Familial Hyperekplexia

Synonyms:

a.k.a. Familial startle disease

Diagnosis:

This is a clinical diagnosis

Genetics:

  • Autosomal dominant, autosomal recessive (frame shift)
  • Glycine Receptor alpha subunit GLRA1 5q32

Clinical features:

Infants: stiff (except when sleeping), excessive startle response
Older patients: Sudden myoclonus or falling
Spastic paraparesis in one family
Precipitated by sudden stimuli

Treatment:

Responds to benzodiazepines

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