The familial forms of Episodic Ataxia Type 2 are transmitted in an autosomal dominant manner. In certain cases, however, the mutation appears de novo in a patient although neither of the parents is a carrier. These are sporadic but genetic forms of the disease.
The gene implicated is CACNA1A located on chromosome 19, which codes for a calcium channel.
In two-thirds of cases, the mutations identified lead to the early appearance of a stop codon; in these cases, the damaging nature of the mutation is obvious. In the remaining one-third of cases, the mutations are missense mutations and their damaging nature is sometimes more difficult to confirm.
To meet demand from clinicians, our laboratory has introduced routine comprehensive sequencing of the CACNA1A gene (47 exons). For certain patients, the search for deletion within this gene may be discussed as part of the research programme currently being undertaken into Episodic Type 2 ataxia (cf. Research projects).