For the estimated 3% of people who experience the prickly, twitchy, downright creepy sensation of restless-leg syndrome (RLS), there is a bit of welcome news. Icelandic researchers studied nearly 1,000 RLS subjects and their family members and traced uncontrolled limb movements, one symptom of the condition, to a gene that regulates the body's iron levels. Studying the gene could help scientists figure out how to shut RLS off at its source.