Albinism describes a group of genetic alterations of the melanin pigment system that affect skin, hair follicles, and eyes. It principally involves the synthesis of melanin in these sites, but a normal number of melanocytes is present; also included are some alterations of the pathways of the CNS. Albinism can affect the eyes, ocular albinism (X-linked recessive or autosomal recessive), or the eyes and skin, oculocutaneous albinism (OCA). In OCA, the disorder is autosomal recessive, with dilution of normal amounts of skin, hair, and melanin pigment; nystagmus and iris translucency are always present, and there is a reduction of visual acuity, sometimes severe enough to cause severe impairment of vision.
Causes of Albinism
The defect in melanin synthesis has been shown to result from absence of the activity of the enzyme tyrosinase. Tyrosinase is a copper-containing enzyme that catalyzes the oxidation of tyrosine to dopa and the subsequent dehydrogenation of dopa to dopa-quinone. Recent cloning of complementary DNAs (cDNAs) encoding tyrosinase has made it possible to directly characterize the mutations in the tyrosinase gene responsible for deficient tyrosinase activity in several types of albinism. In type IA, two different missense mutations, one from each parent, result in amino acid substitutions within one of the two copper-binding sites.
Symptoms of Albinism
- Rapid eye movements
- Strabismus (eyes not tracking properly)
- Photophobia (avoidance of light because of discomfort)
- Decreased visual acuity or even functional blindness
- Albinismus
- BADS
- Congenital Achromia
- Hypopigmentation
- Oculocutaneous Albinism
Diagnosis
White persons with very fair skin (skin phototype I), blond hair, and blue eyes may mimic albinos, but they do not have eye changes (iris translucency, nystagmus). Some persons with albinism who have constitutive black or brown skin color may have a dilution of their skin color from black to a light brown and have the capacity to tan; also, some types may have brown irides but still have iris translucency. Therefore, iris translucency and the presence of other eye findings in the fundus are the pathognomonic signs of albinism. The hair and skin color may vary from normal to absent melanin, and the various types. The special types of albinism are diagnosed on the basis of clinical presentation of the hair and skin pigmentation as well as hematologic studies (HPS).
Treatment
Eye Every albino should be under the care of an ophthalmologist.
Skin A lifetime program with a dermatologist beginning in infancy, including the following:
Yearly examination by a dermatologist to detect skin changes: solar keratoses, skin cancers, and dermatoheliosis.
Daily application of topical, potent, broad-spectrum SPF>30 sunblocks, including lip sunblocks.
Avoidance of sun exposure in the high solar intensity season during the 1 to 2 h either side of noon, depending on the latitude, in the winter also.
Use of topical tretinoin for dermatoheliosis and for its possible prophylactic effect against sun-induced epithelial skin cancers. Treatment of solar keratoses to prevent the development of squamous cell carcinomas which are not infrequent, especially in the thirdworld countries.
Systemic β-carotene (30 to 60 mg tid) imparts a more normal color to the skin and may have some protective effect on the development of skin cancers, although this has been proved only in mice.
General It is helpful for albinos to belong to a national volunteer group of albinos in the United States called the National Organization for Albinism and Hypomelanosis (NOAH).(Noah, the builder of the ark in the old Testament, was alleged to be an albino.) This group assists albinos in various ways, especially in dealing with vision problems: obtaining driver’s license, etc.
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