By Jacque Wilson, CNN

updated 1:44 PM EDT, Tue June 12, 2012

2009: Robin Roberts on her cancer

STORY HIGHLIGHTS

(CNN) -- Robin Roberts' battle against myelodysplastic syndrome, or MDS, is just beginning. The "Good Morning America" anchor will undergo chemotherapy before having a bone marrow transplant later this year.

"Bone marrow donors are scarce and particularly for African-American women," Roberts wrote Monday. "I am very fortunate to have a sister who is an excellent match, and this greatly improves my chances for a cure."

More than 10,000 people in the United States are diagnosed with blood-related disorders every year, according to the National Marrow Donor Program. Often the best treatment is a bone marrow transplant. During the procedure, a donor's stem cells are directly transfused into the sick patient's bloodstream. The patient's new cells multiply over time to create healthy bone marrow.

Unfortunately, the chance of finding a match on the national registry is as low as 66% for African-Americans and other minorities, compared with 93% for Caucasians.

Be the Match, the national registry, has 10 million potential donors, but only 7% are African-American. While the percentage is comparable to the overall African-American population in the United States (which is 12%), the registry is meeting only about a third of the needs for African-American transplants, said Dr. Jeffrey Chell, CEO of the National Marrow Donor Program.

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Read more:
Roberts found a match -- others won't