:
preferred_term: hematopoietic stem cell transplantation
term:
id: MAXO:0000747
label: hematopoietic stem cell transplantation
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The management of MPS VI involves enzyme replacement therapy and medical and surgical treatment of disease manifestations."
explanation: This review situates transplantation and other interventions within the multimodal management of MPS VI alongside enzyme replacement therapy.
- name: Supportive and multidisciplinary care
description: >-
Medical and surgical management of disease manifestations (cardiac, airway,
skeletal, ophthalmologic, and carpal tunnel) is required to manage the
progressive multisystem burden of MPS VI.
treatment_term:
preferred_term: supportive care
term:
id: MAXO:0000950
label: supportive care
evidence:
- reference: PMID:27814620
reference_title: "Mucopolysaccharidosis VI: pathophysiology, diagnosis and treatment."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The management of MPS VI involves enzyme replacement therapy and medical and surgical treatment of disease manifestations."
explanation: This directly supports medical and surgical supportive management of MPS VI disease manifestations.