Oculocutaneous albinism is an inherited defect in melanin formation that causes diffuse hypopigmentation of the skin, hair, and eyes. Ocular albinism affects the eyes and usually not the skin. Ocular involvement causes strabismus, nystagmus, and decreased vision. Diagnosis of oculocutaneous albinism is usually obvious from the skin examination, but ocular evaluation is necessary. No treatment for the skin involvement is available other than protection from sunlight.
Oculocutaneous albinism (OCA) is a group of rare inherited disorders in which a normal number of melanocytes are present but melanin production is absent or greatly decreased. OCA occurs in people of all races throughout the world. Cutaneous and ocular pathologies (ocular involvement) are both present. Findings in ocular involvement include abnormal optic tract development manifested by foveal hypoplasia with decreased photoreceptors and misrouting of optic chiasmal fibers. Ocular albinism (OA) does not usually affect the skin.
Most cases of OCA are autosomal recessive; autosomal dominant inheritance is rare. There are 4 main genetic forms:
OA types Nettleship-Falls (OA1) and Forsius-Eriksson (OA2) are extremely rare compared to OCA. They are inherited in an X-linked dominant fashion. Usually findings are confined to the eyes, but skin may be hypopigmented. Patients with OA1 may have late-onset sensorineural deafness.
In another group of inherited diseases, a clinical phenotype of OCA occurs in conjunction with bleeding disorders. In Hermansky-Pudlak syndrome, OCA-like findings occur with platelet abnormalities and a ceroid-lipofuscin lysosomal storage disease. This syndrome is rare except in people with family origin in Puerto Rico, where its incidence is 1 in 1800. In Chédiak-Higashi syndrome, OCA-like cutaneous and ocular findings occur, hair is silvery gray, and a decrease in platelet-dense granules results in a bleeding diathesis. Patients have severe immunodeficiency due to abnormal lymphocyte lytic granules. Progressive neurologic degeneration occurs.
Symptoms and Signs
The different genetic forms have a variety of phenotypes.
Type I (OCA1A) is classic tyrosinase-negative albinism; skin and hair are milky white, and eyes are blue-gray. Pigmentary dilution in OCA1B ranges from obvious to subtle.
Type II has phenotypes with pigmentary dilution that ranges from minimal to moderate. Pigmented nevi and lentigines may develop if skin is exposed to the sun; some lentigines become large and dark. Eye color varies greatly.
In type III, skin is brown, hair is rufous (reddish), and eye color can be blue or brown.
In type IV, the phenotype is similar to that for type II.
Patients with ocular involvement may have decreased retinal pigmentation, leading to sensitivity to light and light avoidance. In addition, nystagmus (see Sidebar 1: Nystagmus), strabismus (see Strabismus), reduced visual acuity, and loss of binocular stereopsis likely result from defective routing of the optic fibers.
Diagnosis of all types of OCA and OA is based on examination of the skin and eyes. Early ocular examination may detect iris translucency, reduced retinal pigmentation, foveal hypoplasia, reduced visual acuity, strabismus, and nystagmus.
There is no treatment for albinism. Patients are at high risk of sunburn and skin cancers (especially squamous cell carcinoma) and should avoid direct sunlight, use sunglasses with ultraviolet (UV) filtration, wear protective clothing, and use sunscreen with a sun protection factor (SPF) as high as possible (eg, 50 or higher) that protects against UVA and UVB wavelengths (see Prevention). Some surgical interventions may lessen strabismus.
Last full review/revision September 2014 by Peter C. Schalock, MD
Content last modified October 2014