How is blue eyes a mutation

Some of you may remember making Punnett Squares in school and learning that two blue eyed individuals would always have blue eyed offspring. However, that is not always the case. There are a lot of factors that contribute to eye color. Eye color is affected by several genes, including the genes that control the amount of melanin pigment in our irides, a gene that controls whether melanin is produced in the outer layer of the iris, and the genes that control the structure of the iris and how much collagen it contains.

Just as many genetic factors affect eye color, there may have been a combination of several factors that lead to the evolution of blue eyes. Of course, we will understand if you have blue eyes and want to stick strictly to the attractiveness theory! Make an appointment today at one of our eight convenient Atlanta-area locations. Schedule an Appointment Online. Request an Appointment or call Blue Eyes are More Sensitive to Light. Since blue eyes contain less melanin than green, hazel or brown eyes, photophobia is more prevalent in blue eyes compared to darker coloured eyes.

Therefore, it is recommended to those with blue eyes to stay out of the sun for long periods of time and try to wear protective eyewear when you are outdoors. Originally we all had brown eyes, however, according to researchers at the University of Copenhagen, it appears that a genetic mutation in a single individual in Europe 6, to 10, years ago led to the development of blue eyes.

Therefore, we can conclude that this genetic mutation is the cause of eye colour of all blue-eyed humans alive on the planet today. What is the genetic mutation? The OCA2 gene codes for the 'P protein', which is involved in the production of melanin the pigment that determines the colour of our eyes, skin and hair. They have all inherited the same switch at exactly the same spot in their DNA. Since the human eye does not have its full adult amount of pigment at birth, most Caucasian babies are born with blue eyes.

However, since human melanin tends to develop over time — this causes the child's eye colour to change as more melanin is produced in the iris during early childhood. A new study suggests that individuals with blue eyes are at a higher risk for alcohol dependency compared to those with darker eyes. Therefore, this finding adds further evidence to the idea that alcoholism has a genetic component.

The mutation affected the so-called OCA2 gene, which is involved in the production of melanin, the pigment that gives color to our hair, eyes and skin. The genetic switch is located in the gene adjacent to OCA2 and rather than completely turning off the gene, the switch limits its action, which reduces the production of melanin in the iris.

In effect, the turned-down switch diluted brown eyes to blue. If the OCA2 gene had been completely shut down, our hair, eyes and skin would be melanin-less, a condition known as albinism. Hawks was not involved in the current study. Eiberg and his team examined DNA from mitochondria, the cells' energy-making structures, of blue-eyed individuals in countries including Jordan, Denmark and Turkey. 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 , years ago and is the cause of the eye colour of all blue-eyed humans alive on the planet today. The "switch," which is located in the gene adjacent to OCA2 does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the iris -- effectively "diluting" brown eyes to blue. The switch's effect on OCA2 is very specific therefore.

If the OCA2 gene had been completely destroyed or turned off, human beings would be without melanin in their hair, eyes or skin colour -- a condition known as albinism. Variation in the colour of the eyes from brown to green can all be explained by the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes. Professor Eiberg and his team examined mitochondrial DNA and compared the eye colour of blue-eyed individuals in countries as diverse as Jordan, Denmark and Turkey.

His findings are the latest in a decade of genetic research, which began in , when Professor Eiberg first implicated the OCA2 gene as being responsible for eye colour.