Isolation of rare transcripts by representational difference analysis.

Representational difference analysis (RDA) is a powerful technique for cloning the differences between genomes, and has recently been adapted for cloning differentially expressed genes. RDA, like other PCR-based differential screening methods, is prone to the production of false positives. We have identified a major source of false positives in RDA of cDNA and have introduced improvements which minimise their production. These modifications also significantly increase sensitivity, allowing for the isolation of rare differential transcripts from nanogram amounts of mRNA.