E2A/HLF fusion gene in an acute lymphoblastic leukemia patient with disseminated intravascular coagulation and a normal karyotype

Abstract

Introduction: Disseminated intravascular coagulation (DIC) is a rare event in acute lymphoblastic leukemia (ALL). However, it has been described in a few cases of pre-B ALL with translocation t(17;19)(q22;p13) which results in the fusion of E2A gene with sequences of HLF gene. Here, we report a case of pre-B ALL with DIC and an apparently normal karyotype by R banding.

Materials and methods: Fluorescent in situ hybridization (FISH) studies were performed on bone marrow cells from the patient at presentation and after three months of therapy. RT-PCR was used to detect the E2A-HLF transcript. The type of rearrangement was characterized by sequencing.

Results: The t(17;19)(q22;p13) was detected by FISH analysis. The fusion E2A-HLF was amplified by RT-PCR and sequenced, giving a type I rearrangement with a long insertion (146 nucleotides) between E2A exon 13 and HLF exon 4.

Conclusion: While translocation t(17;19) is undetectable by R-banding technique, it can be detected with FISH and amplified with RT-PCR. Therefore, systematic molecular investigations should be conducted for all patients with pre-B ALL associated with DIC, in order to appreciate the incidence and the prognostic value of this rare abnormality.