Researchers have noted that there are portions of the DNA that look similar to functional genes, but contain lesions or premature stop codons. These genes have been assumed to be largely non-functional, but recent research suggests that many of these ‘pseudogenes’ are actually functional. This paper is an overview of some of the research done in the area of pseudogene functionality. I address several recent advances in the area of genetic research regarding pseudogene functionality chronologically, starting from one of the first discoveries of a functional pseudogene and ending with a paper from this year (2013). Broadly speaking, it would seem that the assumption of non-functionality has been overturned regarding many pseudogenes, and the evidence suggests that many more pseudogenes may have a function that has yet to be discovered.
Pseudogenes have been typically understood as portions of DNA that have lost their function and remain in the DNA as a relic that signifies past functionality. The prefix ‘pseudo-‘ indicates that something is fake or false, and a pseudogene is a portion of DNA that looks like a functioning gene, but is not actually functional. Pseudogenes have been placed in the ‘junk DNA’ category, ‘dead’, non-functional by-products of evolution. If a pseudogene is transcribed at all, it is often considered to be largely a neutral process that hasn’t been weeded out by selection. However, recent evidence has shown that many pseudogenes have very important functions in the genome of nearly every organism, humans included. There are very good reasons to revise the definition of ‘pseudogene’ to include a wide variety of biological functions, from gene expression and cellular function to gene regulation and tumor suppression. The newly discovered functions are making the term ‘pseudogene’ notoriously ambiguous. This review will analyze a small handful of functions discovered for pseudogenes that were previously assumed to be non-functional byproducts of genome evolution. It is not intended to be an exhaustive treatment of newly discovered pseudogene functionality. Functions are being ascribed to pseudogenes on a fairly regular basis in contemporary genetics literature, and some of the literature is reviewed in chronological order.