Increased likelihood of post-polycythemia vera myelofibrosis in Ph-negative MPN patients with chromosome 12 abnormalities.

Chromosome 12 (Chr12) abnormalities have been described for individual patients with Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-neg MPN), however the frequency, characteristics, and outcomes of such patients as a whole have not been investigated. We reviewed a database of 1787 consecutive Ph-neg MPN patients seen at our institution and determined that 2% of Ph-neg MPN patients harbored an alteration involving Chr12 by cytogenetic evaluation. Retrospective chart review revealed that patients with Chr12 abnormalities had a higher likelihood of having myelofibrosis (MF) compared to patients without a Chr12 abnormality, and were more likely to have post-polycythemia vera MF. The most common alterations in Chr12 in MF patients involved 12q13, 12q15, 12q24, and trisomy 12, and >40% of Chr12 Ph-neg MPN patients had cytogenetic evolution. Chr12 abnormalities did not significantly correlate with JAK2 status, progression to acute myeloid leukemia, or survival, however patients with 12q24 abnormalities trended toward poorer outcomes.