The coloursound experiment: What is synaesthesia?

The Breaking Science team discussed the latest thinking about an unusual condition

Chris Smith: Talking about genes and how they’re linked to different conditions, there’s one very exciting condition which I’ve always wished I had just to be able to experience it, and that’s synaesthesia - the mixing of the senses - and scientists now reckon they’ve got one of the genes for that.

Kat Arney: Yes. Synaesthesia is a really fascinating neurological condition and it manifests itself in a range of ways. And it’s reasonably rare, it affects fewer than one in a hundred people, and it’s really described as if the sensory wires were crossed in your brain.

So for example, people with synaesthesia can smell colours or taste sounds, and now researchers in London, Cambridge and Oxford have tracked down specific regions of the genome that harbour genes that are linked to audiovisual synaesthesia. And we do know from previous research that this condition can run in families, but researchers haven’t been able to pinpoint the genes that might be involved. But now writing in the American Journal of Human Genetics, Dr Julian Asher and his team used new genome scanning technology to hunt for genes that were linked to synaesthesia, and they used 43 families that had this condition in the family.

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Tasting the colours? A woman with a lollipop.

Chris Smith: And what have they found in those families?

Kat Arney: So far they’ve found four regions of the genome that are linked to synaesthesia. These were on human chromosomes 2, 5, 6 and 12. Now they haven’t found specific genes, they’ve just tracked down some general regions, and the regional chromosome 2 is probably the most intriguing, as it’s also been linked to autism and people with autism often have differences in their perception and their senses.

Chris Smith: But in what they did find, was there anything of interest in there?

Kat Arney: Well of the regions that they did find there are some very interesting genes in there, such as genes for epilepsy, genes that have been linked to dyslexia, learning and memory in some of these regions which obviously need a lot more investigation. And so far, although they haven’t found any specific genes, there’s a lot of candidates which we could look at in future.

Chris Smith: As they say, nature normally reveals her workings through her mistakes because it gives us an insight into the molecular clockwork of how things like the brain actually work.

Kat Arney: Absolutely.

Episode originally broadcast February 2009 on BBC Radio Five Live. Listen to the full programme online.

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