Familial Migraine With Aura: Association Study With 5-HT1B/1D, 5-HT2C, and hSERT Polymorphisms

Association of Polymorphisms within the Serotonin Receptor Genes 5-HTR1A, 5-HTR1B, 5-HTR2A and 5-HTR2C and Migraine Susceptibility in a Turkish Population

Objective

Migraine, a highly prevelant headache disorder, is regarded as a polygenic multifactorial disease. Serotonin (5-HT) and their respective receptors have been implicated in the patogenesis.

Methods

We investigated the 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT2C receptor gene polymorphisms and their association with migraine in Turkish patients. The rs6295, rs1300060, rs1228814, rs6311, rs6313, rs6314, rs6318, rs3813929 (−759C/T) and rs518147 polymorphisms were analyzed in 135 patients with migraine and 139 healthy subjects, using a BioMark 96.96 dynamic array system.

Results

We found no difference in the frequency of the analyzed eight out of nine polymorpisms between migraine and control groups. However, a significant association was found between the rs3813929 polymorphism in the promoter region of 5-HTR2C gene and migraine. Also, the allele of rs3813929 was more common in the migraine group.

Conclusion

This result suggests that the 5-HTR2C rs3813929 polymorphism can be a genetic risk factor for migraine in a Turkish population.

Genetic insights into migraine and glutamate: a protagonist driving the headache

Migraine is a complex polygenic disorder that continues to be a great source of morbidity in the developed world with a prevalence of 12% in the Caucasian population. Genetic and pharmacological studies have implicated the glutamate pathway in migraine pathophysiology. Glutamate profoundly impacts brain circuits that regulate core symptom domains in a range of neuropsychiatric conditions and thus remains a "hot" target for drug discovery. Glutamate has been implicated in cortical spreading depression (CSD), the phenomenon responsible for migraine with aura and in animal models carrying FHM mutations. Genotyping case-control studies have shown an association between glutamate receptor genes, namely, GRIA1 and GRIA3 with migraine with indirect supporting evidence from GWAS. New evidence localizes PRRT2 at glutamatergic synapses and shows it affects glutamate signalling and glutamate receptor activity via interactions with GRIA1. Glutamate-system defects have also been recently implicated in a novel FHM2 ATP1A2 disease-mutation mouse model. Adding to the growing evidence neurophysiological findings support a role for glutamate in cortical excitability. In addition to the existence of multiple genes to choreograph the functions of fast-signalling glutamatergic neurons, glutamate receptor diversity and regulation is further increased by the post-translational mechanisms of RNA editing and miRNAs. Ongoing genetic studies, GWAS and meta-analysis implicate neurogenic mechanisms in migraine pathology and the first genome-wide associated locus for migraine on chromosome X. Finally, in addition to glutamate modulating therapies, the kynurenine pathway has emerged as a candidate for involvement in migraine pathophysiology. In this review we discuss recent genetic evidence and glutamate modulating therapies that bear on the hypothesis that a glutamatergic mechanism may be involved in migraine susceptibility.

Genetic association of 5-HT1A and 5-HT1B gene polymorphisms with migraine in a Turkish population

Migraine, a very common headache disorder, is regarded as a polygenic disease and serotonergic pathways appear to play a major role in its pathogenesis. The present study was designed to explore the associations of polymorphisms of 5-hydroxytryptamine (serotonin) receptor 1A (5-HT1A) and 5-hydroxytryptamine receptor 1B (5-HT1B) genes in Turkish migraine patients. 5-HT1A C-1019G (rs6295) promoter and 5-HT1B G861C (rs6296) exon polymorphisms in 203 migraine patients and 202 healthy subjects were analyzed by using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. Allele and genotype frequencies were not significantly different between migraine patients and healthy subjects for both the 5-HT1A C-1019G promoter and 5-HT1B G861C exon polymorphisms. Our data do not support the hypothesis that 5-HT1A C-1019G and 5-HT1B G861C polymorphisms have effects on migraine.

Emerging genomic biomarkers in migraine

Migraine is a debilitating neurovascular condition classified as either migraine with aura or migraine without aura. A significant genetic basis has been implicated in migraine and has probed the role of neurotransmitters, hormones and vascular genes in this disorder. The aim of this review is to highlight the recent genetic discoveries contributing to our understanding of the complex pathogenesis of migraine. The current review will discuss the role of neurotransmitter-related genes in migraine, including the recently identified TRESK and variants of the KCNN3 gene, as well as outlining studies investigating hormone receptor genes, such as ESR1 and PGR, and vascular-related genes, including the MTHFR and NOTCH 3 genes.

Association of 5-HTT gene polymorphisms with migraine: a systematic review and meta-analysis

BACKGROUND/AIMS

Serotonin is known to play an important role in the pathogenesis of migraine, but individual genetic association studies that examine the relationship between polymorphisms of serotonin transporter (5-HTT) gene and migraine have yielded inconsistent results. This study aimed to evaluate the association between 5-HTT gene variants (including 5-HTTLPR, VNTR and SNP) and migraine using systematic review with meta-analysis.

METHODS

Relevant studies were identified by searching English and Chinese databases extensively. Allele and genotype frequencies for each included study were extracted. The odds ratio (OR) was calculated using a random-effects or fixed-effects model. Q statistic was used to evaluate homogeneity, and Egger's test and Funnel plot were used to assess publication bias. For family-based association studies, a descriptive analysis was carried out.

RESULTS

A total of 15 studies were identified for meta-analysis. It was found that the 5-HTT VNTR Stin2.12 allele or 12/12 genotype had an increased risk for migraine in the general population (Stin2.12 allele: OR, 95% CI: 1.34, 1.09-1.64, p=0.006; 12/12 genotype: OR, 95% CI: 1.55, 1.17-2.05, p=0.002), but there was no significant association between migraine and 5-HTTLPR or SNP rs2020942.

CONCLUSIONS

Existing evidence indicates that the 5-HTT VNTR polymorphism (mainly the STin2.12 genotype) is associated with an increased risk of migraine in the general population. Future studies with larger sample sizes will be necessary to confirm the present results.

STin2 VNTR polymorphism in the serotonin transporter gene and migraine: pooled and meta-analyses

Data on the association between the SLC6A4 STin2 VNTR polymorphism and migraine are conflicting. To perform pooled and meta-analyses, we searched for studies published until September 2009 using electronic databases (MEDLINE, EMBASE, Science Citation Index) and reference lists of studies. Assessment for eligibility and extraction of data was performed by two independent investigators. We extracted allele and genotype frequencies for each study. We then calculated study-specific and pooled odds ratios (OR) and 95% confidence intervals (CI) assuming allele and genotype models. We also calculated pooled ORs and 95% CIs based on study-specific effect estimates for the allele model. We included five studies investigating the association between the STin2 VNTR polymorphism and migraine. Results from the allele model suggested a protective effect against migraine for the STin2.9 and STin2.10 alleles compared to the STin2.12 allele among populations of European descent, which however was not significant. Results from the genotype model indicated a significant ~25% reduced risk for migraine among carriers of the 10/12 genotype compared with carriers of the 12/12 genotype among all study populations (OR = 0.76, 95% CI 0.60–0.97) for any migraine, which was more pronounced among populations of European descent (OR = 0.68, 95% CI 0.53–0.87). Results for migraine with and without aura were of similar magnitude, but were not statistically significant. Our results suggest a protective effect of non-STin2.12 alleles compared to STin2.12 alleles, respectively, 10/12 and 10/10 genotypes compared to the 12/12 genotype against migraine among populations of European descent. Associations in non-European populations may differ.

5-HTTLPR polymorphism in the serotonin transporter gene and migraine: a systematic review and meta-analysis

BACKGROUND AND METHODS

Data on the association between the SLC6A4 5-HTTLPR polymorphism and migraine are conflicting. We performed a systematic review and meta-analysis among studies published up to September 2009. For each study with genotype information, we calculated odds ratios (OR) and 95% confidence intervals (CI) assuming additive, dominant, and recessive genetic models. We then calculated pooled ORs and 95% CIs.

RESULTS

Among the ten studies identified there was no overall association between the polymorphism and any migraine for Europeans or Asians. However, European women carrying the S allele had an increased risk for any migraine (dominant model: pooled OR=2.02; 95% CI 1.24-3.28). Results among Europeans further suggested an increased risk for migraine with aura among carriers of the S/S genotype (recessive model: pooled OR=1.41; 95% CI 0.83-2.40).

CONCLUSIONS

While our results indicate no overall association between the SLC6A4 5-HTTLPR polymorphism and migraine among Europeans and Asians, gender and migraine aura status may have modifying roles among Europeans.

Genetic bases of comorbidity between mood disorders and migraine: possible role of serotonin transporter gene

Migraine is a common neurological disease in the population and the most associated headache with mood disorder. Although the relationship between migraine and depression is well known, the reverse correlation between depression and migraine was observed but not well understood. The tight relationship between the two disturbances is also suggested by the efficacy of antidepressants for migraine treatment. Starting from these observations, we can presume that both migraine and depression have overlapping biological bases. The main target of antidepressant treatments belonging to the serotonin selective reuptake inhibitors (SSRI) type is the serotonin transporter (SERT); a well-studied polymorphic variant, in the promoter region of the gene (SERTPR), has been demonstrated to influence the availability of serotonin in the synaptic cleft. So, our group studied the possible role of the SERT as a risk factor, both for migraine and mood disorders, in a sample of 96 patients affected by both pathologies.

Investigation of gamma-aminobutyric acid (GABA) A receptors genes and migraine susceptibility

BACKGROUND

Migraine is a neurological disorder characterized by recurrent attacks of severe headache, affecting around 12% of Caucasian populations. It is well known that migraine has a strong genetic component, although the number and type of genes involved is still unclear. Prior linkage studies have reported mapping of a migraine gene to chromosome Xq 24-28, a region containing a cluster of genes for GABA A receptors (GABRE, GABRA3, GABRQ), which are potential candidate genes for migraine. The GABA neurotransmitter has been implicated in migraine pathophysiology previously; however its exact role has not yet been established, although GABA receptors agonists have been the target of therapeutic developments. The aim of the present research is to investigate the role of the potential candidate genes reported on chromosome Xq 24-28 region in migraine susceptibility. In this study, we have focused on the subunit GABA A receptors type epsilon (GABRE) and type theta (GABRQ) genes and their involvement in migraine.

METHODS

We have performed an association analysis in a large population of case-controls (275 unrelated Caucasian migraineurs versus 275 controls) examining a set of 3 single nucleotide polymorphisms (SNPs) in the coding region (exons 3, 5 and 9) of the GABRE gene and also the I478F coding variant of the GABRQ gene.

RESULTS

Our study did not show any association between the examined SNPs in our test population (P>0.05).

CONCLUSION

Although these particular GABA receptor genes did not show positive association, further studies are necessary to consider the role of other GABA receptor genes in migraine susceptibility.

5-hydroxytryptamine1B receptor and triptan response in migraine, lack of association with common polymorphisms

Triptans mediate vasoconstriction of meningeal vessels via stimulation of vascular 5-hydroxytryptamine (5-HT)(1B) receptors. These drugs are recommended for acute treatment in patients with moderate-to-severe migraine attacks and in those patients with mild-to-moderate headache that are not controlled adequately by other agents. Yet, approximately 25% of all migraine users and 40% of all attacks do not respond to triptan treatment. Among the hypothesis to explain this is the possibility that genetic single nucleotide polymorphisms that alter the receptor, for example changing the transcriptional rate and therefore the amount of target protein might change the clinical response to these drugs. In the present contribution, we therefore decided to evaluate whether single nucleotide polymorphisms on the 5-HT(1B) gene might contribute to inter-individual variability in clinical responses to triptans. Two polymorphisms in the promoter region of the 5-HT(1B) receptor (T-261G and A-161T) and the synonymous variation G861C in the coding region were genotyped by restriction fragment length polymorphism in 105 migraine patients. In our sample population, 71% of patients responded to triptans. Allelic and diplotype frequencies were not significantly different between responders and non-responders. On the other hand, extrapolation of in vitro data on promoter activity would suggest that patients with higher copy number of receptors respond slightly better. Our data therefore do not support the involvement of 5-HT(1B) single nucleotide polymorphisms in mediating the inter-individual variability to triptans.

A pharmacogenomic evaluation of migraine therapy

Migraine is a common idiopathic primary headache disorder with significant mental, physical and social health implications. Accompanying an intense unilateral pulsating head pain other characteristic migraine symptoms include nausea, emesis, phonophobia, photophobia and in approximately 20-30% of migraine cases, neurologic disturbances associated with the aura phase. Although selective serotonin (5-HT) receptor agonists (i.e., 5-HT(1B/1D)) are successful in alleviating migrainous symptoms in < or = 70% of known sufferers, for the remaining 30%, additional migraine abortive medications remain unsuccessful, not tested or yet to be identified. Genetic characterization of the migrainous disorder is making steady progress with an increasing number of genomic susceptibility loci now identified on chromosomes 1q, 4q, 5q, 6p, 11q, 14q, 15q, 17p, 18q, 19p and Xq. The 4q, 5q, 17p and 18q loci involve endophenotypic susceptibility regions for various migrainous symptoms. In an effort to develop individualized pharmacotherapeutics, the identification of these migraine endophenotypic loci may well be the catalyst needed to aid in this goal. In this review the authors discuss the present treatment of migraine, known genomic susceptibility regions and results from migraine (genetic) association studies. The authors also discuss pharmacogenomic considerations for more individualized migraine prophylactic treatments.

Family-based analysis of serotonin transporter gene polymorphisms in migraine with and without aura

Genetic epidemiological twin studies have demonstrated a significant heritability for migraine, with > 60% of liability to migraine either with or without aura coming from additive genetic factors. Because of the essential role of serotonin in the pathophysiology and treatment of migraine, genes of the serotonin system are candidates for involvement in migraine. Consequently, we examined two functional VNTR polymorphisms in the serotonin transporter gene, the 5-HTTLPR and the intron 2 VNTR, in a sample of 212 family trios each with a proband with childhood migraine, 153 with migraine without aura (MoA) and 59 with migraine with aura (MA). For the first time, we used transmission disequilibrium test analysis with the program TDTPHASE to examine the transmission of these two markers and their haplotypes to offspring affected by migraine. We found no significant transmission distortion of any marker, with the common L allele of the 5-HTTLPR transmitted 170 times and not transmitted 178 times, and the S allele 130 vs. 122 times. Likewise, the common 12 allele of the intron 2 VNTR was transmitted 201 times and not transmitted 188 times, and the 10 allele 107 vs. 120 times. The markers were not associated with MoA and MA and none of the haplotypes was associated with overall migraine, MoA or MA. The 5-HTTLPR and the intron 2 VNTRs do not play a major role in susceptibility to migraine.

Genetic association study and meta-analysis of the HTR2C Cys23Ser polymorphism and migraine

The objectives of this study were to determine if the HTR2C Cys23Ser polymorphism is associated with migraine in a case-control study, and to perform a meta-analysis with present and previous available studies. The HTR2C gene is located at the Xq24-q28 chromosomal band. This band was linked to migraine with aura (MA) in two Australian families. Using the HTR2C Cys23Ser allelic variant, this gene has been ruled out as a migraine gene in 3 out of 4 studies. Only the Japanese study reported a higher risk for MA (OR=6.11; 95% CI=1.70-21.97, p trend<0.01). We performed a case-control study with 335 migraine subjects and 335 sex- and age-matched controls, and a meta-analysis pooling the results of the available data from MA subsets of patients. In the association study we found no significant differences among migraine and MA patients for this polymorphism. In the meta-analysis, under the fixed-effect model, the Ser allele did not confer higher risk for suffering MA (pooled OR=1.1; 99% CI=0.8-1.5, p=0.499). Our study did not confirm the HTR2C Cys23Ser polymorphism as a risk factor for migraine and MA.

Migraine aura

Recurrent episodes of transient focal neurologic symptoms, known as aura, occur in association with migraine headache in about 11.9 million people in the United States. At present, the International Headache Society has recognized 3 "typical" auras: visual, sensory, and language. Increasing evidence from investigations in human subjects suggests that typical auras may be the clinical manifestation of a cortical spreading depression (CSD)-like phenomenon. Other studies have shown altered reactivity and processing within the cortices of migraineurs who experience an aura, which might render them more vulnerable to CSD-like events. Recent investigations also support the hypothesis that events intrinsic to the cerebral cortex are capable of activating trigeminal nociceptive neurons and of affecting the caliber of vascular structures innervated by them. A better understanding of the mechanisms underlying the aura may potentially lead to more effective therapies, which will aim at preventing migraine headaches before they start.

Functional polymorphisms of the 5-HT1A and 5-HT1B receptor are associated with clinical symptoms in migraineurs

Migraine is regarded as a polygenic disease and serotonergic pathways appear to play a major role in its pathogenesis. In the present study, the role of the 5-HT1A and 5-HT1B receptors in migraine was evaluated. The human 5-HT1A receptor gene transcription is modulated by a functional C-1019G promoter polymorphism. The 5-HT1B receptor is the main effector of vasoconstriction in meningeal and cerebral arteries and its functional G861C promoter polymorphism was investigated. We report a positive association of the GG genotype of the 5-HT1A promoter polymorphism with avoidance of physical activity during a migraine attack in comparison to the CC genotype (p = 0.008). Moreover, a positive association of the CC genotype of the G861C polymorphism of the 5-HT1B receptor with the reported intensity of the headache attack on the visual analogue scale was observed (CC 8.3 +/- 1.5 vs. GG 6.9 +/- 1.8; p < 0.05). An association of either polymorphism with migraine with or without aura could not be found. For the first time, our results indicate a role of allelic variation of the 5-HT1A receptor in motion related discomfort in migraineurs and a role of the 5-HT1B receptor polymorphism in headache intensity.

G Protein β3 Polymorphism and Triptan Response in Cluster Headache

Only about 70% of migraine and cluster headache (CH) patients report significant treatment responses to triptans, which are agonists at 5-HT(1B/D) receptors belonging to the family of G protein-coupled receptors. We analyzed whether a common polymorphism in the gene for the G protein beta3 subunit (GNB3 C825T) modulates responder rates to triptans among a cohort of 231 unrelated Caucasian CH patients. A total of 180 CH patients used triptans, of whom 71.1% reported treatment success. The adjusted odds ratio for treatment response to triptans for heterozygous carriers of the GNB3 825T allele was 2.96 (95% confidence interval 1.34-6.56; P=0.0074) vs carriers of the 825CC genotype. The GNB3 genotype status did not affect responses to other acute and preventive therapeutic regimes including oxygen, verapamil, and corticosteroids, i.e., drugs not directly affecting G proteins. We conclude that pain relief by triptans is significantly modulated by a common genetic GNB3 variant.

Contribution of Serotonin Transporter Gene Polymorphisms to Pediatric Migraine

BACKGROUND

The serotonin transporter gene is a promising candidate locus for the genetic susceptibility of migraine.

OBJECTIVE

Two functional polymorphisms of the serotonin transporter gene (5-HTTLPR and STin2) were analyzed to assess whether these variants are associated with pediatric migraine.

METHODS

Eighty-seven Hungarian pediatric migraine patients and 464 controls were genotyped using polymerase chain reaction. Patients suffering from migraine with (n = 38) or without aura (n = 49) were interviewed regarding the clinical symptoms before or during the attacks.

RESULTS

There was no difference between genotype or allele distribution of 5-HTTLPR and STin2 polymorphisms in the entire group of migraineurs and controls. Analysis of subgroups showed an association between STin2 and migraine with aura, as the 12,12 homozygote genotype was overrepresented in this group of patients. Furthermore, similar allele and genotype patterns were found in cases with severe vomiting and abdominal pain.

CONCLUSIONS

These results confirm and extend the association between the STin2 polymorphism of 5-HTT gene and migraine with aura using pediatric probands. Our data also suggest a novel endophenotype for pediatric migraine characterized by excessive vomiting and abdominal pain during the attack.

Visual disturbances and migraine

There is a close relationship between headache and the visual system. Visual symptoms are prominent features of clinical syndromes such as migraine, cluster headache, and the trigeminal autonomic cephalgias. There are also strong links between headache and the visual system on the basis of genetics, molecular biology, neurophysiology, and neuroimaging. Studies of these links are leading to the development of novel therapies for a variety of headache syndromes. This review is designed to summarize the most recent literature on headache and the visual system. A particular emphasis is placed on publications of interest to clinicians.