A t(4;19) pediatric undifferentiated sarcoma with a novel variant of the CIC-DUX4 fusion transcript

We report cytogenetic and molecular genetic analysis of a pediatric tumor positive for the CIC-DUX4 fusion. The tumor belongs to a rare, diagnostically challenging subgroup of undifferentiated small round cell sarcomas. A balanced t(4;19)(q35;q13.1-2) was identified by G-banding, as a sole cytogenetic finding. The translocation was also identified by the M-FISH technique. After RT-PCR, the tumor sample was positive for the CIC-DUX4 fusion. The PCR product contains a novel, so far unreported variant of the CIC-DUX4 fusion transcript, with a fusion of the exon 20 from the CIC gene and the exon 1 from the DUX4 gene.