Profiling the adult human liver transcriptome: analysis by cDNA array hybridization

Background/Aims: A comprehensive profile of genes expressed at the mRNA level (transcriptome) in human liver tissue is important for elucidating the pathogenesis and treatment of hepatic diseases. The recent development of cDNA array hybridization allows the parallel monitoring of thousands of genes expressed in a single organ. Methods: High-density microarrays containing 4043 known and unique human cDNA gene targets were used to quantitatively analyze the expression of genes in human livers. Expressed gene transcripts were classified by function and listed with information of their chromosomal positions. Computational analysis was used to cluster genes according to similarity in pattern of gene expression. Results: A total of 2418 unique gene transcripts were detected in five liver specimens. Through relational database analysis, we determined 1212 genes that were commonly expressed in 4 of the five liver specimens. Furthermore, analysis of the total 2418 expressed genes by self-organizing maps and hierarchical clustering unexpectedly revealed a genomic acute phase response in two of the liver specimens. Conclusions: These findings represent a comprehensive preliminary molecular index of genes transcribed in the adult human liver. The information may serve as a resource for speeding up the discovery of genes underlying human hepatic diseases.