Human Anatomy & Physiology (9th Edition)

Published by Pearson
ISBN 10: 0321743261
ISBN 13: 978-0-32174-326-8

Chapter 15 - The Special Senses - Review Questions - Critical Thinking and Clinical Application Questions - Page 589: 7


Albinism is a condition caused by genetic mutations in the genes that are responsible for color of hair skin and eyes. There are several pigment responsible for skin color (melanin, carotene, hemoglobin), but albinism is due to inability of albinos to produce normal amounts of melanin. Melanin is the major pigment that gives color to skin hair and eyes; it is produced by melanocytes. There are two main classes of albinism, oculocutaneous (OCA) and oculoalbinism(OA). The former type, OCA, has several subdivisions but people with this type produce no melanin in skin hair or eyes (irises). People with oculoalbinism do produce some melanin Signs and symptoms: In oculocutaneous albinism (OCA) hair color varies from white to brown to reddish brown, eye lashes are pale brown, eye color varies from brown to light blue, irises are translucent and may appear pink to red. The main function of melanin is to confer protection from damage by ultraviolet radiation of sunlight. Because albinos do not have this protection they are at great risk for skin and eye damage by sunlight. In the case of skin injury this may range from mild sunburn to life-threatening skin cancer or melanoma. Visual abnormalities that may develop in OCA patients include nystagmus, myopia, hyperopia and impaired depth perception.

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Albinism is a genetic condition in which the afflicted subject/patient is unable to make melanin, the major pigment that gives color to skin, hair and eyes (irises). In the most prevalent form of albinism, the patient can make no melanin at all. This results in photophobia because the deficit in melanin males the OCA patient very susceptible to sunburn and skin cancer (melanoma). Albinos have several visual system morphological abnormalities: the structure of the retina may be abnormal and the malformations of the optic tracts may lead to misrouting of visual signals. One consequence of this is impaired depth perception. Other visual abnormalities expressed in albinos are strabismus (crossed eyes), nyatagmus, astigmatism , myopia and hyperopia. Albinism exists in all races and both seses. The condition does no decrease life expectancy, but some albinos are legally blind. Note: In some countries of Subsaharan Africa albinos are at great risk for they are believed to have magical qualities. Their body parts are craved by tribal medicine men to be used in compounding tribal medical potions. Albinos are often kidnapped and murdered, and their body parts sold to medicine men to be used in the concoction of medical potions. Murders of albinos are most common in Tanzania, Burundi, and Malawi. Among Zulus and several African tribes albinos are considered to be cursed, but magical. The body parts of an albino is worth almost $100,000 from the witch doctors and medicine men in some African tribes (Through Albino Eyes. International Federation of Red Cross and Red Crescent Societies, Geneva Switzerland , 2009).
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