Representative cDNA libraries and their utility in gene expression profiling

An increasing interest in gene expression profiles in human diseases has le d to the use of microdissected tumors and biopsies in gene discovery approa ches. Since many of these clinical samples yield extremely small amounts of RNA, reproducible methods are needed to amplify this RNA while maintaining the original message profile. Using the SMART(TM) cDNA Synthesis Method, w e show that high-, medium- and low-abundance transcripts can be amplified i n a representative fashion and that the resulting cDNA can also be used as a complex probe to confirm gene expression differences identified by other techniques.