Contents1. Introduction: Gene regulation by chromosomal domains2. Domain-wide regulation of gene expression in the human genome3. Genes in chromosomal Ridge domains have increased mRNA folding stability and half-life, further contributing to their high expression 4. A model to explain natural selection for extreme levels of protein expression in the human genome 5. EZH2 overexpression associated with gain of chromosome arm 7q is essential for neuroblastoma cell cycle progression and a marker of poor prognosis6. Discussion: Mechanism of Ridges and implications for evolution7. Summary8. Nederlandse samenvatting9. Dankwoord10. Curriculum vitae11. List of publicationsChromosomes are the long DNA molecules that carry the genetic code of our genes. Each gene encodes a protein, but also contains the information that controls the activity of that gene. In this thesis, we find that chromosomal domains with many active genes (so-called 'Ridges'), also control gene activity. Our results imply that Ridges facilitate the high activity of important genes. Ridges might thus provide an alternative mechanism for changes in gene activity during human evolution.Gierman onderzocht de invloed van chromosomale domeinen op genexpressie, door virussen die fluorescerende eiwitten produceren op willekeurige plekken in chromosomen in te bouwen. Domeinen met veel act