Researchers at Mayo Clinic have identified several gene types contributing to the increased incidence of multiple myeloma among those of African American descent. A rare cancer affecting plasma cells, multiple myeloma is 2 to 3 times more common among African Americans than it is among European Americans, giving it one of the highest racial disparities of any cancer.
For the study, published in Blood Cancer Journal, researchers analyzed DNA from bone marrow samples of 881 patients with monoclonal gammopathies who had undergone uniform testing to identify primary cytogenetic abnormalities. Monoclonal gammopathies, which involve abnormal plasma cells, can precede multiple myeloma. The heightened prevalence of multiple myeloma among African Americans is attributed to a similarly increased prevalence of monoclonal gammopathy of undetermined significance (MGUS).
In addition to genotyping the bone marrow DNA, the researchers used it to quantitatively assess biogeographical ancestry. "Previous efforts to understand this disparity have relied on self-reported race rather than on genetic ancestry, which may have resulted in bias," commented Mayo Clinic hematologist Vincent Rajkumar, MD, the study's senior author. "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."
Of multiple myeloma's various unique cytogenetic subtypes, 3 specific translocations—t(11;14), t(14;16), and t(14;20)—occurred significantly more frequently (51% vs 33%) in individuals whose ancestry was at least 80% African than in those whose ancestry was less than 0.1% African.
Dr. Rajkumar emphasized the value of these results: "There are efforts to enroll more minorities in clinical studies, and this is important. However, it is equally, 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."
For More Information
Baughn LB, Pearce K, Larson D, et al (2018). Differences in genomic abnormalities among African individuals with monoclonal gammopathies using calculated ancestry. Blood Cancer J, 8:96. DOI:10.1038/s41408-018-0132-1