Identification of CACNA1A large deletions in four patients with episodic ataxia.

Episodic ataxia is an autosomal dominant ion channel disorder characterized by paroxysmal attacks of incoordination. Episodic ataxia type 2 (EA2) is caused by mutations in CACNA1A. EA2 mutations are mostly nonsense and sometimes missense mutations. However, in some typical EA2 families, CACNA1A sequencing does not detect any point mutation. Herein, we have designed a quantitative multiplex polymerase chain reaction of short fluorescent fragment test to screen the 50 exons of CACNA1A and investigated 27 probands referred for molecular diagnosis of EA2 who did not show any point mutation in CACNA1A. We have identified four different exonic deletions in four patients with a typical EA2 phenotype. These results establish the need to complete sequencing analysis by a screening for deletions to ensure an accurate molecular diagnosis of EA2.