Anatomy of the 5q- deletion: different sex ratios and deleted 5q bands in MDS and AML.

Deletion of part of the long arm of chromosome 5 (5q-) is the most common structural chromosome aberration in patients with myeloid disorders. Most patients are women. Although widely varying 5q segments are deleted, the vast majority of cases share a common deleted region (5q31). Whether or not other deleted 5q regions are of clinical importance is unknown. In an attempt to throw light on this question, 439 published 5q- cases were analyzed. The female preponderance was found to be limited to refractory anemia (RA), RA with excess of blasts (RAEB) and myeloproliferative disease, all with 5q- as the only chromosome aberration. When other chromosome aberrations had developed or the diagnosis was AML, only marginal female preponderance was observed. The 5q31 was deleted in all patients with MDS and 5q- as the only aberration. In contrast, in AML and following cytogenetic progression other bands were deleted more often than 5q31. This difference, together with a different female preponderance suggests diverse pathogenetic mechanisms in MDS and AML. Furthermore, the bands 5q13-5q21 were found to be of importance for clinical progression from RA to RAEB, and 5q22-5q33 of importance for development of AML and cytogenetic progression. In conclusion, the 5q bands deleted affect both clinical and cytogenetic progression.