Orphanet: Allan Herndon Dudley syndrome

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Allan-Herndon-Dudley syndrome

Disease definition

Allan-Herndon-Dudley syndrome (AHDS) is an X-linked intellectual disability syndrome with neuromuscular involvement characterized by infantile hypotonia, muscular hypoplasia, spastic paraparesis with dystonic/athetoic movements, and severe cognitive deficiency.


  • Synonym(s):
    • AHDS
    • MCT8 deficiency
    • Monocarboxylate transporter 8 deficiency
    • X-linked intellectual disability-hypotonia syndrome
  • Prevalence: <1 / 1 000 000
  • Inheritance: X-linked recessive 
  • Age of onset: Neonatal, Infancy
  • ICD-10: G31.8
  • OMIM: 300523
  • UMLS: C0795889
  • MeSH: C537047
  • GARD: 5617
  • MedDRA: -

Detailed information

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Additional information

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