Translocation t(8;21)(q22;q22): cytogenetics and molecular biology

The t(8;21)(q22;q22) translocation, usually present with a subtype of acute myeloblastic leukemia with maturation in young patients, is associated with other chromosome abnormalities in about 75% of the cases. These secondary changes are mainly loss of sex chromosome (X in 41% of females and Y in 61% of males). The genes rearranged by t(8;21), named AML-1 on 21 and ETO on 8, were recently identified. AML-1 shows homology with the Drosophila segmentation gene runt and ETO with cyclin D2. The chromosomal breakpoints are clustered within introns of the two genes and t(8;21) results in a fusion gene that makes possible the detection of translocation by polymerase chain reaction (RT-PCR).