Low frequency of the JAK2 617V>F mutation in bone marrow immature CD34⁺CD38⁻ derived lymphomyeloid clones and LTC-ICs from ET and PV patients. (A) Single CD34⁺CD38⁻ cells from 6 ET patients, 1 PV patient with a heterozygous profile, and 6 PV patients with a JAK2 617V>F homozygous profile were cultured in B/NK/myeloid (M) differentiation conditions. Clones with lymphomyeloid potentialities (B/M, NK/M, and B/NK/M) were subsequently genotyped. The histograms represent the numbers of lymphomyeloid clones from each patient. □, Wild-type JAK2; ▩, heterozygous JAK2 617V>F; ■, homozygous JAK2 617V>F. (B) CD34⁺CD38⁻ cells from 4 ET, 1 PV patient with a heterozygous profile, and 5 PV patients with a homozygous profile were grown in LTC-IC medium using the limiting dilution method. The LTC-IC frequencies were calculated. LTC-IC–derived erythroid and granulocytic colonies were subsequently genotyped to determine the proportion of mutated LTC-ICs. Histograms represent the frequency of wild-type (□), heterozygous mutant (▩), and homozygous mutant (■) LTC-ICs per CD34⁺CD38⁻ cell.