 The tumor microenvironment has an inhibitory effect on DNA repair pathways contributing to genomic instability, which promotes tumor survival, proliferation, and malignant transformation.The protein coding regions of the human genome, collectively called the exome, constitutes only 1.5% of the total genome.As pointed out above, ordinarily there are only an average of 0.35 mutations in the exome per generation (parent to child) in humans.