Albinism

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Introduction0:00–0:15

Albinism, meaning white, is a non-contagious, congenital condition that is defined by a drastic reduction or complete lack of pigmentation in the hair, skin and eyes.
Albinism is often portrayed negatively, like Silas the antagonist in the book “The Da Vinci Code”, which contributes to his diminished quality of life with the disease.

Skin0:15–2:28

The skin is divided into three layers--the epidermis, dermis, and hypodermis. The hypodermis is made of fat and connective tissue that anchors the skin to the underlying muscle.
Just above is the dermis, which contains hair follicles, nerves and blood vessels. And just above, the outermost layer of skin, is the epidermis.
The epidermis itself has multiple cell layers that are mostly keratinocytes - which are named for the keratin protein that they’re filled with.
Keratin is a strong, fibrous protein that allows keratinocytes to protect themselves from getting destroyed when you rub your hands through the sand at the beach.
Keratinocytes start their life at the deepest layer of the epidermis called the stratum basale, or basal layer, which is made of a single layer of small, cuboidal to low columnar stem cells that continually divide and produce new keratinocytes that continue to mature as they migrate up through the epidermal layers.
But the stratum basale also contains another group of cells - melanocytes, which secrete a protein pigment, or coloring substance, called melanin.
Melanin is actually a broad term that constitutes several types of melanin found in people of differing skin color. These subtypes of melanin range in color from black to reddish yellow and their relative quantity and rate at which they are metabolized define a person’s skin color.
When keratinocytes are exposed to the sun, they send a chemical signal to the melanocytes, which stimulates the melanocytes to produce melanin through a multistep enzymatic reaction that begins with tyrosine.
Once it’s made, the melanocytes move the melanin into small sacs called melanosomes, and these get taken up by newly formed keratinocytes, which will later metabolize the melanin as they migrate into higher layers of the epidermis.
Melanin then acts as a natural sunscreen, because its protein structure dissipates, or scatters, UVB light--which if left unchecked can damage the DNA in the skin cells and lead to skin cancer.
Melanin can also be found at the base of hair follicles to color hair; and in the eyes, including the iris where it contributes to eye color, and the choroid tissue layer of the eye where it helps prevent light reflection.

Causes2:28–3:00

Albinism is caused by a recessive gene mutation encoding any one of the enzymes needed to produce melanin. The resulting dysfunctional or deficient enzyme drastically decreases the amount of melanin that’s made.
Albinism can also occur if there are mutations in proteins responsible for the transport of tyrosine or melanosomes. It’s linked to Chediak Higashi which causes hypopigmentation, recurrent infections, mild coagulation defects, and varying neurologic problems.

Symptoms3:00–3:42

Symptoms of albinism can be seen in the coloring of hair, irises, and skin. Coloring can range from drastically reduced pigmentation to white hair; milky white skin; and very light blue or translucent irises, which appear pink or red because of the retinal tissue lining the back of the eye.
An absence of melanin in the eyes can lead to a variety of vision problems ranging from focusing and depth perception to nystagmus and amblyopia which is when there’s misalignment of the eyes.
In addition, albinism can cause freckles, moles, and lentigines - which are large freckle-like spots - to form on the skin, and it also increases the risk of skin cancers.

Diagnosis3:42–3:59

Diagnosis is typically made based on clinical observations, initially. But a firmer diagnosis can be made with a skin biopsy or hair bulb extractions to test for the presence of melanin.
Finally, genetic testing can give a definitive diagnosis. Treatment for albinism centers around preventing additional ailments that may occur from a lack of protection melanin normally provides.

Treatment3:59–4:25

So, that means wearing tinted glasses to protect eyes, sunscreen to counter an increased risk of skin cancer. Some forms of albinism may be helped with medications that increase tyrosine levels; and others may be helped by low-vision aids if eyesight is also affected.
So, to recap: Albinism is a recessive genetic condition causing dysfunction in one or more enzymes involved in the multi-step production of melanin inside melanocytes.

Review4:25–5:02

A decrease or absence of melanin can reduce or obliterate pigmentation of the skin, hair, and eyes causing them to appear lighter in color or completely white.
Definitive diagnosis can be made with genetic testing, and skin biopsies or hair bulb extractions to test for the presence of melanin.
Treatment generally includes supplementing the protection melanin would have provided to the eyes and skin.