Albinism


Albinism

Description, Causes and Risk Factors:

A group of inherited (usually autosomal recessive) disorders with deficiency or absence of pigment in the skin, hair, and eyes, or eyes only, due to an abnormality in production of melanin.

The word "albinism" refers to a group of inherited conditions. People with this disease have little or no pigment in their eyes, skin, or hair. They have inherited altered genes that do not make the usual amounts of a pigment called melanin. One person in 17,000 in The USA has some type of albinism. Albinism affects people from all races. Most children with albinism are born to parents who have normal hair and eye color for their ethnic backgrounds. Sometimes people do not recognize that they have albinism. A common myth is that people with albinism have red eyes. In fact there are different types of albinism and the amount of pigment in the eyes varies. Although some individuals with albinism have reddish or violet eyes, most have blue eyes. Some have hazel or brown eyes. However, all forms of albinism are associated with vision problems.

albinism

Genetic mutations that affect the production of a pigment called melanin. There is a cell called the melanocyte that is responsible for giving skin, hair, and eyes pigmentation. In albinism, the melanocytes are present, but genetic mutations interfere with their pigment production or their ability to distribute it to keratinocytes, the major cell type comprising the epidermis, or outer layer of the skin. There are currently five known genetic types of albinism, the most common being oculocutaneous type 1 (OCA1) and type 2 (OCA2). Oculocutaneous means affecting the eyes and skin ("oculo" meaning eye and "cutaneous" meaning skin).

Patients with OCA1 have mutations in a gene called TYR that is responsible for creating the enzyme tyrosinase, used by cells to convert the amino acid tyrosine into pigment molecules that color the skin, hair, and eyes. OCA2, the most common form of albinism in Africa, results from a mutation in the OCA2 gene, which encodes the P protein.

Symptoms:

Most people with OCA1 have snow-white skin, snow-white hair, and no pigment in their eyes. The iris (colored part of the eye that encircles the pupil) is a pale bluish pinkish color, while the pupil may actually be red. This redness comes from light entering the pupil and reflecting off of blood vessels in the retina, the light-sensitive layer of tissue lining the back of the eyeball. Normally, the pupil appears black because pigment molecules in the retina absorb light entering the eye, preventing it from bouncing back to the outside world.

Those with OCA2 can make a small amount of pigment and thus may have light blond to brown hair color. Their irises are blue to light gray and their pupils dark red to light gray.

Diagnosis:

The diagnosis of albinism can be challenging. If albinism is suspected, concernsshould be communicated to the pediatrician who will refer the family to a pediatricophthalmologist. If a child has OCA, diagnosis will often be based first on the faircolor of the child's skin and hair. A diagnosis of albinism may be suspected when achild develops rhythmic, involuntary eye movements (nystagmus) within the firstfew weeks of life and the eye exam identifies:

    If light passes through the iris (transillumination),

  • The underdevelopment of the central retina (foveal hypoplasia), and

  • The absence of melanin pigment.

While hair bulb testing has been used as a diagnostic test for albinism in the past,newer, more accurate genetic tests are now available for diagnosis, classification,and prenatal genetic counseling. The visual evoked potential test (VEP), designedto identify the misrouting of retinal fibers of the optic nerve, can be valuable inproviding a specific diagnosis.

Treatment:

Because albinism is a genetic disorder, treatment is limited. Your child will most likely need to wear prescription lenses, which provide improvements in vision, and he or she should receive annual examinations by an ophthalmologist. Although surgery is rarely part of treatment for albinism, your ophthalmologist may recommend surgery on optical muscles that minimizes nystagmus. Surgery to correct strabismus may make the condition less noticeable, but it won't improve vision.

Your doctor will also conduct an annual assessment of your child's skin to screen for skin cancer or lesions that can lead to cancer. Adults with albinism need annual eye and skin exams throughout their lives.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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