ALBINISM

ALBINISM

01

What's albinism ?

Features :

• A very pale skin
• White hair
• Discolouration of the eyes

It will qualify as ocular albinism when it affects only the eyes and not the rest. Its particularity comes from the fact that it is transmuted by the X chromosome thus making the carrier boys sick and the carrier women healthy.

Albinism, from the Latin «albus», meaning white, is a rare genetic condition due to a hereditary abnormality characterized by the absence of melanin in the tissues derived from the skin.

TYPE III

It has a phenotype similar to type II and is characterized by brown skin, red hair and a color of the eyes that can be either blue or brown.

TYPE IV

Form of oculo-cutaneous albinism characterized by varying degrees of skin and hair hypopigmentation and numerous eye changes.

TYPE II

The most common form of albinism in the world caused by gene 15 of the P chromosome. It is characterized by variable hypopigmentation of the skin and hair and many eye changes characteristic.

TYPE I

The most severe form of albinism characterized by the total absence of melanin and manifested by white skin and hair and completely translucent blue irises.

There are currently 7 types of oculo-cutaneous albinism (OCA):

TYPE VII

For this type of albinism, there is not yet enough information to characterize it.

TYPE VI

Characterized by hair of light color at birth and tending to darken with age, white skin and transparent iris.

TYPE V

Form of oculo-cutaneous albinism described only in a Pakistani family on this date and characterized by white skin and golden hair.

There are currently 7 types of oculo-cutaneous albinism (OCA):

02

Epidemiology

8%

Distribution in the world

OCA IV

With a prevalence of 1 in 100,000, it represents 24% among the Japanese. It is also described in the German, Turkish, Moroccan, Coorean, Chinese and Danish populations.

OCA I

With a prevalence of 1 in 40,000 worldwide, it is more common in America and China at 70%.

OCA II

One in 39,000 cases has a prevalence of 1 in 10,000 among African Americans. 1 in 36,000 Americans and 1 in 3,900 in sub-Saharan Africa.

OCA III

1 out of 8,500 Africans are affected in southern Africa but can also be seen in Pakistani, German, Indian and Japanese populations.

OCA V

There are only 1 cases at the moment with a Pakistani family.

OCA VI

Only two cases exist, in a Chinese family and a man from eastern India.

OCA VII

With a prevalence of 1 in 500,000 cases worldwide but 1 in 1800 in Puerto Rico, this type constitutes Hermansky-Pudlak syndrome (HPS).

03

Pathophysiology

MELANOSOME

Albinism comes from a disorder of melanin metabolism that can either occur during its synthesis or during its distribution. The synthesis of melanin, responsible for the pigmentation of the skin, hair and eyes, is done in the melanosomes thanks to an enzyme, tyrosinase, which allows the conversion of tyrosine into dopa. A disorder of this metabolism can either be caused by a defect in synthesis or by a concern during distribution. As a result, oculocutaneous albinism comes from a reduction in the amount of melanin, while the ocular comes from a reduction in the number of melanosomas.

Dopaquinone

Tyrosinase

Dopa

Tyrosine

Melanin synthesis

04

Risks

Sun damage and burns significantly increase the risk of skin cancer.

With very sensitive skin to light and sun exposure, sunburn is one of the most serious complications.

Skin cancer

Sunburn

Albinos have a high prevalence of photophobia due to abnormal retinal development that has the impact of reduced vision.

Photophobia

05

Evaluation

Despite the obvious physical signs that exist, it is the ophthalmological examination that will allow to make the diagnosis of OCA. This is why people with albinism need to educate themselves about this condition in order to diagnose early cancer. Painful lesions, itching, bleeding, as well as nonhealing are some of the symptoms to watch very closely.

06

Treatment and management

There is no treatment for albinsim being a genetic disease but several actions are used to prevent complications that may occur.

• Perform repetitive ophthalmogic surgeries
• Evaluate for eye correction 2-4 times for babies, 1-3 times for children and every 2-3 years for adults
• Wear corrective lenses from 4 months of age

To treat their visual deficits, they can:

• Avoid prolonged exposure to UV rays
• Avoid drugs that increase photosensitivity
• Put on sunscreen every two hours
• Wear protective clothing and goggles
• Perform periodic lifetime skin exams

To manage the dermatological complications, they must:

Eye Abnormalities

Dermal Manifestations

• A clinical trial on nitisinone that will trigger tyrosine in the blood
• Aminoglycosides which would be a potential unconfirmed therapy
• Adeno-associated virus (AAV) vectors are thought to be a potential gene therapy introducing a functional copy of the tyrosinase gene in patients with type 1 disease

Although there are only searches left at the moment, there are several studies:

Direct Therapeutic Modalities

Ingrid Nahour

« The difference is a beauty you have to learn to see »

All the photos used were taken by Yulia Taits

Thanks!