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| ARSA | |
|---|---|
| Name | ARSA |
| Synonyms | arylsulfatase A deficiency; metachromatic leukodystrophy (juvenile/adult forms related) |
| Field | Neurology; Genetics; Metabolic disorders |
ARSA
ARSA denotes arylsulfatase A, a lysosomal enzyme whose deficiency underlies certain leukodystrophies and sulfatide storage disorders. The enzyme is encoded by the ARSA gene on human chromosome 22 and participates in glycosphingolipid catabolism within lysosomes. Defects in ARSA manifest with neurodegenerative features, peripheral neuropathy, and varied age-at-onset phenotypes that overlap with pediatric, adolescent, and adult neurologic syndromes.
ARSA encodes a sulfatase critical for degradation of cerebroside 3-sulfate (sulfatide) in lysosomes; its loss causes accumulation of sulfatide in oligodendrocytes and Schwann cells, leading to demyelination and white matter degeneration. The biochemical cascade links ARSA deficiency to demyelinating phenotypes documented in clinical series and case reports from centers such as Mayo Clinic, Johns Hopkins Hospital, Massachusetts General Hospital, Great Ormond Street Hospital, and research groups at NIH, Wellcome Trust Sanger Institute, and European Molecular Biology Laboratory. The disorder intersects with clinical entities described in classic neurology texts by authors at Oxford University Press, Springer Nature, and Elsevier.
The ARSA gene resides on chromosome 22q13 and produces a precursor protein processed in the endoplasmic reticulum and Golgi before lysosomal trafficking. Pathogenic variants include missense, nonsense, frameshift, splice-site mutations, and large deletions reported in databases curated by ClinVar, Human Gene Mutation Database, and consortia such as the 1000 Genomes Project and Genome Aggregation Database. The molecular mechanism involves impaired hydrolysis of cerebroside 3-sulfate by ARSA, with secondary effects on lysosomal function, sphingolipid homeostasis, and inflammatory cascades mediated by microglia and astrocytes studied at institutions like Karolinska Institutet and Max Planck Institute.
Models of ARSA deficiency employ knockout mice and patient-derived induced pluripotent stem cells developed at laboratories including University of California, San Francisco, Stanford University, and University College London; these models reveal demyelination, neuronal dysfunction, and peripheral nerve pathology paralleling findings in historical neuropathology series from Charité – Universitätsmedizin Berlin and neuropathologists such as those trained at Hopkins Medical Institutions.
Phenotypes range from infantile to late-onset forms, with early-onset presentations classically described in pediatric neurology cohorts at Children’s Hospital of Philadelphia and Boston Children’s Hospital, and adult-onset phenotypes reported by investigators at Mayo Clinic and Cleveland Clinic. Clinical features include progressive motor regression, hypotonia, spasticity, ataxia, cognitive decline, peripheral neuropathy, and visual or auditory impairment noted in longitudinal studies from Johns Hopkins University and University of Toronto.
Diagnosis integrates biochemical assays measuring ARSA enzymatic activity in leukocytes or fibroblasts performed in reference laboratories at ARUP Laboratories, Quest Diagnostics, and Molecular Genetics Laboratories alongside neuroimaging with MRI patterns of diffuse white matter hyperintensity described in radiology series from Massachusetts General Hospital Radiology Department and electrophysiology demonstrating demyelinating neuropathy documented in electrophysiology centers at Mayo Clinic. Genetic confirmation uses sequencing panels or whole-exome sequencing offered by commercial providers such as Invitae, GeneDx, and academic centers participating in the Undiagnosed Diseases Network.
Management is multidisciplinary, involving neurology, rehabilitation, pain specialists, and genetic counseling teams at tertiary centers including Mount Sinai Hospital, UCSF Medical Center, and Toronto General Hospital. Supportive care targets spasticity, seizures, respiratory compromise, and nutritional needs, drawing on therapeutic approaches refined in clinics affiliated with Royal Free Hospital and Hospital for Sick Children (SickKids). Disease-modifying strategies under investigation include hematopoietic stem cell transplantation protocols pioneered by groups at St. Jude Children’s Research Hospital and Great Ormond Street Hospital, enzyme replacement therapies explored by biotechnology firms collaborating with National Institutes of Health, and gene therapy programs advanced at University of Pennsylvania and corporate-academic partnerships with Bluebird Bio and Sangamo Therapeutics.
Clinical trials have been coordinated through trial networks such as ClinicalTrials.gov, academic consortia at European Leukodystrophy Association, and patient advocacy organizations including Leukodystrophy Care, which facilitate natural history studies, outcome measure development, and regulatory interactions with U.S. Food and Drug Administration and European Medicines Agency.
Epidemiologic estimates derive from newborn screening panels, population genetics surveys from Icelandic Biobank and FinnGen, and registry data maintained by advocacy groups; incidence varies by population with founder mutations reported in distinct ethnic groups documented in studies from Israel, Japan, Finland, and Brazil. Prognosis depends on age at onset and therapeutic access: infantile-onset forms carry rapid progression and high mortality without intervention, whereas late-onset presentations may show protracted courses with variable disability, as reported in outcome series from Mayo Clinic and European referral centers.
Historical descriptions of sulfatide storage and leukodystrophy trace to early 20th-century neuropathologists and biochemical work at laboratories such as Rockefeller University and Pasteur Institute. Key advances include molecular cloning of the ARSA gene, characterization of pathogenic alleles by investigators at Cold Spring Harbor Laboratory and structural elucidation of sulfatases through work at European Synchrotron Radiation Facility. Contemporary research priorities emphasize biomarker discovery, improved cellular and animal models produced at MIT, and translational trials integrating gene editing and stem cell approaches discussed at conferences hosted by Society for Neuroscience and American Academy of Neurology.
Category:Lysosomal storage disorders