An emotional Robin Roberts informed America on Monday that she is very sick.
The disorder is sometimes called pre-leukemia. The Good Morning America co-host says it was caused by the treatment she underwent for breast cancer five years ago.
Roberts also revealed she's going to require a life-saving bone marrow transplant and the donor is her sister.
Roberts said, "The reason I say that I am blessed, my big sister is a virtually perfect match! She's there with Diane, Anne Sweeney, and she is going to be my donor."
Roberts close pal, Diane Sawyer held hands with Robin's sister, who is a well known anchor in New Orleans. Also present was ABC's chief health and medical editor, Dr. Richard Besser, who Roberts said is advising her on the treatment.
There wasn't a dry eye on the set of Good Morning America. Robin even joked about how producers put a box of Kleenex within easy reach.
"You know we are in trouble when they have Kleenex Velcroed to the couch," she said.
We're now learning that Roberts got the news that she was very sick the day before she conducted her headline-making interview with President Obama.
Love and support has already begun pouring in from Robert's colleagues.
Barbara Walters on The View said, "Robin you are a wonderful woman, you are in our thoughts, you are in our prayers, and you are going to be just fine."
Today show's Hoda Kotb and Kathy Lee Gifford said, "She's a lovely sweet lady, we wish her the best."
Roberts held her co-hosts hands for support as she broke the tough news that she must begin treatment right away.
She said, "Later today I am going to begin what's known as pre-treatment. I am going to have a pick line in my arm and I didn't want you to be concerned if you saw a bandage tomorrow."
In about one third of patients, the disease transforms into an acute form of leukemia. Most patients diagnosed with M.D.S. are in their sixties and seventies. Roberts is just 51, so she has a better chance at survival
Dr. Leonard Farber of the Farber Center for Radiation Oncology is an expert on the disease.
"The fact that Robin is young, otherwise medically healthy, has a good match with her sister, affords her the best possible long-term outcome," said Dr. Farber.
As Roberts faces the biggest fight of her life, she says she's determined to do whatever it takes to get through this.
"Bottom line, I am going to beat this. My doctors say it and my faith says it to me," she declared.