From DMJ Productions
Kim Peek, the savant who was the inspiration for the main character in the movie Rain Man

Savant syndrome () is a phenomenon, sometimes following a brain injury, where someone demonstrates exceptional aptitude in one domain, such as art or mathematics, despite significant social or intellectual impairment.

Those with the condition generally have a neurodevelopmental disorder such as autism spectrum disorder or have a brain injury. About half of cases are associated with autism, and these individuals may be known as "autistic savants". While the condition usually becomes apparent in childhood, some cases develop later in life. It is not recognized as a mental disorder within the DSM-5, as it relates to parts of the brain healing or restructuring.

Savant syndrome is estimated to affect around one in a million people.

From Wikipedia