In the Realms of the Unreal (2004)

a.k.a. 

Disabilities:  Learning difficulties

Comments:   The story of the fraught difficult life of Henry Darger, an American painter. At four his mother died and his older sister was removed from the family and adopted. His father died at eight which resulted in Darger being put in an institution for children with learning difficulties. At eighteen he escaped and worked as a janitor (caretaker).

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http://www.imdb.com/title/tt0390123/