Neurological Disorder Linked to Genetic Mutations

A gene has been detected that is linked to epilepsy in babies and movement disorders in older children.

The gene has been associated with the rare childhood neurological disorder known as paroxysmal kinesigenic dyskinesia with infantile convulsions or PKD/IC.

A large international team led by scientists at the University of California, San Francisco (UCSF; USA) studied ways that could help to improve the diagnosis of PKD/IC and may also help to explain other movement disorders, such as Parkinson's disease. The team has identified a perplexing gene in the brain called proline-rich transmembrane protein 2 (PRRT2). No knowledge exists about the function or ability of this gene, which bears little resemblance to anything else in the human genome.

The scientists conducted the study on a cohort of 103 families, which included one or more members with the PKD/IC manifestation. The investigators identified mutations in the PRRT2 gene that is present in the brain and spinal cord, during genetic testing of the families. The mutation causes the proteins that the PRRT2 gene encodes to shorten or to completely disappear from the individual's brain and spinal cord. According to the investigative team, the neurological symptoms may be caused due to a loss of neuronal regulation, meaning that when the genetic mutations cause the gene products to disappear, the nerve cells, which normally appear in those locations, may become overly excited, firing signals too frequently or strongly, which leads to the involuntary movements.

Louis Ptacek, MD, the senior author of the study, said, "This is both exciting and a little bit scary. Understanding the underlying biology of this disease is absolutely going to help us understand movement disorders in general." PKD/IC is a rare disorder in infants with epileptic seizures, affecting approximately one in every 100,000 children in the US, according to Prof. Ptacek's estimation. It commonly disappears within a year or two but often reemerges later in childhood as a movement disorder, which is characterized by sudden, startling, involuntary jerks when the children start moving. In some children just the thought of moving will cause them to jerk involuntarily. The disease is classified as idiopathic, which, is basically just another way of saying the cause is unknown. The study was published in the January 2012 issue of Cell Reports.

UCSF

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