Codon conservation of the three gene groups. The conservation score of amino acids of the three groups of genes are compared. (a) The distribution of disease causing mutation sites' conservation score is plotted in the solid line. The dotted line is drawn based on the conservation scores of all the sites in the coding region (i.e., the distribution of the conservation score when sites are randomly chosen). (b) The distribution of polymorphism mutation sites' conservation score vs. the random distribution as in (a). (c) The distribution of conservation score for UEHGs (black line), disease gene (broken blue line) and disease causing mutation sites (red broken line). (d) The distribution of the fraction of the highly conserved regions (Cons. Score>0.9). Each human gene group is represented in a different color.