Deletions of chromosome arms 7p and 7q in adult acute myeloid leukemia: a marker chromosome confirmed by array comparative genomic hybridization

Acute myeloid leukemia (AML) cases with monosomy 7 (−7) and del(7q) comprise a heterogeneous subgroup. The association of losses in 7q with myeloid leukemia suggests that this region contains a tumor suppressor gene or genes whose loss of function contributes to leukemic transformation or tumor progression. The −7/del(7q) aberrations frequently coexist with complex karyotypes such as −5/del(5q) and trisomy 8. In the present case, we identified a rare abnormality involving deletion of both arms of chromosome 7 presenting with a marker chromosome-like appearance in an AML patient. Bone marrow aspiration and biopsy revealed acute myelomonocytic leukemia. Immunophenotyping study showed CD13, CD14, CD33, CD117, and myeloperoxidase positivities. Analysis of 20 metaphases indicated a diploid cell number with an unidentifiable tiny marker chromosome instead of one normal chromosome 7, described as 46,XY,−7,+mar[20]. Array comparative genomic hybridization test confirmed the chromosome 7 origin of the marker chromosome with deletions of 7p and 7q. The evaluation after remission induction treatment indicated morphological and cytogenetic remissions. There is evidence that the outcome is better when −7 or del(7q) occurs in patients with a simple karyotype, compared with a complex karyotype.