Recurrent genetic abnormalities including BCR-ABL, PML-RARA, AML1-ETO translocations and MLL and CBFB changes are critical to diagnosis, risk stratifications, therapy and disease monitoring of hematologic malignancies. However, low levels of many leukemia-associated genetic changes are incidentally found in normal, healthy individuals. What is the prevalence of such changes in normal individuals?
Reporting in the Journal of Molecular Diagnostics, senior author Marilyn Li and coauthors attempt to establish baseline prevalence of leukemia- and lymphoma-associated gene rearrangements in normal populations. They extracted RNA and DNA from venous blood and anonymous, discarded cord blood obtained from healthy adults, children, and neonates with no history of leukemia or lymphoma at Tulane University Medical Center. MLL partial tandem duplication transcripts were detected in 67% of individuals at a calculated level of 1 in 1000 to 10,000 circulating cells. BCR-ABL minor (p190) transcripts were detected in 74%and major (p210) transcripts in 42% of individuals at a calculated level of 1 in 10,000 circulating cells. The prevalence of p210 transcripts increased progressively from 20% in neonates to 90% in elderly adults. MLL-AF4 and AML1-ETO fusion transcripts were detected in 56% and 18% , respectively, of individuals at calculated levels of 1 in 10,000 circulating cells. PML-RARA and CBFB-MYH11 fusion transcripts were detected in 50% and 3%of individuals, respectively.
There is a very high prevalence of very low level genetic abnormality involving BCR-ABL, PML-RARA, MLL, AML1-ETO, and CBFB in normal individuals. It is important to note that these levels are within limits of detection for minimal residual disease assays and could impact on interpretation of those test results.
Editorial. Guy E.Nichols MD, PhD.