However, little is known about the incidence of the translocation in relapsed patients and the duration of complete remission (CR) in children expressing the TEL/AML1 fusion gene.     ///    Incidence of TEL/AML1 fusion gene analyzed consecutively in children with acute lymphoblastic leukemia in relapse..     ///    "Most of the TEL/AML1-positive children showed no adverse clinical features at diagnosis (eg, white blood cell [WBC] count <100 x 10(9)/L or age <10 years), and regarding these data, there were no differences versus children who were negative for the fusion gene. "    ///    "However, using fluorescence in situ hybridization (FISH) and by screening for the TEL/AML1 rearrangement by the polymerase chain reaction (PCR), it has been demonstrated to be the most frequent known structural chromosomal abnormality in childhood acute lymphoblastic leukemia (ALL). "    ///    "The TEL/AML1 rearrangement could be identified in nine of 44 (20%) of the patients, a result similar to the reported incidence at diagnosis. "    ///    "However, the period of remission was about 1 year longer in children expressing TEL/AML1 (P = .046), and the majority of relapses in this group appeared late (<2 years after diagnosis). "