Bone marrow cells from 80 paediatric patients with ALL at diagnosis were analysed for the presence of the TEL/AML1 fusion gene by interphase FISH.     ///     The TEL/AML1 (ETV6/RUNX1) fusion gene is the most common genetic rearrangement in paediatric acute lymphoblastic leukaemia (ALL).     ///    Co-existence of multiple subclones in TEL-AML1 at diagnosis of acute lymphoblastic leukaemia in association with submicroscopic deletion of AML1..     ///    "Other abnormalities included TEL deletion, trisomy and tetrasomy 21 as well as double TEL-AML1 fusion. "