Like a silent assassin neurodegenerative diseases can cause the central nervous system to slowly deteriorate over time, which can lead to severe disorders involving movement or cognition. Neurodegenerative diseases, which can include Parkinson’s, Alzheimer’s, and Huntington’s disease, cause permanent damage, so symptoms tend to worsen over time, with no cure available currently.
A new neurodegenerative disease
Now, a study from researchers led by MCRI identifies a previously unknown neurodegenerative disease in children where they experience developmental degradation and severe epilepsy. The team states they have identified a variation in the specific gene that causes this never-before-recorded chronic neurodegenerative disorder in children. The study is published in the journal American Journal of Human Genetics.
Previous studies show Reactive Oxygen Species (ROS) produced by immune cells called phagocytes are essential for host defense against bacterial and fungal infections. It has been established that individuals with defective ROS regulation are at risk of developing serious, life-threatening infections or tissue damage due to a malfunctioning immune system.
Most recently a protein dubbed as the Negative Regulator of ROS (NRROS) has been shown to be heavily involved in regulating ROS, enabling phagocytes to produce higher amounts of ROS when controlling pathogens whilst minimizing tissue damage. The current study investigates whether the loss of NRROS functionality causes a previous unknown childhood neurodegenerative disorder.
The genetic basis of a new disease
The current study examines six children from four different families with normal or mild developmental delay and seizures starting before one year of age. Results show a mutation in the NRROS gene was present in all the study participants requiring two copies of the defective gene, meaning both parents must be carriers. Data findings show all participants with the NRROS mutation had neurodegenerative disease consisting of intractable epilepsy, developmental retrogradation, and reduced white matter volume with insufficient myelination, a protective covering for nerves.
The lab then traced the cellular pathway affected by the NRROS mutation via the insertion of the NRROS gene into cells in culture. Results show the molecules the NRROS gene interact with are crucial for a number of brain cell functions, including myelination and producing microglia, the immune cells of the brain. The group states these data are in-line with neuroimaging results, verified by genomic sequencing which has saved years of study.
Target for the new brain disorder
The team surmises they have identified a previously unrecorded neurological developmental disorder in six children presenting with mutations in the NRROS gene. For the future, the researchers state targeted therapeutics may now be developed specific to this disorder due to the fact the causative gene has been identified.
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