Researchers ID gene types behind racial disparities in myeloma

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The discoveries may help shed light on myeloma causes and improve treatment for African-Americans.

Researchers at Mayo Clinic have identified three specific gene types that account for a known twofold to threefold increase in myeloma diagnoses among African-Americans. Researchers also demonstrated the ability to study race and racial admixture more accurately using DNA analysis. The findings were published in Blood Cancer Journal in October 2018.

Photo of S. Vincent Rajkumar, M.D.
S. Vincent Rajkumar, M.D.

"Myeloma is a serious blood cancer that occurs two to three times more often in African-Americans than in Caucasians," said S. Vincent Rajkumar, M.D., senior author of the study, Edward W. and Betty Knight Scripps Professor of Medicine in Honor of Dr. Edward C. Rosenow III, and a hematologist at Mayo Clinic in Rochester, Minnesota. "We sought to identify the mechanisms of this health disparity to help us better understand why myeloma occurs in the first place and provide insight into the best forms of therapy."

Dr. Rajkumar and his colleagues studied 881 patients of various racial groups. They found that the higher risk of myeloma known to occur in African-Americans was driven by three specific subtypes of the cancer characterized by the presence of genetic translocations in cancer cells. Translocations are genetic abnormalities in cancer cells caused by the rearrangement of parts between nonhomologous chromosomes. The translocations that researchers identified in this study were t(11;14), t(14;16) and t(14;20).

"Previous efforts to understand this disparity have relied on self-reported race rather than on genetic ancestry, which may have resulted in bias," Dr. Rajkumar explained. "A major new aspect of this study is that we identified the ancestry of each patient through DNA sequencing, which allowed us to determine ancestry more accurately."

According to Dr. Rajkumar, the probability of a person having one of the three specific translocations responsible for myeloma was significantly higher in the 120 patients who researchers identified with the highest level of African ancestry compared with the 235 patients identified with lowest level of African ancestry.

"There are efforts to enroll more minorities in clinical studies, and this is important," Dr. Rajkumar said. "However, it is equally important, if not more important, to determine the mechanisms of racial disparities in terms of why cancers occur more often in certain racial groups. Our findings provide important information that will help us determine the mechanism by which myeloma is more common in African-Americans, as well as help us in our quest to find out what causes myeloma in the first place."

Response to cancer treatment varies based on the genetic subtype of cancer. These findings will help researchers develop more-effective treatment strategies for African-Americans with myeloma.