CD34 and myelodysplastic syndrome: Because MDS samples are heterogeneous with multiple cell types and varying degrees of cellular differentiation, enrichment techniques using highly purified CD34+ positive progenitor cells may result in improved microarray resolution Moreover, aCGH should not be used as an MRD assay, however, the detection of pathogenetic CNAs at presentation allows for disease-specific FISH and PCR MDR assays at follow-up.