The D20S108/8q11 DNA-FISH Probe is designed to detect the deletion of the D20S108 locus on 20q12 and the gain of chromosome 8 using fluorescence in situ hybridization (FISH).  Genomic copy number changes are frequent in myeloid disorders such as myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML).^[1-3]  Deletion of the D20S108 locus is observed in 0.6 – 5% of de novo MDS patients and in less than 2% of de novo AML patients.^[1,2]  In MDS patients, deletion of the D20S108 locus is associated with a good prognosis^[3] whereas in AML patients it is a marker of either an intermediate or an unfavorable outcome.^[2]  The trisomy of chromosome 8 is observed as a sole abnormality in  ~5% of MDS patients or as part of a complex karyotype in >15% of such patients and is generally associated with an intermediate prognosis.^[2,3]  Additionally, trisomy 8 can be observed as a sole aberration in 5% of de novo AML patients or simultaneously with other aberrations in 15% in such patients.^[2]  However, trisomy 8 is more common in de novo AML cases than in therapy related AML (t-AML) with an occurence of 7.4% vs. 3.3%, respectively^[4,5] and has been associated with an intermediate prognosis.^[2,3]