Albinism is a genetic disease characterized by a defect in the production of melanin that has effects on the eyes and skin. Definition, cause, symptoms of a person with albinism, transmission of ocular albinism, treatment … An update on this anomaly with Dr. Mederic Jean, a geneticist at the University Hospital of Tours.
Albinism is a disease caused by hereditary. Up to leather And the eyes. Among the symptoms, albino babies are born white With very light blonde hair. Ocular albinism He has a certain method of transmission. Definition of albinism, its consequences and treatment.
Definition: What is albinism?
albinism he is rare genetic diseasedue to a genetic defect characterized by Partial or total absence of melanin. “Melanin is a pigment found in the skin, hair, and hair but also in the eyes in the iris and retina. Albinism affects the skin and eyes, hence its name oculocutaneous albinism (AOC) ” explains Dr. Mederic Jean, a geneticist at the University Hospital of Tours.
What is ocular albinism?
We are talking aboutOcular albinism When the attack is for the eyes only without any fungal skin manifestation. So the skin pigmentation is normal. Specificity of ocular albinism Mode of transmission, where it is transmitted through the sex chromosome X. “Ocular albinism is secondary to a defect in the GPR143 . gene Which is located on the X chromosome, a gene that exists in two copies in women because they have two X chromosomes and in one copy in men who have only one X chromosome, Dr. Jane explains. Thus, boys who are carriers are affected but only women are carriers of the disease. They have a 50% risk of having an affected boy or 50% of having a girl who is pregnant.“
What are the different types of albinism?
We are currently calculating 7 types of classic AOC They are characterized by the different genes involved. “Clinically, they are distinguished mainly by dermatological and vasovagal intervention because ophthalmological involvement is the same globally.Dr. Jane says. type 1A It is the most severe, because sufferers have no pigment, whether in the skin, hair or eyes that appear red (you can see the red retina through the iris). type 2 It is the most prevalent, and is caused by the P gene of chromosome 15. Babies are born white with blond hair, once adults, freckles may appear and their hair take on a straw color. The eyes may remain blue or turn from yellow to light brown.
Albinism is a rare disease with a low prevalence.
How many people have albinism?
Albinism is a rare disease with a low prevalence. affects the average 1 out of 17,000 people worldwide But some areas are hardest hit. In some African countries, its frequency increases to 1 in 1,000 births and 1 in 12,000 among African Americans. There are approximately 6000 people with albinism in France.
What is the genetic origin of albinism?
All these diseases are hereditary with a risk of recurring in the family. As Dr. Jane explains,Currently, 19 genes are known to be involved in AOC, including 11 genes for syndromic polymorphisms.. The various forms of AOC are almost all from an autosomal recessive transmission. This means that both copies of the same gene must be abnormal in order to be affected. In this case, both parents must be healthy carriers (or heterozygotes). For the parents of a child with COA, the risk of having another affected child is therefore 25% with each pregnancy“Ocular albinism is an X-linked transmission as described above.”Other genes are likely involved but are not currently knownGeneticist adds.
“The first manifestation is fungal dermal hypopigmentation of variable degree depending on the type of AOC. The skin is very white, pink to cream, and the hair, eyelashes and eyebrows are white to yellow by type. In Caucasian communities, cutaneous involvement is not always evident, and ophthalmological involvement is often what comes to the fore.Dr. Jane’s details. At the ophthalmological level, we find children who have Great light disturbanceCall Photophobia. “We also observe in these children nystagmus, meaning that the eye is abnormal. Amblyopia, ocular torticollis, myopia or farsightedness are also frequent signs. It is associated with visual impairment which can be profound to moderate.The specialist continues.
Although the above symptoms are suggestive, they areophthalmology examination This allows the diagnosis to be made. “Specific signs of AOC are characterized by a pale iris and transient luminescence, that is, allowing light reflected by the retina to pass through. The retina also appears hypopigmentedDr. Jane says.
There is no cure for albinism.
Are there treatments for albinism?
There is no There is no cure against albinism. Support consists of prevent complications And treat them when they are present. “Several methods have been explored, and are still being explored, such as gene therapy and drugs that interfere with the melanin production pathway. Today these tracks are only a matter of research.Geneticist adds.
What are the consequences of having albinism?
The role of melanin is to protect the skin from ultraviolet rays from the sun. Therefore, the main risks of the classic forms of AOC are related to the lack of protection normally provided by melanin, making it The skin is exposed to ultraviolet rays. “The complications that can result are Actinic keratosis-like skin lesions (aesthetically disabling) or precancerous lesions of the skin such as basal cell and squamous cell carcinomaDr. Jane explains. In particular, it is estimated that a significant proportion of people with albinism in Africa die of skin cancer between the ages of 30 and 40. So it is necessary Effective protection for the skin from the sun’s rays With full sunscreen, long-sleeved UV clothing and a long-brimmed hat. Eyes can be protected by UV goggles. “At the eye level, it is also necessary to correct aberrations in refraction as quickly as possible in order to promote the most normal visual development possible.says the specialist.
No method of prevention can rule out disease, albinism hereditary.
Thanks to Dr. Mederic Jean, a geneticist at the University Hospital of Tours.