Clinical and molecular analyses of a patient with RSP19 mosaic DBA. (A) Hemoglobin level (left y-axis) is plotted as a function of time in months from eltrombopag initiation to present. Blue shading indicates dosing of eltrombopag (right y-axis). Red triangles indicate RBC transfusions; green triangle indicates a single therapeutic phlebotomy for iron removal (ferritin was 2985 mcg/L, see panel B). (B) Ferritin (left y-axis) is plotted as a function of time from eltrombopag initiation to present. Blue shading indicates dosing of eltrombopag (right y-axis). (C) Fraction of mutant alleles (RPS19 c.356 + 3A>C) in cultured skin fibroblasts, bone marrow mononuclear cells, and marrow subpopulations measured by digital droplet PCR at different time points in months in relation to eltrombopag initiation. (D) Fraction of mutant allele of granulocyte–macrophage and erythrocyte colony-forming unit (CFU-GM and CFU-E) grown from the patient’s bone marrow before and on treatment with eltrombopag. All CFUs were wild-type or heterozygous-mutated. Grans, granulocytes; NRBC, nucleated red blood cells; RBC, red blood cells.