Scientists succeed in predicting eye colour from genes
By analysing just six genes, it is possible to predict a person's eye colour with 90% accuracy, according to new Dutch research published in the journal Current Biology. The study demonstrates that it is possible to use genetic tests to predict so-called 'complex traits' which are determined by several genes. The findings also have implications for forensics, where such tests could be used to help establish the likely appearance of a suspect who has left DNA at a crime scene. Scientists are constantly discovering new genes that influence human health, for example genes that can raise our risk of developing a certain disease or condition. Ultimately, the goal is to be able to test a person's genetic make-up to predict their risk profile and tailor their healthcare accordingly. However, most diseases and traits are determined by a combination of several genes, making it hard to develop a test that can accurately predict a person's risk of developing a given disease. In this latest study, scientists from the Erasmus University Medical Center Rotterdam set out to develop a test for eye colour. Over the years, researchers have identified a number of genes that contribute to the colour of our eyes, helping us understand that eye colour is a complex trait. The scientists tested the DNA of over 6,000 people whose eye colour had been recorded, focusing their attention on eight genes that are linked to eye colour. All of the test subjects were of Dutch European descent; 67.6% had blue eyes, 22.8% brown eyes and 9.6% eyes of an intermediate colour. The tests revealed that, for people with blue or brown eyes, testing just six of these eight genes allowed the scientists to predict a person's eye colour with over 90% accuracy. However, the test was less accurate (around 75%) for people with eyes of an intermediate colour, and as the researchers note, further investigation of the genetic variations associated with these subtle variations in colour is needed. For the researchers, the study has two important implications. Firstly, it proves that complex traits can be predicted on the basis of a person's genes with a high degree of accuracy, if the genes with a strong influence on that trait are known. Secondly, the genetic markers associated with blue and brown eye colour could assist police forces in investigating cases where the suspect's appearance is a mystery and their DNA is the only lead. The team cautions that its test is only valid for people of European descent, so any forensics expert wishing to run the test on a DNA sample from a suspect would first have to determine whether or not the suspect is of European ancestry, not an easy task.