Understanding the Genetics and Inheritance of Albinism

Jun 13, 2023

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Every year on June 13, the world comes together to observe International Albinism Awareness Day. This day is intended to raise awareness about albinism, celebrate the achievements of individuals with albinism, and advocate for their rights and inclusion in society. Albinism is a group of hereditary conditions that is characterized by the decrease or absence of melanin, the pigment responsible for hair, skin, and eye colour. People who are affected by this condition have lighter hair, skin, and eyes, as a result of which, they are more susceptible to sun damage, can have visual impairments, and experience challenges relating to social acceptance and inclusion. It affects people of all ethnicities, and occurs in around 1/17,000 to 1/20,000 people worldwide. 

 

Since there are several types of albinism, the genetics, inheritance, symptoms, and management of these conditions varies. The most common form of albinism is Oculocutaneous Albinism (OCA), which has skin and eye related manifestations. The severity of the symptoms depends on which of the seven subtypes of OCA a patient has. Another common type of albinism is Ocular Albinism (OA), in which the reduced pigmentation is limited to the eye, and only the visual pathway is clinically affected. 


Additionally, albinism can be an isolated symptom (meaning that there aren’t any other medical concerns aside from the decreased pigmentation, and the resulting problems), or it can be part of a syndrome, in which albinism can occur with other system-wide problems. OCA1-OCA7 are considered isolated forms of albinism, but other conditions including Chediak-Higashi Syndrome and Hermansky-Pudlak Syndrome are also associated with other medical concerns.


Chediak-Higashi syndrome is albinism that occurs with severe immunodeficiency, mild bleeding, and progressive neurological abnormalities, while Hermansky-Pudlak syndrome is albinism that occurs with bleeding anomalies due to a platelet storage pool deficiency. 


Genetics and inheritance

Most forms of albinism are autosomal recessive, though they involve different genes. This means that in order for a person to be affected with this condition, they must carry two copies of the mutated gene. When two unaffected parents who are both carriers of the same form of albinism have a child, that child has a 25% chance of having albinism. 


If you are interested in finding out the likelihood that you are a carrier of a form of albinism, or want to understand the probability that you and your partner will have a child with albinism, you should consider carrier screening, which is a genetic test that tells you if you are an unaffected carrier for a genetic disorder that your child might be at risk of inheriting. This test informs you of the probability of having a child with several genetic conditions, not just albinism. You can discuss your concerns and interests with a genetic counsellor to get a better understanding of whether this test is right for you. 


There are different genes that are involved with the different forms of albinism. For example, the table below highlights some of the genes involved in some of the different forms of this condition. In order for someone to be affected with one of these conditions, there needs to be a mutation in both of their copies of one of the genes listed. 

 

Condition Gene
OCA1 TYR
OCA2 OCA2
Chediak-Higashi Syndrome LYST
OA1 GPR143


Interestingly, the inheritance of Ocular Albinism varies from most other forms of albinism, because the GPR143 gene is found on the X chromosome, which is one of the two sex chromosomes. The X and Y chromosomes are involved in the development of biological sex. Biological males have one X chromosome and one Y chromosome, while females have two X chromosomes. If there is a mutation in the GPR143 gene in a female, she generally will not experience symptoms for this condition, because she has another copy of the gene (on her second X chromosome) that is still working. However, males with a mutation in this gene experience symptoms, because they only have one copy of the gene, since they only have one X chromosome. 


(This is a simplification of complex genetics concepts, and it is possible (though relatively unlikely) for a female to be affected with this condition, even though she has two copies of the X chromosome, because of a genetic mechanism known as X-inactivation.)


If you’re concerned that you or someone you know might be affected with albinism, the genetic diagnostic test that can help you understand whether you have this condition is known as Whole Exome Sequencing. This is a type of test that reads through your genetic information to find out if there are any spelling mistakes in your genes that might cause a disease. Genetic testing for albinism is important to understand what type of albinism a patient might be affected with, which in turn will help provide personalized and targeted care and management. If someone is affected with a syndromic form of albinism, we want to find out as soon as possible, because they might experience symptoms besides reduced pigmentation, and finding out the genetic basis for their condition will allow us to prepare for the medical management that they need. 


Management, care, and support

Although there is no cure for albinism, most individuals with this condition can lead fulfilling lives with appropriate management strategies. 


One of the primary management considerations for people with albinism is sun protection. Because of the decreased or absent melanin production, these people are at increased risk for sun damage, including sunburns and a higher risk for skin cancer. It is crucial for affected individuals to use a sunscreen with a high SPF, and to wear protective clothing, hats, and sunglasses. This is especially important in the summer months in India, where the temperatures and intensity of sunlight become unbearable even for people with sufficient melanin. It can cause incredible damage to withstand such temperatures for these patients and appropriate protective measures should be taken to protect the skin and eyes as much as possible. 


Additionally, albinism often affects visual acuity and sensitivity to light. Regular eye exams and using prescribed corrective lenses (glasses or contact lenses) can improve visual function. Tinted lenses or photochromic glasses can reduce light sensitivity, and it is essential to wear sunglasses while out in the sun.


It is also important for these individuals to have a multi-disciplinary care team to provide them with the healthcare that they require. This includes dermatologists, ophthalmologists, and genetic counsellors. Additionally, as mentioned previously, some forms of albinism can also have other medical concerns, and it is important for patients to have access to the specialized care that they need. 


Besides this, living with albinism can lead to self-esteem and body image issues due to societal misconceptions. Counselling, therapy, or other mental health interventions and support can help individuals cope with these challenges and foster a positive self-image. However, it is not sufficient for people to seek individual mental health support because of the damage caused by misinformed social stigma. Societal changes are necessary to better support these people, who have faced challenges when it comes to inclusion and acceptance on a familial level, as well as at a larger social level. This can be achieved through spreading awareness, supporting albinism organizations, and even kindness and acceptance on an individual level with patients that you know or see. 


Resources

Patient support groups can also be helpful, and the Albinism India Group is a Facebook group where people with albinism can share information and connect. 

The Jeevan Trust also has a series of informative webinars and videos on albinism, and the care that individuals with this condition require. 

International Albinism Awareness Day is a time to unite, celebrate diversity, and advocate for the rights of people with albinism. Understanding the genetics of the condition and the management that it requires is just the first step in providing more social support to these people. 

Disclaimer: The information provided here is not exhaustive by any means. Always consult your doctor or other qualified healthcare provider with any questions you may have regarding a medical condition, procedure, or treatment, whether it is a prescription medication, over-the-counter drug, vitamin, supplement, or herbal alternative.