Characterization of t(11;19)(q23;p13.3) by fluorescence in situ hybridization analysis in a pediatric patient with therapy-related acute myelogenous leukemia

This case presents a Caucasian girl diagnosed with early pre-B cell acute l ymphoblastic leukemia at age 2 years. The only chromosomal anomaly detected in her bone marrow cells at this time was an add(12p). By age 4 years, she had a bone marrow and central nervous system (CNS) relapse of ALL and was treated with chemotherapy that included etoposide. She was in complete remi ssion for 2 years following chemotherapy with etoposide, but later develope d therapy-related acute myeloid leukemia (t-AML). At this time, a t(11:19)( q23:p13.3) rearrangement was detected in her bone marrow cells. The AML rel apsed again 1 year after allogeneic bone marrow transplant (BMT). The prese nce of a chromosome 11 abnormality involving band 11q23 in this patient sug gests that the transformation from ALL to t,AML was a consequence of etopos ide included in her chemotherapy. Studies have shown that the 11q23 breakpo int in the t(11;19) rearrangement is consistent, and involves the MLL gene in t-AML patients. However, the breakpoint in 19p is variable in that it co uld be located either at 19p13.1 or 19p13.3 and thus could involve either o f two genes: ELL (11-19 lysine-rich leukemia gene) on 19p13.1 or ENL (11-19 leukemia gene) on 19p13.3. In this study, the t(11:19)(q23:p13.3) was furt her characterized and the breakpoint regions were defined by fluorescence i n situ hybridization (FISH) analysis. (C) 2001 Elsevier Science Inc. All ri ghts reserved.