Association analysis of chromosome 1 migraine candidate genes

Possible Involvement of the CACNA1E Gene in Migraine: A Search for Single Nucleotide Polymorphism in Different Clinical Phenotypes

OBJECTIVE

To search for differences in prevalence of a CACNA1E variant between migraine without aura, various phenotypes of migraine with aura, and healthy controls.

BACKGROUND

Familial hemiplegic migraine type 1 (FHM1) is associated with mutations in the CACNA1A gene coding for the alpha 1A (Ca_v 2.1) pore-forming subunit of P/Q voltage-dependent Ca²⁺ channels. These mutations are not found in the common forms of migraine with or without aura. The alpha 1E subunit (Ca_v 2.3) is the counterpart of Ca_v 2.1 in R-type Ca²⁺ channels, has different functional properties, and is encoded by the CACNA1E gene.

METHODS

First, we performed a total exon sequencing of the CACNA1E gene in three probands selected because they had no abnormalities in the three FHM genes. In a patient suffering from basilar-type migraine, we identified a single nucleotide polymorphism (SNP) in exon 20 of the CACNA1E gene (Asp859Glu - rs35737760; Minor Allele Frequency 0.2241) hitherto not studied in migraine. In a second step, we determined its occurrence in four groups by direct sequencing on blood genomic DNA: migraine patients without aura (N = 24), with typical aura (N = 55), complex neurological auras (N = 19; hemiplegic aura: N = 15; brain stem aura: N = 4), and healthy controls (N = 102).

RESULTS

The Asp859Glu - rs35737760 SNP of the CACNA1E gene was present in 12.7% of control subjects and in 20.4% of the total migraine group. In the migraine group it was significantly over-represented in patients with complex neurological auras (42.1%), OR 4.98 (95% CI: 1.69-14.67, uncorrected P = .005, Bonferroni P = .030, 2-tailed Fisher's exact test). There was no significant difference between migraine with typical aura (10.9%) and controls.

CONCLUSIONS

We identified a polymorphism in exon 20 of the CACNA1E gene (Asp859Glu - rs35737760) that is more prevalent in hemiplegic and brain stem aura migraine. This missense variant causes a change from aspartate to glutamate at position 859 of the Ca_v 2.3 protein and might modulate the function of R-type Ca²⁺ channels. It could thus be relevant for migraine with complex neurological aura, although this remains to be proven.

Genetic findings in sport-related concussions: potential for individualized medicine?

Concussion is a traumatic transient disturbance of the brain. In sport, the initial time and severity of concussion is known giving an opportunity for subsequent analysis. Variability in susceptibility and recovery between individual athletes depends, among other parameters, on genetic factors. The genes-encoding polypeptides that determine incidence, severity and prognosis for concussion are the primary candidates for genetic analysis. Genetic polymorphisms in the genes contributing to plasticity and repair (APOE), synaptic connectivity (GRIN2A), calcium influx (CACNA1E), uptake and deposit of glutamate (SLC17A7) are potential biomarkers of concussion incidence and recovery rate. With catalogued genetic variants, prospective genotyping of athletes at the beginning of their career will allow medical professionals to improve concussion management and return-to-play decisions.

Genetics of migraine: an update with special attention to genetic comorbidity

PURPOSE OF REVIEW

To highlight recent genetic findings in migraine and discuss, new mutations in hemiplegic migraine genes in familial and sporadic cases and relevant candidate gene association studies. Special attention will be given to comorbid diseases of migraine.

RECENT FINDINGS

Familial hemiplegic migraine (FHM) is genetically heterogeneous with mutations in the CACNA1A (FHM1), ATP1A2 (FHM2) and SCN1A (FHM3) genes. Nineteen novel ATP1A2 mutations were identified last year, eleven of them in FHM2 families. A systematic genetic analysis of patients with sporadic hemiplegic migraine revealed five mutations in this gene, which has implications for genetic counselling. The identification of a second FHM3 SCN1A mutation definitely established SCN1A as a migraine gene. The identification of TREX1 mutations in families with retinal vasculopathy and associated diseases such as migraine may provide new insights in migraine pathophysiology.

SUMMARY

Many novel ATP1A2 mutations were identified in patients with familial and sporadic hemiplegic migraine. In sporadic patients, ATP1A2 screening has the highest chance of finding a causal mutation. A second FHM3 mutation definitely established the epilepsy SCN1A gene as a migraine gene. The discovery of genes in monogenic diseases in which migraine is prominent may lead to new insights in the molecular pathways involved in migraine pathophysiology.