However, patients with PMF are more likely to have splenomegaly, CALR or MPL mutations, and megakaryocytes with hyperchromatic nuclei, while patients with MDS/MPN-RS-T tend to have SF3B1 mutations, a much more increased number of ring-sideroblasts, and multilineage dysplasia. The gene discussed is SF3B1; the disease is myelodysplastic syndrome.