Distinct from Cbl-c (or Cbl-b), mutations of Cbl have been found in ~5% of myeloid neoplasms including myelodysplastic syndrome, myelofibrosis, refractory anemia with excess blasts, de novo and secondary acute myeloid leukemia, atypical chronic myelogenous leukemia, CML in blast crisis, chronic myelomonocytic leukemia, and juvenile myelomonocytic leukemia (reviewed in [1, 12]). The gene discussed is CBLB; the disease is myelodysplastic syndrome with single lineage dysplasia.