Comparative Genomic Hybridization of Wilms tumor

Cytogenetic analysis of solid tumors including Wilms’ tumor is challenging due to poor chromosome morphology, complexity of abnormalities, and to the possibility of stromal cell overgrowth in tissue culture. Molecular cytogenetic techniques such as chromosomal comparative genomic hybridization (CGH) have improved the diagnosis of chromosomal aberrations in Wilms’ tumor since they can provide results based on the analysis of DNA from nondividing cells. However, chromosomal CGH provides only a limited resolution across the whole genome, which is not different than routine cytogenetic analysis (gains or losses of less than one chromosome band or 10 Mb are not detectable by routine cytogenetics or chromosomal CGH). More recently, the development of genomic arrays opened the possibility of assessing the whole genome at a much higher resolution at a sub-microscopic or sub-band level. Based on the principle of chromosomal CGH, this approach, frequently termed array-CGH, opens the possibility to find invisible changes at the whole genome level not only in abnormal but also in normal tumor karyotypes. Here, we discuss the main technical features, benefits, and limitations of the above three techniques as applied to Wilms’ tumor and summarize the main advances in our knowledge about the genetic changes of Wilms’ tumor and their clinical relevance.