Genome duplication

Surveying the landscape of the human genome leads to several other observations. 

These two forms of duplication are very different one form mediated at the DNA level (segmental duplication), and another mediated at the RNA level (retro-transposition). Both mechanisms produce paralogs - a term for genes that make their appearance in more than one copy in the genome (albeit with possible modifications). 

The study of the genome supports the fundamental unity of human beings throughout the world. We all share at least 99.9% of the letters of code (nucleotide sequence) in our genome [1, 77]. And yet, it is remarkable that the extraordinary diversity of human beings at the genetic level is encoded by less than 0.1% variation in our DNA. In a sense, this is the variation that is the basis for pharma-cogenomics. In any physician s practice, patients are predisposed to different con- 

Biological Complexity and the Role of Medicine in the Future of the Genome 

In addition, there is growing evidence for illnesses caused by genes whose product is an RNA molecule, not a protein per se. Also, the protean manifestations of RNA molecules and their modifications (including RNA editing) may contribute to our understanding of disease [82, 101-103], 

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Gratacos M, Nadal M, Martin-Santos R, Pujana MA, Gago J, Peral B, Armen-gol L, Ponsa I, Miro R, Bulbena A, Estivill X. A polymorphic genomic duplication on human chromosome 15 is a susceptibility factor for panic and phobic disorders. Cell 2001 106(3) 367-379. 

Fredman D, White SJ, Potter S, Eichler EE, Den Dunnen JT, Brookes AJ. Complex SNP-related sequence variation in segmental genome duplications. Nat Genet 2004 36(8) 861-866. 

Panopoulou G, Poustka AJ. Timing and mechanism of ancient vertebrate genome duplications—the adventure of a hypothesis. Trends Genetics 2005 21 559-567. 

Taylor, J.S., Y. Van de Peer, I. Braasch and A. Meyer. Comparative genomics provides evidence for an ancient genome duplication event in fish. Phil. Trans. R. Soc. London B 356 1661 — 1679, 2001. 

Robinson-Rechavi, M., O. Marchand, H. Escriva and V. Laudet. An ancestral whole-genome duplication may not have been responsible for the abundance of duplicated fish genes. Curr. Biol. 11 R458-R459, 2001. 

Thirty years ago. Ohno (1970) proposed that two complete genome duplications took place at the origin of vertebrates, and that this tetraploidization was followed by the diversification of the functions of duplicated genes. Ohno s hypothesis is also called the 2R hypothesis (for two rounds of genome duplication). 

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