Blue eyes are a rare occurrence among black people. However, they can occur due to a genetic mutation or via parents with European ancestry on both sides who carry the gene for blue, green or hazel eyes.
A study from Professor Hans Eiberg and his team at the University of Copenhagen has found that nearly all blue-eyed individuals share a common genetic mutation. This mutation occurs in the OCA2 gene formerly known as the P gene, which is associated with melanin production cells.
Genetics is a study of the inherited traits that make us what we are. It grew out of the work of Gregor Mendel, who discovered that traits were inherited in discrete units.
One of these is eye color. Originally, all humans had brown eyes, but about 6,000 to 10,000 years ago, a mutation in the OCA2 gene switched off a key mechanism that allows people to produce enough melanin (the pigment that gives skin, hair and eyes their color) to allow blue eyes to develop.
The OCA2 gene is located on chromosome 15. Researchers believe that the OCA2 gene plays a major role in controlling the brown/blue color spectrum by controlling levels of a protein called P-protein, which is produced by specialized cells known as melanocytes.
When the OCA2 gene is mutated, it stops the production of P-protein. In some cases, this results in a form of albinism. In other cases, it changes how much melanin is produced in the melanocytes.
A person can also have a non-disease-causing version of the OCA2 gene, which alters the amount of OCA2 RNA that is produced. These variants are called alleles and are passed to children.
There are other genes that can also affect eye color. These are called alleles, and they can boost or decrease the amount of melanin in the melanocytes, causing a child to have more or less melanin than either parent.
In recent years, researchers have discovered that eye color is not determined by a single gene. Instead, it is determined by a combination of different genes and the interactions between them.
Using linkage analysis, the researchers identified an identifiable group of genes that were inherited together from a single parent–the scientific term for this group is a “haplotype.” The haplotype was common among 155 blue-eyed individuals from Denmark and five blue-eyed individuals from Turkey.
This research is important because it reveals that there are several genes that determine eye color. Some of these genes can raise or lower melanin levels, resulting in blue eyes, while other genes can boost melanin to produce hazel or brown eyes.
Black people with blue eyes have a higher risk of developing ocular albinism than other ethnic groups. This is because their genes make less of a pigment called melanin. Normally, the body produces this pigment to protect your skin and other tissues from the sun’s harmful UV rays.
The amount of melanin in a person’s skin, hair and eyes depends on the type and number of genes that are active. People with ocular albinism have a lower number of melanocytes, the cells that make melanin, in their eyelids and iris, and this causes problems with vision.
Ocular albinism can cause a variety of problems with eyesight and may also increase your risk of getting skin cancer. For example, people with ocular albinism are more sensitive to the sun’s UV rays than other people, and they have a greater risk of developing basal and squamous cell carcinomas, the most common type of skin cancer.
In people with ocular albinism, the optic nerve fibers in the eyes travel to the opposite side of the brain than normal. This can cause alternating strabismus, a type of eye movement that’s not healthy for your eyes. It can also lead to problems with your vision, like amblyopia.
A person with ocular albinism should have regular eye exams by an ophthalmologist to make sure they have the proper strength glasses and contact lenses for their eyes. They can also talk to other people who have ocular albinism or low vision to learn more about the condition and get tips on how to manage it.
Some of the most common symptoms of ocular albinism are nystagmus, or shaking your head quickly; photophobia, or fear of light; and decreased visual acuity, or the ability to see clearly in dark places. These symptoms can vary from person to person, and they can be worse in some cases than others.
Blue eyes are a sign of a rare genetic condition called the Waardenburg Syndrome. This disorder is linked to a mutation in one of the genes for melanocytes, which produce pigments that give skin, hair and eyes their color.
This gene is mutated in about 1 in 40,000 people. The gene is located on chromosome 2 and is called the PAX3 gene. Doctors can diagnose Waardenburg syndrome based on symptoms, such as asymmetrical eye color (widely spaced eyes), hypoplasia of the inner ear structures that help convert vibrations into neurological signals the brain can understand, and other disorders.
Symptoms of Waardenburg syndrome vary among individuals and families. For example, a person with type II Waardenburg syndrome may have abnormalities in the structures that make up the inner ear and deafness. Another person with type III Waardenburg syndrome may have limb differences, such as short upper limbs and abnormal bending of the fingers or fusion of the wrist bones.
Most cases of Waardenburg syndrome are inherited in an autosomal dominant pattern. This means that the mutated gene is passed down from an affected parent to each child in the family.
The genetic change that causes the Waardenburg Syndrome can’t be reversed or cured, but it can be treated with medicines and other treatments. Treatments can also improve the quality of life for people with this genetic condition.
In most cases, doctors diagnose Waardenburg syndrome at birth or in early childhood. Usually, doctors will use blood samples from the baby to test for the gene.
Occasionally, the doctor will diagnose Waardenburg Syndrome based on an infant’s unusual appearance. For example, a child with this condition may have a pale blue iris and white forelock of hair.
Another child with the syndrome may have heterochromia irides, which are areas of one iris that are different in color. Heterochromia irides are more common in people with type 2 Waardenburg syndrome.
In rare cases, the Waardenburg Syndrome can occur sporadically, or without any history of the disease in a family. These sporadic instances are caused by new genetic changes.
Blue eyes are one of the most beautiful eye colors in the world. But they can also be a bit tricky to use makeup on, so it’s important to know the right shades and techniques to enhance them.
The most popular color to wear with blue eyes is brown, but there are plenty of other shades that work well too. Whether it’s a bright pink, a gold fleck or even an orange-y terracotta, these hues will give your blue eyes the perfect pop of attention.
If you’re unsure of how to incorporate these hues into your makeup, here are some tips from experts on what looks best on blue eyes:
1. Choose colors that complement the color of your eye.
While you don’t want to go too far with the shade of your eyeshadow, a light-colored smoky brown or even a warm taupe will help highlight the depth of your eyes while still keeping them natural. Apply a thin coat of an all-over brown shadow like Victoria Beckham Beauty’s Lid Lustre in Chiffon to the lid and then add a rich black eyeliner for an instant look that’s sultry yet glam.
2. Try a smoky eyeliner with a dark color instead of black for a more sultry look.
Smoky eyeliner is a common look on red carpets, but it works great with blue eyes too! If you’re a fan of smoky eyes, opt for a brown or black pencil liner and then follow up with a mascara in your shade of choice.
3. Make sure your eyeliner contrasts with your iris’s color.
Unlike brown or green eyes, blue eyes are more susceptible to damage from the sun’s UV rays. That’s why it’s important to protect them with sunglasses as much as possible.
4. Avoid using a heavy amount of eye makeup.
While it’s tempting to overdo the makeup if you have blue eyes, excessively applying cosmetics can overshadow your eyes and make them appear pale. This can be a risk for those with paler eye colors, so steer clear of heaviness in your look.