Two childhood cases of acute leukemia with t(16;21)(p11.2;q22): second case report of infantile acute lymphoblastic leukemia with unusual type of FUS-ERG chimeric transcript.

We report two childhood cases of acute leukemia with t(16;21)(p11.2;q22) and FUS-ERG rearrangements. Patient 1 (14 years old) was initially diagnosed with acute myeloid leukemia. Chromosome study showed a t(16;21)(p11.2;q22) clone in more than one third of the cells analyzed, and further investigation with reverse-transcriptase polymerase chain reaction, cloning, and sequencing confirmed FUS-ERG rearrangement (type B). Patient 2 (8 months old) was diagnosed with acute lymphoblastic leukemia (ALL) on the basis of bone marrow morphology and immunophenotyping. Chromosome study revealed a 45,XY,-16,der(21)t(16;21)(p11.2;q22) in 50% of the cells analyzed. Further studies for the detection of a FUS-ERG chimeric transcript were conducted, and an unusual type of FUS-ERG rearrangement was discovered, which has been reported in only three patients including a 1-year-old infant with ALL. Although more clinical studies are necessary, we believe that a possible association between ALL and a specific type of FUS-ERG fusion transcript might be considered, especially in childhood cases with t(16;21).
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