Case 1 (A) Bone marrow aspirates from patient 1. Large, round nucleus with a blocky chromatin pattern in agranular cytoplasm (Wright stain, ×1,000). (B) Karyotype of patient 1: 46,XY,t(4;12)(q12;p13),del(5)(q22q35)[20]. (C) FISH analysis using a Vysis LSI 4q12 tricolor probe showed cells with 1 tri-color fusion, 1 orange/green fusion, and 1 aqua signal (arrow). (D) FISH analysis using a Vysis LSI ETV6/RUNX1 ES probe showed 3 green and 2 orange signals in interphase and metaphase cells, revealing an ETV6 rearrangement [purple arrow: ETV6 signal on der(4)t(4;12), blue arrow: ETV6 signal on native chromosome 12, red arrow: ETV6 signal on der(12)t(4;12)].