假基因
假基因功能的例子

The term "pseudo-pseudogene" was coined in the publication that investigated the gene in the chemosensory ionotropic glutamate receptor Ir75a of Drosophila sechellia, which bears a premature termination codon (PTC) and was thus classified as a pseudogene based on that in silico analysis. However, in vivo the D. sechellia Ir75a locus produces a functional receptor, owing to translational read-through of the PTC. Read-through is detected only in neurons and depends on the nucleotide sequence downstream of the PTC.
The Drosophila jingwei gene produces a functional alcohol dehydrogenase enzyme in vivo. However, previous in silico analysis classified it as a processed pseudogene. The evolution of this gene has been discussed.
A human processed pseudogene of phosphoglycerate mutase was initially reported by interpretation of both in silico and experimental evidence. That pseudogene was investigated more fully by another group, which found convincing evidence that it was a functional gene, which is now named PGAM4. The gene is expressed in the testes and polymorphisms in that gene appear to account for about 5% of cases of male infertility.
siRNAs. Some endogenous siRNAs appear to be derived from pseudogenes, and thus some pseudogenes play a role in regulating protein-coding transcripts, as reviewed. One of the many examples is psiPPM1K. Processing of RNAs transcribed from psiPPM1K yield siRNAs that can act to suppress the most common type of liver cancer, hepatocellular carcinoma. This and much other research has led to considerable excitement about the possibility of targeting pseudogenes with/as therapeutic agents
Some piRNAs are derived from pseudogenes located in piRNA clusters. Those piRNAs regulate genes via the piRNA pathway in mammalian testes and are crucial for limiting transposable element damage to the genome.BRAF pseudogene acts as a ceRNA
There are many reports of pseudogene transcripts acting as microRNA decoys. Perhaps the earliest definitive example of such a pseudogene involved in cancer is the pseudogene of BRAF. The BRAF gene is a proto-oncogene that, when mutated, is associated with many cancers. Normally, the amount of BRAF protein is kept under control in cells through the action of miRNA. In normal situations, the amount of RNA from BRAF and the pseudogene BRAFP1 compete for miRNA, but the balance of the 2 RNAs is such that cells grow normally. However, when BRAFP1 RNA expression is increased (either experimentally or by natural mutations), less miRNA is available to control the expression of BRAF, and the increased amount of BRAF protein causes cancer. This sort of competition for regulatory elements by RNAs that are endogenous to the genome has given rise to the term ceRNA.
The PTEN gene is a known tumor suppressor gene. The PTEN pseudogene, PTENP1 is a processed pseudogene that is very similar in its genetic sequence to the wild-type gene. However, PTENP1 has a missense mutation which eliminates the codon for the initiating methionine and thus prevents translation of the normal PTEN protein. In spite of that, PTENP1 appears to play a role in oncogenesis. The 3' UTR of PTENP1 mRNA functions as a decoy of PTEN mRNA by targeting micro RNAs due to its similarity to the PTEN gene, and overexpression of the 3' UTR resulted in an increase of PTEN protein level. That is, overexpression of the PTENP1 3' UTR leads to increased regulation and suppression of cancerous tumors. The biology of this system is basically the inverse of the BRAF system described above.
Pseudogenes can, over evolutionary time scales, participate in gene conversion and other mutational events that may give rise to new or newly-functional genes. This has led to the concept, used in a major review from 2003, that pseudogenes could be viewed as potogenes: potential genes for evolutionary diversification.