[Familial hemiplegic migraine].

Familial hemiplegic migraine (FHM) is an autosomal dominant disorder characterized by transient hemiplegia followed by migraine headache, and recently approximately half of FHM families have been elucidated to be caused by mis-sense mutations in P/Q-type Ca channel alpha(1)-subunit gene (CACNA1A). This subunit forms channel pore and is implicated in the regulation of membrane excitability as voltage sensor, therefore FHM is thought to be channelopathy. The CACNA1A gene is causative of episodic ataxia type-2 and of spinocerebellar atrophy type 6. Moreover, FHM with cerebellar ataxia is only associated with the mutation in CACNA1A, dysfunction of the calcium channel may cause cerebellar degeneration. New genotype and phenotype have been reported, more reports and analyses are expected.