CHAPTER 28

MICROARRAY GENE EXPRESSION DATA ANALYSIS

Alan Wee-Chung Liew and Xiangchao Gan

28.1 INTRODUCTION

Research in life science, in particular, the study of the genetic codes in living organisms, has reached its epic with the sequencing of the full human genome. With the availability of the vast number of genetic sequences, the next major challenge is to study gene activity or gene function. Important insights into gene function can be gained by gene expression profiling. Gene expressing profiling is the process of determining when and where particular genes are expressed. For example, some genes are turned on (expressed) or turned off (repressed) when there is a change in external conditions or stimuli. In multicellular organisms, gene expressions in different cell types is different during different developmental stages in life. Even within the same cell type, gene expressions are dependent on the cell cycle the cells are in. DNA mutation may alter the expression of certain genes, which causes illness such as abnormal tumor growth or cancer. Furthermore, the expression of one gene often is regulated by the expression of another gene. A detailed analysis of all this information will provide an understanding about the networking of different genes and their functional roles.

In the past, genes and their expression profiles are studied one at a time. However, this method is inadequate for the holistic study of the complete genome of an organism because the expressions of different ...

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