A treatment for one form of albinism?

Individuals with oculocutaneous albinism, type 1 (OCA1) have white hair, very pale skin, and light-colored irises because they have none, or very little, of the pigment melanin in their skin, hair, and eyes. Affected individuals have impaired eyesight and a substantially increased risk of skin cancer. Current treatment options are limited to attempts to correct eyesight and counseling to promote the use of sun protective measures. A team of researchers, led by Brian Brooks, at the National Eye Institute, Bethesda, has now generated data in mice that provide hope for a new treatment for a subset of patients with OCA1.

OCA1 is caused by mutations in the gene Tyr that result in either complete loss of activity of the protein tyrosinase (which is key to the generation of melanin) or the generation of a tyrosinase protein with reduced activity. Brooks and colleagues found that treating mice that model OCA1 caused by mutations that generate a tyrosinase protein with reduced activity (OCA-1B) with nitisinone, which is already FDA-approved for treating a blood condition known as hereditary tyrosinemia type 1, increases their eye and hair pigmentation. They therefore suggest that nitisinone could improve pigmentation in patients with OCA-1B and potentially ameliorate their vision loss.

In an accompanying commentary, Seth Orlow and Prashiela Manga, at New York University School of Medicine, New York, discuss the inspired study of Brooks and colleagues but caution that there are issues that might limit the use of nitisinone as a treatment for OCA-1B.

TITLE: Nitisinone improves eye and skin pigmentation defects in a mouse model of oculocutaneous albinism

The word "albinism" refers to a group of inherited conditions. People with albinism have little or no pigment in their eyes, skin, or hair. They have inherited altered genes that do not make the usual amounts of a pigment called melanin. One person in 17,000 in the U.S.A. has some type of albinism. Albinism affects people from all races. Most children with albinism are born to parents who have normal hair and eye color for their ethnic backgrounds. Sometimes people do not recognize that they have albinism. A common myth is that people with albinism have red eyes. In fact there are different types of albinism and the amount of pigment in the eyes varies. Although some individuals with albinism have reddish or violet eyes, most have blue eyes. Some have hazel or brown eyes. However, all forms of albinism are associated with vision problems.

Vision Problems

People with albinism always have problems with vision (not correctable with eyeglasses) and many have low vision. The degree of vision impairment varies with the different types of albinism and many people with albinism are “legally blind,” but most use their vision for many tasks including reading and do not use Braille. Some people with albinism have sufficient vision to drive a car. Vision problems in albinism result from abnormal development of the retina and abnormal patterns of nerve connections between the eye and the brain. It is the presence of these eye problems that defines the diagnosis of albinism. Therefore the main test for albinism is simply an eye examination.