 The TEL (ETV6)-AML1 (CBFA2) gene fusion is the most common reciprocal chromosomal rearrangement in childhood cancer occurring in approximately 25% of the most predominant subtype of leukemia- common acute lymphoblastic leukemia.     ///    Fetal origins of the TEL-AML1 fusion gene in identical twins with leukemia..     ///    "The TEL-AML1 genomic sequence has been characterized in a pair of monozygotic twins diagnosed at ages 3 years, 6 months and 4 years, 10 months with common acute lymphoblastic leukemia. "    ///    The twin leukemic DNA shared the same unique (or clonotypic) but nonconstitutive TEL-AML1 fusion sequence. 