Savant syndrome
Savant syndrome, sometimes abbreviated as savantism, is not a recognized medical diagnosis, but researcher Darold Treffert defines it as a rare condition in which persons with developmental disorders (including autism spectrum disorders) have one or more areas of expertise, ability or brilliance that are in contrast with the individual's overall limitations.  Treffert says the condition can be genetic, but can also be acquired,  and coexists with other developmental disabilities "such as mental retardation or brain injury or disease that occurs before (pre-natal) during (peri-natal) or after birth (post-natal), or even later in childhood or adult life."
Individuals with the syndrome are often simply called savants. This can be a source of confusion since savant can also mean a person of learning, especially one of great knowledge in a particular subject. The terms idiot savant or autistic savant are also used.  "Idiot" was used by the medical profession in the late 19th and early 20th century to refer to a person whose IQ was less than 20, although that usage has now given way to "profound mental retardation"; the term idiot savant is no longer regarded as a valid medical term.
According to Treffert, about half of persons with savant syndrome have autistic disorder, while the other half have another developmental disability, mental retardation, brain injury or disease. He says, "...  not all savants are autistic, and not all autistic persons are savants."  Other researchers state that autistic traits and savant skills may be linked, or have challenged some earlier conclusions about savant syndrome as "hearsay, uncorroborated by independent scrutiny".

# Characteristics
According to Treffert, something that almost all savants have in common is a remarkable memory: a memory that he describes as "exceedingly deep but very, very narrow".
Savant-like skills may be latent in everyone.  Allan Snyder attempted to simulate savant impairment in normal controls by "directing low-frequency magnetic pulses into the left fronto-temporal lobe" of the brain.  Differences were observed in four of 11 subjects.
An autistic savant (historically described as an idiot savant) is a person with both autism and savant skills.   Autistic savants may have mental abilities called splinter skills. Why autistic savants are capable of these astonishing feats is not quite clear. Some savants have obvious neurological abnormalities (such as the lack of corpus callosum in Kim Peek's brain). Many savants are known to have abnormalities in the left hemisphere of the brain.

# Causes and pathophysiology
The Savant Syndrome is poorly understood. There is no cognitive theory that explains the combination of talent and deficit found in savants 
Savant syndrome is four to six times more frequent in males than females, and this delta is not entirely explained by the preponderance of males in the autistic population . This has led to suggestions  that the Geschwind-Galaburda Hypothesis applies to savant syndrome where both the brain injury and savantism appear to be congenital.
The vast majority of savants are born savants, there are also cases in which an individual gains savant status in later life due to a brain injury.  Examples of these rare occurrences are; Orlando Serrell who was hit by a baseball on the left side of the head at age 10 in 1979.  After the accident he developed calendar calculating skills and  an autobiographical memory.

# Epidemiology
According to Treffert:
- 10% of people on the autistic spectrum have savant skills
- Less than 1% of persons with other developmental disabilities have savant skills
- 50% of savants are autistic; the other 50% have different disabilities, mental retardation, brain injury or a brain disease
- Male savants outnumber female savants by four to six times.

# History
According to Treffert, the term idiot savant was first used to describe the condition in 1887 by Dr. John Langdon Down, who is known for his description of Down Syndrome.
Working in an institution for people with mental illness, he was stunned by the occasional "idiot savant" he would come across.  There are accounts of him meeting a boy who after reading a book once could recite it back perfectly, another who could do considerably large mental calculations faster than someone could write them down on paper, and  a savant who could calculate time with near perfect accuracy without looking at a clock.  In that time period it was a mystery to scientists and psychologists alike how genius can be mixed with disability.  Today much more is known about savants, but it has been only within the past 20 years that the mystery of savants has begun to unravel.

# Society and culture
Kim Peek was the basis for the 1988 fictional film Rain Man, although his diagnosis is no longer autism.

## Famous prodigious savants
There are only about 100 recognized prodigious savants in the world.
- Alonzo Clemons, American clay sculptor.
- Tony DeBlois, blind American musician.
- Leslie Lemke, blind American musician.
- Jonathan Lerman, American artist.
- Thristan Mendoza, Filipino marimba prodigy.
- Derek Paravicini, blind British musician.
- James Henry Pullen, gifted British carpenter.
- Matt Savage, U.S. autistic jazz prodigy.
- Henriett Seth-F., Hungarian autistic savant, poet, writer and artist.
- Daniel Tammet, British autistic savant.
- Stephen Wiltshire, British architectural artist.
- Richard Wawro, Scottish artist.