Blue eye colour variant

 

This is the second SangerArtwork that I created called “Blue eye colour variant”. It was inspired by the genetic variation that leads to blue eye colour. Along with "Fred Sanger in insulin gene sequence" it was displayed at the Australian Society for Medical Research (ASMR) National Scientific Conference - "Inspired Creativity - When Art meets Science" in Adelaide in November 2018, where it won the inaugural Synapse Award for best creative artistic entry.

It depicts the single nucleotide variant on chromosome 15, an A to G change in an intron of the HERC2 gene that leads to blue eye colour. People with blue eyes carry 2 copies of this variant. It is thought that everyone with blue eyes is related through a common ancestor that lived around 10,000 years ago and that no one living in Europe before that time had blue eyes. It’s pretty amazing what genomic science can tell us!!


The artwork is made up of >8000 bases of Sanger DNA sequence chromatogram with the image of an eye embedded into it with iris tinted in blue. There are 27 rows of sequence at 300 bases across, designed to be printed at a size of around 22x22 in or 55x55 cm.

The sequence is centred around the single base change, also known as a single nucleotide polymorphism (SNP - pronounced "snip") with the ID number rs12913832 that is located at peak number 4001 of the chromatogram. This all important SNP is located in the iris of the eye, relating the sequence of the DNA to its functional effect in determining eye colour.


This artwork is designed to be viewed both closeup - to reveal the DNA sequence, and far away - to reveal the image. The closeup that you can see below reveals some important details. The origin of the sequence (bases 1 to 8000) is shown in the bottom right corner - human genome version 38 - chromosome 15 - from base 28116472 to 28124471 - the SNP rs12913832 (an A to G change at position 28120472 on chromosome 15) is located at peak number 4001 of the sequence. It changes a base in an intron of the HERC2 gene transcript. The Human Genome Variation Society (HGVS) notation for this variant is NM_004667.5:c.13272+874T>C. Notice that the HGVS notoation describes the change as a T to C rather than an A to G. This is becuase the HERC2 gene is transcribed from the reverse strand of chromosome 15, so A becomes T and G becomes C due to the base-pairing rule of the 2 DNA strands. As with most of my SangerArtworks I have used the bases after 8000 to sign and date the design with a hidden “Sangerism”.

So how does the rs12913832 SNP cause blue eye colour. Well the SNP itself is located 874 bases into intron 86 of the HERC2 gene. It is quite unusual for variants this far into introns of genes to have functional effects. The region of DNA around this SNP is well conserved across species and is thought to be involved in regulating the expression of the neighbouring OCA2 gene, which is located over 21,000 bases away. The OCA2 gene is involved in the production of the pigment melanin. The rs12913832 SNP causes a reduction in the transcription of the OCA2 gene. There is a knock on effect happening here, as reduced OCA2 mRNA then leads to lower amounts of the OCA2 protein and reduced melanin production in the iris of the eye. There is actually no blue pigment in blue eyes but rather a lack of melanin pigment. The blue colour comes from an optical effect making the lightly pigmented iris look blue.

You can purchase this artwork in a number of different formats from Society6 or Redbubble using the links below.

Society6

Redbubble

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© 2020 by Daniel Wallace