TEL-AML1

(ETV6-RUNX1) chimeric gene, is the most common genetic lesion in pediatric acute lymphoblastic leukemia (ALL). It is observed in 22-27% of pediatric ALL and 3% of adult B-ALL patients; and is particularly associated with the early B-lineage ALL subtype. The most common breakpoint in the TEL gene resides in exon 5 which fuses to the 2nd exon of the AML-1 gene. Rarely a fusion between TEL exon 5 and AML-1 exon 3 is also observed. It is important to perform molecular diagnostic screening for the presence of t(12;21), along with t(9;22), t(4;11)and t(1;19) in pediatric ALL to determine prognosis and therapeutic approaches.