Albinism (Ocular)

Definition

Definition of Albinism (Ocular)
Ocular albinism is a genetic condition that primarily affects the eyes. This condition reduces the coloring (pigmentation) of the iris, which is the colored part of the eye, and the retina, which is the light-sensitive tissue at the back of the eye. Pigmentation in the eye is essential for normal vision.

Ocular albinism is characterized by severely impaired sharpness of vision (visual acuity) and problems with combining vision from both eyes to perceive depth (stereoscopic vision). Although the vision loss is permanent, it does not worsen over time. Other eye abnormalities associated with this condition include rapid, involuntary eye movements (nystagmus); eyes that do not look in the same direction (strabismus); and increased sensitivity to light (photophobia). Many affected individuals also have abnormalities involving the optic nerves, which carry visual information from the eye to the brain.

Unlike some other forms of albinism, ocular albinism does not significantly affect the color of the skin and hair. People with this condition may have a somewhat lighter complexion than other members of their family, but these differences are usually minor.

Symptoms

Symptoms of Albinism (Ocular)
The patient has abnormal eye pigmentation, which causes vision problems such as reduced visual acuity, involuntary eye movement, crossed eyes, and sensitivity to bright light and glare.

Causes

Causes of Albinism (Ocular)
Ocular albinism type 1 is inherited in an X-linked pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the GPR143 gene in each cell is sufficient to cause the characteristic features of ocular albinism. Because females have two copies of the X chromosome, women with only one copy of a GPR143 mutation in each cell usually do not experience vision loss or other significant eye abnormalities. They may have mild changes in retinal pigmentation that can be detected during an eye examination.

Diagnosis

Diagnosis of Albinism (Ocular)
These resources address the diagnosis or management of ocular albinism and may include treatment providers.

• Gene Review: Ocular Albinism, X-LinkedThis link leads to a site outside Genetics Home Reference.
• Gene Tests: Ocular Albinism, X-LinkedThis link leads to a site outside Genetics Home Reference.
• MedlinePlus Encyclopedia: AlbinismThis link leads to a site outside Genetics Home Reference.

Treatment

Treatment of Albinism (Ocular)
Patients may seek a genetic counselor to help deal with their emotional and social adjustment problems. Others seek medical help and use ordinary or special glasses, or contact lenses to help correct their vision. Other patients are also treated using visual aids and environmental changes to expand the limit of their vision.

Prognosis

Prognosis of Albinism (Ocular)
Consult with your doctor.

Prevention

Prevention of Albinism (Ocular)
The OA1 mutants were classified into two major groups based on glycosylation and localization patterns. While group I consisted of normally glycosylated OA1, group II represented aberrantly glycosylated OA1 which is indistinguishable from the wild type. However, both these studies revealed that in >60% of these mutations, the protein was retained in the ER and which is assumed to be the major cause of OA1. They also revealed that the protein levels decreased drastically, probably due to misfolding of the protein in the ER. Some of the mutations reported in second and third cytoplasmic loops (these regions are known to be critical for GPCR downstream signaling) are believed to affect transduction of the signals from OA1 via G proteins.