We analyzed 1,200 patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) harboring a 5q deletion in order to clarify whether the type of 5q loss is associated with other biological markers and prognosis. We investigated all patients by chromosome banding analysis, FISH with a probe for EGR1 (5q31) and, if necessary, to resolve complex karyotypes with 24-color-FISH. Moreover, 420 patients were analyzed for mutations in the TP53 gene. The patient cohort was subdivided based on type of 5q loss: Patients with interstitial deletions and patients with 5q loss due to unbalanced rearrangements or monosomy 5. Loss of the long arm of chromosome 5 due to an unbalanced rearrangement occurred more often in AML (286/627; 45.6%) than MDS (188/573; 32.8%; P < 0.001). In both entities, patients with 5q loss due to unbalanced translocations showed complex karyotypes more frequently (MDS: 179/188; 95.2% vs. 124/385; 32.2%; P < 0.001; AML: 274/286; 95.8% vs. 256/341; 75.1%; P < 0.001). Moreover, in MDS unbalanced 5q translocations were associated with clonal evolution (109/188; 58.0% vs. 124/385; 32.2%; P < 0.001), mutation of TP53 (64/67; 95.5% vs. 40/120; 40.0%; P < 0.001), and shorter survival (15.3 months vs. not reached; P < 0.001). In MDS, complex karyotype was an independent adverse prognostic factor (HR = 5.34; P = 0.032), whereas in AML presence of TP53 mutations was the strongest adverse prognostic factor (HR = 2.21; P = 0.026). In conclusion, in AML and MDS, loss of the long arm of chromosome 5 due to unbalanced translocations is associated with complex karyotype and in MDS, moreover, with clonal evolution, mutations in the TP53 gene and adverse prognosis.
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