The comparison of the differentially expressed genes in these BM and PB JAK2 and CALR-mutated ET samples compared to healthy donors might help to better understand the altered processes and molecular mechanisms underlying this disease according to the degree of maturation of the malignant cell (immature CD34 + HSCs from BM vs. mature neutrophils from PB) and the type of mutation. The gene discussed is CD34; the disease is essential thrombocythemia.