Gene mutations may have extensive effects and mutations in the CACNA1A gene are a good example. The gene product is especially active in the brain and nervous tissue regulating a variety of processes in neuronal cells.
Abnormal eye movements can occur in isolation on a congenital basis but they may also be an early sign of underlying neurologic disease. In one series of patients the median age of presentation was 1.2 years. The abnormal eye movements consisted of nystagmus (involuntary rapid to-and-fro movements), abnormal jerkiness of voluntary movements (saccades), and spastic paroxysmal upward gaze).
The importance of abnormal eye movements in this group of hereditary disorders lies in the fact that they can be early clues to more extensive and serious neurologic disease. Conditions resulting from mutations in a specific gene (CACNA1A) include episodic migraine with partial paralysis, and rare disorders of unsteadiness (ataxia).
A mutation in a single gene is responsible for this condition and it is transmitted in a vertical pattern known as autosomal dominant inheritance. It can therefore be passed directly from an affected parent to each child with a 50% probability.
The abnormal eye movements may be noted by parents or pediatricians. It can be more specifically diagnosed by an ophthalmologist or a neurologist. It is important that other more generalized disorders of the nervous system are ruled out by a full neurological evaluation.
There is no specific treatment for the abnormal ocular movements but certain specific drugs (called calcium channel blockers) may be useful in associated migraine conditions. Nothing is known regarding vision or longevity.