Savants are people who lack many attributes across the spectrum of how humans view mental capacity, however they are extremely skilled in one or two areas. Savant syndrome can be congenital or brought on by injury/disease, and is often compounded with autism. Prodigious savants normally lack in emotional intelligence, but excel in crystallized intelligence in specific areas. One skill that shows up most often in savants is exceptional musical ability. Rex Lewis-Clack is one such example. He shows exceptional skills with the piano, while also being blind, autistic, and relatively unsociable. These skills are replicable in other savants, although areas of interest differ from person to person.
According to this article, around 100 prodigious savants have been recorded in the last 100 years. The qualities in many of them are replicable in other savants as well. They all show enormous talent in some specific area and are, in many cases, more talented than average people in the savant's area of expertise. Take for instance Daniel Tammet, who is a mathematical savant. He is capable of doing huge calculations in his head and can out-calculate calculators and computers. His exceptional skills in one area of his intelligence does not transfer over to other areas.
Although it is possible that supposed savant syndrome sufferers achieved their exceptional skills through years of hard work, it is extremely unlikely. The skills that savants have develop quickly and it is almost impossible to replicate through training. It is truly like their brains are able to tap into something most humans can't.