Though facing high hurdles, gene therapy remains the best long-term hope for treating many genetic diseases. But for some devastating disorders, such as polycystic kidney disease, simply supplying patients with healthy copies of their disease-causing genes-the traditional approach in gene therapy-may not be enough. Molecular geneticist Al George at Vanderbilt University in Nashville, TN, has demonstrated a type of gene therapy that can repair the damage caused by such diseases. George created a gene that encodes an RNA enzyme that can excise defective portions of mRNA molecules-short templates that translate a gene’s code into a protein-and replace them with the correct sequences. He showed that after injection with the new gene, cells carrying a mutated gene that causes a muscle-wasting disease stopped producing the harmful protein and began producing the normal one. George hopes to improve the process enough to begin animal studies within two years.