What is a Gene?

Mark Gerstein and colleagues published a very nice review of the gene in Genome Research this summer, and I missed it. I think I was on vacation in Wyoming. Anyway, I just found it now. If you missed it too, definitely check it out. The review covers how genes were conceptualized since their "discovery" by Mendel, and touches upon all the major milestones in the history of genetics. The authors then discuss issues with the current conception of the gene, and propose a new model. Here is their summary:

A proposed updated definition
There are three aspects to the definition that we will list below, before providing the succinct definition:

1. A gene is a genomic sequence (DNA or RNA) directly encoding functional product molecules, either RNA or protein.
   
2. In the case that there are several functional products sharing overlapping regions, one takes the union of all overlapping genomic sequences coding for them.
   
3. This union must be coherent—i.e., done separately for final protein and RNA products—but does not require that all products necessarily share a common subsequence.
   

This can be concisely summarized as:

The gene is a union of genomic sequences encoding a coherent set of potentially overlapping functional products.

We've come a long way from "One Gene, One Protein".

If you have some way of printing it out, there is a fantastic time-line poster of genetics milestones here.