Retrogene
One-sentence definition. A retrogene is an mRNA-derived copy of a gene that has been reverse-transcribed and reinserted into the genome at a new location — typically losing introns and regulatory elements in the process.
One-sentence analogy. A retrogene is like a photocopy of a document made at one office and taped up at another: the copy lacks the original’s binder tabs (introns) and official stamps (promoters), but it can still be read if the new location provides the right context.
Why it matters. Retrogenes are key evidence for meiotic sex chromosome inactivation (MSCI). During male meiosis the X chromosome is transcriptionally silenced, so genes needed for spermatogenesis that reside on the X must escape to autosomes to function. This creates the “out-of-the-X” pattern: a statistically significant excess of retrogenes that have moved from the X to autosomes. This excess has been independently confirmed in both humans and Drosophila melanogaster with p ≈ 0 from Monte Carlo tests, providing strong support for the MSCI hypothesis.
Where you meet it in the wiki.
- Sex chromosome evolution — out-of-the-X retrogenes validate MSCI as a driver of gene movement.
- Sex-linkage mutation — patterns of sex-linked gene retention and movement.
Primary citation.
“After calculating the test statistic from our data, significant results were found in both species, with p ∼ 0.” — Lo & Blackmon 2022, Finding 2
Prerequisites: meiotic sex chromosome inactivation, heterogamety Next, learn about: MSCI, autosome