fusietranscript

A fusietranscript, or fusion transcript, is a chimeric messenger RNA formed when portions of two distinct genes are joined together. Such transcripts often arise from genomic rearrangements, including chromosomal translocations and inversions, but can also result from read-through transcription or trans-splicing. When in-frame, a fusion transcript can be translated into a fusion protein with novel or constitutive activity; out-of-frame fusions may be nonfunctional or degraded.

In cancer, fusietranscripts are a common consequence of oncogenic chromosomal rearrangements and can drive disease by altering signaling pathways, transcriptional control, or cellular localization. Not all fusion transcripts produce functional proteins; some reflect regulatory changes or partial transcripts. Distinguishing functional fusions from incidental events is a key aspect of research and clinical interpretation.

Common examples include BCR-ABL1 in chronic myeloid leukemia and some ALL cases, PML-RARA in acute promyelocytic leukemia, EML4-ALK in non-small cell lung cancer, and TMPRSS2-ERG in prostate cancer. Others include ETV6-RUNX1 in pediatric ALL and FGFR3-TACC3 in glioblastoma. These fusions can guide diagnosis, prognosis, and treatment decisions, particularly when targeted therapies are available.

Detection and characterization rely on molecular methods such as RNA sequencing, reverse transcription PCR, and fluorescence in situ hybridization. While fusion transcripts can be highly informative clinically, interpretation must consider expression level, tissue context, and potential technical artifacts.