Melanin is the pigment that gives most living organisms their color. In humans, melanin is responsible for skin color, eye color, and hair color. In people with normal levels of melanin, this substance protects the skin from the damaging effects of exposure to ultraviolet (UV) rays. Humans and animals that lack normal levels of melanin have a condition known as albinism. Albinism is actually a group of similar inherited conditions that cause a lack of pigment in the eyes, skin, and hair. The National Organization for Albinism and Hypopigmentation reports that approximately one in 17,000 people in the United States have some form of albinism.
What Causes Albinism?
Humans who do not produce enough melanin have mutations in the genes responsible for melanin production. The TYR gene, also known as tyrosinase (oculocutaneous albinism 1A), helps the body produce tyrosinase. This enzyme is found in the specialized cells responsible for producing melanin, where it converts tyrosine into a compound called dopaquinone. Dopaquinone undergoes several chemical changes and eventually becomes melanin. TYR gene mutations prevent the normal production of melanin. The OCA2 gene is responsible for the production of a protein known as P protein. This is a protein found in the specialized cells that produce melanin. Scientists do not know the exact function for this protein, but they suspect that it is involved in melanin production. OCA2 gene mutations disrupt the normal production of melanin.
TYRP1 is responsible for providing instructions on how to produce tyrosinase-related protein 1. This enzyme is also found in the specialized cells that produce melanin. Although scientists do not know the exact function of TYRP1, they know it is involved in producing melanin. Some people with albinism have mutations of the TYRP1 gene. The SLC45A2 gene is also responsible for making protein in the cells that produce melanin. Scientists believe that this gene is responsible for transporting molecules that help the melanin-producing cells function normally.
Types of Albinism
There are five different types of albinism, but three of them are rare. Ocular albinism affects just the eyes and occurs mostly in males. Oculocutaneous albinism affects the hair, eyes, and skin. It has several different subtypes. People with OCA1a have no pigment and completely lack the enzyme tyrosinase. People with OCA1b have some pigment and some tyrosinase. OCA type 2 is more common in those of African descent. People with this type of oculocutaneous albinism have some pigment, but they do not have the ability to tan when exposed to the sun. OCA3 is not understood very well due to the lack of research of this type of oculocutaneous albinism. It is related to mutations of the TYRP1 gene, which may cause a child born with albinism to have red hair. OCA4 has the same signs and symptoms as OCA2, but it involves mutations in the SLC45A2 gene.
The three rare types of albinism are Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, and Griscelli syndrome. Hermansky-Pudlak syndrome affects mostly people of Puerto Rican descent. In addition to a lack of pigmentation, people with this form of albinism also experience intestinal disorders, respiratory problems, easy bruising, and bleeding disorders. Chediak-Higashi syndrome causes abnormalities in the infection-fighting white blood cells. This weakens the immune system and makes people with this type of albinism more susceptible to infections. Griscelli syndrome is the rarest form of albinism, with only 60 documented cases throughout the world. People with this type of albinism have compromised immune systems and neurological problems.
The lack of pigmentation in the eyes causes several vision problems in those who have ocular albinism. African-Americans with albinism may have 20/25 vision, which is close to normal, but other people with this condition may have visual acuity as poor as 20/400. This means that the person can only see something 20 feet away that a person with normal vision could see from 400 feet away. This condition can also cause strabismus and nystagmus. Strabismus is also known as “lazy eye” or “crossed eyes.” Nystagmus causes the eyes to move back and forth involuntarily. People with ocular albinism may also be very sensitive to glare and bright lights. This type of albinism can also cause the optic nerve to misdirect the nerve signals that travel from the retina to the brain.
Oculocutaneous albinism also causes problems with the skin. The skin of a child with albinism may be lighter than the skin of his or her parents. One of the major skin problems associated with this condition is sun damage. Because melanin protects the cells from UV damage, people without melanin are at greater risk for burns and other complications when they spend time in the sun. People with albinism should use caution when going outdoors. Long sleeves, long pants, and wide-brimmed hats can help protect the skin. Sunscreen can also protect some of the most vulnerable areas of the skin, such as the lips and ears.
Treatment for Vision Problems
Many of the vision problems linked to albinism require visual rehabilitation. Even though surgery can correct problems like strabismus, it will not improve vision if the optic nerve does not route the signals from the retina to the brain properly. Surgery can help those with crossed eyes by expanding the visual field. Prescription sunglasses or tinted contact lenses protect the eyes from the sun while improving vision. Optical aids, such as bifocals, hand-held magnifiers, reading glasses, screen magnifiers, and small telescopes can improve vision when reading and working with computers.
Most people with albinism have normal life spans and do not develop any medical problems other than those experienced by the rest of the population. The rare forms of albinism, however, do cause medical problems. Those with Hermansky-Pudlak syndrome may have reduced life spans due to respiratory problems. Those with Chediak-Higashi syndrome and Griscelli syndrome may develop problems associated with their inability to fight infections properly. Those with albinism need to take sun protection seriously, especially in tropical countries. Not using the right skin protection can result in the development of fatal skin cancers.
- What is Albinism?: The National Organization for Albinism and Hypopigmentation explains the genetics behind albinism and discusses the medical problems that can occur in people with this condition.
- Albinism: This resource from the Nemours Foundation explains albinism using kid-friendly terminology.
- Oculocutaneous Albinism: Genetics Home Reference offers a guide to oculocutaneous albinism and its genetic causes.
- Albinism Database: The University of Minnesota lists the known mutations associated with the ocular and oculocutaneous forms of albinism.
- Albinism Resources: Kansas City University Medical Center lists several resources for people affected by albinism. This resource also includes links to genetic clinics for people interested in undergoing genetic testing for albinism before having children.
- Oculocutaneous Albinism Type 1A: A Case Report: Dr. Ali Karaman discusses the major types of albinism and presents the case of a 13-year-old boy with albinism type 1A.
- Dermatological Manifestations of Albinism: Medscape explains the skin problems associated with albinism and shows pictures of these effects.
- Complications of Albinism: Mayo Clinic details the physical, social, and emotional complications of albinism.
- Sun Protection and Albinism: The Albinism Fellowship offers tips and advice for protecting the skin against the UV rays of the sun, a very important step for people with albinism.
- Effects of Albinism on Vision: The Vision for Tomorrow Foundation explains how albinism affects the eyes.
- Allele Variations in the OCA2 Gene: This technical article from the European Journal of Human Genetics discusses mutation of the OCA2 gene.
- Strabismus: This resource explains what strabismus is and how it can be corrected.
- Understanding Nystagmus: This article explains nystagmus in detail and lists some of the problems associated with nystagmus.
- Griscelli Syndrome Restricted to Hypopigmentation: This technical journal article discusses Griscelli syndrome and its effects.
- Chediak-Higashi Syndrome: This resource explains what Chediak-Higashi syndrome is and the complications associated with the condition.
- Albinism: Low Vision Considerations: This article discusses the vision problems associated with albinism and explains some of the treatment options.
- Social and Emotional Effects of Albinism: This resource explains how albinism affects a person’s emotions and social interactions.
- Low Vision Aids: This resource lists some of the inexpensive classroom aids teachers can use to teach children with albinism and other conditions that cause vision problems.
- Understanding Albinism: This resource explains how albinism affects teens with the condition.
- Teaching Children with Albinism: This resource provides teachers with several tips for teaching children with albinism.
- Sunlight and Skin Damage: The Merck Manuals website explains how to protect the skin from UV damage, which is especially important for people with albinism.
- Photos of People with Albinism: DermAtlas has several photos of people with albinism and other pigmentation disorders.
- Ocular Type 1 Albinism: The University of Arizona discusses the characteristics of ocular type 1 albinism.
- Human Genetics of Albinism: This resource offers an in-depth look at the genetic causes of albinism.
- Color On, Color Off: This resource explains how animals develop albinism.