From Sonic hedgehog to sasquatch: how genes get their names
Sonic hedgehog is a fundamentally important gene in human development. So why does it have such an odd name?
Its roots lie in the traditions of genetics research. Modern genetics owes much to Thomas Hunt Morgan, who was the first to use fruit flies in research in the search for the gene in the 1920s.
He was looking for a genetic variation that changed the fly’s eye colour – a nice obvious phenotypic effect. The mutation was known as ‘white’, and other mutations that affected eye colour were given similarly appropriate names.
Thus began the tradition of naming fly genes after their altered phenotypes. It has also given fly geneticists a chance to exhibit their inner creativity, learning and, on occasion, sly sense of humour.
A series of mutations that cause sterility were named after European royal houses, which suffered similar problems; a set of strains that cause long-term memory issues were named after Pavlov’s dogs. Inspired by ‘The Wizard of Oz’, a gene causing flies to lack a heart became known as ‘tinman’.
And who says scientists are not down with popular culture? The ‘grunge’ mutation was so called because it affected activity of the ‘teeshirt’ gene, while a gene that causes flies to die prematurely was named ‘kenny’ in honour of the ‘South Park’ character.
Some names are more risqué. Flies with a disrupted ‘ken and barbie’ gene lack external genitalia. ‘Lush’ flies have a fondness for alcohol, while ‘cheap date’ flies are especially susceptible to its effects. Flies with the misfortune to inherit a ‘stuck’ mutation have difficulty disengaging after mating, while ‘baboon’ flies have large anal pads.
Although physical appearance commonly inspires gene names, so too does behaviour. Flies with deformed wings that could run but not take off were named ‘taxi’ (other similar genes include ‘grounded’, ‘rhea’ and ‘moa’). ‘Ether a go go’ flies jiggle uncontrollably in the presence of ether.
So what of ‘Sonic hedgehog’? This name originated via the famous developmental screen carried out by Ed Lewis, Christiane Nüsslein-Volhard and Eric Wieschaus, which earned them the 1995 Nobel Prize in Physiology or Medicine. The screen identified large numbers of mutants affecting embryogenesis, one of which was named ‘hedgehog’ – mutant embryos were short, stubby and their backs were coated in a mass of tiny spines. When similar genes were found, they were given related names – including ‘Indian hedgehog’, ‘Desert hedgehog’ and ‘Sonic hedgehog’ (Shh). (Rather delightfully, a gene found in zebrafish was called ‘tiggy-winkle hedgehog’.)
Only later, usually, does it become clear what the full role of a gene is. Shh has turned out to have many important roles, human digit formation being one of them.
Researchers working with organisms other than flies tend to be more restrained in their naming conventions, though some mice strains have imaginative names. One, known as ‘sasquatch’, had duplicated digits, which turned out to be due to altered regulation of the Shh gene. Nowadays, most genes get a series of letters and numbers related to their possible function or similarity to known genes.
Though engaging, the inventive approach to naming fly genes has caused problems. A proposal to call one strain ‘velcro’ was vetoed by the product’s manufacturers, while some Japanese businessmen were none too pleased when a fruit fly gene named after their product was linked to human tumours – thanks to the ‘Pokémon causes cancer’ headlines that followed.
More seriously, the fact that genes are found across species, and may be linked to medical conditions, can raise sensitive issues. Would you like to be told that a family member’s condition was linked to a gene called ‘Sonic hedgehog’, ‘sasquatch’ or ‘baboon’?
- New York Times: Sex and the fruit fly – price of promiscuity is premature death
- Los Angeles Times: Fruit fly geneticists are known for flights of fancy when it comes to naming mutant genes
- Tinman function is essential for vertebrate heart development (2008)
- Pavlov’s flies: researchers identify fruit fly memory mutants
- Grunge, related to human Atrophin-like proteins, has multiple functions in Drosophila development (2002)
- NPR: Fruit fly scientists swatted down over ‘cheap date’
- Phenotypic and transcriptional response to selection for alcohol sensitivity in Drosophila melanogaster (2007)
- Drosophila melanogaster entry in the online bioinformatics database, Flybase
- The Drosophila Activin receptor Baboon signals through dSmad2 and controls cell proliferation but not patterning (1999)
- The press release announcing Lewis, Nüsslein-Volhard and Wieschaus winning a Nobel Prize
- Mutations affecting segment number and polarity in Drosophila (1980) [PDF]
- The hedgehog family of paracrine factors, in Gilbert SF. Developmental Biology. Sunderland MA: Sinauer Associates; 2013
- Identification of sonic hedgehog as a candidate gene responsible for the polydactylous mouse mutant Sasquatch (1999)
- Pokemon USA threatens to sue cancer researchers