Similarities between ML-DS and the leukemias that developed in the patients with germline GATA1 c.-21 A>G and c.2 T>C variants. (A) Immunochemical and histochemical characteristics of ML-DS and the patient leukemias. The overlap includes the unique characteristics of ML-DS compared with non-DS myeloid leukemia such as co-expression of myeloid markers (CD13, CD33, and CD38), early progenitor markers (CD34 and CD117), megakaryocytic/erythroid markers (CD41/61, CD42b, CD36, CD71, and CD235a), T-lymphocyte markers (CD4 and CD7), natural killer cell markers (CD56), but absence of monocytic and B-lymphocyte markers.^16,17 CD7 expression (indicated in bold) is an important marker distinguishing ML-DS from non-DS AMKL.^16,17 (B) Heat map showing gene expression (using Human Genome U133 Plus 2.0 Array) of samples from diagnostic blood and BM of AMKL in non-DS (3864-5036) and ML-DS (5809-7535) using unsupervised hierarchical clustering.¹⁸ Red, high gene expression; green, low gene expression. Patient IV-2 clusters with most of the ML-DS patients. (C) In vitro drug sensitivity (lethal concentration [LC₅₀]) of the leukemia from family 1 patient IV-2 compared with ML-DS and non-DS myeloid leukemia patients.¹⁹ MPO, myeloperoxidase; p25-p75, 25th – 75th percentile; TdT, terminal deoxynucleotidyl transferase.