Robin Roberts has MDS. What is that?

Good Morning America co-anchor Robin Roberts announced Monday morning that she’s been diagnosed with a condition calledmyelodysplastic syndrome, or MDS.

MDS is a rare blood disorder in which “the bone marrow produces enough blood cells, but they’re “fragile,” or “cracked,” so when they try to get into the blood stream to do what they do, they break apart prematurely,” explains Martin Tallman, chief of the leukemia service at Memorial Sloan-Kettering Cancer Center in New York.

Roberts reported Monday morning that she was preparing for a bone-marrow transplant, with her sister serving as the donor.

Tallman says the medical community has “shifted away” from calling such procedures “bone marrow transplants,” which term he says has largely been replaced with “stem cell transplant.” In that procedure, he explains, “the patient receives chemotherapy and sometimes radiation to kill the bad cells.” When the healthy blood cells are instilled, Tallman explains, “Stem cells grow like seeds in a garden and reestablish normal blood cell production.”

Tallman was unable to comment directly on Roberts’s case or her prognosis. But he says, “It is true that if you develop MDS subsequent to chemotherapy, you tend to have unfavorable genetic changes” to your cells that suggest a less-favorable prognosis. Roberts was treated for breast cancer five years ago; the treatment reportedly included chemotherapy.

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