Show me your DNA and I'll tell you your eye color

Mar 09, 2009

More and more information is being gathered about how human genes influence medically relevant traits, such as the propensity to develop a certain disease. The ultimate goal is to predict whether or not a given trait will develop later in life from the genome sequence alone (i.e. from the sequence of the bases that make up the DNA strands that store genetic information in every cell of the body).

Now, writing in the journal a group of researchers form the Netherlands put this goal to a test using eye colour. The group around Manfred Kayser of the Medical Center Rotterdam showed that it can be predicted with an accuracy of over 90% whether a person has blue or brown eyes by analysing DNA from only 6 different positions of the genome.

Human eye colour, which is determined by the extent and type of pigmentation on the eye's iris, is what geneticists call a 'complex trait'. This means that several control which colour the eyes will ultimately have. Over the past decades a number of such 'eye-colour genes' have been identified, and people with different eye colour, will have a different DNA sequence at certain points in these genes.

Such differences are known as single (SNPs). Manfred Kayser and his colleagues analysed the DNA of over 6000 Dutch people whose eye colour had been scored. They determined the sequence at 37 SNPs in 8 eye colour genes for each of these and found that the eye colour of a given individual can be predicted with over 90% confidence already with the best 6 SNPs from 6 genes, as long as the persons's eyes are blue or brown. For the intermediate colour, shown by about 10% of the people tested, the accuracy is lower at about 75%.

The implications of this study are two-fold. For one, it is a proof-of-principle that complex traits can be predicted from the genome sequence alone, provided that genes with strong effects on the trait exist and are known. This can have implications for predicting disease risks based on DNA, before the disease breaks out. In addition, these findings have direct relevance in the forensic sector. Consider a case where the only trace of the suspect is a DNA trace but the DNA profile generated does not match that of known suspects or any in the Criminal Database.

There currently is in fact one such open case in Germany where the DNA of a single woman was found at dozens of crime sites over several years. Using the approach of the new study, the eye colour of a suspect— and in principle also other traits such as hair colour — can be predicted, thus helping to find unknown suspects. Needless to say, there are also caveats, one of them is that the prediction was only tested for individuals of Dutch European descent, and, although expected, it needs to be shown that similarly high prediction accuracies are obtainable in other populations across Europe.

Also, the reliability of such DNA-based prediction test currently depends on an accurate knowledge that the unknown person whose DNA was tested is of European descent, since the used SNPs are associated with eye color but have no direct functional implications as far as known. Inferring highly accurate information on European ancestry from a DNA sample is not trivial, although such research is underway as well.

Source: Cell Press

Explore further: How do our muscles work? Scientists reveal important new insights into muscle protein

add to favorites email to friend print save as pdf

Related Stories

Blue-eyed humans have a single, common ancestor

Jan 30, 2008

New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of the eye colour ...

Human vision inadequate for research on bird vision

May 12, 2008

The most attractive male birds attract more females and as a result are most successful in terms of reproduction. This is the starting point of many studies looking for factors that influence sexual selection in birds. However, ...

The importance of gene regulation for common human disease

Sep 16, 2007

A new study published in Nature Genetics on Sunday 16 September 2007 show that common, complex diseases are more likely to be due to genetic variation in regions that control activity of genes, rather than in the regions that s ...

Recommended for you

How calcium regulates mitochondrial carrier proteins

Nov 26, 2014

Mitochondrial carriers are a family of proteins that play the key role of transporting a chemically diverse range of molecules across the inner mitochondrial membrane. Mitochondrial aspartate/glutamate carriers are part of ...

Team conducts unprecedented analysis of microbial ecosystem

Nov 26, 2014

An international team of scientists from the Translational Genomics Research Institute (TGen) and The Luxembourg Centre for Systems Biomedicine (LCSB) have completed a first-of-its-kind microbial analysis of a biological ...

Students create microbe to weaken superbug

Nov 25, 2014

A team of undergraduate students from the University of Waterloo have designed a synthetic organism that may one day help doctors treat MRSA, an antibiotic-resistant superbug.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.