Complex variant t(4;11) characterized by fluorescence in situ hybridization in infant acute lymphoblastic leukemia

A h-month-old girl was diagnosed with acute lymphoblastic leukemia (ALL). C hromosome analysis of bone marrow aspirate showed 46.XX,t(4;11)(q21:q23) wi th an atypical appearance of the lip on the der(ll) chromosome. FISH studie s to fully characterize the translocation utilised 8 probes: whole chromoso me painting probes for chromosome 11 and chromosome 4: separate chromosome 11 short arm and long arm paints: specific subtelomere probes from lip, 11q . and 4q: MLL gene probe. Taken together. the results indicated a two-step abnormality: an initial standard t(4:11)(q21:q23). followed by another t( l :ll)-this time, between the two derivative chromosomes. The MLL gene was sp lit by the first translocation and its position altered by the second. (C) 2001 Elsevier Science Inc. All rights reserved.