[Molecular genetic findings in migraine]

This review focuses on the different molecular genetic findings in migraine. Familial hemiplegic migraine (FHM) is a rare subtype of migraine with aura, which is inherited as an autosomal dominant. Half the cases of FHM are caused by point mutations in the CACNA1A gene on the short arm of chromosome 19 (19p). The gene encodes a calcium ion channel. Other mutation types cause episodic ataxia 2 (EA-2). Expansions of the CAG repeat in the 3' end bring about spinocerebellar ataxia 6 (SCA 6). Some families with FHM link to loci on the long arm of chromosome 1 (1q). The genes have not yet been identified. Some families neither link to 1q nor to 19p. Population-based family and twin studies have shown that migraine both with and without aura have a multifactorial inheritance. The CACNA1A gene may be of importance for ordinary forms of migraine in a few families. Mutations in genes on the X chromosome, dopamine receptor genes, and the ACE gene appear to be involved in migraine in a few families, whereas genes for nitric oxide synthase, serotonin receptors, and mitochondrial DNA do not seem to be involved. The positive associations have not been reproduced in other studies and therefore they should be interpreted with care. It is to be hoped that in the next few years much more will be known about the molecular genetic mechanisms of migraine with and without aura. FHM is an ion channel disorder, and many factors suggest that migraine is also an ion channel disorder, which is consistent with the paroxysmal nature of the illness.