Two of the holy grails of medicine - stem cell technology and precision gene therapy - have been united for the first time in humans, say scientists.It means patients with a genetic disease could, one day, be treated with their own cells. A study in Nature corrected a mutation in stem cells made from a patient with a liver disease. Researchers said this was a "critical step" towards devising treatments, but safety tests were still needed. At the moment, stem cells created from a patient with a genetic illness cannot be used to cure the disease as those cells would...