Rapid identification of gene sequences for transcriptional map assembly by direct cdna screening of genomic reference librairies

We have used the direct cDNA screening protocol to identify sequences transcribed in cerebral cortex from a reference library of human Xq28. To derive coding sequences from these genomic clones, we first identified fragments containing transcribed sequences and subjected these to exon trapping or to partial sequencing and analysis by Grail. In a preliminary analysis of three clones, coding sequences from two novel genes expressed In brain were identified. This method allows the rapid Identification of coding sequences of genes expressed In specific tissues without recourse to cDNA libraries. The approach is amenable to large scale applications and should be useful for isolating candidate disease genes and in particular for assembling Integrated transcriptional maps from large genomic regions.