Evolutionary conservation of protein interaction properties has been shown to be a valuable indication for functional importance.Rodent orthologs are more conserved in human and the human disease genes are functional in rat genome. Some are inherited disease gene are highly conserved in rat. The investigation of evolutionary rates among large sets of genes has become feasible with the availability of the genome sequences of human, rat & mouse. Evolutionary conservation of protein composition and biochemical properties is usually a valuable indication for the cellular importance of a specific protein complex. In this study we analyzed whether association rates of protein in 5 major biochemical pathways of autoimmune disorders are conserved during evolution, because evolutionary conservation of protein biochemical properties is usually a valuable indication of its importance.