Clinical Evaluation of Massively Parallel RNA Sequencing for Detecting Recurrent Gene Fusions in Hematologic Malignancies

The application of next-generation sequencing (NGS) technology in clinical diagnostics should proceed with care. We have evaluated the clinical validity of two commercially available RNA fusion panels, the TruSight RNA fusion panel (Illumina) and FusionPlex Pan-Heme Kit (ArcherDx), to detect recurrent translocations in hematologic malignancies. Twenty-four bone marrow samples taken at the initial diagnosis of patients with acute leukemia and chronic myeloid leukemia were included. To assess the limit of detection, serial dilutions of BCR-ABL1 (e1a2)-positive RNAs were prepared using a commercial reference material. Both NGS panels detected 19 cases with recurrent translocations identified with RT-PCR, as well as a case with KMT2A-AFF1 with false-negative results on RT-PCR. Two rare translocations, DDX3X-MLLT10 and NUP98-H0XC13, were additionally identified using NGS panels. The detection limit ranged from 10(-1) to 10(-2), which was not satisfactory for samples with low tumor burden. To conclude, RNA fusion panels were suitable for the initial diagnosis; however, for follow-up samples, conventional RT-PCR should be selected.