 Despite its rarity by routine karyotypic analysis, cryptic t(12;21)(p12-13;q22) translocation leading to TEL/AML1 fusion has been recognized as the most frequent genetic rearrangement in childhood acute lymphoblastic leukemia (ALL) in two recent studies, one from France and the other from the United States.     ///    High incidence of TEL/AML1 fusion resulting from a cryptic t(12;21) in childhood B-lineage acute lymphoblastic leukemia in Taiwan..     ///    None of the patients with AML had TEL/AML1 fusion transcripts.     ///    "In addition to its association with the B-lineage immunophenotype, TEL/AML1 was also correlated with a low presenting leukocyte count and favorable age (1-10 years). "    ///    "These findings, combined with earlier reports, indicate that TEL/AML1 fusion is the most frequent genetic abnormality in childhood ALL, regardless of race. "