To that aim, PLA was performed on samples of mononuclear cells from 4 patients with pre-B-ALL suspicion. Karyotype features and fusion transcript of the patients were presented in Table 3. The cohort was composed of 3 males and 1 female with a median age of 4-year-old. Lymphoblasts from two of them (patients #3 and #4) were positive for t(12;21) chromosomal translocation and ETV6-RUNX1 fusion transcript while the two others patients’ lymphoblasts (patients #1 and #2) did not carry this translocation. PLA was carried out on an aliquot of the bone marrow diagnosis sample. As previously, we used a single antibody anti-RUNX1 as negative control, and two antibodies against RUNX1 as positive control.Table 3Biological and cytogenetic characteristics of the B-acute lymphoblastic patientsPatientSexAge at diagnosis (year)CytogeneticFusion transcript#1Male2Hyperploidy3 copy RUNX12 copy ETV6none#2Female8t(1;19)E2A-PBX1#3Male4t(12;21)del ETV6ETV6-RUNX1#4Male3t(12;21)del ETV6ETV6-RUNX1