In a new study, researchers found that the mutant(変異体)MECP2 gene that causes Rett syndrome, an autism-like(自閉症のような)disease that leaves roughly one in 10,000 girls unable to talk or walk, does not cause permanent brain damage. When scientists restored MECP2 gene function in mice crippled(手足の不自由な)by Rett-like symptoms, the mice began moving normally. Thursday's report challenges the long-held belief that the brain damage from Rett syndrome is permanent, but researchers don't yet know how to try such treatment in people.