The purpose of this study was to evaluate the detection rate of chromosomal rearrangements in leukemia using single nucleotide polymorphism array (SNP-A) in combination with metaphase cytogenetics (MC), with the aim of proposing a practical approach for clinical karyotyping applications of SNP-A. The Genome-Wide Human SNP Array 6.0 (Affymetrix, Santa Clara, CA) was applied in 469 patients with a variety of hematologic malignancies. Combined use of SNP-A with MC improved the detection rate in comparison with MC alone: acute myeloid leukemia (AML) with normal karyotype (NK), 32% versus 0%; core binding factor (CBF)-AML 40% versus 29%; myelodysplastic syndrome (MDS), 54% versus 39%; chronic myeloid leukemia (CML), 24% versus 3%; and acute lymphoblastic leukemia (ALL), 88% versus 63%. Different patterns of abnormalities (especially the type, size, and location) were noted in the leukemia subtypes. Copy neutral loss of heterozygosity lesions was detected in 23% of AML-NK, 3% of CBF-AML, 25% of MDS, 2% of CML, and 20% of ALL. SNP-A also provided information on cryptic deletions and a variety of aneuploidies in ALL, while the benefit was minimal in CML. In conclusion, different patterns of abnormal lesions were presented according to the disease category, thus requiring a different approach of adopting SNP-A-based karyotyping among different leukemia subtypes.
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