The following information may help to address your question:
What is Duane syndrome?
is a disorder of eye movement. This condition prevents outward movement of the eye (toward the ear), and in some cases may also limit inward eye movement (toward the nose). As the eye moves inward, the eyelids partially close and the eyeball pulls back (retracts) into its socket. Usually only one eye is affected. Some people with Duane syndrome develop amblyopia ("lazy eye"), a condition that causes vision loss in the affected eye. Most cases occur without other signs and symptoms. There are three forms of Duane syndrome, designated types 1, 2, and 3. The types vary in which eye movements are most severely restricted (inward, outward, or both). All three types are characterized by retraction of the eyeball as the eye moves inward and are inherited in an autosomal dominant
Last updated: 3/26/2012
What causes Duane syndrome?
Given the evidence that Duane syndrome (DS) results from an absence of the abducens nerve (cranial nerve VI) and aberrant innervation, and that it is associated with other anomalies in some cases, it is thought to result from a disturbance of normal embryonic development by either a genetic or an environmental factor at the time when the cranial nerves and ocular muscles are developing (between the third and sixth week of pregnancy). Genetic studies of two large families with DS inherited autosomal dominantly (without associated abnormalities) established that mutations
in the CHN1
gene were found to be the cause in these and several other families.Duane-radial ray syndrome
(DRRS), inherited in an autosomal dominant
manner, has been shown to be caused by mutations in the SALL4
gene. However, no SALL4 gene mutations were found in 25 sporadic cases of isolated DS (occurring in one individual in a family with no additional abnormalities).
DS can also be found as part of another complex autosomal recessive
disorder (that can include deafness, facial weakness, vascular malformations and leaning difficulties) due to mutations in the HOXA1
gene. In addition, chromosome studies of individuals with DS and other abnormalities have, in rare cases, shown abnormalities that suggest other locations for genes responsible for causing DS.
Last updated: 3/21/2012
Is Duane syndrome inherited?
The majority of cases of Duane syndrome are sporadic (occurring in individuals with no history of the condition in the family). About 10% of affected individuals appear to have other affected family members. Both autosomal dominant
(most commonly) and autosomal recessive
forms of Duane syndrome have been documented. In some families with dominant Duane syndrome, it has appeared to "skip a generation" (showing reduced penetrance
) and it has also been shown to range in severity within the same family (showing variable expressivity
Most familial cases are not associated with other anomalies. Given the large percentage of sporadic cases, it seems likely that both genetic and environmental factors play a role in the development of Duane syndrome amongst affected individuals.
Last updated: 3/21/2012
What is the probability of passing Duane syndrome on to my future offspring?
Most individuals with isolated Duane syndrome (having no other features or underlying disorder) are simplex cases (i.e., a single occurrence in a family) of unknown cause.
However, up to 10% of cases of Duane syndrome are familial,
, and may result from mutations
in the CHN1
gene; these cases are inherited in an autosomal dominant
manner with incomplete penetrance
Each child of an individual with Duane syndrome that is known to result from a CHN1 mutation has a 50% chance of inheriting the condition. However, a large degree of clinical variability exists with this condition, so not all individuals who are affected will have the same type or degree of symptoms.
Prenatal diagnosis is possible for pregnancies at increased risk for isolated Duane syndrome if the mutation has been identified in an affected family member.
Individuals hoping to gain a better understanding of the specific risk posed to their offspring should consult with a genetics professional.
Last updated: 3/3/2011
How can I find a genetics professional in my area?
Last updated: 7/15/2016
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