Robin Roberts taking 'extended' leave from 'Good Morning America' for bone marrow transplant

"Good Morning America" anchor Robin Roberts will take an extended medical leave after this week to prepare for a bone-marrow transplant.

Roberts announced her leave on Monday's (Aug. 27) "GMA." Her last day on air will be Friday, and there's no word yet on when she might return.

The 51-year-old Roberts, who only last week returned from some time off, suffers from myelodysplastic syndrome, a disease in which bone marrow doesn't make enough healthy blood cells. She's been going through chemotherapy to prepare for the marrow transplant; her sister Sally-Ann is the donor. Roberts is due to check into the hospital next week for a process that takes about 10 days.

ABC News says "Good Morning America" will "celebrate Robin" throughout the week and will run a series of reports on her treatment and the bone marrow transplant procedure. It will also feature stories of people who have overcome MDS.

You can go here to watch Roberts announce her leave from "GMA."