A t(16;21)(p11;q22) in Acute Myeloid Leukemia (AML) Resulting in Fusion of the FUS/TLS and ERG Genes: A Review of the Literature.

The t(16;21)(p11;q22) is a rare chromosomal abnormality that appears in approximately 1% of acute myeloid leukemia (AML) cases. Previously, between 50 and 60 cases have been reported. In this review, we will discuss the literature regarding t(16;21) as well as cases published. We compiled 68 cases from the Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer as well as 10 additional cases in the literature, for a total of 78 cases. The t(16;21) results in the TLS(FUS)-ERG fusion protein, which is believed to function as a transcriptional activator in leukemogenesis and has been demonstrated to interfere in normal pre-mRNA splicing functions of FUS/TLS. Reverse-transcriptase polymerase chain reaction of fusion transcripts in patients, has been demonstrated to have diagnostic significance in monitoring for minimal residual disease. Cytogenetically, about half of the cases had secondary chromosomal abnormalities; we found that trisomy 8 and 10 were the most common abnormalities, occurring in 9.1% of the otal cases for each. t(16;21) in AML has been described with various morphological features, such as phagocytosis and vacuolation, and is present in multiple FAB types. Immunophenotypic characteristics such as CD33 and CD34 expression have also been noted, and several studies have examined the relation between CD56 receptor expression and t(16;21) AML. In general, t(16;21) in AML is associated with a poor prognosis and this abnormality could serve as cytogenetic indicator in determining diagnosis and prognosis. Herein, we summarize the cytogenetic features found in the the Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer for t(16;21) in AML, as well as review the current literature associated with t(16;21), AML and its features.