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Hyperekplexia: pedigree studies in two families
T Hayashi1, H Tachibana, T Kajii
1Department of Pediatrics, Yamaguchi University School of Medicine, Japan.
American Journal of Medical Genetics
|August 1, 1991
Summary
Hyperekplexia, a rare neonatal startle disorder, was studied in Japanese families. Clonazepam effectively treated symptoms in infants and children, suggesting autosomal dominant inheritance with variable expression.
Area of Science:
- Genetics
- Neurology
- Pediatrics
Background:
- Hyperekplexia is a rare autosomal dominant disorder characterized by an exaggerated startle response.
- Neonatal onset is typical, often presenting with infantile hypertonia and hypokinesia.
Purpose of the Study:
- To investigate the genetic basis and clinical manifestations of hyperekplexia in Japanese families.
- To evaluate the efficacy of clonazepam in treating hyperekplexia symptoms.
Main Methods:
- Clinical observation and genetic analysis of affected individuals across two Japanese families and literature review.
- Treatment response assessment with clonazepam in affected infants and children.
Main Results:
- Two unrelated Japanese families exhibited hyperekplexia with varied symptoms including exaggerated startle, hypertonia, and myoclonus.
- Clonazepam treatment provided significant relief for affected infants and children.
- Genetic analysis supports autosomal dominant inheritance with complete penetrance and variable expressivity, distinct from reported autosomal recessive forms.
Conclusions:
- Hyperekplexia in these families demonstrates autosomal dominant inheritance with significant clinical variability.
- Clonazepam is an effective therapeutic option for managing hyperekplexia symptoms in neonates and children.