Video: Robin Roberts has rare disorder

FILE - This Dec. 8, 2011 file photo shows ABC News personality Robin Roberts arriving to the opening night performance of the Broadway play Show caption
FILE - This Dec. 8, 2011 file photo shows ABC News personality Robin Roberts arriving to the opening night performance of the Broadway play "Stick Fly", in New York. On Monday, June 11, 2012, Roberts announced on "Good Morning America" that she has been diagnosed with MDS or myelodysplastic syndrome, a disease of the blood and bone marrow and was once known as preleukemia. She will start pre-treatment chemotherapy in advance of a bone marrow transplant later this year. (AP Photo/Charles Sykes, file)

The "Good Morning America" host who beat breast cancer reveals she's facing another medical issue. Watch Robin's tearful announcement.

The "Good Morning America" host who beat breast cancer reveals she's facing another medical issue. Watch Robin's tearful announcement.