Does monosomy 5 really exist in myelodysplastic syndromes and acute myeloid leukemia?

Abnormalities of chromosome 5 are common aberrations in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML), being del(5q) the most frequent. In contrast, monosomy 5 is not so frequent and, usually, is associated with complex karyotypes, conferring poor prognosis. The aim of this study was to analyze, by FISH for 5q31 (EGR1), a series of 28 MDS and AML cases with monosomy 5 detected by G-banding. FISH results revealed deletion of 5q31 in 24 of them (85.7%) and monosomy 5 just in three. FISH for 5q31 can complement conventional cytogenetics and improve the karyotype definition, leading to a better diagnostic and prognostic stratification.