Test Details: Deletion of parts of the q arm of Chromosome 20 is often associated with Myelodysplastic syndrome (MDS) and Acute Myeloid Leukaemia (AML). Fluorescence in situ hybridization (FISH) is designed to detect the chromosomal aberrations which have diagnostic and prognostic implications. In patients with AML, 20q deletion is considered as poor prognosis while in patients with MDS, 20q deletion is considered as a good prognosis.