Ring Chromosome 7: A Rare Structural Abnormality in Acute Myeloid Leukemia (AML)

Ring chromosomes, often leading to partial deletions, are found in about 2% of cases of acute myeloid leukemia (AML) and are typically associated with a poor prognosis. Herein, we present the case of a 62-year-old female who showed markedly hypercellular marrow with sheets of myeloblasts, monoblasts, and promonocytes, confirmed by flow cytometry and cases of AML with r(7) have been reported. Analysis of these cases demonstrated that r(7) was a sole abnormality in 20%, a primary abnormality in 14%, and in the context of a complex karyotype in 66%. The most common concomitant abnormality, seen in 26% of these cases, was 5q-, though a large variety of other concurrent abnormalities were reported at lower frequencies. The most common r(7) breakpoints were r(7)(p22q22) and r(7)(p11q11), occurring in 20% and 13% of the cases that specified breakpoints, respectively. This case study and analysis of previously reported cases demonstrates the diversity of cytogenetic contexts in which r(7) can occur in AML and underscores the importance of FISH in the characterization of this abnormality. Further investigation of the role of r(7) in AML and other hematological malignancies is warranted in order to properly characterize it and concomitant abnormalities to elucidate its clinical implications.