Nystagmus 5, Congenital, X-linked
Patient Information
Characteristics
Background and History
Nystagmus, sometimes called ‘dancing eyes’ comes in many forms and has multiple causes. It may result from other eye disease or from more general neurological conditions. When present at birth (congenital), it is usually inherited in one of several patterns. Usually there is some reduction in vision since patients are unable to focus steadily on objects.
Clinical Correlations
In nystagmus 5, abnormal eye movements may be evident at birth but may not appear until about a year of age. No other eye or neurological disease is present. Nothing is known about the impact on vision.
Genetics
Inheritance
The genetics of this condition is murky. No mutation has been identified but it may be X-linked since a suspected region has been identified on the X-chromosome. Females primarily are affected suggesting to some that this may be an X-linked dominant condition that reduces male survival.
Pedigree
X-linked dominant, father affected
X-linked inheritance patterns result when disease-causing mutations are located on the X chromosome. Males have one X chromosome while females have two. A mutation on the male's X chromosome frequently is lethal or renders him unable to reproduce. However, in rare cases when males have children, they can expect that all of then will inherit the condition.
X-linked inheritance patterns result when disease-causing mutations are located on the X chromosome. Males have one X chromosome while females have two. A mutation on the male's X chromosome frequently is lethal or at least renders them unable to reproduce. However, in rare cases when males have children, they can expect that all of then will inherit the condition.
X-linked dominant, mother affected
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.
Diagnosis and Prognosis
This form of nystagmus may be detected first by a pediatrician or an eye doctor. Infants should be thoroughly evaluated especially by a neurologist to rule out other diagnoses. No treatment for the nystagmus has been reported but low vision aids could be helpful for school children with below normal vision. Individuals with nystagmus 5 should live a normal healthy life.
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