Subtraction hybridization - an approach to the isolation of genes differentially expressed in cancer and other biological-systems.

Subtraction hybridization allows for the isolation and identification of genes which are differentially expressed in different cell types. It allows for such isolation without any a priori knowledge of the sequence or function of the target gene. The only requirement is that there be a difference in the relative abundance of the nucleic acid (mRNA or genomic DNA) in the two cell types being compared. In contrast to differential hybridization, cDNA clones representing mRNAs of very low abundance (0.001% to 0.1%) can be discerned using subtraction hybridization. The concept, applications and techniques of performing subtraction hybridization is discussed.