Robin Roberts announced on Monday, Aug. 27 during a live telecast on "Good Morning America" that Friday, Aug, 31 will be her last day on air. Roberts, 51, made the announcement about her upcoming medical leave while sitting alongside her co-anchor George Stephanopolous. She will check into a hospital next Tuesday, Sept.4 to "begin the process." The process she is referring to is undergoing a bone marrow transplant. Roberts was diagnosed with blood and bone marrow disease myelodysplastic syndrome, also known as "MDS". Her donor is her sister, who is also a news anchor who turned out to be a "perfect match," said Roberts.