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Duane syndrome affects eye movement due to the absence of a cranial nerve and is a rare condition. It usually affects one eye and has three types of symptoms. There is no cure, but patients can compensate by tilting their head.
Duane syndrome is a congenital condition that affects eye movement. While the cause of the condition is not fully understood, it likely results from the absence of a cranial nerve. Duane syndrome is not life-threatening and is a very rare condition, accounting for 1-5% of eye movement disorders.
People with Duane syndrome usually have trouble moving one of their eyes away from their nose. Often, the affected eye stays still or moves up when a person attempts to look down the nose with the unaffected eye. These symptoms are referred to as Duane syndrome type I and account for 70-80% of cases.
There are also two other types of Duane syndrome. In type II, one or both eyes have difficulty looking down the nose. Type II accounts for about 7% of all cases. The third type, which accounts for 15% of cases, combines symptoms of types I and II.
People with Duane syndrome fail to develop a cranial nerve called the abducens nerve. This nerve is responsible for the eye muscles that move the eye sideways. The condition develops before birth, and most people with the syndrome are diagnosed before age 10. Most cases of Duane syndrome affect the left eye only, although it can affect the right eye or both at the same time. The condition is more common in females than in males, although it is not understood why.
Duane syndrome probably develops during the first trimester, and genetic and environmental factors may play a role. Dominant and recessive genes have also been linked to the condition. In a dominant case of the disease, a patient needs only one copy of the faulty gene, while in a recessive case, two are needed. People with a recessive variety of the syndrome can carry it without showing symptoms.
Most patients with the syndrome have no other birth defects. In about 30% of cases, however, other congenital conditions may be present. Duane syndrome has been linked to Goldenhar syndrome, Holt-Oram syndrome, Wildervanck syndrome, Morning Glory syndrome, and Okihiro syndrome. In addition, malformations of the eyes, ears, skeleton, nervous system and kidneys may be present.
There is no cure for Duane syndrome, although the condition is not life threatening. Many patients learn to compensate for the difficulty with lateral eye movement by keeping their head tilted or sideways. By tilting the head towards the affected eye, patients with this condition can maintain single binocular vision.
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