Test Details: Myelodysplastic syndromes (MDSs) are heterogeneous hematopoietic disorders associated with various degrees of myelosuppression and transformation into acute leukaemia. Complete loss of chromosome 7 (monosomy 7) or partial deletion involving its long arm [del(7q)] are highly recurrent chromosomal aberrations in myeloid disorders, including myelodysplastic syndrome (MDS). Fluorescence in situ hybridization (FISH) complements conventional karyotyping by the ability to evaluate large numbers of both interphase and metaphase nuclei. This has an important diagnostic and prognostic role which affects the choice of therapies.