Deletion (8)(q22) as the only chromosomal abnormality in a patient with RAEB-t with progression to acute myelocytic leukemia.

Cytogenetic investigation of the bone marrow cells of an 88-year-old woman with refractory anemia with an excess of blasts in transformation with progression to acute myelocytic leukemia (AML), FAB classification M4, revealed a deleted chromosome #8 with the breakpoint at band q22 as the sole abnormality. This breakpoint is the same as that in t(8;21)(q22;q22), mostly found in patients with AML. This finding is discussed in relation to the possible oncogenesis of AML, which in this case may mean that the deletion of chromosome #8 at band 8q22 and the resultant loss of genetic material with possible antioncogenic activity is the critical event leading to malignant transformation in AML and not the translocation of the end of 21q next to 8q.