Genetic roots of synaesthesia unearthed - health - 05 February 2009 - New Scientist

Description

The regions of our DNA that wire some people to "see" sounds have been discovered. So far, only the general regions within chromosomes have been identified, rather than specific genes, but the work could eventually lead to a genetic test to diagnose the condition before it interferes with a child's education.

It has long been known that synaesthesia - which can take many other forms , but generally involves a cross-wiring between the senses - seems to run in families, although it also appears to be affected by environmental factors.

To investigate the nature of the genetic component of the condition, Julian Asher , now at Imperial College London, and colleagues from the Wellcome Trust Centre for Human Genetics at the University of Oxford took genetic samples from 196 individuals of 43 families. Of these, 121 individuals exhibited the synaesthetic trait of seeing a colour in response to a sound

"When I hear a violin, I see something like a rich red wine," says Asher, who is a synaesthete himself. "A cello is more like honey."

Autism link

The team performed a genetic analysis that tracked common "markers" - specific sets of base pairs that are repeated throughout the genome and which vary from person to person. By comparing these markers within the family, the researchers were able to infer which regions had been inherited from each parent. Together with knowledge about who exhibited synaesthesia within the families, the team identified the regions of DNA linked to the condition.

A region on chromosome 2, which has been associated with autism, exhibited the strongest link. This is particularly intriguing: the autistic savant Daniel Tammet , for example, possesses extraordinary abilities and also has a combination of the two conditions, as do some other autistic savants.

The region is also thought to ...

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http://www.newscientist.com/article/dn16537-genetic-roots-of-synaesthesia-unearthed.html

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