Molecular characterization of a novel chromosomal translocation t(12;14)(q23;q11.2) in T‐lymphoblastic lymphoma between the T‐cell receptor delta‐deleting elements ( TRDREC and TRAJ61 ) and the hypothetical gene C12orf42

Chromosomal aberrations have diagnostic, prognostic, and therapeutic relevance in hematologic malignancies. By combining fine‐tiling comparative genomic hybridization (FT‐CGH) and ligation‐mediated PCR (LM‐PCR), we established a fast, robust approach to precisely characterize chromosomal breakpoints. Using this approach, we clarified at the molecular level novel chromosomal translocation t(12;14)(q23;q11.2) in T‐lymphoblastic lymphoma. The translocation occurred during the deletional rearrangement of the T‐cell receptor delta gene ( TRD ), which is a pivotal step in T cell differentiation toward the alpha/beta vs. the gamma/delta lineage. We found that this rearrangement disrupted the hypothetical gene C12orf42 and brought the Achaete‐scute complex homolog 1 gene into proximity of the TRA enhancer, which encodes a member of the basic helix‐loop‐helix family of transcription factors and is overexpressed in thyroid and lung cancers.