Nystagmus 4, AD
Patient Information
Characteristics
Background and History
Abnormal eye movements are unfortunately not rare. There are numerous eye conditions and neurological disorders in which the eyes cannot focus properly and the eyes exhibit ‘dancing’ (nystagmus) with to-and-fro movements, for example. But in many individuals there is no anatomic or neurological disease and the eye movements may be present at birth (congenital).
Clinical Correlations
The nystagmus is not present at birth but usually becomes evident by 2 years of age. Vision is normal in many individuals but mildly decreased in others. It is a stable condition and vision does not worsen with time. In nystagmus 4, the eye movements are somewhat variable and patients have difficulty following targets with smooth “pursuit” movements. Many individuals also have strabismus, the medical term applied when the two eyes are not aligned.
Some patients have reported balance problems and dizziness but it is unknown if this is part of the condition.
Genetics
Inheritance
Based on the single large family reported, the most likely pattern of inheritance is autosomal dominant which means that parents, male and female, with nystagmus have a 50% probability of passing the condition to each child. No gene mutation has been found.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission
Diagnosis and Prognosis
Nystagmus in young children is most likely to be noted first by pediatricians and eye doctors. It is important that a full neurological and physical evaluation be done to rule out other disease.
There is no effective treatment for nystagmus. Low vision aids might be helpful especially in school children when vision is subnormal. There is no known impact on general health or longevity.
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