Whole genome scanning as a cytogenetic tool in hematologic malignancies

Over the years, methods of cytogenetic analysis evolved and became part of routine laboratory testing, providing valuable diagnostic and prognostic information in hematologic disorders. Karyotypic aberrations contribute to the understanding of the molecular pathogenesis of disease and thereby to rational application of therapeutic modalities. Most of the progress in this field stems from the application of metaphase cytogenetics (MC), but recently, novel molecular technologies have been introduced that complement MC and overcome many of the limitations of traditional cytogenetics, including a need for cell culture. Whole genome scanning using comparative genomic hybridization and single nucleotide polymorphism arrays (CGH-A; SNP-A) can be used for analysis of somatic or clonal unbalanced chromosomal defects. In SNP-A, the combination of copy number detection and genotyping enables diagnosis of copy-neutral loss of heterozygosity, a lesion that cannot be detected using MC but may have important pathogenetic implications. Overall, whole genome scanning arrays, despite the drawback of an inability to detect balanced translocations, allow for discovery of chromosomal defects in a higher proportion of patients with hematologic malignancies. Newly detected chromosomal aberrations, including somatic uniparental disomy, may lead to more precise prognostic schemes in many diseases.