The advantage of using SNP array in clinical testing for hematological malignancies--a comparative study of three genetic testing methods.

Cytogenetic methods, including G-banded chromosome analysis and fluorescence in situ hybridization (FISH) analysis, serve as a critical part of routine clinical testing for hematological malignancies and provide important diagnostic and prognostic information; however, the limitations of cytogenetic methods, including the requirement for actively dividing cells and lower resolution of G-banded chromosome analysis as well as the inability of both G-banded chromosome analysis and FISH to detect copy number neutral loss of heterozygosity (CN-LOH), can result in a failure to detect genomic abnormalities with diagnostic and prognostic significance. Here, we compared the abnormality detection rate of clinically requested testing (i.e., G-banded chromosome analysis and FISH) with high-resolution oligo (i.e., array comparative genomic hybridization (aCGH)) and single-nucleotide polymorphism (SNP)/oligo hybrid (i.e., SNP-CGH) arrays in a series of patients, in an effort to assess the ability of newer technologies to overcome these limitations. This series found the detection rate for SNP-CGH to be 62.5% for myelodysplastic syndrome (MDS) cases and 72.7% for chronic lymphocytic leukemia (CLL) cases, which are significantly higher than the detection rates of aCGH (31.3% for MDS and 54.5% for CLL) and G-banding and/or FISH (43.8% for MDS and 54.5% for CLL). This demonstrates the advantages of combining SNP-CGH with conventional cytogenetics to provide comprehensive clinical information by detecting clonality, large balanced rearrangements, copy number aberrations, and CN-LOH.