Bi-Allelic Involvement in AML: Examples of 16q Aberrations in Two Cases.

Acute Myeloid Leukaemia is a heterogeneous clonal disorder of the bone marrow, which has characteristic acquired chromosomal abnormalities. Cytogenetic rearrangements of chromosome 16 have a well-established association with AML subtype M4Eo although they have also been described in other AML FAB types. Patients with rearrangements involving CBFb (16p13) and MYH11 (16q22) are associated with a more favourable prognosis. We describe two cases of AML where both homologues of chromosome 16 are involved in separate rearrangements; this to our knowledge has not been reported previously. Further more both patients have had previous treatment and thus the abnormality of the second homologue of chromosome 16 is thought to be treatment related, in-spite of which they have responded well and are both currently in remission. In case 1 (male, AML M5a) it is chromosome16 at band q22 that is involved, inv(16)(p13q22) and t(16;17)(q22;q11), while in case 2 (female, t-AML) chromosome 16 band q24 appears rearranged in der(16)t(8;16)(q1?3;q24) and t(16;21)(q24;q22). Extensive molecular cytogenetic investigations including mapping are presented and candidate gene aberrations discussed.