Abstract
Abstract Introduction: Tissue-specific genes are a class of genes whose functions and expressions are preferred in one or several tissues, restrictedly. Identification of tissue-specific genes is essential for discovery of multi-cellular biological processes such as tissue-specific molecular regulations, tissue development, physiology and also pathogenesis of tissue-associated diseases. In this study, we aimed to identify tissue-specific genes for various human tissues/organs in more robust and rigorous fashion. Method: Gene expression data, derived from five large RNA sequencing(RNA-seq) projects, spanning 96 different human tissues was retrieved fromArrayExpress and ExpressionAtlas. The first step is categorization of genes using significant filters and tau score as specificity index. After calculation of tau for each gene in all datasets separately, statistical distance from maximum expression level was estimated using a new meaningful procedure. Specific expression of agene in one or several tissues was calculated after integration of tau and statistical distance estimation that is called as extended tau approach. Obtainedtissue-specific genes for 96 different human tissues were functionally annotated and some comparison were carried out to show effectiveness of extended taumethod. Results: Categorization of genes based on expression level and identification of tissue-specific genes for a large number of tissues/organs were executed. Genes were successfully assigned to multiple tissues by generating extended tau approach as opposed to original tau score which can assign tissue specificity to single tissue only. Keywords: Tissue-specific genes, RNA-Seq, Tau score