Abraham Lincoln's appearance and historical documents that note his especially clumsy gait have long caused researchers to puzzle over whether he may have had a genetic disorder called Marfan syndrome. Now, members of the beloved president's family tree are wondering if Lincoln had a different, incurable hereditary disease called ataxia that affects the coordination it takes to walk, write, speak and swallow. Researchers at the University of Minnesota have discovered a gene mutation in 11 generations of relatives who descended from Lincoln's grandparents. There's a 25 percent chance that Lincoln also inherited the gene, said Laura Ranum, a genetics professor...