Hyperekplexia in two siblings.

Hyperekplexia is a rare, hereditary, non-epileptic disorder characterized by an exaggerated startle reaction to unexpected auditory, somatosensory and visual stimuli. The authors describe a one-day-old term neonate, who presented with jitteriness and episodic tonic spasms, and his elder sister with hyperekplexia. Hyperekplexia though is a rare disorder is one of the differential diagnoses for refractory tonic spasms in infancy. The prognosis is generally good in hereditary hyperekplexia. Recent molecular studies have revealed many associated mutations in the glycine receptor alpha and beta subunit genes.