Chapter 22 - The Role of Human Endogenous Retroviruses (HERVs) in the Pathologies of the Nervous System

Abstract

The present chapter is trying to give an overview of how data from current genomic research could unveil the role of hidden parts of our genome in our health. This hidden part was called “junk DNA” in the past, and even today, its role has been quite underestimated. In the recent past, our tools were too general or broad to give enough evidence about the activity of this part of our genome. We just called it “junk DNA,” but accumulating data suggest that this hidden part of our genome orchestrates several important processes necessary for normal physiology. If regulation of these processes fails, diseases emerge, and given our blindness for the unconventional approaches, we consider these diseases as “idiopathic” or “cryptic,” and we blame the bluntness of our tools (“missing heritability”). Fortunately, modern genomic techniques started to uncover the activity of so-called human endogenous retroviruses (HERVs), which form at least 8% of our genomes. This 8% is far more than all the coding sequences that are explored in most of our biomedical studies. Without proper and thorough understanding of the function of this part of our genome, it is hopeless to explore the genetics of human diseases. Most Genome Wide Association Studies (GWAS) studies end up with variations in the genomic regions considered to be “gene-deserts,” because no coding sequences, hence no meaningful translation events, occur in these regions. The number of studies on the role of HERVs in relation to physiological regulation and diseases is increasing. Results of these studies indicate that HERVs have substantial impact on the regulation of genome function. This chapter focuses on the findings on the role of HERVs in development of neuropsychiatric diseases.