In one study of cases of acute myeloid leukemia with t(8;21)(q22;q22.1), 75% were positive for B cell marker PAX5 by immunohistochemical staining, 81% were positive for CD19 by flow cytometric analysis, with partially positive or positive expression by 11–96% of blasts (mean 42%), and 24% were positive for CD79a, with partially positive or positive expression by 11–45% of blasts (mean 25%) [5]. The gene discussed is CD19; the disease is acute myeloid leukemia.