In a shocking announcement this morning, breast cancer survivor Robin Roberts announced she is suffering from Myelodysplastic Syndrome and will undergo a bone marrow transplant. Our hearts are with her.

We’re so sorry to report that GMA host Robin Roberts, 51, has been diagnosed with MDS — Myelodysplastic Syndrome.

The breast cancer survivor announced that this is a rare side effect of breast cancer treatment and will begin pre-treatment for the disease today, June 11, in preparation for a bone marrow transplant.

“I will beat this,” she told viewers on June 11.

Her older sister Sally-Ann Roberts, 55, will be her bone marrow donor.

“I am blessed,” Robin said, holding back tears, because her sister is a “virtually perfect” bone marrow match.

Robin revealed that she has known about her devastating disease for awhile now. She found out about her diagnosis when GMA’s ratings beat The Today Show for the first time in 16 years on April 17. Then after going through a painful procedure to extract bone marrow for testing, the journalist received word she would interview President Barack Obama on May 9.

“Talk about your highs and lows,” she said.

Fortunately, doctors are hopeful for her recovery.

“My doctors tell me I’m going to beat this — and I know it’s true,” Robin said.

However, she will be off the GMA couch for “a chunk of time” as she battles her illness.

“Bottom line: I’ve been living with this diagnosis for awhile and will continue to anchor GMA,” she said. “Going forward, it’s business as usual at GMA, which means I’ll be right here every day with George, Sam, Josh and Lara. When I miss a day here or there, I’m fortunate that some very talented friends at ABC News will fill-in. When I undergo the transplant later this year, I’ll miss a chunk of time.”

Our hearts and prayers are with Robin at this time.