However, a subset of patients with a PICALM-MLLT10 fusion (3 of 23 in one series) have a mediastinal mass, no expression of T-cell antigens, and positive expression of myeloid antigens such as CD33, CD34, or MPO, and were given a diagnosis of M1 AML or acute undifferentiated leukemia (AUL)43. The gene discussed is CD34; the disease is acute myeloid leukemia.