Test Details: Del(5q) is among the most extensively studied cytogenetic abnormalities in Myelodysplastic syndrome (MDS). Involvement of chromosome 5 is found in 40% of therapy-related myeloid disorders. 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. 5q deletion in MDS is considered as a favourable prognosis.