Evolution/Population Genetics

Wednesday, February 27, 2013


Presentation: “The Population Bomb: Explosive population growth and the excess of rare, deleterious variation within the human genome”
Presenter: Raul Torres (second-year Biomedical Sciences student)
Paper: Fu W, et al. Analysis of 6,515 exomes reveals the recent origin of most human protein-coding variants. Nature. 2013 Jan 10;493(7431):216-20.

In a nutshell:

You may sometimes wonder, “Gee, with all these scientists doing research, why don’t we have more treatments and cures for diseases?” 

Part of the difficulty lies in the complexity of disease: There are often a huge number of genetic and environmental components that are difficult to separate out.  Regarding the former, humans have a great deal of genetic diversity, and individuals have a lot of gene variants that may or may not predispose them to disease. 

Evolution is usually pretty good at selecting against deleterious, disease-causing variants, but humans experienced a massive population explosion pretty recently (keep in mind that in evolutionary terms, “recent” is on the scale of thousands of years ago).  Because of this, evolution probably hasn’t had time to catch up. 

The authors of this paper determined that most deleterious and/or disease-associated gene variants tend to be on the younger side.  Furthermore, the younger the variant is, the more unlikely it is to be found in the population.  This is pretty intuitive, but being able to base this on mathematical algorithms allows scientists to more confidently prioritize genes to target.