*3.1.2 The t(12;21)(p13;q22)(ETV6-RUNX1)*

The most prevalent translocation in childhood acute lymphoblastic leukemia is TEL-AML1 gene fusion, induced by t(12;21) (p12;q22). However, this anomaly is rare among adults. The translocation of t(12;21) is cryptic by normal G-banding and includes FISH examination for cytogenetic detection [16]. ETV6-RUNX1 patients were thought to have a good prognosis at first, and they were associated with favorable risk factors including female gender, young age, low white cell count, and CD10+ immunophenotype [17]. However, some studies found no gain for ETV6-RUNX1 patients [18], while others found a high incidence of gene fusion in relapse patients and a predilection for late relapse [19, 20]. However, it is now clear that the initial optimism was justified. Almost every major clinical trial group in the world has confirmed that children with the ETV6-RUNX1 fusion have excellent overall survival and very low relapse rates [21, 22], and the presence of added cytogenetic or molecular abnormalities does not modify this good prognosis.
