Abstract
We report a 3-year-old girl with precursor B-cell acute lymphoblastic leukemia (ALL). Cytogenetic analysis at diagnosis showed 46, XX, t (3;12) (q12;p12), -18, +mar/47, idem, +8; however, cDNA panhandle polymerase chain reaction revealed the TEL-AML1 fusion transcript created by t (12, 21) (p13;q22). The counterpart gene of TEL was not located to the gene on 3q12 predicted by cytogenetic analysis but to AML1 gene on 21q22. She has so far survived to the age of five and half years. TEL-AML1 fusion gene is the most common molecular genetic abnormality in childhood ALL. However, the t (12, 21) (p13;q22) is usually difficult to detect by chromosome analysis because of reciprocal translocation in the refined region of the chromosomal tail end. Molecular analysis would be needed to detect TEL-AML1 fusion gene in normal karyotype and the other chromosomal abnormality involving chromosome 12 at band p12-13.
