Daniel Tammet was, for the last several years, hailed as the world's first-ever prodigious autistic savant. His language and mathematical skills seemed quite amazing.
But, I haven't read about him since a year or two ago. Why?
He had somewhat quietly described his increasing disinterest in agreeing with even more research about himself. He had already been poked and prodded, measured and weighed, questioned and spotlighted more than most others would tolerate. So, maybe he "dropped out" of the racket.
Others have doubted his skills claiming that he used simple memory skills to achieve feats like reciting Pi to about 23,000 decimal points. So, maybe he had been "found out" and suddenly went into hiding.
Who knows?