Canavan disease is a leukodystrophy characterized by neurodevelopmental delays, macrocephaly, and tone abnormalities. The phenotypic spectrum ranges from the more severe typical Canavan disease (85%-90% of individuals) to the less severe atypical Canavan disease (10%-15%). Typical Canavan disease is characterized by neurodevelopmental impairment evident by ages three to five months, followed by neurodegeneration and developmental regression. The clinical course of atypical Canavan disease is more variable, with neurodevelopmental delay usually becoming evident in the first years of life and frequently followed by developmental regression later in childhood or adolescence. All individuals with Canavan disease have reduced life expectancy, with the majority surviving to age ten years and the minority living to adulthood.