06/12/2012 08:52 am ET Updated Jun 12, 2012

Robin Roberts MDS: 'Good Morning America' Host Thanks Viewers For 'Comfort And Support' (VIDEO)

Robin Roberts thanked viewers for the tremendous outpouring of "comfort and support" she has received since revealing that she is battling a rare blood and bone-marrow disorder called MDS.

The "Good Morning America" co-host announced her diagnosis, and said that she will undergo a bone marrow transplant. The disease is a complication from the treatment Roberts received for breast cancer in 2007.

"I slept like a baby for the first time since my diagnosis," she said at the start of Tuesday's show. She expressed gratitude for the kind words and advice she's received from viewers.

She also said that First Lady Michelle Obama and Ann Romney both reached out to her. "Barack and I have you in our prayers," Obama tweeted Monday. "We believe in you and thank you for bringing awareness and hope to others." Roberts revealed that she spoke with Romney, "who has had her own health challenges … [and] had a lovely conversation." Romney has battled multiple sclerosis and breast cancer.

Later, Roberts did a segment about MDS with ABC News chief health and medical editor Dr. Richard Besser. She said that she hoped her diagnosis would encourage people to donate bone marrow, and bring awareness to the condition.