Good Morning America anchor Robin Roberts is taking a leave of absence from the program.Roberts has a rare blood disease called myelodysplastic syndromes, or MDS. Formerly known as preleukemia, MDS damages the vital functioning of a patient's bone marrow -- the spongy material inside bones where blood cells are made, according to the Mayo Clinic's website.Next week, Roberts will begin final preparations for a bone marrow transplant.Her last day was supposed to be Friday, but Roberts made her final appearance on GMA Thursday so she could fly home to Mississippi to be with her ailing mother and her family, who live in an area affected by Hurricane Isaac."Dear ones, this is my final morn @GMA for a while," Roberts tweeted on Thursday. "Heading home after the show to be w/ my ailing mom in MS. You'll be in my heart & soul."Roberts fought breast cancer in 2007. She was diagnosed with MDS in June 2012. Roberts' sister Sally-Ann will be her bone marrow donor.GMA created the Twitter hashtag #TeamRobin where well-wishers can send her messages. It was quickly flooded with support for the popular journalist."Robin Roberts is one strong woman. My money is on her," tweeted talk show host Ellen DeGeneres."Keep on fighting! We all stand with you!" tweeted Ann Romney, wife of Republic presidential nominee Mitt Romney."Emotional powerful morning. So honored to be with @RobinRoberts today. Such a strong woman. We're gonna love you (through) it Robin," country singer Martina McBride wrote.ABC News anchor Diane Sawyer tweeted: "Send one word to @RobinRoberts -- my one word is champion."