However, other genes have been reported with similar clinical presentation including the ATP1A2 gene, GLUT-1 gene, and CACNA1A gene .
Tabarki, "A wide clinical phenotype spectrum in patients with ATP1A2 mutations," Journal of Child Neurology, vol.
Currently, we recognize three types of FHM, each of them linked to a different gene : CACNA1A, ATP1A2, and SCN1A.
Shankar et al., "Migrainous vertigo: mutation analysis of the candidate genes CACNA1A, ATP1A2, SCN1A, and CACNB4," Headache, vol.
Several mechanisms have been proposed to explain comorbidity of epilepsy and chronic pain (such as that characterizing migraine), such as (i) the essential role of glutamate as a mediator of the hyperexcitability in both focal seizures and migraine, considering that seizure generation and spread are mediated by synaptically released glutamate acting on AMPA receptors, while triggering of cortical spreading depression depends on NMDA receptors and spread does not require synaptic transmission; (ii) mutations in genes for the membrane ion transport proteins CACNA1A (P/Q-type voltage-gated calcium channel), ATP1A2
(Na+-K+ ATPase), and SCN1A (voltage-gated sodium channel) .
More recently, mutations in ATP1A2
on chromosome 1g23 that encode the [[alpha].sub.2]-subunit of the [Na.sup.+]/[K.sup.+] pump has been identified in a few families.
Recently, a variant of ATP1A2 was associated with a new form of progressive hearing loss with migraine in a Korean family .
Weigand et al., "A missense variant of the ATP1A2 gene is associated with a novel phenotype of progressive sensorineural hearing loss associated with migraine," European Journal of Human Genetics, vol.