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X-linked intellectual disability, Snyder type

Orpha number ORPHA3063
Synonym(s) Snyder-Robinson syndrome
Prevalence <1 / 1 000 000
  • X-linked recessive
Age of onset Adolescence / Young adulthood
ICD-10 -
MeSH -
MedDRA -


This syndrome is characterised by moderate intellectual deficit, hypotonia, an unsteady gait, osteoporosis, kyphoscoliosis and facial asymmetry. It has been described in 11 males. Transmission is X-linked recessive and the syndrome has been associated with a mutation in the spermine synthase (SMS) gene, localised to segment 22.1 on the short arm of the X chromosome (Xp22.1).

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Detailed information

Clinical genetics review
  • EN (2013)
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