INFORMATION ABOUT JUVENILE (X-LINKED) RETINOSCHISIS

Information courtesy of "The Foundation for Fighting Blindness"

Juvenile retinoschisis is an inherited disease diagnosed in childhood that causes progressive loss of central and peripheral (side) vision due to degeneration of the retina.

Clinical description

Juvenile retinoschisis, also known as X-linked retinoschisis, occurs almost exclusively in males. Although the condition begins at birth, symptoms do not typically become apparent until after the age of 10. About half of all patients diagnosed with juvenile retinoschisis first notice a decline in vision. Other early symptoms of the disease include an inability of both eyes to focus on an object (strabismus) and roving, involuntary eye movements (nystagmus).

Vision loss associated with juvenile retinoschisis is caused by the splitting of the retina into two layers. This retinal splitting most notably affects the macula, the central portion of the retina responsible for fine visual detail and color perception. On examination, the fovea (the center of the macula) has spoke-like streaks. The spaces created by the separated layers are often filled with blisters and ruptured blood vessels that can leak blood into the vitreous body (the transparent, colorless mass of jelly-like material filling the center of the eye). The presence of blood in the vitreous body causes further visual impairment. The vitreous body degenerates and may eventually separate from the retina. The entire retina may also separate from underlying tissue layers causing retinal detachments.

The extent and rate of vision loss vary greatly among patients with juvenile retinoschisis. Central vision is almost always affected. Peripheral (side) vision loss occurs in about half of all cases. Some patients retain useful vision well into adulthood, while others experience a rapid decline during childhood.

Inheritance

Juvenile retinoschisis is genetically passed through families by the X-linked pattern of inheritance. In this type of inheritance, the gene for the disease is located on the X chromosome. Females have two X chromosomes and can carry the disease gene on one of their X chromosomes. Because they have a healthy version of the gene on their other X chromosome, females typically are not affected by X-linked diseases such as juvenile retinoschisis.

Sometimes, however, when carrier females are examined, the retina shows minor signs of the disease.

Males have only one X chromosome (paired with one Y chromosome) and are therefore genetically susceptible to X-linked diseases. Males cannot be carriers of X-linked diseases. Males affected with an X-linked disease always pass the gene on the X chromosome to their daughters, who then become carriers. Affected males never pass an X-linked disease gene to their sons because fathers pass the Y chromosome to their sons.

Female carriers have a 50 percent chance (or 1 chance in 2) of passing the X-linked disease gene to their daughters, who become carriers, and a 50 percent chance of passing the gene to their sons, who are then affected by the disease.

Treatment

At this time, there is no treatment for juvenile retinoschisis. However, in some cases, surgery can repair retinal detachments. Ongoing scientific research is directed at identifying the gene that causes juvenile retinoschisis as the first step in developing means of prevention and treatment.

Individuals with juvenile retinoschisis may benefit from the use of low-vision aids, including electronic, computer-based and optical aids. Orientation and mobility training, adaptive training skills, job placement and income assistance are available through community resources.

Related diseases

Juvenile retinoschisis can resemble other retinal degenerative diseases such as retinitis pigmentosa (RP), Goldman-Favre vitreoretinal dystrophy, Wagner's vitreoretinal dystrophy, and Sticklers syndrome. A thorough ophthalmologic examination, including diagnostic tests measuring retinal function and visual field, combined with an accurate documentation of family history, can distinguish between these diseases.

For more information contact:

Retina New Zealand inc.
P.O. Box 27 177
Wellington
NEW ZEALAND

Tel: [04] 389 1538
Fax: [04] 389 5254
Email: retinanz@ihug.co.nz