Connie Yates and Chris Gard, parents of terminally-ill 10-month-old Charlie Gard, pose with a petition of signatures supporting their case, prior to delivering it to the Great Ormond Street Hospital for Children in central London on July 9, 2017. | TOLGA AKMEN/AFP/Getty Images

The Experimental Therapy Charlie Gard's Parents Are Fighting For, Explained

Nucleoside bypass therapy is highly experimental and has never been used on someone with Charlie's rare mitochondrial disease, but it has also shown promise in some cases.