Patient ALMA_13_BM and PB (60 + years, female; coverage 14.04x BM, 7.23x PB), presenting ambiguous flow cytometry suggesting biphenotypic leukemia (35% myeloblasts, dim CD19), was confidently predicted as MDS-related secondary myeloid in both specimens, supported genomically by RUNX1/RUNX1-AS1 mutations. Here, CD19 is linked to leukemia.