Learn About Hereditary Hyperekplexia

What is the definition of Hereditary Hyperekplexia?

Hereditary hyperekplexia is a condition in which affected infants have increased muscle tone (hypertonia) and an exaggerated startle reaction to unexpected stimuli, especially loud noises. Following the startle reaction, infants experience a brief period in which they are very rigid and unable to move. During these rigid periods, some infants stop breathing, which, if prolonged, can be fatal. Infants with hereditary hyperekplexia have hypertonia at all times, except when they are sleeping.

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What are the causes of Hereditary Hyperekplexia?

Mutations in multiple genes have been found to cause hereditary hyperekplexia. Most of these genes provide instructions for producing proteins that are found in nerve cells (neurons). These proteins are involved in the response of neurons to a molecule called glycine. This molecule is an amino acid, which is a building block of proteins. Glycine also acts as a neurotransmitter, which is a chemical messenger that transmits signals in the nervous system. Gene mutations that cause hereditary hyperekplexia disrupt normal glycine signaling in neurons in the spinal cord and the part of the brain that is connected to the spinal cord (the brainstem). Abnormal signaling in neurons in the brain and neurons that send signals to muscles throughout the body result in abnormal muscle movements, exaggerated startle reaction, and other symptoms characteristic of this disorder.

How prevalent is Hereditary Hyperekplexia?

The exact prevalence of hereditary hyperekplexia is unknown. This condition has been identified in more than 150 individuals worldwide.

Is Hereditary Hyperekplexia an inherited disorder?

Hereditary hyperekplexia has different inheritance patterns.

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What are the latest Hereditary Hyperekplexia Clinical Trials?
Hyperekplexia in Patients With Loss-of-function CTNNB1 Mutation

Summary: A few years ago, a new genetic disorder (OMIM # 615075) has been associated with loss-of-function variations in the CTNNB1 gene. The clinical features include a delayed psychomotor development usually leading to severe intellectual disability with or without autistic spectrum disorders, progressive spastic diplegia, and various visual defects. Among over 30 cases described worldwide, 2 were report...

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High-Dose Immunosuppressive Therapy Using Carmustine, Etoposide, Cytarabine, and Melphalan (BEAM) + Thymoglobulin Followed by Syngeneic or Autologous Hematopoietic Cell Transplantation for Patients With Autoimmune Neurologic Diseases

Summary: This phase II trial studies the side effects and how well carmustine, etoposide, cytarabine and melphalan together with antithymocyte globulin before a peripheral blood stem cell transplant works in treating patients with autoimmune neurologic disease that did not respond to previous therapy. In autoimmune neurological diseases, the patient's own immune system 'attacks' the nervous system which mi...

Who are the sources who wrote this article ?

Published Date: May 01, 2018Published By: National Institutes of Health

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