Albinism is an autosomal disorder that presents with hypopigmentation of the skin, eyes, and hair. The lack of pigmentation could either be partial or complete. It is also characterized by visual disorders. It is primarily a metabolic disorder. It can be classified into two broad categories; oculocutenous and ocular albinism. Subtypes of the two categories exist. It may also be the classified basis of systemic diseases it is associated with. This paper will discuss the etiology/how it occurs, the genetic location of the defective gene, characteristics of a person with albinism, prevention, diagnosis, and how to manage it.
The disorder is caused by a metabolic derangement that is inherited from both parents (Kumar, Cotran, Robbins, 2005). It is a recessive disorder. Almost all forms of the disorder affect only individuals who have inherited two copies of the gene. Heterozygous individuals do not show the phenotypic characteristics of the genetic disorder. Only one variant of the disorder is linked to the X-chromosome. The disorder alters the biochemical production of melanin; a colored pigment present in the eyes, skin, and hair of animals and humans. The genetic defect causes the absence or deficiency of tyrosinase enzyme which catalyzes the conversion of tyrosine to DOPA; an intermediate chemical in melanin synthesis (Carden et al, 1998). The metabolic disorder is a direct consequence of gene mutation. For this reason, albinism usually afflicts the offspring of distant cousins.
Albinism occurs almost equally in all races. It does not show a significant racial variation. However, some types of albinism may be common in some parts of the world. The phenotypical characteristics of albinism are more pronounced in dark-skinned individuals. For instance, albinos of Caucasian origin may not be easily noticeable. The genetic cross of albinism is as follows:
Albinism may have one or many of several signs and symptoms. This is dictated by the form of the disorder. Oculocatenous albinism is restricted to the eyes, hair, and skin while ocular albinism is largely confined to the eyes. Hypopigmentation and visual defects are among the most obvious signs and symptoms of the genetic disorder. Hypopigmentation is a direct consequence of lack or deficiency of melanin. Melanin usually occurs in three colors; brown, black, and yellow.
Lack of pigment makes the iris, skin, and hair abnormally light in color. Lack of melanin predisposes to other skin conditions. Albinos are at an increased risk for skin cancer because they are overexposed to ultraviolet rays. Skin ulceration may also be present in an individual with albinism. The skin also appears dry and scaly. Various eye problems afflict albinos. Some visual disorders are related to lack of melanin while others are related to the underlying genetic defect. In general, ocular disorders associated with albinism include photophobia, nystagmus, strabismus, amblyopia, optic disc hypoplasia, astigmatism, abnormal decussation of optic fibers, and foveal hypoplasia.
All these defects manifest through reduced visual acuity. Some of the defects are developmental. This is because the normal development of the eye depends on the presence of melanin. The absence or deficiency of melanin retards the development of the retina. Abnormal decussation of nerve fibers results in double vision. Foveal hypoplasia alters color vision. However, the life expectancy of albinos does not appear to be affected. Albinos can live to adulthood like normal people. Albinism neither affects the cognitive development nor intelligence of a person.
Diagnosis of albinism relies on genetic testing and conventional methods like history taking. In the oculocutenous type, signs and symptoms are usually obvious and suggestive. In this type, hypopigmentation and visual disorders may be enough to make a diagnosis. However, genetic testing (DNA typing) may be required to aid the diagnosis of ocular albinism (Charles et al., 1994). This is necessitated by the fact that this type is accompanied by other disorders that may reduce the quality of life. Genetic testing may also be used to diagnose oculocutenous albinism though it has little clinical value.
It is difficult to prevent albinism because it is a genetic disorder. This problem is compounded by the fact that albinism is a recessive disorder. An individual who has the trait does not show any signs and symptoms of the disorder. Pediatric testing for the disorder is not necessary because the disorder is not pervasive. Individuals who have the disorder can function normally in society. Discouraging albinos from getting married and siring offspring appears to be the only preventive measure that may yield some results. In addition to the above-mentioned preventive measure, people who have a family history of albinism may be advised to do genetic testing of their children to rule out ocular albinism.
At the moment, there is no cure for the disorder. Individuals who have the disorder have to live with it for life. However, methods of managing the symptoms are available. Visual defects can be managed using various methods. Visual defects like photophobia and poor visual acuity can be corrected using prescription spectacles. Serious defects like strabismus and nystagmus may be corrected surgically (Lee, 2002). However, this is reserved for serious cases only. It is important to remember that surgical intervention does not correct loss of visual acuity because the surgery is directed at extrinsic ocular muscles. That is, it only corrects the range and quality of eyeball movements.
Other forms of management are aimed at improving the quality of life. They include the use of sunscreens, use of hats, use of protective clothes, avoiding overexposure to the sun, and sitting in front of a classroom for school-going children. Sunscreens create a physical barrier between the skin and the ultraviolet rays of the sun. Sunscreens are available in various formulations but those with a protective factor of at least 30 are preferable. Wide-brimmed hats are preferred because they protect both the eyes and upper torso. Sitting in front ensures that the children can see both the teacher and teaching aids well.
Albinism is an autosomal disorder that may present with insufficient pigmentation of the eyes, hair, and skin. It is classified into oculocutenous and ocular albinism. It is inherited from both parents. Only individuals who have inherited two defective genes manifest with the disease. Heterozygotes do not become ill. The genetic defect affects the synthesis of melanin. Tyrosinase, an enzyme required during the conversion of tyrosine to DOPA is either deficient or absent.
Signs and symptoms may include insufficient pigmentation of hair, eyes, and skin. Visual defects are also common in people with albinism. The disorder is managed symptomatically. Visual problems are managed using prescription spectacles and surgical intervention. Surgical intervention is used to correct defects of eye movement. Other methods of management include the use of sunscreens, the use of protective clothing, sitting in front of a classroom, avoiding over-exposure to sunlight, and wearing wide-brimmed hats. These methods are aimed at enhancing the quality of life.
References
Carden et al. (1998). Albinism: Modern Molecular Diagnosis. Br J Ophthalmol, 82(2), 189-195. Web.
Charles et al. (1994). Carrier Detection in X Linked Ocular Albinism Using Linked DNA Polymorphisms. Br J Ophthalmol, 78(7), 539–541. Web.
Kumar, V., Cotran, R., Robbins, S. (2005). Basic Pathology. Philadelphia: Saunders.
Lee, J. (2002). Surgical Management of Nystagmus. Journal of the Royal Society of Medicine, 95 (5), 238–41. Web.