Recently, a new rearrangement involving AML1, the t(12;21), producing the TEL/AML1 hybrid transcript, has been described by molecular analysis as the most recurrent genetic lesion in childhood acute lymphoblastic leukemia (ALL).     ///    "In order to investigate whether the t(12;21) could give a molecular clue as to the precise basis of the etiologic association between DS and acute lymphoblastic leukemia, we tested a series of 11 consecutive cases of ALL in DS children for the presence of the TEL/AML1 transcript, by RT-PCR analysis. "    ///    The common TEL/AML1 rearrangement does not represent a frequent event in acute lymphoblastic leukaemia occuring in children with Down syndrome..     ///    We report absence of the TEL/AML1 rearrangement among the 11 cases tested. 