Albinism
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Albinism Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Albinism On the Web |
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American Roentgen Ray Society Images of Albinism |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shadan Mehraban, M.D.[2]
Overview
Historical Perspective
Albinism was first discovered in 1908 by a British physician named Sir Archibald Edward Garrod. At first, it was believed that albinism is caused by a lack of melanocytes. In late 1950, it was proved that albinism is caused by tyrosine kinase inactivity.
Classification
Albinism is classified based on genetic mutation. The different types of albinism include: Oculocutaneous albinism(OCA), Hermansky-Pudlak syndrome (HPS),Chediak-Higashi syndrome (CHS),Ocular albinism (OA).
Pathophysiology
Melanocytes are derived from neural crest ectoderm and are found in hair follicles, skin, eyes, and inner ear. Melanocytes produce melanin which protects skin from ultraviolet. Tyrosinase converts tyrosine to DOPA, dopaquinone, and then melanin. Mutation in Tyrosinase enzyme is responsible for causing albinism. Additionally, melanin is responsible for development of the fovea, optic nerves, optic tracts, and visual cortex.Decussation of some optic nerve fibers at optic chiasm are essential for binocular vision. However, in albinism, most of nerve fibers decussate at optic chiasm and cause monocluar vision presented as strabismus. In ocular albinism, macular pigment is absent and fovea hypoplasia leads to decreased visual acuity.
Causes
Albinism is caused by genetic mutations that impair melanin synthesis. The number of melanocytes is preserved.
Differentiating Albinism from Other Diseases
Epidemiology and Demographics
The prevalence of albinism is estimated to be 1:17,000 to 1:20,000 in the general population.The Prevalence of different types of albinism varies and the most prevalent form is Oculocutaneous albinism 2 (OCA2).
Risk Factors
Albinism is inherited due to genetic mutations. Individuals with positive familial history are at risk of having albinism.
Screening
There is no screening test for albinism.Individuals with familial history of albinism can undergo genetic sequence analysis.
Natural History, Complications and Prognosis
The complications of albinism include skin cancer, sunburn, decreased visual acuity, poor self-image and self-isolation lead to depression. Patients with albinism has a normal life expectancy and do not have developmental delay or mental retardation.
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | Electrocardiogram | X Ray | CT | MRI | Echocardiography or Ultrasound | Other Imaging Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies |
See also
- Vitiligo (or leukoderma), the patchy loss of skin pigmentation
- Melanism (or melanosis), the condition of having an unusually high level of skin pigmentation
- Leucism, a condition similar to albinism in animals, characterized by reduced pigmentation
- List of Mendelian traits in humans