Double TEL/AML1 fusion, lack of TEL signal and extra AML1 signals were frequent additional FISH abnormalities.     ///    Fluorescence in situ hybridization study of TEL/AML1 fusion and other abnormalities involving TEL and AML1 genes.     ///    We found a frequency of TEL/AML1 fusion of 17% in our sample.     ///    The frequency of TEL/AML1 fusion is similar to that found in other populations (17%).     ///     The TEL/AML1 fusion is the most common genetic abnormality found in childhood acute lymphoblastic leukemias (ALL). 