This research program aims at characterizing new forms of pediatric-onset neurodegenerative disorders and at improving the knowledge on the known forms of neurodegenerative disorders. For the next four years, I will concentrate my work on pediatric-onset leukodystrophies or inherited degenerative diseases of the white matter of the brain (myelin). These diseases have a huge impact on the affected child, its parents and caregivers. At the end of their disease, before they die, these children are totally dependent. There are only few data on the epidemiology of this group of orphan diseases. It is estimated that 30-40% of patients with leukodystrophies remain without a precise diagnosis despite the fact that multiple tests were done. From a constantly growing cohort of affected children, this research program aims at (1) Characterizing new forms of leukodystrophies; describing their manifestations, their abnormalities on brain imaging and their causal gene(s) as well as studying the reason(s) why children with these disorders are sick, (2) Improving the knowledge on the already described leukodystrophies and, (3) Establish the first Quebec patient Registry on leukodystrophies. This research program will improve our knowledge on this group of orphan diseases, the reason why these disorders occur and eventually will lead to the development of treatments. It will allow doctors to better diagnose the affected patients. Finally, what is learned through this research project will lead to a better understanding of how the myelin develop in the brain and will shed light on the mechanisms underlying the more common acquired cerebral myelin disorders.