Question: What are the genetic changes related to hereditary hyperekplexia ?
Answer: At least five genes are associated with hereditary hyperekplexia. Most of these genes provide instructions for producing proteins that are found in nerve cells (neurons). They play a role in how neurons respond to a molecule called glycine. This molecule acts as a neurotransmitter, which is a chemical messenger that transmits signals in the nervous system. Gene mutations that cause hereditary hyperekplexia disrupt normal cell signaling in the spinal cord and the part of the brain that is connected to the spinal cord (the brainstem). Approximately 80 percent of cases of hereditary hyperekplexia are caused by mutations in the GLRA1 gene. The GLRA1 gene provides instructions for making one part, the alpha ()1 subunit, of the glycine receptor protein. GLRA1 gene mutations lead to the production of a receptor that cannot properly respond to glycine. As a result, glycine is less able to transmit signals in the spinal cord and brainstem. Mutations in the other four genes account for a small percentage of all cases of hereditary hyperekplexia. A disruption in cell signaling caused by mutations in the five genes associated with hereditary hyperekplexia is thought to cause the abnormal muscle movements, exaggerated startle reaction, and other symptoms characteristic of this disorder.
Source: GHR