t(10;12)(q24;q15): A new cytogenetic marker in hematological malignancies.

Cytogenetic studies have played a crucial role in the discovery of genes involved in several diseases. In the field of oncohematology, cytogenetics is still necessary for the classification and prognosis of many diseases. Here we report a new recurrent chromosome translocation, t(10;12)(q24;q15), in two patients with different hematological malignancies: myelodysplastic syndrome with excess blasts (MDS-EB), and myelofibrosis (MF) secondary to essential thrombocythemia (ET). The chromosome alteration was observed as a sole karyotype change in the patient with MDS-EB, both at the initial diagnosis and following progression to MDS-EB2. A putative HMGA2-KLLN rearrangement by RNA-sequencing was detected in this patient. The patient with ET, had a normal karyotype at diagnosis and the t(10;12)(q24;q15) translocation emerged as a sole cytogenetic alteration after transformation, and when MF was evident. We reviewed the literature to determine whether this chromosome abnormality had previously been described in other hematological patients and found two cases: an aggressive T-cell lymphoblastic lymphoma (T-LBL) and a case of transformed chronic myeloproliferative syndrome (CMS), in both of which t(10;12)(q24;q15) was also the only karyotype change. The clinical evolution of all four cases suggested that t(10;12)(q24;q15) is associated with a poor outcome in oncohematological patients.