Is Genetic Evolution Predictable?
Here is an interesting paper from Science by Stern and Orgogozo that suggests epistasis and pleiotropy may be features of short-term rather than long-term evolution. This is important for human genetics because it suggests that phenotypic variation within species (e.g. humans) may result from mutations that have epistatic effects.
Stern DL, Orgogozo V. Is genetic evolution predictable? Science. 2009 Feb 6;323(5915):746-51. [PubMed]
Ever since the integration of Mendelian genetics into evolutionary biology in the early 20th century, evolutionary geneticists have for the most part treated genes and mutations as generic entities. However, recent observations indicate that all genes are not equal in the eyes of evolution. Evolutionarily relevant mutations tend to accumulate in hotspot genes and at specific positions within genes. Genetic evolution is constrained by gene function, the structure of genetic networks, and population biology. The genetic basis of evolution may be predictable to some extent, and further understanding of this predictability requires incorporation of the specific functions and characteristics of genes into evolutionary theory.