Epilepsy and electroencephalographic abnormalities in C9orf72 repeat expansion

Area of Science:

• Neuroscience
• Genetics
• Neurology

Background:

• Frontotemporal dementia (FTD) is a group of disorders characterized by progressive behavioral changes or language impairment.
• C9orf72 repeat expansion is the most common genetic cause of FTD and amyotrophic lateral sclerosis (ALS).
• Electroencephalography (EEG) is a neurophysiological monitoring method used to record electrical activity of the brain.

Purpose of the Study:

• To investigate the electroencephalographic (EEG) characteristics of patients with C9orf72 repeat expansion.
• To determine if specific EEG findings are associated with the C9orf72 phenotype.
• To identify previously unrecognized features of C9orf72-related frontotemporal cognitive decline.

Main Methods:

• Retrospective analysis of EEG recordings from five patients with genetically confirmed C9orf72 repeat expansions.
• Clinical data review focusing on cognitive decline and neurological symptoms.
• Comparison of EEG findings with existing literature on C9orf72-related disorders.

Main Results:

• One patient previously described showed abnormally slowed background EEG activity and a photoparoxysmal response.
• Analysis of five patients revealed abnormally slowed background activity in some individuals with C9orf72 repeat expansions.
• Epilepsy was identified as a potential, previously unrecognized feature in some patients with this genetic expansion.

Conclusions:

• Abnormally slowed background EEG activity is a potential feature of the C9orf72 phenotype.
• Epilepsy may represent a previously unrecognized clinical manifestation in patients with C9orf72 repeat expansions.
• These findings expand the understanding of the C9orf72-related neurological disorder spectrum.