The most commonly used cytoreductive treatments in the front-line setting include hydroxyurea and recombinant interferon (pegylated interferon alfa-2a or ropeginterferon alfa-2b), for both PV and ET, and the JAK1/JAK2 inhibitor ruxolitinib in PV patients who are hydroxyurea resistant or intolerant. The gene discussed is JAK1; the disease is acquired polycythemia vera.