RT Journal
A1 Misra, Jatin
A1 Schmitt, William
A1 Hwang, Daehee
A1 Hsiao, Li-Li
A1 Gullans, Steve
A1 Stephanopoulos, George
A1 Stephanopoulos, Gregory
T1 Interactive Exploration of Microarray Gene Expression Patterns in a Reduced Dimensional Space
JF Genome Research 
JO Genome Research 
YR 2002 
FD July 01 
VO 12 
IS 7 
SP 1112 
OP 1120 
DO 10.1101/gr.225302 
UL http://genome.cshlp.org/content/12/7/1112.abstract 
AB The very high dimensional space of gene expression measurements obtained by DNA microarrays impedes the detection of underlying patterns in gene expression data and the identification of discriminatory genes. In this paper we show the use of projection methods such as principal components analysis (PCA) to obtain a direct link between patterns in the genes and patterns in samples. This feature is useful in the initial interactive pattern exploration of gene expression data and data-driven learning of the nature and types of samples. Using oligonucleotide microarray measurements of 40 samples from different normal human tissues, we show that distinct patterns are obtained when the genes are projected on a two-dimensional plane spanned by the loadings of the two major principal components. These patterns define the particular genes associated with a sample class (i.e., tissue). When used separately from the other genes, these class-specific (i.e., tissue-specific) genes in turn define distinct tissue patterns in the projection space spanned by the scores of the two major principal components. In this study, PCA projection facilitated discriminatory gene selection for different tissues and identified tissue-specific gene expression signatures for liver, skeletal muscle, and brain samples. Furthermore, it allowed the classification of nine new samples belonging to these three types using the linear combination of the expression levels of the tissue-specific genes determined from the first set of samples. The application of the technique to other published data sets is also discussed.[Online supplementary material available atwww.genome.org.]