This page has been adapted from the Blind Babies Fact Sheet located at www.blindbabies.org.
Albinism
- Introduction
- Disorder
Information
- Symptoms
- Behaviors
- Treatment
- Well
Known Cases
- Surgical
Procedures
- Research
- Links
Introduction
The word "albinism"
refers to a group of inherited conditions. People with albinism have
little or no pigment in their eyes, skin, or hair. They have inherited
genes that do not make the usual amounts of a pigment called melanin.
One person in
17,000 in the U.S.A. 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. Often
people do not recognize that they have albinism.
A common myth
is that by definition 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.
Disorder
Information
While most people
with albinism have very light skin and hair, not all do. Oculocutaneous
(pronounced Ock-you-low-kew-Tain-ee-us) albinism involves the eyes,
hair, and skin. Ocular albinism involves primarily the eyes, while
skin and hair may appear similar or slightly lighter than that of
other family members.
Over the years
researchers have used various systems for classifying oculocutaneous
albinism. In general, these systems contrasted types of albinism having
almost no pigmentation with types having slight pigmentation. In less
pigmented types of albinism, hair and skin are cream-colored, and
vision is often in the range of 20/200. In types with slight pigmentation,
hair appears more yellow or red-tinged, and vision often corrects
to 20/60. Early descriptions of albinism called these main categories
of albinism "complete" and "incomplete" albinism.
Later researchers used a test that involved plucking a hair root,
and seeing if it would make pigment in a test tube. This test separated
"ty-neg" (no pigment) from "ty-pos" (some pigment).
Further research showed that this test was inconsistent, and added
little information to the clinical exam.
Recent research
has used analysis of DNA, the chemical which encodes genetic information,
to arrive at a more firm classification system for albinism. Type
1 albinism (also called tyrosinase-related albinism) is the type involving
almost no pigmentation. Type 1 albinism results from a genetic defect
in an enzyme called tyrosinase. This enzyme helps the body to change
the amino acid tyrosine into pigment. (An amino acid is a "building
block" of protein, and comes from protein in the diet.) Type
2, a type with slight pigmentation, results from a defect in a different
gene called the "P" gene.
Researchers have
identified several other genes that cause forms of albinism. In one
form of albinism, the Hermansky-Pudlak syndrome, there can be problems
with bleeding, and with lung and bowel disease as well. Hermansky-Pudlak
syndrome is a less common form of albinism, but should be suspected
if a child with albinism shows unusual bruising or bleeding.
Symptoms
Symptoms of albinism
may include the following: · very light skin color ·
blondish-white colored hair · eyes that are sensitive to light
· visual impairments that require glasses or contact lenses,
because normal levels of melanin are required for normal vision ·
tendency to sunburn easily, since there is not enough melanin to block
ultraviolet rays
While some rare
forms of albinism can cause hearing impairments or blood-clotting
problems, most people with albinism have normal health. Children with
albinism grow and develop normally and reach normal intelligence levels.
Behaviors
Treatment
Those considering
prenatal testing should be made aware that people with albinism can
adapt well to their disabilities, and lead fulfilling lives.
Vision Rehabilitation:
Eye conditions common in albinism include
Nystagmus, irregular
rapid movement of the eyes back and forth.
Strabismus, muscle imbalance of the eyes ("crossed eyes"
or "lazy eye")
Sensitivity to bright light and glare.
People with albinism may be either far-sighted or near-sighted,
and often have astigmatism (distortion of a viewed image).
These eye problems result from abnormal development of the eye because
of lack of pigment. The retina, the surface inside the eye that
receives light, does not develop normally before birth and in infancy.
The nerve signals from the retina to the brain do not follow the
usual nerve routes. The iris, the colored area in the center of
the eye, does not have enough pigment to screen out stray light
coming into the eye. (Light normally enters the eye only through
the pupil, the dark opening in the center of the iris, but in albinism
light can pass through the iris as well.)
For the most part,
treatment of the eye conditions consists of visual rehabilitation.
Surgery to correct strabismus may improve the appearance of the eyes.
However, since surgery will not correct the misrouting of nerves from
the eyes to the brain, surgery will not provide fine binocular vision.
In the case of esotropia or "crossed eyes," surgery may
help vision by expanding the visual field (the area that the eyes
can see while looking at one point).
People with albinism
are sensitive to glare, but they do not prefer to be in the dark,
and need light to see just like anyone else. Sunglasses or tinted
contact lenses help outdoors. Indoors, it is important to place lights
for reading or close work over a shoulder rather than in front.
Various optical
aids are helpful to people with albinism, and the choice of an optical
aid depends on how a person uses his or her eyes in jobs, hobbies,
or other usual activities. Some people do well using bifocals which
have a strong reading lens, prescription reading glasses, or contact
lenses. Others use hand-held magnifiers or special small telescopes.
Some use bioptics, glasses which have small telescopes mounted on,
in, or behind their regular lenses, so that one can look through either
the regular lens or the telescope. Newer designs of bioptics use smaller
light-weight lenses. Some states allow the use of bioptic telescopes
for driving. (See also NOAH bulletin "Low Vision Aids.)
Optometrists or
ophthalmologists who are experienced in working who have people with
low vision can recommend various optical aids. Clinics should provide
aids on trial loan, and provide instruction in their use. The American
Foundation for the Blind (1-800-AFB-LIND) maintains a directory of
low vision clinics.
Surgical
Procedures
Children with
ocular albinism usually have nystagmus (an involuntary to and fro
movement of the eyes). Many of these children will turn or tilt their
head in a specific direction. If turning of the eye inward, outward
or upward does not develop in the first few years of life, then therapy
depends upon the specific head position. Surgically moving specific
eye muscles in each eye will decrease the nystagmus, improve vision,
and eliminate the unusual head position. I usually don't recommend
this type of surgery until approximately age six to be sure that the
favorite head position does not change. Some children with ocular
albinism and nystagmus don't turn their heads. In these cases the
inside (medial) and outside muscle (lateral)of each eye is relaxed
(recessed) a large amount to decrease the eye movement.
Well
Known Cases
Johnny
& Edgar Winters (The Blues Brothers)
Yellowman (Reggae
Icon)
Research
PubMed
Journal Search
Effective
Retrovirus-Mediated Gene Transfer in Normal and Mutant Human Melanocytes
Genetic
Screening available
Links
The links below
are the sources of our information and additional pages that you may
find helpful.
Blind Babies Fact Sheet
NOAH:
The National Organization for Albinism and Hypopigmentation
Ocular Manifestations
of Albinism (eMedicine)
Facts about Albinism
Albinism Database
Online Mendelian Inheritance in Man
Type I
Type Ib
Type II
Handbook of Ocular Disease Management
ACKNOWLEDGMENTS
Project Coordinator: Julie Bernas-Pierce, M.Ed.
Dr. Doug Fredrick, Nancy Akeson, Susan Gomez, June Waugh,
Michele Daly, Hsiao-hui Ning, Gail Calvello.
Reviewers: Dr. Jim Haefemeyer, Kathryn Neale Manalo
The Pediatric Visual Diagnosis Fact Sheets are sponsored by a grant from the Blind Children's Center and with support from the Hilton/Perkins through a grant from the Conrad Hilton Foundation of Reno, Nevada
REPRODUCTION FOR RESALE IS STRICTLY PROHIBITED
Site
updated:
May 1, 2007
|
