Breakpoints Involved in Deletions of the Long Arm of Chromosome 5 in Myelodysplasia and Acute Non-Lymphoblastic Leukemia do not Correlate with the Morphological Diagnosis

Abstract

Recent suggestions of a correlation between the extent of acquired deletions of the long arm of chromosome 5 [del(5q)] in association with myelodysplastic syndromes and acute non-lymphoblastic leukemia, and the morphological features, prompted us to review 34 patients with these conditions and del(5q). We found no correlation between the morphological diagnosis with which the patient presented and the extent of the deletion of 5q. All cases showed involvement of band 5q31, in common with most previously reported series. The consistent involvement of 5q31 is in keeping with the concept that a single gene at band 5q31 may be involved in the pathogenesis of these myeloid clonal expansions and that the deletion of genes in the long arm of chromosome 5, known to be involved in hemopoietic growth regulation, is unlikely to be the principal determinant of the hematological disorder.

Oncogene Involvement in Myelodysplasia and Acute Myeloid Leukemia

“…Deletions of 5 and 7 are particularly interest ing due to the concentration of genes for growth factors and growth factor receptors on 5q and 7q, but evidence of oncogene acti vation has not been observed. The break point of the 5q-is variable [117,118], and no rearrangement of the FMS gene, located at 5q34, has been seen, although diminished hybridization was detected as a result of the deleted allele [119. 120].…”