Human Genetics’ Phenomenon: Heterochromia

Tuesday, 02 August 2022

There exist several genetic diseases, some stranger than others. Heterochromia is one of the weirdest human genetic diseases that we can find. If you are interested in human genetics, keep on reading this article to find out more information about it. 

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We, as human beings, go through lots of illnesses throughout our lives. Besides, some of us are born with specific illnesses and have to live with them our whole life. There are some diseases that are caught throughout our lives and they can last a period of time or forever. However, there are some other diseases we are born with and some of them can be hereditary. 

There are people who are in charge of investigating certain human diseases to help the people who suffer from the affliction. One of these afflictions a person can suffer is heterochromia, which is the phenomenon of having eyes of two different colours. In this article, the definition, causes, and types of heterochromia will be developed, apart from a summary of what human genetics is. If you find the information interesting to you, we provide information about where to study to get a degree in human genetics. Keep on reading to find out more!


As mentioned before, heterochromia is a condition in which a person is born with or develops eyes of different colours (the irises). This disease is rare in humans, although not impossible. It can be classified according to the colours of the eyes; for instance, hypochromic heterochromia refers to the abnormal iris being of a lighter colour than the normal one; on the other hand, hyperchromic heterochromia refers to the abnormal iris being of a darker colour than the normal iris. 

FACT: Although rare in humans, heterochromia is pretty normal in animals such as dogs, cats, or horses. 

Types of Heterochromia

The scientific explanation for this disease is that your iris changes colours thanks to a pigment called melanin. This pigment is what makes the eyes blue, green, brown, or hazel.  When there is more melanin, the eye colour will be darker, and when there is less melanin, the colour will be lighter. 

Heterochromia can be classified into three different types: 

What Causes Heterochromia? 

The causes of heterochromia can be different and they are divided into two. In most of the cases, people are born with heterochromia, but there are some other cases in which they acquired later in life. 

When the child is born with the disease, it is called congenital heterochromia, and the child will not suffer from any symptoms. Some of the causes of congenital heterochromia might be: 

  • Horner’s syndrome: It is a condition caused by damage to the nerves connecting to the brain and eyes. 
  • Sturge-Weber syndrome: It is a condition that causes abnormalities in the brain, skin, eyes, and more. 
  • Waardenburg syndrome: It is a disease that causes a change of colour in the skin, eyes, and hair.
  • Piebaldism: This disease leads to a lack of pigment in the skin, eyes, and hair. 
  • Hirschsprung disease: It is a condition affecting the large intestine. 
  • Parry-Romberg syndrome: It is a condition that makes the skin, bones, muscles, and skin tissue of one side of the face weaken. 

When the person gets heterochromia later in life, it is called acquired heterochromia. Some of the causes of acquired heterochromia might be: 

  • Eye injury or trauma
  • Eye surgery
  • Melanoma of the eye
  • Some drugs
  • Diabetes
  • Glaucoma
  • Neuroblastoma

A person who develops or was born with heterochromia should see an ophthalmologist. There is usually no treatment for the disease but there is, in some cases, for the diseases that cause heterochromia. 

Human Genetics 

Human genetics is an area of research that is in charge of studying and understanding the biology of the human species. It is a branch of biology that deals with how human traits and certain diseases are passed among generations. By studying for a degree in Human Genetics, the students will get the experience needed to contribute to different genetics research teams. Students will get enough information to be able to prepare a research paper, a thesis, and a project presentation. 

Where can I Study? 

In South Africa, you can study in a 2 years program in which you will have to prepare a research project and present it to the Committee for Postgraduate Teaching to earn a degree in Master of Science in Human Genetics. 

Stellenbosch University - Master of Science in Human Genetics 

Have you ever heard about Heterochromia? Have you ever seen someone who suffers from it? Heterochromia is very rare in humans, but less than 20,000 people suffer from it in the United States. By getting a degree in Human Genetics, you will be able to learn more about the diseases that cause Heterochromia and a lot more. 

If you are interested in Human Genetics, fill in the form on our site and one of our advisors will contact you as soon as possible to answer any questions you may have. 

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